Evaluation of weight, caloric intake, and behavior of rats after bilateral ablation of the nucleus accumbens shell

Abstract

Introduction: Deep brain stimulation and ablation of certain regions of the brain are being widely used in research aiming to link some region of the cortex with certain psychiatric disorders. The nucleus accumbens, for example, belonging to the basal ganglia, responsible for modulating the reward system and limbic-motor integration, according to studies, is related to the pathophysiology of alterations in neurotransmitters and neuronal connections in anorexia nervosa. Research in animals and humans reinforces this theory. Objective: To evaluate whether even in healthy rats, it is possible to observe changes in eating patterns and behavior that would justify such relationship. Materials and methods: A total of 24 female Wistar rats were randomly divided into experimental group (n=20) and control group (n=4). The rats in the experimental group underwent surgery with bilateral ablation of the nucleus accumbens shell using a stereotactic-guided radiofrequency needle. After surgery, the rats had their weights and caloric intake measured daily. Their behavior was empirically observed and then compared with that exhibited by the control group. Results: Regarding behavioral changes, it was observed an exaggerated increase in grooming, sniffing, searching/exploration, and avoidance/escape. Aggressiveness was present in only one animal of the experimental group. Regarding weight gain and caloric intake, a statistically significant relationship was found between them in relation to the time after the surgical intervention, when comparing the experimental and control groups. Discussion/Conclusion: In this study we investigated whether even in healthy rats, performing an inhibition – ablation of the Nucleus Accumbens – would cause an increase in caloric intake and consequently weight of the rats, and whether the procedure would cause changes in their behavior. From the results obtained we can infer that such assumption is true. Moreover, other research, both in humans and animals, support the data and the connection of the Nucleus Accumbens given by the reward system, to psychiatric disorders, in this case, anorexia nervosa. More investigations are necessary to further elucidate such interactions and consequences.