[Pharmacological study of nicergoline. (I): Protective effect against anoxic brain damages in animals]

The protective effects of nicergoline (NCG) against anoxic brain damages in animals were compared with those of dihydroergotoxine (DHE) and phentolamine (PTA). NCG (16 mg/kg, i.p.) prolonged the survival time of mice under hypobaric hypoxia, but DHE and PTA shortened the time. NCG (1-16 mg/kg, i.p. and 16-64 mg/kg, p.o.), like DHE, dose-dependently prolonged the survival time of mice after a lethal dose of KCN (3 mg/kg, i.v.), but PTA did not. NCG (8-128 micrograms/kg, i.v.), like DHE, dose-dependently protected against disappearance of EEG of rats in histotoxic anoxia induced by a sublethal dose of KCN (1.5 mg/kg, i.v.), but PTA did not. Its protective effect was 10 times or more stronger than that of DHE. NCG (1-16 mg/kg, i.p.) dose-dependently promoted recovery from behavioral disorders and disturbance of cerebral energy metabolism of mice in histotoxic anoxia induced by a sublethal dose of KCN (1.8 mg/kg, i.v.). NCG (100 microM), like DHE, showed antagonistic action against inhibition of cerebral cytochrome oxidase activity by KCN, but PTA did not. The ED50 values of NCG, DHE and PTA for the protective effect against adrenaline-induced death in mice were 1.18, 0.27 and 0.35 mg/kg (i.p.), respectively. 7) These results suggest that NCG may show protective effects against the anoxic brain damages due to its ameliorating action on cerebral energy metabolism, mainly contributed by an activation of cerebral cytochrome oxidase, without relation to its alpha-blocking action.