Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

Summary

The present protocol describes a rat model of fluid percussion-induced traumatic brain injury followed by a series of behavioral tests to understand the development of dominant and submissive behavior. Using this model of traumatic brain injury in conjunction with specific behavioral tests enables the study of social impairments following brain injury.

Abstract

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social hierarchies that are often based on dominant-submissive relationships. The dominant-submissive relationship is a normal behavioral pattern among the individuals of a species. Traumatic brain injury is a frequent cause of social interaction impairment and the reorganization of dominant-submissive relationships in animal pairs. This protocol describes submissive behavior in adult male Sprague-Dawley rats after the induction of traumatic brain injury using a fluid-percussion model compared to naive rats through a series of dominant-submissive tests performed between 29 days and 33 days after induction. The dominant-submissive behavior test shows how brain injury can induce submissive behavior in animals competing for food. After traumatic brain injury, the rodents were more submissive, as indicated by them spending less time at the feeder and being less likely to arrive first at the trough compared to the control animals. According to this protocol, submissive behavior develops after traumatic brain injury in adult male rats.

Introduction

Intraspecies competition occurs when members of the same species compete for a limited resource at the same time¹. In contrast, interspecies competition occurs between members of two different species². Intraspecies competition is divided into two types, including interference (adapted) and exploitation (contest), and arises depending on the type of resource in contention, such as food and territory³.

The existence of social hierarchies is impossible without dominant-submissive relationships (DSRs). Dominance presents as "winning" and subordination as "losin....

Protocol

The experiments were approved by the Animal Care Committee of the Ben-Gurion University of the Negev.The experiments were performed following the recommendations of the Declarations of Helsinki and Tokyo and the Guidelines for the Care and Use of Laboratory Animals of the European Community. Adult male Sprague-Dawley rats, weighing 300-350 g, were used in the present study. The animals were housed at a room temperature of 22 °C ± 1 °C and a humidity of 40%-60% with light-dark cycles.

1. Animal preparation

1. Select at random 30 adult male rats, and divide them into two groups: TBI and sham.

Results

Neurological severity score assessment
Neurological deficits were assessed in male rats after TBI using the NSS. The rats were divided into two groups: one TBI group and one control group. The control group was subjected to sham surgery. The NSS allowed for the assessment of motor function and behavior alteration by a points system^22,23; a score of 24 indicated a severe neurological dysfunction, and a score of 0 represented intact neurologica.......

Discussion

Clinical studies indicate that brain injury may increase the risk of psychiatric disorders^26,27. Moreover, TBI affects the development of social behavior^28,29. In this protocol, the TBI model had an effect on the presentation of dominant-submissive behavior. Dominant-submissive behavior manifested itself in terms of time spent on the feeder and who came first to the feeder.

In .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
2% chlorhexidine in 70% alcohol solution	SIGMA - ALDRICH	500 cc	For general antisepsis of the skin in the operatory field
4 boards of different thicknesses (1.5 cm, 2.5 cm, 5 cm and 8.5 cm)	This is to evaluate neurological defect
4-0 Nylon suture	4-00
Bottles	Techniplast	ACBT0262SU
Bupivacaine 0.1 %
Diamond Hole Saw Drill 3 mm diameter	Glass Hole Saw Kit		Optional.
Digital Weighing Scale	SIGMA - ALDRICH	Rs 4,000
Dissecting scissors	SIGMA - ALDRICH	Z265969
Ethanol 99.9 %	Pharmacy		5%-10% solution used to clean equipment and remove odors
Fluid-percussion device	custom-made at the university workshop		No specific brand is recommended.
Gauze Sponges	Fisher
Gloves (thin laboratory gloves)			Optional.
Heater with thermometer	Heatingpad-1	Model: HEATINGPAD-1/2	No specific brand is recommended.
Horizon-XL	Mennen Medical Ltd
Isofluran, USP 100%	Piramamal Critical Care, Inc	NDC 66794-017	Anesthetic liquid for inhalation
Logitech Webcam Software	Logitech	2.51	Software for video camera
Operating forceps	SIGMA - ALDRICH
Operating Scissors	SIGMA - ALDRICH
PC Computer for USV recording and data analyses	Intel		Intel core i5-6500 CPU @ 3.2GHz, 16 GB RAM, 64-bit operating system
Plexiglass boxes linked by a narrow passage			Two transparent 30 cm × 20 cm × 20 cm plexiglass boxes linked by a narrow 15 cm × 15 cm × 60 cm passage
Purina Chow	Purina	5001	Rodent laboratory chow given to rats,  is a lifecycle nutrition that has been used in biomedical research
Rat cages (rat home cage or another enclosure)	Techniplast	2000P	No specific brand is recommended
Scalpel blades 11	SIGMA - ALDRICH	S2771
SPSS	SPSS Inc., Chicago, IL, USA	A 20 package
Stereotaxic Instrument	custom-made at the university workshop		No specific brand is recommended
Timing device	Interval Timer:Timing for recording USV's		Optional. Any timer will do, although it is convenient to use an interval timer if you are tickling multiple rats
Video camera	Logitech	C920 HD PRO WEBCAM	Digital video camera for high definition recording of rat behavior under dominant submissive test