Name: a complex diving-for-food task to investigate social organization and interactions in rats
Uploaded: 2021-05-08T14:00:00
Description: Watch this Scientific Journal Video about A Complex Diving-For-Food Task to Investigate Social Organization and Interactions in Rats at JoVE.com

We would like to thank Professor Olena Severynovska, Anastasia Halinska and Maryna Kuscheriava of the Department of Physiology, Faculty of Biology, Ecology, and Medicine, as well as Oles Honchar of Dnipro University, Dnipro, Ukraine, for their help in analyzing video recordings of the social organization test.

The experiments were conducted in accordance with recommendations of the Declarations of Helsinki and Tokyo and the Guidelines for the Use of Experimental Animals of the European Community. The experiments were approved by the Animal Care Committee of Ben-Gurion University of the Negev. The authorization code for this experiment was IL-55-8-12.
1. Rat preparation
<ol>
	<li>Obtain approval for experiments from Institutional Animal Care and Use Committee (IACUC).</li>
	<li>Select adult Sprague...

Social hierarchies determine the behavior of many species, including humans, and are often defined by relationships based on aggression and submission. These relationships often depend on environmental factors in additional to social structures35. Social formations based on dominance and submission are multifaceted36,37. Among humans, aggression is described as consisting of behaviors ranging from non-physical bullying to war and violence<...

Rats are highly social animals, making them an ideal model for understanding social behavior and how it relates to decision making. Rats divide themselves into hierarchical groups based on dominant and submissive relationships. Rats can be trained for tasks that express cooperation, risk management, deceptive behavior, and behaviors that change depending on the decisions of other rats1,2. Studies with rat models expressing these behaviors prove helpful in understanding social structure and its relationship to decision making with relevance for human psychology.
As a necessary resource, access to food is a major reason for social organization among rats3.&#160;Na&#239;ve rats have been observed engaging in social interaction and differentiation in situations where access to food was limited1,2,4,5,6,7,8. In one study, adult rats were required to cross a tunnel underwater to access the food and then bring the food back through the tunnel to the cage9. Individual rats within each group were able to be categorized according to their method of obtaining food. Two behavioral profiles have emerged: the first are the &#34;carriers&#34;, who dive down and swim underwater to the feeder, obtain a pellet, and hold the pellet in its mouth as they swim back to the cage. The second group are the &#34;non-carriers&#34;, who do not dive and obtain food only by stealing from the carriers. In groups of six rats, approximately one-half were carriers and the other half were not9. All of the rats were observed to be carriers when they were trained individually in the diving apparatus10.
Similar animal behavioral tasks involve competition for food or space and have been employed with chickens11, rodents12,13,14,15, and pigs16. In the tube test, two mice are sent through a narrow tube from opposite ends, with one mouse necessarily ceding right of way to the other. This test assists in measuring social dominance17,18,19. A behavioral test referred to as the warm spot test has mice compete for a position in a small warm spot in an otherwise cold cage19,20.
A subsequent diving-for-food task that is more complex allows carrier rats to have access to a second cage, away from non-carriers, where they could consume their food separately4. In this protocol, we present a diving-for-food task&#160;as an alternative model for social hierarchy and behavior in rats. This diving-for-food task provides a method for rats to avoid the social groups of the main cage and therefore escape aggression and the social interactions of other rats. This task introduces the option of avoidant social behavior in rats that can elucidate our understanding of social aggression.
Social functioning, which describes the ability to engage in normal social roles, can be affected by conditions such as depression3. Depressed individuals often struggle with unemployment, have few social contacts, and scarcely engage in leisure activities3. Effective treatment of depression is often measured by improvement in social and interpersonal function21. Antidepressant treatments, however, vary in their efficacy in treating impairments in social functioning related to depression3.
In this methodology, we induced a depressive-like condition in rats through the Chronic Stress test and evaluated the rats&#39; level of anhedonia, one of the features of a depression-like state, with a sucrose preference test. Anhedonic rats, as well as anhedonic rats who were administered anti-depressants, were monitored through the diving-for-food task in comparison to a control group.
The previously-mentioned diving-for-food tasks resemble food competition tests that often use only one pair of animals or one dichotomy as a point of comparison, such as carriers and non-carriers and a single analysis that compares submission to dominance15,17,22. Our method defines more complex interactions between rats through divisions into multiple types of behavior, including: carriers and non-carriers, those who fight for food and those who do not, and rats who share food or go to separate cages. We believe that this protocol is the only type that uses a hierarchy to assess a complex structure of social interaction in a group of animals, rather than in pairs. It will be helpful for studies that test dominance based on food preference, as well as studies that aim to clarify more hierarchical relationships that are not limited to a dominant-submissive model.
In this protocol, we describe in detail the complex diving-for-food task to investigate social organization and interactions in rats with changes in individual behavior, particularly after the development of anhedonia. This animal model may also be utilized to study other psychiatric conditions associated with changes in social behavior and hierarchy.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alcohol</td>
			<td>Pharmacy</td>
			<td></td>
			<td>99% pharmaceutical alcohol diluted to 5% and used for cleaning the open field test box before the introduction of each rat</td>
		</tr>
		<tr>
			<td>Bottles</td>
			<td>Techniplast</td>
			<td>ACBT0262SU</td>
			<td>150 mL bottles filled with 100 mL of water and 100 mL of 1% (w/v) sucrose solution</td>
		</tr>
		<tr>
			<td>Equipment for Diving for Food Task (Plexiglas)</td>
			<td>self made in Ben Gurion University of Negev</td>
			<td></td>
			<td>Two cages (50 x 50 x 50 cm) to an aquarium (130 x 35 x 50 cm) via tunnels</td>
		</tr>
		<tr>
			<td>Imipramine hydrochloride</td>
			<td>SIGMA</td>
			<td>Lot# SLBB9914V</td>
			<td>(Tricyclic antidepressant) 20 mg/kg intraperitoneally once per day for 3 weeks</td>
		</tr>
		<tr>
			<td>Purina Chow</td>
			<td>Purina</td>
			<td>5001</td>
			<td>Rodent laboratory chow given to rats, mice and hamster is a life-cycle nutrition that has been used in biomedical researc for over 5</td>
		</tr>
		<tr>
			<td>Rat Cages</td>
			<td>Techniplast</td>
			<td>2000P</td>
			<td>Conventional housing for rodents. Was used for housing rats throughout the experiment</td>
		</tr>
		<tr>
			<td>Video Camera</td>
			<td>Canon</td>
			<td></td>
			<td>Digital video camera for high definition recording of rat behavior under plus maze test</td>
		</tr>
	</tbody>
</table>

a complex diving-for-food task to investigate social organization and interactions in rats

For many species, where status is a vital motivator that can affect health, social hierarchies influence behavior. Social hierarchies that include dominant-submissive relationships are common in both animal and human societies. These relationships can be affected by interactions with others and with their environment, making them difficult to analyze in a controlled study. Rather than a simple dominance hierarchy, this formation has a complicated presentation that allows rats to avoid aggression. Status can be stagnant or mutable, and results in complex societal stratifications. Here we describe a complex diving-for-food task to investigate rodent social hierarchy and behavioral interactions. This animal model may allow us to assess the relationship between a wide range of mental illnesses and social organization, as well as to study the effectiveness of therapy on social dysfunction.

Body weight changes 
A one-way ANOVA did not show any differences in changes in body weight between experimental groups for the 21 days of the diving-for-food task. From days 2 to 21, there were changes in body weight for all 3 groups (p&#60;0.01, Table 1).
Sucrose preference test 
At the start of the experiment (day 0), there was no difference in the percent of sucrose preference between the experimental group of rats induced with a...

Watch this Scientific Journal Video about A Complex Diving-For-Food Task to Investigate Social Organization and Interactions in Rats at JoVE.com

A Complex Diving-For-Food Task to Investigate Social Organization and Interactions in Rats

This protocol describes a method of examining social hierarchy in a rat model. Rats perform a complex diving-for-food task in which they form a distinct hierarchy according to their willingness to dive underwater and swim to obtain a food pellet. This method is used to understand decision making and social relationships among highly social animals in small groups.

For many species, where status is a vital motivator that can affect health, social hierarchies influence behavior. Social hierarchies that include ...

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