We would like to acknowledge VPC, CJR, and MCP for the development of this protocol. EMM received financial support from the American University College of Arts and Sciences Graduate Student Support to carry out this research.&#160;This work was also supported by an American University Faculty Mellon Award and funding through the American University College of Arts and Sciences (both to VPC).

All procedures were approved by the Institutional Animal Care and Use Committee at American University.
1. Preparing the Solution Tanks
<ol>
	<li>Obtain six tanks, two for each experimental group (glucose, mannitol, and water). Label one of the two tanks &#8216;housing tank&#8217; (it will house the fish) and label the other &#8216;solution tank&#8217; (it will hold the solution). 
	NOTE: The mannitol treatment group is the osmotic control, and the water treatment group is a handling/st...

<ol>
	<li>Rubinstein, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish:+from+disease+modeling+to+drug+discovery.">Zebrafish: from disease modeling to drug discovery.</a> Current Opinion in Drug Discovery and Development. 6 (2), 218-223 (2003).</li><li>Gerlai, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Associative+learning+in+zebrafish+(Danio+rerio).">Associative learning in zebrafish (Danio rerio).</a> Methods in Cell Biology. 101, 249-270 (2011).</li><li>Goldsmith, J. R., Jobin, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Think+small:+zebrafish+as+a+model+system+of+human+pathology.">Think small: zebrafish as a model system of human pathology.</a> BioMed Research International. , (2012).</li><li>Moss, J. B., 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=Regeneration+of+the+pancreas+in+adult+zebrafish.">Regeneration of the pancreas in adult zebrafish.</a> Diabetes. 58 (8), 1844-1851 (2009).</li><li>Connaughton, V. P., Baker, C., Fonde, L., Gerardi, E., Slack, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternate+immersion+in+an+external+glucose+solution+differentially+affects+blood+sugar+values+in+older+versus+younger+zebrafish+adults.">Alternate immersion in an external glucose solution differentially affects blood sugar values in older versus younger zebrafish adults.</a> Zebrafish. 13 (2), 87-94 (2016).</li><li>Etuk, E. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+for+studying+diabetes+mellitus.">Animal models for studying diabetes mellitus.</a> Agriculture and Biology Journal of North America. 1 (2), 130-134 (2010).</li><li>Agardh, E., Bruun, A., Agardh, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+glial+cell+immunoreactivity+and+neuronal+cell+changes+in+rats+with+STZ-induced+diabetes.">Retinal glial cell immunoreactivity and neuronal cell changes in rats with STZ-induced diabetes.</a> Current Eye Research. 23 (4), 276-284 (2001).</li><li>Carmo, A., Cunha-Vaz, J. G., Carvalho, A. P., Lopes, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nitric+oxide+synthase+activity+in+retinas+from+non-insulin-dependent+diabetic+Goto-Kakizaki+rats:+correlation+with+blood-retinal+barrier+permeability.">Nitric oxide synthase activity in retinas from non-insulin-dependent diabetic Goto-Kakizaki rats: correlation with blood-retinal barrier permeability.</a> Nitric Oxide. 4 (6), 590-596 (2000).</li><li>Ramsey, D. J., Ripps, H., Qian, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+electrophysiological+study+of+retinal+function+in+the+diabetic+female+rat.">An electrophysiological study of retinal function in the diabetic female rat.</a> Investigative Ophthalmology &amp; Visual Science. 47 (11), 5116-5124 (2006).</li><li>Biessels, G. J., Gispen, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+diabetes+on+cognition:+what+can+be+learned+from+rodent+models.">The impact of diabetes on cognition: what can be learned from rodent models.</a> Neurobiology of Aging. 26 (1), 36-41 (2005).</li><li>Intine, R. V., Olsen, A. S., Sarras, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+zebrafish+model+of+diabetes+mellitus+and+metabolic+memory.">A zebrafish model of diabetes mellitus and metabolic memory.</a> Journal of Visualized Experiments. (72), e50232 (2013).</li><li>Sarras, M. P., Intine, R. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+zebrafish+as+a+disease+model+provides+a+unique+window+for+understanding+the+molecular+basis+of+diabetic+metabolic+memory.">Use of zebrafish as a disease model provides a unique window for understanding the molecular basis of diabetic metabolic memory.</a> Research on Diabetes. , (2013).</li><li>Gleeson, M., Connaughton, V., Arneson, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+hyperglycaemia+in+zebrafish+(Danio+rerio)+leads+to+morphological+changes+in+the+retina.">Induction of hyperglycaemia in zebrafish (Danio rerio) leads to morphological changes in the retina.</a> Acta Diabetologica. 44 (3), 157-163 (2007).</li><li>Capiotti, K. 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=Hyperglycemia+induces+memory+impairment+linked+to+increased+acetylcholinesterase+activity+in+zebrafish+(Danio+rerio).">Hyperglycemia induces memory impairment linked to increased acetylcholinesterase activity in zebrafish (Danio rerio).</a> Behavioural Brain Research. 274, 319-325 (2014).</li><li>Capiotti, K. 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=Persistent+impaired+glucose+metabolism+in+a+zebrafish+hyperglycemia+model.">Persistent impaired glucose metabolism in a zebrafish hyperglycemia model.</a> Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 171, 58-65 (2014).</li><li>Capiotti, K. 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=Hyperglycemia+alters+E-NTPDases,+ecto-5'-nucleotidase,+and+ectosolic+and+cytosolic+adenosine+deaminase+activities+and+expression+from+encephala+of+adult+zebrafish+(Danio+rerio).">Hyperglycemia alters E-NTPDases, ecto-5'-nucleotidase, and ectosolic and cytosolic adenosine deaminase activities and expression from encephala of adult zebrafish (Danio rerio).</a> Purinergic Signaling. 12 (2), 211-220 (2016).</li><li>Ali, 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=Photoreceptor+Degeneration+Accompanies+Vascular+Changes+in+a+Zebrafish+Model+of+Diabetic+Retinopathy.">Photoreceptor Degeneration Accompanies Vascular Changes in a Zebrafish Model of Diabetic Retinopathy.</a> Investigative Ophthalmology &amp; Visual Science. 61 (2), 43 (2020).</li><li>Wiggenhauser, L. 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=Activation+of+Retinal+Angiogenesis+in+Hyperglycemic+pdx1-/-+Mutants.">Activation of Retinal Angiogenesis in Hyperglycemic pdx1-/- Mutants.</a> Diabetes. 69 (5), 1020-1031 (2020).</li><li>Chen, X. L., 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=Involvement+of+HMGB1+mediated+signalling+pathway+in+diabetic+retinopathy:+evidence+from+type+2+diabetic+rats+and+ARPE-19+cells+under+diabetic+condition.">Involvement of HMGB1 mediated signalling pathway in diabetic retinopathy: evidence from type 2 diabetic rats and ARPE-19 cells under diabetic condition.</a> Journal of Ophthalmology. 97, 1598-1603 (2013).</li><li>Costa, E., 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=Effects+of+light+exposure,+pH,+osmolarity,+and+solvent+on+the+retinal+pigment+epithelial+toxicity+of+vital+dyes.">Effects of light exposure, pH, osmolarity, and solvent on the retinal pigment epithelial toxicity of vital dyes.</a> American Journal of Ophthalmology. 155, 705-712 (2013).</li><li>Alvarez, 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=Predominant+cone+photoreceptor+dysfunction+in+a+hyperglycemic+model+of+non-proliferative+diabetic+retinopathy.">Predominant cone photoreceptor dysfunction in a hyperglycemic model of non-proliferative diabetic retinopathy.</a> Disease Models and Mechanisms. 3, 236-245 (2010).</li><li>Fletcher, E. L., Phipps, J. A., Wilkinson-Berka, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dysfunction+of+retinal+neurons+and+glia+during+diabetes.">Dysfunction of retinal neurons and glia during diabetes.</a> Clinical and Experimental Optometry. 88, 132-145 (2005).</li><li>Fletcher, E. L., Phipps, J. A., Ward, M. M., Puthussery, T., Wilkinson-Berka, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+and+glial+abnormality+as+predictors+of+progression+of+diabetic+retinopathy.">Neuronal and glial abnormality as predictors of progression of diabetic retinopathy.</a> Current Pharmaceutical Design. 13, 2699-2712 (2007).</li><li>Agardh, E., Bruun, A., Agardh, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+glial+cell+immunoreactivity+and+neuronal+cell+changes+in+rats+with+STZ-+induced+diabetes.">Retinal glial cell immunoreactivity and neuronal cell changes in rats with STZ- induced diabetes.</a> Current Eye Research. 23, 276-284 (2001).</li><li>Barber, A. J., Antonetti, D. A., Gardner, T. W., Group, T. P. S. R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+expression+of+retinal+occludin+and+glial+fibrillary+acidic+protein+in+experimental+diabetes.">Altered expression of retinal occludin and glial fibrillary acidic protein in experimental diabetes.</a> Investigative Ophthalmology &amp; Visual Science. 41, 3561-3568 (2000).</li><li>Lieth, E., 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=Glial+reactivity+and+impaired+glutamate+metabolism+in+short-term+experimental+diabetic+retinopathy.">Glial reactivity and impaired glutamate metabolism in short-term experimental diabetic retinopathy.</a> Diabetes. 47, 815-820 (1998).</li><li>Rungger-Brandle, E., Dosso, A. A., Leuenberger, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+reactivity,+an+early+feature+of+diabetic+retinopathy.">Glial reactivity, an early feature of diabetic retinopathy.</a> Investigative Ophthalmology &amp; Visual Science. 41, 1971-1980 (2000).</li><li>Zeng, X. X., Ng, Y. K., Ling, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+and+microglial+response+in+the+retina+of+streptozotocin-induced+diabetic+rats.">Neuronal and microglial response in the retina of streptozotocin-induced diabetic rats.</a> Visual Neuroscience. 17, 463-471 (2000).</li><li>Mizutani, M., Gerhardinger, C., Lorenzi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Muller+cell+changes+in+human+diabetic+retinopathy.">Muller cell changes in human diabetic retinopathy.</a> Diabetes. 47, 445-449 (1998).</li><li>Tanvir, Z., Nelson, R., DeCicco-Skinner, K., Connaughton, V. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One+month+of+hyperglycemia+alters+spectral+responses+of+the+zebrafish+photopic+electroretinogram.">One month of hyperglycemia alters spectral responses of the zebrafish photopic electroretinogram.</a> Disease Models and Mechanisms. 11, (2018).</li><li>Hancock, H. A., Kraft, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oscillatory+potential+analysis+and+ERGs+of+normal+and+diabetic+rats.">Oscillatory potential analysis and ERGs of normal and diabetic rats.</a> Investigative Ophthalmology &amp; Visual Science. 45, 1002-1008 (2004).</li><li>Layton, C. J., Safa, R., Osborne, N. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oscillatory+potentials+and+the+b-wave:+partial+masking+and+interdependence+in+dark+adaptation+and+diabetes+in+the+rat.">Oscillatory potentials and the b-wave: partial masking and interdependence in dark adaptation and diabetes in the rat.</a> Graefe's Archives for Clinical and Experimental Ophthalmology. 245, 1335-1345 (2007).</li><li>Li, Q., Zemel, E., Miller, B., Perlman, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+retinal+damage+in+experimental+diabetes:+electroretinographical+and+morphological+observations.">Early retinal damage in experimental diabetes: electroretinographical and morphological observations.</a> Experimental Eye Research. 74, 615-625 (2002).</li><li>Kohzaki, K., Vingrys, A. J., Bui, B. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+inner+retinal+dysfunction+in+streptozotocin-induced+diabetic+rats.">Early inner retinal dysfunction in streptozotocin-induced diabetic rats.</a> Investigative Ophthalmology &amp; Visual Science. 49, 3595-3604 (2008).</li><li>Phipps, J. A., Yee, P., Fletcher, E. L., Vingrys, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rod+photoreceptor+dysfunction+in+diabetes:+activation,+deactivation,+and+dark+adaptation.">Rod photoreceptor dysfunction in diabetes: activation, deactivation, and dark adaptation.</a> Investigative Ophthalmology &amp; Visual Science. 47, 3187-3194 (2006).</li></ol>

Diabetes is a nationwide problem. Studies show that by 2030, an estimated 400 million people will have some form of diabetes. In rodent models, Type 2 DM is studied using genetic manipulation. In rats, the Zucker diabetic fatty rats (ZDF), and the Otsuka Long-Evans Tokushima fatty rats (OLETF), are providing more information on the effects of Type 2 DM10. In addition, high fat diets have been used in rodent to induce hyperglycemia. This mirrors the noninvasive procedure proposed in this paper. Usi...

Zebrafish (Danio rerio) are quickly becoming a widely used animal model to study both disease and cognition1. The ease of genetic manipulation and embryonic transparency through the early developmental stages, make them a prime candidate to study human diseases with a known genetic basis. For example, zebrafish have been used to study Holt-Oram syndrome, cardiomyopathies, glomerulocystic kidney disease, muscular dystrophy, and diabetes mellitus (DM) among other diseases1. In addition, the zebrafish model is ideal because of the species&#8217; small size, ease of maintenance, and high fecundity2,3.
The zebrafish pancreas is both anatomically and functionally similar to the mammalian pancreas4. Thus, the unique characteristics of size, high fecundity, and similar endocrine structures make zebrafish a suitable candidate for studying DM-related complications. In zebrafish, there are two experimental methods used to induce the prolonged hyperglycemia that is characteristic of DM: an influx of glucose (modeling Type 2) and cessation of insulin secretion (modeling Type 1)5,6. Experimentally, to stop insulin secretion, pancreatic &#946;-cells can be chemically destroyed using either Streptozotocin (STZ) or Alloxan injections. STZ has been used successfully in rodents and zebrafish, resulting in complications associated with retinopathy7,8,9, cognitive impairments10, and limb regeneration11. However, in zebrafish, &#946;-cells regenerate after treatment, causing &#8220;booster injections&#8221; of STZ to be necessary to maintain diabetic conditions12. Alternatively, the pancreas of the zebrafish can be removed6. These are both highly invasive procedures, due to the multiple injections, and extensive recovery time.
Conversely, hyperglycemia can be induced noninvasively through exposure to exogenous glucose. In this protocol, fish are submerged in a highly concentrated glucose solution for 24-hours5,13 or continually for 2-weeks14,15,16. Exogenous glucose is taken up transdermally, by ingestion, and/or across the gills resulting in elevated blood sugar levels. Since this non-invasive technique does not directly manipulate insulin levels, it cannot claim to induce Type 2 DM. However, it can be used to examine complications induced by hyperglycemia, which is one of the main symptoms of Type 2 DM.
Recently, the zebrafish mutant pdx1-/- was developed by manipulating the pancreatic and duodenal homeobox 1 gene, a gene linked to the genetic cause of Type 2 DM in humans. Using this mutant, researchers have been able to replicate pancreatic development disruption, high blood sugar, and study hyperglycemia-induced diabetic retinopathy17,18.
In this paper, we describe a noninvasive hyperglycemia induction method that uses an alternating immersion protocol. This protocol maintains hyperglycemic conditions for up to 8 weeks with subsequent complications observed. In brief, adult zebrafish are placed in a sugar solution for 24 hours and then a water solution for 24 hours. As opposed to continuous immersion in external glucose solutions, alternating days between sugar and water mimics the rise and fall of blood sugar in diabetes. An alternating glucose protocol additionally allows hyperglycemia to be induced for longer periods of time, as the zebrafish are not as able to compensate for the high external glucose conditions. As proof of principle, we provide data showing that hyperglycemia induced using this protocol alters retinal chemistry and physiology.

<table>
	<tbody>
		<tr>
			<td>Airline Tubing</td>
			<td>petsmart</td>
			<td>5291863</td>
			<td>This can be used in the tank to circulate air</td>
		</tr>
		<tr>
			<td>Airpump</td>
			<td>petsmart</td>
			<td>5094984</td>
			<td>This can be used in the tank to circulate air</td>
		</tr>
		<tr>
			<td>Airstones</td>
			<td>petsmart</td>
			<td>5149683</td>
			<td>This can be used in the tank to circulate air</td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>Sigma</td>
			<td>G8270-5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>D-mannitol</td>
			<td>Acros Organics</td>
			<td>AC125340050</td>
			<td></td>
		</tr>
		<tr>
			<td>Freestyle Lite Meter</td>
			<td>Amazon</td>
			<td>B01LMOMLTU</td>
			<td></td>
		</tr>
		<tr>
			<td>Freestyle Lite Strips</td>
			<td>Amazon</td>
			<td>B074ZN3H2Z</td>
			<td></td>
		</tr>
		<tr>
			<td>Net</td>
			<td>petsmart</td>
			<td>5175115</td>
			<td></td>
		</tr>
		<tr>
			<td>Tanks</td>
			<td>Amazon</td>
			<td>B0002APZO4</td>
			<td></td>
		</tr>
	</tbody>
</table>

alternate immersion in glucose to produce prolonged hyperglycemia in zebrafish

Zebrafish (Danio rerio) are an excellent model to investigate the effects of chronic hyperglycemia, a hallmark of Type II Diabetes Mellitus (T2DM). This alternate immersion protocol is a noninvasive, step-wise method of inducing hyperglycemia for up to eight weeks. Adult zebrafish are alternately exposed to sugar (glucose) and water for 24 hours each. The zebrafish begin treatment in a 1% glucose solution for 2 weeks, then a 2% solution for 2 weeks, and finally a 3% solution for the remaining 4 weeks. Compared to water-treated (stress) and mannitol-treated (osmotic) controls, glucose-treated zebrafish have significantly higher blood sugar levels. The glucose-treated zebrafish show blood sugar levels of 3-times that of controls, suggesting that after both four and eight weeks hyperglycemia can be achieved. Sustained hyperglycemia was associated with increased Glial Fibrillary Acidic Protein (GFAP) and increased nuclear factor Kappa B (NF-kB)&#160;levels in retina and decreased physiological responses, as well as cognitive deficits suggesting this protocol can be used to model disease complications.

Using this protocol (Figure 1), blood sugar values are significantly elevated after both 4-weeks and 8-weeks of treatment (Figure 2A), with hyperglycemia defined as 3x the control averages from both water-treated and mannitol-treated groups. Water-treated controls are transferred in and out of water daily, providing a stress/handling control. Mannitol serves as an osmotic control in in vitro glucose studies19,...

Watch this Scientific Journal Video about Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish at JoVE.com

Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish

This protocol noninvasively induces hyperglycemia in zebrafish for up to 8 weeks. Using this protocol, an in-depth study of the adverse effects of hyperglycemia can be made.

Zebrafish (Danio rerio) are an excellent model to investigate the effects of chronic hyperglycemia, a hallmark of Type II Diabetes Mellitus (T2DM). This ...

This protocol induces hyperglycemia in zebra fish in a rise and fall pattern that mimics the hyperglycemia that is seen in type two diabetes. The main advantage of this technique is that it is a noninvasive technique that makes it possible to ensure that hyperglycemia is the cause of any alterations observed in the hyperglycemic fish. This protocol could potentially be used to explore therapeutic avenues or pharmaceuticals that target complications of hyperglycemia.This protocol has a lot of steps, but when the steps are followed correctly and with care, it should quickly become second nature. Remember however, to always treat the animals gently and humanely throughout the entire protocol. Begin by setting up six tanks, two for each experimental group.Use two liter tanks, if the total number of fish is less than 20 and four liter tanks if the total number of fish is more than 20. Label one of the two tanks, housing tank and the other solution tank. Keep the tanks in a water bath at 28 to 29 degrees Celsius to maintain water temperature.On day one, place the fish into their respective treatment solutions for 24 hours. On day two, transfer the fish from their treatment solutions to water for 24 hours. On day three, transfer the fish from water to treatment solutions.Continue this alternating exposure for the remainder of the experiment. Transferring water treated control fish from water-to-water daily. Ensure that the fish are fed and transferred within the same two-hour window each day throughout the duration of the experiment.Transfer fish in each treatment group from the housing tank to the corresponding solution tank using a standard fish net. Place the tank containing the fish back in the water bath and replace the air stone and tank lid. This tank is now the housing tank and the tank that previously held the fish is now the solution tank.Discard the old solution and clean the tank along with the tank lids, air lines, air stones and nets to prevent buildup of glucose and mannitol. Use water and a dedicated sponge for each treatment condition to properly clean the tanks. Dry the newly cleaned solution tanks with a paper towel and prepare the solutions for the following day using this tank.Ensure the other items are dried and separated by appropriate treatment groups. To prepare the sugar solutions, fill each solution tank with two or four liters of system water. Measure the correct amount of glucose and mannitol using a top-loading scale and separate weigh boats for each chemical.Add the weighed glucose or mannitol aliquot to the appropriate clean solution tank. Stir the solutions with separate glass stir rods until the sugars are completely dissolved. Then return the solution tanks to the water bath and cover them with their corresponding lids.To prepare the water solution, fill experimental tanks with system water Return these solution tanks to the water bath and cover them with their corresponding lids. Blood sugar values were significantly elevated after both four-week and eight-week glucose treatments. With hyperglycemia defined as three times the control averages from both water treated and mannitol treated groups.Retinal tissue collected after four weeks of hyperglycemia had an increase in glial fibrillary acidic protein or GFAP levels. GFAP expression is observed in Mueller glial cells in the retina, which are altered in diabetic retinopathy. This increase in GFAP was associated with an increase in nuclear factor kappaB levels.Suggesting that the induced hyperglycemia triggers an inflammatory response and reactive gliosis. ERG recordings after four weeks of treatment identified a decreased response in glucose treated retinas compared to mannitol treated controls. Amplitudes of both photoreceptor and bipolar cell components were decreased in hyperglycemic fish.This procedure can be supplemented by other tests of hyperglycemia. For instance, a memory assay can be used to look at cognitive deficits or record visual based responses such as the optomotor response to assess vision-based complications. Once this technique was established, our lab was able to use it to study hyperglycemia induced complications in the zebra fish model.We observed these complications relatively quickly, after four weeks of treatment.

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JoVE Journal

Neuroscience

4.5K vistas.  American University. Este protocolo induce hiperglucemia en pescados de la cebra en un patrón de la subida y de la caída que mímico la hiperglucemia que se considera en el tipo diabetes dos. La principal ventaja de esta técnica es que se trata de una técnica no invasiva que permite asegurar que la hiperglucemia es la causa de las alteraciones observadas en los peces hiperglucémicos. Este protocolo se podría potencialmente utilizar para explorar las avenidas terapéuticas o los productos farmacéuticos que ...