Name: a simple and inexpensive method for determining cold sensitivity and adaptation in mice
Uploaded: 2015-03-17T15:00:00
Description: Watch this Scientific Journal Video about A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice at JoVE.com

The authors would like to acknowledge contributions from the entire Gereau Lab for manuscript editing. This work is supported by NINDS funds 1F31NS078852 to DSB and NINDS fund NS42595 to RWG.

All mouse protocols were in accordance with National Institutes of Health guidelines and were approved by the Animal Studies Committee of Washington University School of Medicine (St. Louis, MO).
1. Preparing the Testing Plate and Enclosures
<ol>
	<li>Clean off the glass surface.</li>
	<li>Secure the T-type filament thermocouple probe to the surface in the middle of the glass plate with laboratory tape.</li>
	<li>Place the animal enclosures on the glass plate in a single line along the middl...

<ol>
	<li>Brenner, D. S., Golden, J. P., Gereau, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Novel+Behavioral+Assay+for+Measuring+Cold+Sensation+in+Mice.">A Novel Behavioral Assay for Measuring Cold Sensation in Mice.</a> Plos ONE. 7 (6), 8 (2012).</li><li>Brenner, D. S., Vogt, S. K., Gereau, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+to+measure+cold+adaptation+in+freely+behaving+mice.">A technique to measure cold adaptation in freely behaving mice.</a> Journal of Neuroscience Methods. , (2014).</li><li>Choi, Y., Yoon, T. W., Na, H. S., Kim, S. H., Chung, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+signs+of+ongoing+pain+and+cold+allodynia+in+a+rat+model+of+neuropathic+pain.">Behavioral signs of ongoing pain and cold allodynia in a rat model of neuropathic pain.</a> Pain. 59 (3), 369-376 (1994).</li><li>Gauchan, P., Andoh, T., Kato, A., Kuraishi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Involvement+of+increased+expression+of+transient+receptor+potential+melastatin+8+in+oxaliplatin-induced+cold+allodynia+in+mice.">Involvement of increased expression of transient receptor potential melastatin 8 in oxaliplatin-induced cold allodynia in mice.</a> Neuroscience letters. 458 (2), 93-95 (2009).</li><li>Carlton, S. M., Lekan, H. A., Kim, S. H., Chung, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+manifestations+of+an+experimental+model+for+peripheral+neuropathy+produced+by+spinal+nerve+ligation+in+the+primate.">Behavioral manifestations of an experimental model for peripheral neuropathy produced by spinal nerve ligation in the primate.</a> Pain. 56 (2), 155-166 (1994).</li><li>Pizziketti, R. J., Pressman, N. S., Geller, E. B., Cowan, A., Adler, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+cold+water+tail-flick:+A+novel+analgesic+test+that+distinguishes+opioid+agonists+from+mixed+agonist-antagonists.">Rat cold water tail-flick: A novel analgesic test that distinguishes opioid agonists from mixed agonist-antagonists.</a> European Journal of Pharmacology. 119 (1-2), 23-29 (1985).</li><li>Pinto-Ribeiro, F., Almeida, A., Pego, J. M., Cerqueira, J., Sousa, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+unpredictable+stress+inhibits+nociception+in+male+rats.">Chronic unpredictable stress inhibits nociception in male rats.</a> Neuroscience letters. 359 (1-2), 73-76 (2004).</li><li>Karashima, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TRPA1+acts+as+a+cold+sensor+in+vitro+and+in+vivo.">TRPA1 acts as a cold sensor in vitro and in vivo.</a> Proceedings of the National Academy of Sciences of the United States of America. 106 (4), 1273-1278 (2009).</li><li>Knowlton, W. M., Bifolck-Fisher, A., Bautista, D. M., McKemy, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TRPM8,+but+not+TRPA1,+is+required+for+neural+and+behavioral+responses+to+acute+noxious+cold+temperatures+and+cold-mimetics+in+vivo.">TRPM8, but not TRPA1, is required for neural and behavioral responses to acute noxious cold temperatures and cold-mimetics in vivo.</a> Pain. 150 (2), 340-350 (2010).</li><li>Allchorne, A. J., Broom, D. C., Woolf, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+cold+pain,+cold+allodynia+and+cold+hyperalgesia+in+freely+behaving+rats.">Detection of cold pain, cold allodynia and cold hyperalgesia in freely behaving rats.</a> Molecular pain. 1, 36 (2005).</li><li>Colburn, R. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Attenuated+cold+sensitivity+in+TRPM8+null+mice.">Attenuated cold sensitivity in TRPM8 null mice.</a> Neuron. 54 (3), 379-386 (2007).</li><li>Dhaka, A., Murray, A. N., Mathur, J., Earley, T. J., Petrus, M. J., Patapoutian, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TRPM8+is+required+for+cold+sensation+in+mice.">TRPM8 is required for cold sensation in mice.</a> Neuron. 54 (3), 371-378 (2007).</li><li>Bautista, D. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+menthol+receptor+TRPM8+is+the+principal+detector+of+environmental+cold.">The menthol receptor TRPM8 is the principal detector of environmental cold.</a> Nature. 448 (7150), 204-208 (2007).</li><li>Obata, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TrpA1+induced+in+sensory+neurons+contributes+to+cold+hyperalgesia+after+inflammation+and+nerve+injury.">TrpA1 induced in sensory neurons contributes to cold hyperalgesia after inflammation and nerve injury.</a> The Journal of Clinical Investigation. 115 (9), 2393-2401 (2005).</li><li>Tang, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pirt+functions+as+an+endogenous+regulator+of+TRPM8.">Pirt functions as an endogenous regulator of TRPM8.</a> Nature communications. 4, 2179 (2013).</li><li>Lee, H., Iida, T., Mizuno, A., Suzuki, M., Caterina, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+thermal+selection+behavior+in+mice+lacking+transient+receptor+potential+vanilloid+4.">Altered thermal selection behavior in mice lacking transient receptor potential vanilloid 4.</a> The Journal of neuroscience the official journal of the Society for Neuroscience. 25 (5), 1304-1310 (2005).</li><li>Pogorzala, L. A., Mishra, S. K., Hoon, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cellular+code+for+Mammalian+thermosensation.">The cellular code for Mammalian thermosensation.</a> The Journal of neuroscience the official journal of the Society for Neuroscience. 33 (13), 5533-5541 (2013).</li><li>Yalcin, I., Charlet, A., Freund-Mercier, M. -. J., Barrot, M., Poisbeau, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiating+thermal+allodynia+and+hyperalgesia+using+dynamic+hot+and+cold+plate+in+rodents.">Differentiating thermal allodynia and hyperalgesia using dynamic hot and cold plate in rodents.</a> The journal of pain official journal of the American Pain Society. 10 (7), 767-773 (2009).</li><li>Callahan, B. L., Gil, A. S., Levesque, A., Mogil, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+mechanical+and+thermal+nociceptive+sensitivity+in+the+laboratory+mouse+by+behavioral+state.">Modulation of mechanical and thermal nociceptive sensitivity in the laboratory mouse by behavioral state.</a> The journal of pain: official journal of the American Pain Society. 9 (2), 174-184 (2008).</li><li>Brenner, D. S., Golden, J. P., Vogt, S. K., Dhaka, A., Story, G. M., Gereau, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dynamic+set+point+for+thermal+adaptation+requires+phospholipase+C-mediated+regulation+of+TRPM8+in+vivo.">A dynamic set point for thermal adaptation requires phospholipase C-mediated regulation of TRPM8 in vivo.</a> Pain. , (2014).</li><li>Patwardhan, A. M., Scotland, P. E., Akopian, A. N., Hargreaves, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+TRPV1+in+the+spinal+cord+by+oxidized+linoleic+acid+metabolites+contributes+to+inflammatory+hyperalgesia.">Activation of TRPV1 in the spinal cord by oxidized linoleic acid metabolites contributes to inflammatory hyperalgesia.</a> Proceedings of the National Academy of Sciences of the United States of America. 106 (44), 18820-18824 (2009).</li><li>Fujita, F., Uchida, K., Takaishi, M., Sokabe, T., Tominaga, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ambient+Temperature+Affects+the+Temperature+Threshold+for+TRPM8+Activation+through+Interaction+of+Phosphatidylinositol+4,5-Bisphosphate.">Ambient Temperature Affects the Temperature Threshold for TRPM8 Activation through Interaction of Phosphatidylinositol 4,5-Bisphosphate.</a> Journal of Neuroscience. 33 (14), 6154-6159 (2013).</li><li>Rohacs, T., Lopes, C. M., Michailidis, I., Logothetis, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PI(4,5)P2+regulates+the+activation+and+desensitization+of+TRPM8+channels+through+the+TRP+domain.">PI(4,5)P2 regulates the activation and desensitization of TRPM8 channels through the TRP domain.</a> Nature neuroscience. 8 (5), 626-634 (2005).</li><li>Daniels, R. L., Takashima, Y., McKemy, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activity+of+the+neuronal+cold+sensor+TRPM8+is+regulated+by+phospholipase+C+via+the+phospholipid+phosphoinositol+4,5-bisphosphate.">Activity of the neuronal cold sensor TRPM8 is regulated by phospholipase C via the phospholipid phosphoinositol 4,5-bisphosphate.</a> The Journal of biological chemistry. 284 (3), 1570-1582 (2009).</li><li>Zhang, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurokinin-1+receptor+enhances+TRPV1+activity+in+primary+sensory+neurons+via+PKCepsilon:+a+novel+pathway+for+heat+hyperalgesia.">Neurokinin-1 receptor enhances TRPV1 activity in primary sensory neurons via PKCepsilon: a novel pathway for heat hyperalgesia.</a> The Journal of neuroscience the official journal of the Society for Neuroscience. 27 (44), 12067-12077 (2007).</li><li>Wang, H., Zylka, M. 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The CPA can be used to assess cold sensitivity and cold adaptation in mice. It provides an affordable, efficient way to measure cold responses in unrestrained, acclimated animals at a wide variety of temperature ranges. It also provides an unambiguous behavioral response with an easily quantified and analyzed output variable. It has already been used to assess changes in cold sensitivity induced by inflammation1, neuropathic injury1, analgesics1, genetic knockouts20, and ge...

Measuring cold responsiveness in rodents is important for improving understanding of the potential mechanisms of cold sensitivity in humans under both normal and pathological conditions. The Cold Plantar Assay (CPA), originally developed several years ago1, is designed to generate reproducible, unambiguous murine behavioral responses to a cold stimulus delivered at RT. More recent enhancements of this assay have allowed the reproducible measurement of cold sensitivity at a wide range of temperatures2. Both versions are also designed to be relatively high-throughput, and inexpensive to use.
A great deal of progress has been made in understanding the mechanisms of cold sensitivity using other behavioral methods. One method is the acetone evaporation test, which involves dabbing or spraying acetone on the mouse paw and measuring the amount of time that the mouse spends flicking the paw3,4. Unfortunately, the responses to acetone evaporation are confounded by the wet sensation and the smell of the acetone. Also, the cold stimulus that is applied in the acetone evaporation test can vary based on the amount of acetone applied, and is difficult to quantify. Finally, uninjured mice have minimal responses to acetone at baseline, making it impossible to measure analgesia in the absence of hypersensitivity with this method.
Another classical assay for cold responses is the tail flick assay, where the latency to withdrawal is measured after the tail is immersed in cold water5,6. While the behavioral responses in this assay are unambiguous and the assay measures responses to a specific temperature, the animals must be restrained during testing, which can alter cold responsiveness through well-described stress-induced analgesic mechanisms7.
Another commonly used tool is the cold plate test, which measures the behavioral responses of mice after they are placed on a peltier-cooled plate8-10. While this tool provides information about animal responses at specific temperatures, it has also been inconsistently used; different groups have measured different types of responses including number of jumps8,11, the latency to first response8,11-13, and the number of paw lifts11,13,14 with very different results. The cold plate assay is also relatively low throughput as only one animal can be tested at a time, and it requires an expensive and fragile peltier device.
The 2-plate temperature preference test is a commonly used derivative of the cold plate test that measures the relative amount of time that animals spend on 2 connected plates of different temperatures9,15-17. Another similar commonly used assay is the thermal gradient assay, where the amount of time that mice spend in different temperature zones ranging between 5 &#176;C and 45 &#176;C on a long metal plate is measured16. While these assays allow comparison of temperatures, it is unclear whether the behavior represents temperature aversion or to temperature preference.
Finally, the dynamic cold plate assay has been used to measure how mice respond to changing ambient temperatures18. This method involves placing mice on a RT peltier device and ramping it down to 1 &#176;C while measuring how much the mice jump or lick their paws at different plate temperatures. While this tests how mice adapt to a cooling environment, it does not provide a way to test how mice respond to a cold stimulus in the setting of a cooler ambient temperature. Additionally, it requires expensive equipment to perform and does not provide a way to acclimate mice to the testing equipment before measuring their cold sensitivity.
To complement these assays, the CPA tests the acclimated responses to a well-defined cold stimulus at a variety of temperature ranges, or during the process of adapting to cold ambient temperatures. It can test up to 14 mice at a time with our current apparatus, with the potential to be inexpensively scaled up for high-throughput testing.

<table border="0" cellpadding="0" cellspacing="0" width="1209">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:233px;">Name</td>
			<td style="width:320px;">Company</td>
			<td style="width:353px;">Catalog Number</td>
			<td style="width:303px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">T-type thermocouple probe</td>
			<td>Physitemp</td>
			<td>IT-24p</td>
			<td>Used to measure the surface temperature of the glass (http://www.physitemp.com/products/probesandwire/)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glass plate</td>
			<td>Local glass company (in St. Louis, Stemmerich Inc)</td>
			<td>N/A</td>
			<td>We use pyrex glass (borosilicate float). Our lab generally uses 1/4&#39;&#39;, but 3/16&#39;&#39; and 1/8&#39;&#39; are also useful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermal Data logger</td>
			<td>Extech</td>
			<td>EA15</td>
			<td>Thermologger to keep track of glass temperature (http://www.extech.com/instruments/product.asp?catid=64&#38;prodid=408)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3mL Syringe</td>
			<td>BD</td>
			<td align="right">309657</td>
			<td>The top is cut off, and dry ice is compressed in the syringe to generate a cold probe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Computer</td>
			<td>If using Extech logger, any Pcwill work</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Aluminum boxes</td>
			<td>Washington University in St. Louis machine shop</td>
			<td>N/A</td>
			<td>boxes are 3&#39; long, 4.5&#39;&#39; wide, and 3&#39;&#39; tall with a sealed lid.&#160; There is a 1/2&#39;&#39; hole drilled into one short side of each box, near the bottom. These holes are filled with rubber stopcocks when the boxes are filled with wet ice or hot water.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Heated water circulator</td>
			<td>VWR</td>
			<td></td>
			<td>Any water circulator model with a pump will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">21 gauge needle</td>
			<td>BD</td>
			<td align="right">305165</td>
			<td>The exact needle size is not important</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hand timer</td>
			<td>N/A</td>
			<td></td>
			<td>Any hand timer will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mirror</td>
			<td>N/A</td>
			<td></td>
			<td>Any flat mirror will work</td>
		</tr>
	</tbody>
</table>

a simple and inexpensive method for determining cold sensitivity and adaptation in mice

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity.
Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 &#176;C to 5 &#176;C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above.
This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

The behavioral responses elicited from mice starting at 30 &#176;C, 23 &#176;C, 17 &#176;C, and 12 &#176;C are highly reproducible (Figure 4A)20. In order to measure the cold stimulus being generated under the hindpaw, mice were anesthetized with a ketamine/xylazine/acepromazine cocktail and their paws were secured on the glass on top of a T-type filament thermocouple (Figure 4B)20. The glass was cooled or warmed to the desired testing range. Although the plate is c...

Watch this Scientific Journal Video about A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice at JoVE.com

A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice

The Cold Plantar Assay (CPA) measures cold responsiveness between 30 &#176;C and 5 &#176;C, and can also measure cold adaptation. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life.  The cold ...

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Neuroscience

The Vermicelli and Capellini Handling Tests: Simple quantitative measures of dexterous forepaw function in rats and mice

Previous characterizations of rodent eating behavior have revealed that they use coordinated forepaw movements to manipulate food pieces. We have extended upon this work to develop a simple quantitative measure of forepaw dexterity that is sensitive to lateralized impairments and age-dependent changes. Rodents learn skillful forepaw and digit movements to manage thin pasta pieces, which they eagerly consume. We have previously described methods for quantifying vermicelli handling in rats and showed that the measures are very sensitive to forelimb impairments resulting from unilateral ischemic lesions, middle cerebral artery occlusions and unilateral striatal dopamine depletion [Allred, R.P., Adkins, D.L., Woodlee, M.T., Husbands, L.C., Maldonado M.A., Kane, J.R., Schallert, T. &amp; Jones, T.A. The Vermicelli Handling Test: a simple quantitative measure of dexterous forepaw function in rats. J. Neurosci. Methods 170, 229-244 (2008)]. Here we present a more detailed protocol for this test in rats and compare it with a newly developed version for mice, the Capellini Handling Test. Rats and mice are videotaped while handling short lengths of uncooked vermicelli or capellini pasta, respectively, with a camera positioned to optimize the view of paw movements. Slow motion video playback allows for the identification of forepaw adjustments, defined as any distinct removal and replacement of the paw, or of any number of digits, on the pasta piece after eating commences. Forepaw adjustments per piece are averaged over trials per each testing session. Repeated testing permits sensitive quantitative analysis of changes in forepaw dexterity over time. Protocols for pre-testing habituation and handling practice, as well as procedures for characterizing atypical handling patterns, are described. Because rats and mice perform the pasta handling tests slightly differently, species-specific differences in administration and scoring of these tests are highlighted. All animal use was in accordance with protocols approved by the University of Texas at Austin Animal Care and Use Committee.

The Vermicelli and Capellini Handling Tests of forepaw dexterity take advantage of the natural inclination of rodents to manipulate food items using skillful forepaw and digit movements. Animals are videotaped while handling short strands of uncooked dry pasta. Slow motion video playback allows for the quantification of forepaw adjustments.

Previous characterizations of rodent eating behavior have revealed that they use coordinated forepaw movements to manipulate food pieces. We have extended ...

A Simple Way to Measure Ethanol Sensitivity in Flies

Low doses of ethanol cause flies to become hyperactive, while high doses are sedating. The sensitivity to ethanol-induced sedation of a given fly strain is correlated with that strain s ethanol preference, and therefore sedation is a highly relevant measure to study the genetics of alcohol responses and drinking. We demonstrate a simple way to expose flies to ethanol and measure its intoxicating effects. The assay we describe can determine acute sensitivity, as well as ethanol tolerance induced by repeat exposure. It does not require a technically involved setup, and can therefore be applied in any laboratory with basic fly culture tools.

A simple assay to measure the sedating effects of ethanol on Drosophila flies, based on the loss of righting reflex, is described.

Low doses of ethanol cause flies to become hyperactive, while high doses are sedating. The sensitivity to ethanol-induced sedation of a given fly strain ...

A General Method for Evaluating Incubation of Sucrose Craving in Rats

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and relapse to food taking 1. Food craving conceptualized in this way is akin to drug craving in response to drug-paired cues. A rich literature has been developed around understanding the behavioral and neurobiological determinants of drug craving; we and others have been focusing recently on translating techniques from basic addiction research to better understand addiction-like behaviors related to food 2-4.
As done in previous studies of drug craving, we examine sucrose craving behavior by utilizing a rat model of relapse. In this model, rats self-administer either drug or food in sessions over several days. In a session, lever responding delivers the reward along with a tone+light stimulus. Craving behavior is then operationally defined as responding in a subsequent session where the reward is not available. Rats will reliably respond for the tone+light stimulus, likely due to its acquired conditioned reinforcing properties 5. This behavior is sometimes referred to as sucrose seeking or cue reactivity. In the present discussion we will use the term "sucrose craving" to subsume both of these constructs.
In the past decade, we have focused on how the length of time following reward self-administration influences reward craving. Interestingly, rats increase responding for the reward-paired cue over the course of several weeks of a period of forced-abstinence. This "incubation of craving" is observed in rats that have self-administered either food or drugs of abuse 4,6. This time-dependent increase in craving we have identified in the animal model may have great potential relevance to human drug and food addiction behaviors.
Here we present a protocol for assessing incubation of sucrose craving in rats. Variants of the procedure will be indicated where craving is assessed as responding for a discrete sucrose-paired cue following extinction of lever pressing within the sucrose self-administration context (Extinction without cues) or as responding for sucrose-paired cues in a general extinction context (Extinction with cues).

Responding for food or drug-paired cues increases over the course of a period of abstinence and this may relate to an increased susceptibility to relapse behaviors. Here we detail a procedure for evaluating this "incubation of craving" in rats that have self-administered sucrose.

For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and ...

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps shape attention and also protects cells from over-stimulation. Adaptation within the olfactory circuit of C. elegans was first described by Colbert and Bargmann1,2. Here, the authors defined parameters of the olfactory adaptation paradigm, which they used to design a genetic screen to isolate mutants defective in their ability to adapt to volatile odors sensed by the Amphid Wing cells type C (AWC) sensory neurons. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor3 for 30 min they will adapt their responsiveness to the odor and will then ignore the adapting odor in a chemotaxis behavioral assay for ~1 hr. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor for ~1 hr they will then ignore the adapting odor in a chemotaxis behavioral assay for ~3 hr. These two phases of olfactory adaptation in C. elegans were described as short-term olfactory adaptation (induced after 30 min odor exposure), and long-term olfactory adaptation (induced after 60 min odor exposure). Later work from L'Etoile et al.,4 uncovered a Protein Kinase G (PKG) called EGL-4 that is required for both the short-term and long-term olfactory adaptation in AWC neurons. The EGL-4 protein contains a nuclear localization sequence that is necessary for long-term olfactory adaptation responses but dispensable for short-term olfactory adaptation responses in the AWC4. By tagging EGL-4 with a green fluorescent protein, it was possible to visualize the localization of EGL-4 in the AWC during prolonged odor exposure. Using this fully functional GFP-tagged EGL-4 (GFP::EGL-4) molecule we have been able to develop a molecular readout of long-term olfactory adaptation in the AWC5. Using this molecular readout of olfactory adaptation we have been able to perform both forward and reverse genetic screens to identify mutant animals that exhibit defective subcellular localization patterns of GFP::EGL-4 in the AWC6,7. Here we describe: 1) the construction of GFP::EGL-4 expressing animals; 2) the protocol for cultivation of animals for long-term odor-induced nuclear translocation assays; and 3) the scoring of the long-term odor-induced nuclear translocation event and recovery (re-sensitization) from the nuclear GFP::EGL-4 state.

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

Here we describe a molecular readout of long-term olfactory adaptation in Caenorhabditis elegans. The Protein Kinase G, EGL-4, is necessary for stable adaptation responses in the primary sensory neuron pair called AWC. During prolonged odor exposure EGL-4 translocates from the cytosol to nucleus of the AWC.

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps ...

Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development

Cortical development involves complex interactions between neurons and non-neuronal elements including precursor cells, blood vessels, meninges and associated extracellular matrix. Because they provide a suitable organotypic environment, cortical slice explants are often used to investigate those interactions that control neuronal differentiation and development. Although beneficial, the slice explant model can suffer from drawbacks including aberrant cellular lamination and migration. Here we report a whole cerebral hemisphere explant system for studies of early cortical development that is easier to prepare than cortical slices and shows consistent organotypic migration and lamination. In this model system, early lamination and migration patterns proceed normally for a period of two days in vitro, including the period of preplate splitting, during which prospective cortical layer six forms. We then developed an ex utero electroporation (EUEP) approach that achieves ~80% success in targeting GFP expression to neurons developing in the dorsal medial cortex.
The whole hemisphere explant model makes early cortical development accessible for electroporation, pharmacological intervention and live imaging approaches. This method avoids the survival surgery required of in utero electroporation (IUEP) approaches while improving both transfection and areal targeting consistency. This method will facilitate experimental studies of neuronal proliferation, migration and differentiation.

Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development

This protocol describes an improved explant procedure that involves ex utero electroporation, dissection and culture of entire cerebral hemispheres from the embryonic mouse. The preparation facilitates pharmacological studies and assays of gene function during early cortical development.

Cortical development involves complex interactions between neurons and non-neuronal elements including precursor cells, blood vessels, meninges and ...

An Inexpensive, Scalable Behavioral Assay for Measuring Ethanol Sedation Sensitivity and Rapid Tolerance in Drosophila

Alcohol use disorder (AUD) is a serious health challenge. Despite a large hereditary component to AUD, few genes have been unambiguously implicated in their etiology. The fruit fly, Drosophila melanogaster, is a powerful model for exploring molecular-genetic mechanisms underlying alcohol-related behaviors and therefore holds great promise for identifying and understanding the function of genes that influence AUD. The use of the Drosophila model for these types of studies depends on the availability of assays that reliably measure behavioral responses to ethanol. This report describes an assay suitable for assessing ethanol sensitivity and rapid tolerance in flies. Ethanol sensitivity measured in this assay is influenced by the volume and concentration of ethanol used, a variety of previously reported genetic manipulations, and also the length of time the flies are housed without food immediately prior to testing. In contrast, ethanol sensitivity measured in this assay is not affected by the vigor of fly handling, sex of the flies, and supplementation of growth medium with antibiotics or live yeast. Three different methods for quantitating ethanol sensitivity are described, all leading to essentially indistinguishable ethanol sensitivity results. The scalable nature of this assay, combined with its overall simplicity to set-up and relatively low expense, make it suitable for small and large scale genetic analysis of ethanol sensitivity and rapid tolerance in Drosophila.

An Inexpensive, Scalable Behavioral Assay for Measuring Ethanol Sedation Sensitivity and Rapid Tolerance in Drosophila

Straightforward assays for measuring ethanol sensitivity and rapid tolerance in Drosophila facilitate the use of this model organism for investigating these important ethanol-related behaviors. Here, a relatively simple, scalable assay for measuring ethanol sensitivity and rapid tolerance in flies is described.

Alcohol use disorder (AUD) is a serious health challenge. Despite a large hereditary component to AUD, few genes have been unambiguously implicated in ...

A Simple Flight Mill for the Study of Tethered Flight in Insects

Flight in insects can be long-range migratory flights, intermediate-range dispersal flights, or short-range host-seeking flights. Previous studies have shown that flight mills are valuable tools for the experimental study of insect flight behavior, allowing researchers to examine how factors such as age, host plants, or population source can influence an insects' propensity to disperse. Flight mills allow researchers to measure components of flight such as speed and distance flown. Lack of detailed information about how to build such a device can make their construction appear to be prohibitively complex. We present a simple and relatively inexpensive flight mill for the study of tethered flight in insects. Experimental insects can be tethered with non-toxic adhesives and revolve around an axis by means of a very low friction magnetic bearing. The mill is designed for the study of flight in controlled conditions as it can be used inside an incubator or environmental chamber. The strongest points are the very simple electronic circuitry, the design that allows sixteen insects to fly simultaneously allowing the collection and analysis of a large number of samples in a short time and the potential to use the device in a very limited workspace. This design is extremely flexible, and we have adjusted the mill to accommodate different species of insects of various sizes.

Flight in insects is influenced by a number of factors and the propensity to disperse is an important variable in understanding insect ecology and biological control strategies. We describe the construction and use of a simple, relatively inexpensive, and flexible flight mill for measuring parameters of tethered flight in insects.

Flight in insects can be long-range migratory flights, intermediate-range dispersal flights, or short-range host-seeking flights. Previous studies have ...

A Method to Target and Isolate Airway-innervating Sensory Neurons in Mice

Somatosensory nerves transduce thermal, mechanical, chemical, and noxious stimuli caused by both endogenous and environmental agents. The cell bodies of these afferent neurons are located within the sensory ganglia. Sensory ganglia innervate a specific organ or portion of the body. For instance, the dorsal root ganglia (DRG) are located in the vertebral column and extend processes throughout the body and limbs. The trigeminal ganglia are located in the skull and innervate the face, and upper airways. Vagal afferents of the nodose ganglia extend throughout the gut, heart, and lungs. The nodose neurons control a diverse array of functions such as: respiratory rate, airway irritation, and cough reflexes. Thus, to understand and manipulate their function, it is critical to identify and isolate airway specific neuronal sub-populations. In the mouse, the airways are exposed to a fluorescent tracer dye, Fast Blue, for retrograde tracing of airway-specific nodose neurons. The nodose ganglia are dissociated and fluorescence activated cell (FAC) sorting is used to collect dye positive cells. Next, high quality ribonucleic acid (RNA) is extracted from dye positive cells for next generation sequencing. Using this method airway specific neuronal gene expression is determined.

Organ specific sensory neurons are difficult to identify. Fast Blue tracing is used to identify nodose neurons innervating the airways for cell sorting. Sorted nodose neurons are used to extract high quality ribonucleic acid (RNA) for sequencing. Using this protocol, gene expression of airway specific neurons is determined.

Somatosensory nerves transduce thermal, mechanical, chemical, and noxious stimuli caused by both endogenous and environmental agents. The cell bodies of ...

A Simple One-step Dissection Protocol for Whole-mount Preparation of Adult Drosophila Brains

There is an increasing interest in using Drosophila to model human brain degenerative diseases, map neuronal circuitries in adult brains, and study the molecular and cellular basis of higher brain functions. A whole-mount preparation of adult brains with well-preserved morphology is critical for such whole brain-based studies, but can be technically challenging and time-consuming. This protocol describes an easy-to-learn, one-step dissection approach of an adult fly head in less than 10 s, while keeping the intact brain attached to the rest of the body to facilitate subsequent processing steps. The procedure helps remove most of the eye and tracheal tissues normally associated with the brain that can interfere with the later imaging step, and also places less demand on the quality of the dissecting forceps. Additionally, we describe a simple method that allows convenient flipping of the mounted brain samples on a coverslip, which is important for imaging both sides of the brains with similar signal intensity and quality. As an example of the protocol, we present an analysis of dopaminergic (DA) neurons in adult brains of WT (w1118) flies. The high efficacy of the dissection method makes it particularly useful for large-scale adult brain-based studies in Drosophila.

A Simple One-step Dissection Protocol for Whole-mount Preparation of Adult Drosophila Brains

The adult Drosophila brain is a valuable system for studying neuronal circuitry, higher brain functions, and complex disorders. An efficient method to dissect whole brain tissue from the small fly head will facilitate brain-based studies. Here we describe a simple, one-step dissection protocol of adult brains with well-preserved morphology.

There is an increasing interest in using Drosophila to model human brain degenerative diseases, map neuronal circuitries in adult brains, and study the ...

Novel Assay for Cold Nociception in Drosophila Larvae

How organisms sense and respond to noxious temperatures is still poorly understood. Further, the mechanisms underlying sensitization of the sensory machinery, such as in patients experiencing peripheral neuropathy or injury-induced sensitization, are not well characterized. The genetically tractable Drosophila model has been used to study the cells and genes required for noxious heat detection, which has yielded multiple conserved genes of interest. Little is known however about the cells and receptors important for noxious cold sensing. Although, Drosophila does not survive prolonged exposure to cold temperatures (&#8804;10 &#186;C), and will avoid cool, preferring warmer temperatures in behavioral preference assays, how they sense and possibly avoid noxious cold stimuli has only recently been investigated.
Here we describe and characterize the first noxious cold (&#8804;10 &#186;C) behavioral assay in Drosophila. Using this tool and assay, we show an investigator how to qualitatively and quantitatively assess cold nociceptive behaviors. This can be done under normal/healthy culture conditions, or presumably in the context of disease, injury or sensitization. Further, this assay can be applied to larvae selected for desired genotypes, which might impact thermosensation, pain, or nociceptive sensitization. Given that pain is a highly conserved process, using this assay to further study&#160;thermal nociception will likely glean important understanding of pain processes in other species, including vertebrates.

Novel Assay for Cold Nociception in Drosophila Larvae

Here we demonstrate a novel assay to study cold nociception in Drosophila larvae. This assay utilizes a custom-built Peltier probe capable of applying a focal noxious cold stimulus and results in quantifiable cold-specific behaviors. This technique will allow further cellular and molecular dissection of cold nociception.

How organisms sense and respond to noxious temperatures is still poorly understood. Further, the mechanisms underlying sensitization of the sensory ...