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.

Laser-Induced Brain Injury in the Motor Cortex of Rats.

A common technique for inducing stroke in experimental rodent models involves the transient (often denoted as MCAO-t) or permanent (designated as MCAO-p) occlusion of the middle cerebral artery (MCA) using a catheter. This generally accepted technique, however, has some limitations, thereby limiting its extensive use. Stroke induction by this method is often characterized by high variability in the localization and size of the ischemic area, periodical occurrences of hemorrhage, and high death rates. Also, the successful completion of any of the transient or permanent procedures requires expertise and often lasts for about 30 minutes. In this protocol, a laser irradiation technique is presented that can serve as an alternative method for inducing and studying brain injury in rodent models. When compared to rats in the control and MCAO groups, the brain injury by laser induction showed reduced variability in body temperature, infarct volume, brain edema, intracranial hemorrhage, and mortality. Furthermore, the use of a laser-induced injury caused damage to the brain tissues only in the motor cortex unlike in the MCAO experiments where destruction of both the motor cortex and striatal tissues is observed. Findings from this investigation suggest that laser irradiation could serve as an alternative and effective technique for inducing brain injury in the motor cortex. The method also shortens the time for completing the procedure and does not require expert handlers.

Induction of Diffuse Axonal Brain Injury in Rats Based on Rotational Acceleration.

Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large percentage of TBI patients requiring hospitalization. DAI involves widespread axonal damage from shaking, rotation or blast injury, leading to rapid axonal stretch injury and secondary axonal changes that are associated with a long-lasting impact on functional recovery. Historically, experimental models of DAI without focal injury have been difficult to design. Here we validate a simple, reproducible and reliable rodent model of DAI that causes widespread white matter damage without skull fractures or contusions.

Inducing Acute Liver Injury in Rats via Carbon Tetrachloride (CCl4) Exposure Through an Orogastric Tube.

Acute liver injury (ALI) plays a crucial role in the development of hepatic failure, which is characterized by severe liver dysfunction including complications such as hepatic encephalopathy and impaired protein synthesis. Appropriate animal models are vital to test the mechanism and pathophysiology of ALI and investigate different hepatoprotective strategies. Due to its ability to perform chemical transformations, carbon tetrachloride (CCl4) is widely used in the liver to induce ALI through the formation of reactive oxygen species. CCl4 exposure can be performed intraperitoneally, by inhalation, or through a nasogastric or orogastric tube. Here, we describe a rodent model, in which ALI is induced by CCl4 exposure through an orogastric tube. This method is inexpensive, easily performed, and has minimal hazard risk. The model is highly reproducible and can be widely used to determine the efficacy of potential hepatoprotective strategies and assess markers of liver injury.