Possible involvement of the dopamine D2 receptors of ventromedial hypothalamus in the control of free- and scheduled-feeding and plasma ghrelin level in rat.

Objectives: We investigated effect of the ventromedial hypothalamus (VMH) dopamine D2 receptor inhibition on food intake and plasma ghrelin following chronic free or scheduled meal with different caloric intakes.

Methods: Male Wistar rats (220-250 g) were fed diets containing free (control) or three scheduled diets of standard, restricted and high-fat for 1 month. The animals stereotaxically received an intra VMH single dose of sulpiride (0.005 µg)/or saline (0.5 µL) before meal time. Thirty minutes later, food intake and circulating ghrelin were measured.

Results: Sulpiride significantly reduced food intake and ghrelin concentration in freely fed and scheduled-standard diet (p<0.05), while increased food intake, with ghrelin level on fasted level in scheduled-restricted group (p<0.01) compared to control. Food intake and ghrelin concentration between scheduled-high fat and freely fed or scheduled-standard diets did not show significant changes.

Conclusions: The VMH D2 receptors are possibly involved in controlling scheduled eating behavior, depending on energy balance context.