A Complex Diving-For-Food Task to Investigate Social Organization and Interactions in Rats
May 8th, 2021
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.
This protocol describes a method of examining social hierarchy in a rat model. All the rats perform a complex diving for food task in which they form a distinct hierarchy according to the willingness to dive under water and swim to obtain a food pellet. This method is used to understand decision-making and social relationship among highly social animals in small groups.
Select adult male Sprague Dawley rats weighing 300 to 350 gram. Provide rat chow and water ad libitum. Perform all experiments between 6:00 am and 12:00 pm.
Maintain rats at room temperature of 22 Celsius degrees with 12 hour light and 12 hour dark cycles. A timeline of the experimental protocol. Randomly select 120 rats into one of three experimental groups.
Group one, N equals 60, will be used as a control group. Group two, N equals 30, will be induced with depression. Group three, N equals 30, will also be induced with depression and will subsequently be treated with antidepressant drugs.
Some cross preference tests performed prior and after induction of chronic unpredictable stress and after complex diving for food task. The following stressors are introduced in random order. Group housing by placing six rats per cage for 18 hours.
Tilted cage placement for three hours 45 degrees along the vertical axis. Food deprivation for 18 hours. Water depravation for 18 hours followed by immediate exposure to an empty water bottle.
Soft cage placement for eight hours consisting of 300 milliliters of water spilled into bedding. Continuous lighting and reverse light dark cycle for 48 hours per week And five minutes hot environment at 40 degrees Celsius. Rats are exposed to two of the seven stressors daily in a random order.
One in the daytime, and the second at night for five sequential weeks. Rats from group three are administered antidepressant treatment with amicrom hydrofloride, tricyclic antidepressant 20 milligrams per kilo intraperitoneally once per day for three weeks. Group two of the control group is administered 0.9%saline placebo intraperitoneally once per day for three weeks at the same volume as the antidepressant treatment group.
Prepare apparatus and acclimate rats. Connect two cages 50 on 50 on 50 centimeters to an aquarium 130 on 35 on 50 centimeters via tunnels. Place tubes with food pellets, one food pellet in each tube at one end of the aquarium.
Mark all six rats with different colored marker at the beginning of the experiment to allow individual identification. At any given moment, six rats participated in the experiments simultaneously. Three of them served as control group one and the other three were either depressive group two, or depressive after treatment, group three.
On day one of the experiment, introduce each group of rats to experimental apparatus without water for three hours session. Return rats to standard cage after session. Video-record rats in the apparatus continuously during the three hours session.
Repeat these sessions for days two and three. On days four til 17, add water progressively until maximum water level is reached. On day 17 til 21, maintain maximum water level.
Observe rats diving to access pellets. Record the following parameters. Frequency of entries into tunnel, diving for food, food obtained by attack, food obtained by carrying, and time spent in separate cages.
During the dark cycle place the rats in individual cages in the same room as the housing. Place a bottle of 100 milliliter 1%weight volumes sucrose solution in each cage for 24 hours and allow for adaptation. Remove the bottles and deprive the rats of food and water for 12 hours.
Place two bottles, one containing 100 milliliter of sucrose solution, 1%weight volume and the other 100 milliliter of tap water in each case for four hours. Record the volume in milliliters of both the consumed sucrose solution and water and calculate their affinity to sucrose preference as follows. Sucrose preference in percentage equals sucrose consumption in milliliters, divided by sucrose consumption and milliliters plus water consumption in milliliters.
All times 100%Body weight changes A one way Nova test did not show any differences in changes in body weight between experimental groups for the 21 days of the complex diving for food task. From days to two to 21, there were changes in body weight for all three groups, p-value was less than 0.01. Rats with depressive like symptoms were more active and aggressive than control rats.
Rats induced with the aggressive light behavior showed an increase of entries into the tunnel 130%plus minus 3.7 p value less than 0.01. Diving for food 141%plus minus seven, p value less than 0.01. Food obtained by a pairing, 168%plus minus 12, p value less than 0.01.
Time spent in separate cages 123%plus minus 7.9, p value less than 0.01, and food obtained by attack, 232%plus minus 26, p value less than 0.01. Compared to depressive rats that received antidepressant therapy, 67%plus minus 3.4, 54%plus minus five, 53%plus minus six, 55%plus minus 4.7, 44%plus minus seven respectively. The differences the rats induced with depressive like symptoms and depressed rats treated with antidepressant were statistically greater than the differences between the rats induced with depressive like symptoms and the control group in all five parameters of the complex diving for food tests, p value less than 0.05.
There was no difference in sucrose consumption at the beginning of the experiment. By day 35 of the experiment, the depression group p-value less than 0.01. And the depression group treated with antidepressant therapy, p value less than 0.01 had a significantly lower percent sucrose preference than the control group.
On day 62, the rats induced with depressive like symptoms had a lower percents across preference compared to both the control and the depression group treated with antidepressant treatment, p valued less than 0.05.Conclusion. The complex diving for food task can allow us to assess the relationship between the wide range of mental illness and social organization as well as to study the effectiveness of therapy and social dysfunction. Thank you very much for your attention.
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Overview
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.
Key Study Components
Area of Science
- Neuroscience
- Behavioral Science
- Animal Models
Background
- Understanding social hierarchy is crucial in studying social behaviors.
- Rats are highly social animals that exhibit complex social structures.
- Decision-making processes can be influenced by social dynamics.
- This method allows for observation of interactions in a controlled setting.
Purpose of Study
- To investigate social hierarchy formation in rats.
- To analyze decision-making behaviors in a competitive food acquisition task.
- To enhance understanding of social relationships among group-living animals.
Methods Used
- Select adult male Sprague Dawley rats weighing 300 to 350 grams.
- Provide rat chow and water ad libitum.
- Conduct experiments between 6:00 am and 12:00 pm.
- Utilize a diving-for-food task to assess hierarchy.
Main Results
- Rats establish a clear hierarchy based on their diving willingness.
- Social interactions influence individual decision-making in food acquisition.
- Behavioral patterns reflect underlying social structures.
- The method provides insights into social dynamics in small groups.
Conclusions
- The diving-for-food task is effective for studying social hierarchies.
- Findings contribute to understanding social behavior in rats.
- This model can be applied to further research on social decision-making.
Frequently Asked Questions
Executive Industry Relevance
This protocol enables biopharma researchers to model complex social hierarchies in rats, offering a translational system to study how psychiatric conditions alter social decision-making and group dynamics. By quantifying behavioral outputs such as diving frequency, food acquisition, and sucrose preference, the method supports mechanistic de-risking of CNS-targeted therapeutics. It provides a disease-relevant system for evaluating therapeutic effects on social dysfunction, a domain increasingly relevant in neuropsychiatric drug development.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Interrogates therapeutic hypotheses by linking depressive-like phenotypes to altered social hierarchy formation and competitive food-seeking behavior.
- Operational Value: Enables functional target validation through quantifiable changes in diving behavior and social interaction patterns across experimental groups.
- Scientific Value: Supports predictive confidence by demonstrating reversal of depressive-like social deficits with antidepressant treatment, indicating target engagement.
Screening & Assay Development
- Scientific Value: Prepares validated biological systems for downstream screening by establishing stable, quantifiable social behavioral readouts.
- Operational Value: Addresses assay standardization through consistent measurement of tunnel entries, diving frequency, food obtained by attack or carrying, and time in separate cages.
- Operational Value: Highlights screening readiness via longitudinal tracking of behavioral changes over 21 days of task exposure and subsequent sucrose preference testing.
Translational & Preclinical Research
- Scientific Value: Discusses disease relevance by modeling depressive-like symptoms through chronic unpredictable stress and measuring resultant social withdrawal and altered decision-making.
- Operational Value: Describes continuity from discovery through preclinical validation by showing antidepressant treatment normalizes hyperactive, aggressive, and food-seeking behaviors.
- Scientific Value: Focuses on predictive de-risking by demonstrating that treated depressive rats show statistically significant improvement in all five behavioral parameters compared to untreated depressive rats.
Pipeline & Workflow Integration
The method fits within the discovery continuum from target hypothesis testing to lead identification, particularly for CNS disorders where social withdrawal and anhedonia are core symptomatology.
- Discovery Biology: Explains how the method supports hypothesis testing by linking stress-induced depressive states to measurable changes in social hierarchy and food-motivated behaviors.
- Screening: Describes assay readiness through reproducible quantification of diving behavior, food acquisition strategies, and sucrose preference as quantitative endpoints.
- Analytics: Highlights measurements such as frequency of tunnel entries, diving for food, food obtained by attack or carrying, and time in separate cages as analyzable outputs for group comparison.
- Translational Research: Connects the method to preclinical continuity by showing antidepressant treatment reverses behavioral phenotypes, supporting risk-adjusted advancement decisions.
- Enterprise Reuse: Frames the method as a reusable capability for evaluating multiple compounds targeting social dysfunction in neuropsychiatric disorders.
Operational & Enterprise Impact
- Scientific Value: Predictive confidence in target modulation through behavioral normalization following antidepressant intervention.
- Operational Value: Standardization and reproducibility via defined behavioral metrics and longitudinal tracking across experimental phases.
- Strategic Value: Better go/no-go decisions by quantifying therapeutic effects on complex social behaviors relevant to depression and related disorders.
- Portfolio Impact: Risk-adjusted prioritization based on ability of candidates to rescue stress-induced social behavioral deficits.
Implementation Considerations
- Required scientific expertise in behavioral neuroscience and rodent handling for complex task execution and video-based behavioral scoring.
- Instrumentation and analytical infrastructure needs include aquatic maze apparatus, food-delivery tubes, video recording systems, and sucrose preference testing setup.
- Cross-team standardization requirements for consistent stress induction, antidepressant dosing, and behavioral parameter definition across study sites.
- Adaptation considerations across model systems, particularly regarding species-specific diving propensity and stress reactivity in non-rat models.
- Practical limitations include the need for prolonged acclimation (up to 21 days) and careful monitoring of stressor exposure to avoid confounding welfare effects.
Biopharma FAQs
Chapters in this video
0:00
Introduction
0:43
Preparing Rats for the Experimental Procedure
2:14
Induction of Depression in Rats
3:16
Anti-depression Therapy
3:58
The Social Organization Test (Complex Diving-for-Food Task)
5:19
Performing Diving-for-Food Task
6:03
Assessment of Depressive-like Behavior: The Sucrose Preference Test
7:14
Representative Results
