Abstract
Behavioral and EEG effects of water soluble fraction extracted from Zingiber mioga RoscoE (Z. mioga) were investigated in mice, rats and rabbits. Z. mioga was dissolved in isotonic saline and given i.p. into mice and rats, and i.v. into rabbits, respectively. Z. mioga at doses of 50 ?? 400 mg/kg produced a marked reduction in locomotor activity of mice in the open-field test. The peak time of reduction was 30 min after the injection. In mice, Z. mioga at the same doses lowered significantly the rectal temperature and prolonged the sleeping time induced by thiopental-Na (40 mg/kg, i.v.). Z. mioga at a dose of 400 mg/kg had no anticonvulsant effects and it produced a slight muscle relaxation in mice. Z. mioga at doses of 50 ?? 200 mg/kg induced a significant inhibition of the active conditioned avoidance response of the rat in a shuttle box without affecting the unconditioned escape response. In the step-down method, however, the passive conditioned avoidance response was rarely affected by Z. mioga, but the response was suppressed by chlorpromazine. In rabbits with chronically implanted electrodes, Z. mioga at doses of 20 ?? 30 mg/kg induced a drowsy pattern of spontaneous EEG, i.e. high voltage slow waves in the neocortex and amygdala, and desynchronization in the case of hippocampal theta waves. The EEG arousal response to the external auditory stimulation was inhibited by the same doses of Z. mioga, whereas it failed to suppress the arousal response to either the midbrain reticular or posterior hypothalamic stimulation, as with chlorpromazine. Neither the recruiting response nor the photic driving response were affected by Z. mioga. On the other hand, the limbic after-discharges to the hippocampal or amygdaloid stimulation were enhanced by Z. mioga as well as chlorpromazin, but they were inhibited by diazepam. The EEG effects of Z. mioga were qualitatively similar to chlorpromazine, but not to diazepam. These results indicate the similarty of behavioral and EEG effects of Z. mioga to those seen with neuroleptics such as chlorpromazine.
