Increase of locomotor activity by acupuncture on Bai-Hui point in rats.

The effect of acupuncture on locomotor activity was investigated in rats. Stimulation with acupuncture inserted in Bai-Hui point, which is located at the vertex of the head, increased the spontaneous locomotor activity of rats measured in ANIMEX meter. This effect was obtained in rats which received acupuncture significantly at 60 min later as compared with sham-treated control. The sleeping time induced by hexobarbital was also reduced markedly in rats receiving acupuncture. An activation of the central nervous system by acupuncture at Bai-Hui point can thus be considered. This action was unrelated to opioids because naloxone failed to modify it. Increase in locomotor activity was abolished by an intraperitoneal (i.p.) injection of alpha-methyl-p-tyrosine (200 mg/kg) at 2 h before insertion of acupuncture. Deprenyl at the dose sufficient to elevate monoamine enhanced this action of acupuncture. Mediation of cerebral monoamines can also be considered. This view was supported by the dose-dependent inhibition of chlorpromazine. Action of acupuncture was not observed in apomorphine (0.5 mg/kg, i.p.)-treated rats, probably due to an activated receptor of dopamine. Otherwise, action of acupuncture was enhanced by para-chlorophenylalanine, the depleter of endogenous 5-hydroxytryptamine (5-HT), and eliminated by 5-hydroxytryptophan, the precursor of 5-HT, in the initial stage of insertion. Participation of 5-HT can be considered as an initial way in rats that received acupuncture at Bai-Hui point. These results suggested that stimulation of Bai-Hui point with acupuncture can activate central neurotransmission of monoamines to increase the spontaneous locomotor activity in rats.