ABSTRACT
The basolateral amygdala has been implicated in the regulation of food intake besides the hypothalamic centres. In the present study, we hypothesized that the Orexin B, a polypeptide identified in the lateral hypothalamic region, may be involved in the modification of the functions the of amygdaloid centres. We therefore studied the effect of infusion of Orexin B and its antagonist (TCS-OX2-29) into Basolateral amygdala to study the feeding behaviour. Materials and methods: Adult male Wistar albino rats were selected and grouped into control, sham operated control and experimental groups (n=6 each) Orexin was infused in two doses (3 nmol/μl, 30 nmol/ μl) and TCS-OX2-29(10 μg/μl) was infused in another group. Sequential Food intake and water intake were measured at 1, 2, 4, 6, 12 hours and intake for the day was also recorded in all groups and the results (mean±SEM) were statistically analyzed by Kruskal Wali’s test and p<0.05 was considered significant. Results: The food intake and water intake were significantly increased (p<0.01) in the high dose group though the increase in the low dose treated animals was less. Injection of Orexin B antagonist decreased the food and water intake significantly. Discussion and conclusion: The results suggest that Orexin plays a role in the modulation of feeding behaviour. In the lower doses it did not show significant effect. At higher doses, the effect was marked. The role of orexin in ingestive behaviour is further confirmed by the action of antagonist infusion, which resulted decrease in the feeding activities.
ABSTRACT
Background: Effect of administration of Orexin-A into nucleus accumbens (NAcc) in relation to the regulation of feeding behavior and alcohol consumption at specific time intervals is relatively unknown. Materials and methods: In this study, Male Wistar albino rats (n=54) weighing about 250±10 grams were implanted bilaterally with guide cannula (22 gauze) to target NAcc by stereotaxic surgery. Saline (0.9%) for control and Orexin-A for experimental groups (100 pmol or 250 pmol) were infused by Harvard picoplus pump. Food, water and alcohol (10%) consumption were measured at 1, 2, 4 and 24 hours to evaluate the effect of Orexin-A in fasted rats (24 hours). Preference study was carried out by two bottle choice test. Results: Orexin-A infusion into NAcc showed significant increase in food at 1 hr in all groups compared to controls (p<0.05) and alcohol (p<0.02) intake. The changes were dose dependent. There was no noticeable preference or alcohol. Conclusions for: These findings showed that Orexin-A in NAcc could be involved in feeding and drinking but not alcohol preference. The results highlight the effect of Orexin A infusion into NAcc in consummatory behaviour besides other hypothalamic and mesolimbic centres.