Effect of sulpiride injection into ventromedial nucleus of hypothalamus on food and water intake and weight in male rats

Weight gain, obesity and hyperprolactinemia are important complications of long-term administration of neuroleptic drugs, which may affect the patient's general health and well- being that itself interferes with treatment compliance. The purpose of this study was to identify the mechanism of occurrence of these side-effects. Because of the important role of ventromedial nucleus of hypothalamus (VMN) in the regulation of food intake, effect of sulpiride, a D2 antagonist on food intake was evaluated. For this purpose, 28 adult male rats weighing 280-320 g were used. Cannulae were implanted bilaterally in the VMN. After recovery period, rats were divided into 4 groups and 3 out of them received different doses of sulpiride (4, 8, and 16 µg/0.5 µl). Sham-operated group received daily injection of the vehicle of sulpiride (HCl 0.1 N) through the cannula for seven consecutive days. Food and water intake was measured daily for 7 days and then, mean food and water intake for 24 h was calculated. The results showed that sulpiride increases food and water intake at all doses, but body weight only increases at doses of 8 and 16 µg. It can be concluded that blockade of D2 dopamine receptors in VMN is involved in hyperphagic and dipsogenic effect of neuroleptic drugs, even in rats with no food restriction.