Paraventricular nucleus-microinjected glucose increases food intake in 18 h food-deprived rats: A central regulatory mechanism on serum ghrelin and leptin levels

Our previous study demonstrated that glucose acts in hypothalamic paraventricular nucleus (PVN) to increase gastric acid secretion. However, there is no evidence to show the role of the hypothalamic PVN-microinjected glucose on food intake. On the other hand, it is known that ghrelin and leptin play important roles in food intake. The current study investigated the association between PVN-microinjected glucose and food intake and plasma ghrelin-leptin levels. After the PVN microinjection of glucose, food intake was measured. In other groups, ELIZA kits were used to obtain ghrelin, leptin, insulin and glucose concentrations. All experiments were done in18 h food-deprived rats. The findings revealed that the PVN-microinjected glucose increased food intake in a dose-dependent manner. The stimulatory effect of glucose persisted for more than 2 h. Interestingly, it was found that PVN microinjection of glucose stimulates plasma ghrelin and decreases plasma leptin levels without any effect on plasma insulin and glucose concentrations over 1 h. The results of the present study suggest that the PVN glucose-mediated cells may be involved in the regulatory mechanisms of food intake. This stimulatory effect seems to be mediated, at least in part, through central nervous system regulatory mechanisms of plasma leptin and ghrelin levels.