Etanercept treatment prevents emotional memory deficits of cafeteria diet-fed rats

Abstract

Background: Obesity has been shown to degrade cognitive functions, including memory. Recent evidence suggests that obesity also results in inflammation in the brain. In this study we investigated the effect of etanercept (a TNF-α inhibitor) on emotional memory in cafeteria diet (CD)-fed rats.Methods: Six-week-old male Wistar Albino rats (300-350 g) were divided into three groups (n=10): Control (not exposed to CD), CD-fed (exposed to CD during 5 weeks) and CD-fed+etanercept (exposed to CD and treated with etanercept (0.8 mg/kg/weekly/ subcutaneously during 5 weeks). CD was used to generate diet-induced obesity. The body weights of animals were measured weekly. To determine the effects of CD and etanercept treatment on emotional memory, passive avoidance test (PAT) was used. Total locomotor activity (TLA) was also measured. One-way ANOVA and Tukey’s post hoc test used for statistical analysis. Results: After 5 weeks, the body weight of CD-fed group was higher than control (p<0.001) and CD-fed+etanercept group was lower than CD-fed group (p<0.05). There was no difference between all groups in terms of TLA (F(2,27)=0.6212, p=0.5448). In the PAT, there was no difference between the first day latency of animals (F(2,27)=0.4524, p=0.6408). The retention latency significantly decreased in CD-fed group compared to control group (p<0.05), while there was no difference between CD-fed+etanercept group and control group (p>0.05). Conclusions: Treatment with etanercept reverses the deleterious effects of obesity on emotional memory. Thus, a role for inflammation in mediating memory dysfunction presents an important avenue for the development of therapies to treat memory deficits in obesity.