This work was supported by the National Institutes of Health grant R01DK117872 awarded to OO and the Larry L Hillblom Foundation Fellowship awarded to RCZ.

All procedures involving animal subjects have been approved by the Institutional Animal Care and Use Committee (IACUC) at the University of California, San Diego.
1. Making the drug-peanut butter pellet
<ol>
	<li>Calculate the amount of drug needed to make the desired dose of drug in a pellet of peanut butter and scale to the size of the batch required for an experiment. Importantly, pellets can be kept at -80 &#176;C, depending on drug stability.</li>
	<li>Pulverize the drug tablets using a mortar and pestle.</li>
	<li>Weigh the calculated amount peanut butter required by placing it in a weigh boat on a tared scale.</li>
	<li>Place the peanut butter over a beaker of warm water until melted.</li>
	<li>Add the required amount of pulverized drug into the melted peanut and mix thoroughly.</li>
	<li>Allow the drug-peanut butter mixture to cool so that it can be easily placed into the rubber molds.</li>
	<li>Place the peanut butter-drug mix into a mold. The one used here is a rubber corticosterone pellet mold and creates approximately ~100 mg peanut butter pellets. Adjustment of the ratio of drug to peanut butter may be necessary to ensure palatability.</li>
	<li>Repeat these steps with peanut butter alone to make placebo pellets.</li>
	<li>Freeze the mold at -20 &#176;C or -80 &#176;C (depending on drug stability) to allow the peanut butter to harden until use.</li>
</ol>
2. Mouse setup
<ol>
	<li>Singly house mice in standard mouse cages. Line with highly absorbent paper bedding and enrichment, including paper towels and housing dome. This paper bedding facilitates accurate food intake measurements by allowing quantification of spilled food from feces and bedding. 
	NOTE: ENsure IACUC approval for singly housing mice has been obtained.</li>
	<li>Provide ad libitum food and water and allow the mice to acclimate to the housing for approximately 3 days.</li>
</ol>
3. Training to self-dosing of drug-peanut butter
<ol>
	<li>Plan and select the optimum time of the day for the drug administration.</li>
	<li>Fast the mice for 24 hours and ensure that IACUC approval has been received for the chosen fasting duration.</li>
	<li>Take the mold out the freezer, let the rubber mold soften so that the pellets can be easily extruded out of the mold. All training can be completed using placebo control pellets.</li>
	<li>Place a placebo control peanut butter pellet on the wall of the cage approximately 1.5 inches from the base. On the first day, it may take approximately 1 hour for the mouse to consume the peanut butter pellet due to novelty.</li>
	<li>After the training session provide ad libitum access to food and water.</li>
	<li>On the following day, place the peanut butter pellet on the wall of the cage in the same location for further training on non-fasted mice.</li>
	<li>Repeat the training in fed mice for approximately 3 days. The time taken to consume the peanut butter will be less than 30 minutes by the third day of training.</li>
</ol>
4. Experiment
<ol>
	<li>Randomize mice to treatment groups based on body weight so the groups have the same average body weight before treatment.</li>
	<li>Plan to administer the peanut butter pills (treatment or placebo) to the mice at the same time they were trained to receive the peanut butter pellets.</li>
	<li>Weigh the food and mouse and record the values.</li>
	<li>Ensure that the peanut butter pills (treatment or placebo) are placed at the same location in the cage as established during training.</li>
	<li>Continue the dosing procedure daily for the duration of the experiment.</li>
</ol>

<ol>
	<li>de Meijer, V. E., Le, H. D., Meisel, J. A., Puder, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repetitive+orogastric+gavage+affects+the+phenotype+of+diet-induced+obese+mice.">Repetitive orogastric gavage affects the phenotype of diet-induced obese mice.</a> Physiology and Behavior. 100 (4), 387-393 (2010).</li><li>Perez-Gomez, A., 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=A+phenotypic+Caenorhabditis+elegans+screen+identifies+a+selective+suppressor+of+antipsychotic-induced+hyperphagia.">A phenotypic Caenorhabditis elegans screen identifies a selective suppressor of antipsychotic-induced hyperphagia.</a> Nature Communications. 9 (1), 5272 (2018).</li><li>Corbett, A., McGowin, A., Sieber, S., Flannery, T., Sibbitt, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+reliable+voluntary+oral+administration+of+a+fixed+dosage+(mg/kg)+of+chronic+daily+medication+to+rats.">A method for reliable voluntary oral administration of a fixed dosage (mg/kg) of chronic daily medication to rats.</a> Laboratory Animal. 46 (4), 318-324 (2012).</li><li>Teixeira-Santos, L., Albino-Teixeira, A., Pinho, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+alternative+method+for+oral+drug+administration+by+voluntary+intake+in+male+and+female+mice.">An alternative method for oral drug administration by voluntary intake in male and female mice.</a> Laboratory Animal. 55 (1), 76-80 (2021).</li><li>Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+voluntary+oral+administration+of+drugs+in+mice.">Method for voluntary oral administration of drugs in mice.</a> STAR Protocols. 2 (1), 100330 (2021).</li><li>Cope, M. 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=Risperidone+alters+food+intake,+core+body+temperature,+and+locomotor+activity+in+mice.">Risperidone alters food intake, core body temperature, and locomotor activity in mice.</a> Physiology and Behaviour. 96 (3), 457-463 (2009).</li><li>Barton, B. B., Segger, F., Fischer, K., Obermeier, M., Musil, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Update+on+weight-gain+caused+by+antipsychotics:+a+systematic+review+and+meta-analysis.">Update on weight-gain caused by antipsychotics: a systematic review and meta-analysis.</a> Expert Opinion in Drug Safety. 19 (3), 295-314 (2020).</li><li>Cope, M. 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=Antipsychotic+drug-induced+weight+gain:+development+of+an+animal+model.">Antipsychotic drug-induced weight gain: development of an animal model.</a> International Journal of Obesity. 29 (6), 607-614 (2005).</li><li>Domecq, J. P., 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=Clinical+review:+Drugs+commonly+associated+with+weight+change:+a+systematic+review+and+meta-analysis.">Clinical review: Drugs commonly associated with weight change: a systematic review and meta-analysis.</a> Journal of Clinical Endocrinology and Metabolism. 100 (2), 363-370 (2015).</li><li>Wei, 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=Dopamine+D2+receptor+signaling+modulates+pancreatic+beta+cell+circadian+rhythms.">Dopamine D2 receptor signaling modulates pancreatic beta cell circadian rhythms.</a> Psychoneuroendocrinology. 113, 104551 (2020).</li></ol>

The authors have no conflicts of interest to declare.

When conducting this protocol, it is important to be consistent with the accuracy of the measurements of food intake and body weight and the timing of drug administration throughout the study. While this self-administration method requires a significant training phase, this is particularly important to acclimate the mice to the novelty of the peanut butter and ensure mice consume the drug at the time given. Once established, it also offers great experimental flexibility and can be modified and adapted to deliver drugs at...

The goal of this method is to deliver drugs in mice via a non-invasive, minimally stressful procedure. Preclinical studies in mice often rely on stressful, invasive routes of drug administration that can have significant impacts on metabolic parameters. For example, repetitive daily oral gavage can significantly decrease caloric intake and weight gain in mice1. In addition, oral gavage can be technically challenging and has the potential to cause injuries. As an alternative, mice can self-administer compounds that are mixed in their food or dissolved in their drinking water 2. However, this approach has a major limitation, which is, it relies on the natural circadian timing of food or water intake. Furthermore, drug stability or solubility in water can be major issues when chronically delivered in this way. To overcome these limitations, drugs can be mixed with highly palatable foods, such as cookie dough 3, jelly 4,5 or peanut butter 6 to encourage self-administration in mice at a specified time. This approach has the advantage of facilitating drug delivery with minimal stress compared with an injection or daily gavage1. This procedure can be adapted to deliver a wide variety of drugs to mice. This protocol demonstrates the process of drug preparation, training, followed by drug delivery in highly palatable food. As an example, this method is used to administer the antipsychotic drug risperidone to C57BL/6J female mice. Risperidone is well known to have potent hyperphagic and weight gain effects in patients 7 that is well modelled in rodents 6,8. This system of administration facilitates a highly translational model that could be used to study a wide variety of drugs and their effects on pathways regulating food intake and body weight 9.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>C57B6/J mice</td>
			<td>Jackson Labs, Sacramento, CA, USA</td>
			<td>664</td>
			<td></td>
		</tr>
		<tr>
			<td>corticosterone pellet mold</td>
			<td>Ted Pella Inc, Redding, CA, USA</td>
			<td>106A</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse igloo</td>
			<td>VWR, Visalia, CA, USA</td>
			<td>89067-850</td>
			<td>cage enrichment</td>
		</tr>
		<tr>
			<td>peanut butter</td>
			<td>Jif Peanut Butter, Orrville, OH, USA</td>
			<td></td>
			<td>Creamy peanut butter</td>
		</tr>
		<tr>
			<td>pestle and mortar</td>
			<td>VWR, Visalia, CA, USA</td>
			<td>470148-960</td>
			<td></td>
		</tr>
		<tr>
			<td>risperidone</td>
			<td>Patriot Pharmaceuticals, Horsham, PA, USA</td>
			<td>50458-593-50</td>
			<td></td>
		</tr>
		<tr>
			<td>rodent chow</td>
			<td>LabDiet, St. Louis, MO, USA</td>
			<td>5001</td>
			<td></td>
		</tr>
		<tr>
			<td>weigh boat</td>
			<td>VWR, Visalia, CA, USA</td>
			<td>10803-148</td>
			<td></td>
		</tr>
		<tr>
			<td>weighing scale</td>
			<td>Mettler Toledo, Greifensee, Switzerland</td>
			<td>MS104TS</td>
			<td></td>
		</tr>
		<tr>
			<td>Wypall paper X60</td>
			<td>Kimberly-Clark, Corinth, MS, USA</td>
			<td>34865-05</td>
			<td>absorbent paper bedding</td>
		</tr>
	</tbody>
</table>

self-administration of drugs in mouse models of feeding and obesity

Preclinical studies in mice often rely on invasive protocols, such as injections or oral gavage, to deliver drugs. These stressful routes of administration have significant effects on important metabolic parameters including food intake and body weight. Although an attractive option to circumvent this is to compound the drug in rodent food or dissolve it in water, these approaches also have limitations as they are affected by drug stability at room temperature for extended periods of time, the drug's solubility in water, and that the dosing is highly dependent on timing of food or water intake. The constant availability of the drug also limits translational relevance on how drugs are administered to patients. To overcome these limitations, drugs can be mixed with highly palatable food, such as peanut butter, allowing mice to self-administer compounds. Mice reliably and reproducibly consume the drug/peanut butter pellet in a short time frame. This approach facilitates a delivery approach with minimal stress compared with an injection or gavage. This protocol demonstrates the approach of drug preparation, animal acclimatization to placebo delivery, and drug delivery. The implications of this approach are discussed in studies related to timing of drug administration and the circadian rhythm.

In the example presented here, peanut butter was used to deliver risperidone to mice daily for 14 days.
This study shows the chronic delivery of risperidone via this method facilitates highly reproducible increase in food intake and body weight compared with control (Figure 1a,b). In addition, this delivery method results in highly consistent data compared with alternative, more stressful delivery approaches such as intraperitoneal injections (<st...

Watch this Scientific Journal Video about Self-Administration of Drugs in Mouse Models of Feeding and Obesity at JoVE.com

Self-Administration of Drugs in Mouse Models of Feeding and Obesity

The overall goal of this procedure is to describe a method for self-administration of drugs that can be used in mouse models of feeding and obesity.

Preclinical studies in mice often rely on invasive protocols, such as injections or oral gavage, to deliver drugs. These stressful routes of ...

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4.2K Views.  University of California San Diego. The overall goal of this procedure is to describe a method for self-administration of drugs that can be used in mouse models of feeding and obesity. 

Video: Self-Administration of Drugs in Mouse Models of Feeding and Obesity

Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold standard" method for assessing insulin action in vivo. During an insulin clamp, hyperinsulinemia is achieved by a constant insulin infusion. Euglycemia is maintained via a concomitant glucose infusion at a variable rate. This variable glucose infusion rate (GIR) is determined by measuring blood glucose at brief intervals throughout the experiment and adjusting the GIR accordingly. The GIR is indicative of whole-body insulin action, as mice with enhanced insulin action require a greater GIR. The insulin clamp can incorporate administration of isotopic 2[14C]deoxyglucose to assess tissue-specific glucose uptake and [3-3H]glucose to assess the ability of insulin to suppress the rate of endogenous glucose appearance (endoRa), a marker of hepatic glucose production, and to stimulate the rate of whole-body glucose disappearance (Rd).
The miniaturization of the insulin clamp for use in genetic mouse models of metabolic disease has led to significant advances in diabetes research. Methods for performing insulin clamps vary between laboratories. It is important to note that the manner in which an insulin clamp is performed can significantly affect the results obtained. We have published a comprehensive assessment of different approaches to performing insulin clamps in conscious mice1 as well as an evaluation of the metabolic response of four commonly used inbred mouse strains using various clamp techniques2. Here we present a protocol for performing insulin clamps on conscious, unrestrained mice developed by the Vanderbilt Mouse Metabolic Phenotyping Center (MMPC; URL: www.mc.vanderbilt.edu/mmpc). This includes a description of the method for implanting catheters used during the insulin clamp. The protocol employed by the Vanderbilt MMPC utilizes a unique two-catheter system3. One catheter is inserted into the jugular vein for infusions. A second catheter is inserted into the carotid artery, which allows for blood sampling without the need to restrain or handle the mouse. This technique provides a significant advantage to the most common method for obtaining blood samples during insulin clamps which is to sample from the severed tip of the tail. Unlike this latter method, sampling from an arterial catheter is not stressful to the mouse1. We also describe methods for using isotopic tracer infusions to assess tissue-specific insulin action. We also provide guidelines for the appropriate presentation of results obtained from insulin clamps.

The hyperinsulinemic-euglycemic clamp, or insulin clamp, is the gold standard for assessing insulin action in vivo. A method for performing insulin clamps in mice is described. This includes a method for arterial catheterization that permits experiments to be performed in conscious, unrestrained mice with minimal stress.

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold ...

Segmentation and Measurement of Fat Volumes in Murine Obesity Models Using X-ray Computed Tomography

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are associated with obesity, though the precise underlying mechanisms that contribute to the disease are currently being delineated.2,3 Several small animal models of obesity have been developed and are employed in a variety of studies.4 A critical component to these experiments involves the collection of regional and/or total animal fat content data under varied conditions.
Traditional experimental methods available for measuring fat content in small animal models of obesity include invasive (e.g. ex vivo measurement of fat deposits) and non-invasive (e.g. Dual Energy X-ray Absorptiometry (DEXA), or Magnetic Resonance (MR)) protocols, each of which presents relative trade-offs. Current invasive methods for measuring fat content may provide details for organ and region specific fat distribution, but sacrificing the subjects will preclude longitudinal assessments. Conversely, current non-invasive strategies provide limited details for organ and region specific fat distribution, but enable valuable longitudinal assessment. With the advent of dedicated small animal X-ray computed tomography (CT) systems and customized analytical procedures, both organ and region specific analysis of fat distribution and longitudinal profiling may be possible. Recent reports have validated the use of CT for in vivo longitudinal imaging of adiposity in living mice.5,6 Here we provide a modified method that allows for fat/total volume measurement, analysis and visualization utilizing the Carestream Molecular Imaging Albira CT system in conjunction with PMOD and Volview software packages.

Fat content analysis is routinely conducted in studies utilizing murine obesity models. Emerging methods in small animal CT imaging and analysis are providing for longitudinal detail rich fat content analysis. Here we detail step by step procedures for performing small animal CT imaging, analysis, and visualization.

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are ...

Live Imaging of Drug Responses in the Tumor Microenvironment in Mouse Models of Breast Cancer

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional co-culture systems are frequently used to explicate tumor-stroma interactions, including their role in drug responses. However, many of the interactions that occur in vivo in the intact microenvironment cannot be completely replicated in these in vitro settings. Thus, direct visualization of these processes in real-time has become an important tool in understanding tumor responses to therapies and identifying the interactions between cancer cells and the stroma that can influence these responses. Here we provide a method for using spinning disk confocal microscopy of live, anesthetized mice to directly observe drug distribution, cancer cell responses and changes in tumor-stroma interactions following administration of systemic therapy in breast cancer models. We describe procedures for labeling different tumor components, treatment of animals for observing therapeutic responses, and the surgical procedure for exposing tumor tissues for imaging up to 40 hours. The results obtained from this protocol are time-lapse movies, in which such processes as drug infiltration, cancer cell death and stromal cell migration can be evaluated using image analysis software.

We describe a method for imaging response to anti-cancer treatment in vivo and at single cell resolution.

The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional ...

Mouse Models for Graft Arteriosclerosis

Graft arteriosclerois (GA), also called allograft vasculopathy, is a pathologic lesion that develops over months to years in transplanted organs characterized by diffuse, circumferential stenosis of the entire graft vascular tree. The most critical component of GA pathogenesis is the proliferation of smooth muscle-like cells within the intima. When a human coronary artery segment is interposed into the infra-renal aortae of immunodeficient mice, the intimas could be expand in response to adoptively transferred human T cells allogeneic to the artery donor or exogenous human IFN-&gamma; in the absence of human T cells. Interposition of a mouse aorta from one strain into another mouse strain recipient is limited as a model for chronic rejection in humans because the acute cell-mediated rejection response in this mouse model completely eliminates all donor-derived vascular cells from the graft within two-three weeks. We have recently developed two new mouse models to circumvent these problems. The first model involves interposition of a vessel segment from a male mouse into a female recipient of the same inbred strain (C57BL/6J). Graft rejection in this case is directed only against minor histocompatibility antigens encoded by the Y chromosome (present in the male but not the female) and the rejection response that ensues is sufficiently indolent to preserve donor-derived smooth muscle cells for several weeks. The second model involves interposing an artery segment from a wild type C57BL/6J mouse donor into a host mouse of the same strain and gender that lacks the receptor for IFN-&gamma; followed by administration of mouse IFN-&gamma; (delivered via infection of the mouse liver with an adenoviral vector. There is no rejection in this case as both donor and recipient mice are of the same strain and gender but donor smooth muscle cells proliferate in response to the cytokine while host-derived cells, lacking receptor for this cytokine, are unresponsive. By backcrossing additional genetic changes into the vessel donor, both models can be used to assess the effect of specific genes on GA progression. Here, we describe detailed protocols for our mouse GA models.

We describe protocols for our mouse graft arteriosclerois (GA) models which involve interposition of a mouse vessel segment into a recipient of the same inbred strain. By backcrossing additional genetic changes into the vessel donor, the model can assess the effect of specific genes on GA.

Graft arteriosclerois (GA),  also called allograft vasculopathy, is a pathologic lesion that develops over  months to years in transplanted organs ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

Mouse Kidney Transplantation: Models of Allograft Rejection

Rejection of the transplanted kidney in humans is still a major cause of morbidity and mortality. The mouse model of renal transplantation closely replicates both the technical and pathological processes that occur in human renal transplantation. Although mouse models of allogeneic rejection in organs other than the kidney exist, and are more technically feasible, there is evidence that different organs elicit disparate rejection modes and dynamics, for instance the time course of rejection in cardiac and renal allograft differs significantly in certain strain combinations. This model is an attractive tool for many reasons despite its technical challenges. As inbred mouse strain haplotypes are well characterized it is possible to choose donor and recipient combinations to model acute allograft rejection by transplanting across MHC class I and II loci. Conversely by transplanting between strains with similar haplotypes a chronic process can be elicited were the allograft kidney develops interstitial fibrosis and tubular atrophy. We have modified the surgical technique to reduce operating time and improve ease of surgery, however a learning curve still needs to be overcome in order to faithfully replicate the model. This study will provide key points in the surgical procedure and aid the process of establishing this technique.

Here, we present a protocol to study the immunology of rejection. The surgical model presented reports a short operating time and a concise technique. Depending on the donor-recipient strain combination, the transplanted kidney may develop acute cellular rejection or chronic allograft damage, defined by interstitial fibrosis and tubular atrophy.

Rejection of the transplanted kidney in humans is still a major cause of morbidity and mortality. The mouse model of renal transplantation closely ...

High-frequency Ultrasound Imaging of Mouse Cervical Lymph Nodes

High-frequency ultrasound (HFUS) is widely employed as a non-invasive method for imaging internal anatomic structures in experimental small animal systems. HFUS has the ability to detect structures as small as 30 &#181;m, a property that has been utilized for visualizing superficial lymph nodes in rodents in brightness (B)-mode. Combining power Doppler with B-mode imaging allows for measuring circulatory blood flow within lymph nodes and other organs. While HFUS has been utilized for lymph node imaging in a number of mouse&#160; model systems, a detailed protocol describing HFUS imaging and characterization of the cervical lymph nodes in mice has not been reported. Here, we show that HFUS can be adapted to detect and characterize cervical lymph nodes in mice. Combined B-mode and power Doppler imaging can be used to detect increases in blood flow in immunologically-enlarged cervical nodes. We also describe the use of B-mode imaging to conduct fine needle biopsies of cervical lymph nodes to retrieve lymph tissue for histological&#160; analysis. Finally, software-aided steps are described to calculate changes in lymph node volume and to visualize changes in lymph node morphology following image reconstruction. The ability to visually monitor changes in cervical lymph node biology over time provides a simple and powerful technique for the non-invasive monitoring of cervical lymph node alterations in preclinical mouse models of oral cavity disease.

This protocol describes the application of high-frequency ultrasound (HFUS) for imaging mouse cervical lymph nodes. This technique optimizes visualization and quantification of cervical lymph node morphology, volume and blood flow. Image-guided biopsy of cervical lymph nodes and processing of lymph tissue for histological evaluation is also demonstrated.

High-frequency ultrasound (HFUS) is widely employed as a non-invasive method for imaging internal anatomic structures in experimental small animal ...

Evaluation of Lung Metastasis in Mouse Mammary Tumor Models by Quantitative Real-time PCR

Metastatic disease is the spread of malignant tumor cells from the primary cancer site to a distant organ and is the primary cause of cancer associated death 1. Common sites of metastatic spread include lung, lymph node, brain, and bone 2. Mechanisms that drive metastasis are intense areas of cancer research. Consequently, effective assays to measure metastatic burden in distant sites of metastasis are instrumental for cancer research. Evaluation of lung metastases in mammary tumor models is generally performed by gross qualitative observation of lung tissue following dissection. Quantitative methods of evaluating metastasis are currently limited to ex vivo and in vivo imaging based techniques that require user defined parameters. Many of these techniques are at the whole organism level rather than the cellular level 3-6. Although newer imaging methods utilizing multi-photon microscopy are able to evaluate metastasis at the cellular level 7, these highly elegant procedures are more suited to evaluating mechanisms of dissemination rather than quantitative assessment of metastatic burden. Here, a simple in vitro method to quantitatively assess metastasis is presented. Using quantitative Real-time PCR (QRT-PCR), tumor cell specific mRNA can be detected within the mouse lung tissue.

This protocol describes how to use quantitative Real-time PCR (QRT-PCR) to detect tumor cell specific mRNA representing metastasis within the mouse lung tissue.

Metastatic disease is the spread of malignant tumor cells from the primary cancer site to a distant organ and is the primary cause of cancer associated ...

Assessing Specificity of Anticancer Drugs In Vitro

A procedure for assessing specificity of anticancer drugs in vitro using cultures containing both tumor and non-tumor cells is demonstrated. The key element is the quantitative determination of a tumor-specific genetic alteration in relation to a universal sequence using a dual-probe digital PCR assay and the subsequent calculation of the proportion of tumor cells. The assay is carried out on a culture containing tumor cells of an established line and spiked-in non-tumor cells. The mixed culture is treated with a test drug at various concentrations. After the treatment, DNA is prepared directly from the survived adhesive cells in wells of 96-well plates using a simple and inexpensive method, and subjected to a dual-probe digital PCR assay for measuring a tumor-specific genetic alteration and a reference universal sequence. In the present demonstration, a heterozygous deletion of the NF1 gene is used as the tumor-specific genetic alteration and a RPP30 gene as the reference gene. Using the ratio NF1/RPP30, the proportion of tumor cells was calculated. Since the dose-dependent change of the proportion of tumor cells provides an in vitro indication for specificity of the drug, this genetic and cell-based in vitro assay will likely have application potential in drug discovery. Furthermore, for personalized cancer-care, this genetic- and cell-based tool may contribute to optimizing adjuvant chemotherapy by means of testing efficacy and specificity of candidate drugs using primary cultures of individual tumors.

Assessing Specificity of Anticancer Drugs In Vitro

The goal of this protocol is to assess specificity of anticancer drugs in vitro using mixed cultures containing both tumor and non-tumor cells.

A procedure for assessing specificity of anticancer drugs in vitro using cultures containing both tumor and non-tumor cells is demonstrated. The key ...

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity (RSNA) is of great interest in many areas of research such as chronic kidney disease, hypertension, heart failure, diabetes and obesity. Unequivocal assessment of the role of the sympathetic nervous system is thus imperative for proper interpretation of experimental results and understanding of disease processes. RSNA has been traditionally measured in anesthetized rodents, including mice. However, mice usually exhibit very low systemic blood pressure and hemodynamic instability for several hours during anesthesia and surgery. Meaningful interpretation of RSNA is confounded by this non-physiological state, given the intimate relationship between sympathetic nervous tone and cardiovascular status. To address this limitation of traditional approaches, we developed a new method for measuring RSNA in conscious, freely-moving mice. Mice were chronically instrumented with radio-telemeters for continuous monitoring of blood pressure as well as a jugular venous infusion catheter and custom-designed bipolar electrode for direct recording of RSNA. Following a 48-72 hour recovery period, survival rate was 100% and all mice behaved normally. At this time-point, RSNA was successfully recorded in 80% of mice, with viable signals acquired up to 4 and 5 days post-surgery in 70% and 50% of mice, respectively. Physiological blood pressures were recorded in all mice (116&plusmn;2 mmHg; n=10). Recorded RSNA increased with eating and grooming, as well-established in the literature. Furthermore, RSNA was validated by ganglionic blockade and modulation of blood pressure with pharmacological agents. Herein, an effective and manageable method for clear recording of RSNA in conscious, freely-moving mice is described.

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity ...