Amantadine in the treatment of neuroleptic-induced obesity in rats: behavioral, endocrine and neurochemical correlates.

The efficacy of the antiviral agent Amantadine (AM, 5-100 mg/kg/sc, ip or intrahypothalamically, 12.5-100 micrograms bilaterally) in influencing body weight and food intake in drug-free rats, and in preventing neuroleptic-induced weight gain, was assessed in adult female rats. In drug-free rats, acute administration of systemic AM or directly injected in the lateral hypothalamus (LH) displayed a significant dose-dependent anorectic effect (p < 0.001). This effect could be mediated by the brain monoaminergic system, because systemic or local injections of AM increased dopamine and serotonin overflow in the nucleus accumbens and in the LH. Chronic administration of AM significantly decreased body weight gain in drug-free rats only at the dose of 100 mg/kg/sc. Similarly, obesity induced by the neuroleptic drug sulpiride (SUL, 20 mg/kg/ip for 21 days) was prevented by AM only at the dose of 100 mg/kg. AM did not prevent SUL-induced hyperprolactinemia, disruption of the vaginal cycle and a decrement in the weight of the uterus and ovaries at any dosage. This lack of efficacy of AM contrasts with that of bromocriptine, which completely prevented SUL-induced weight gain and hyperprolactinemia. The results show that despite a potent acute anorectic effect, AM displays a weak antagonistic action on SUL-induced obesity in rats, in contrast to the preliminary results obtained in humans. As AM metabolism differs in humans and rats, additional research is needed before its systematic testing in counteracting neuroleptic-induced obesity in patients with mental disorders.