[GABAergic mechanism of the cerebrovascular effect of melatonin].

In most experiments on rats under conditions of cerebral global transient ischemia, melatonin substantially enhanced local blood flow and decreased arterial blood pressure. In intact rats, the effect of melatonin on brain perfusion was much less pronounced and the arterial pressure was not influenced at all. The mechanism of melatonin action has been studied with the aid of bicuculline. It is established that the cerebrovascular activity of the epiphyseal hormone is mediated by GABA-A receptors of cerebral vessels. Melatonin (in doses of 1.0 and 5.0 mg/kg) significantly increased survival of rats under conditions of hypergravity ischemia.