抄録
A study was made to clarify the mechanisms of amyostatic action of Lyoniol-A isolated from Lyonia ovalifolia var. elliptica. In the intact mice, intraperitoneal injection of 5 mg/kg of Lyoniol-A caused postures characterized by torsion, retrocollis, spasm, and locomotive ataxia. These postures were also observed in rats, chicks, and frogs. Lyoniol-A in a concentration of 5×10-6 g/ml did not alter the twitches of both isolated frog sartorius muscle and rat diaphragm elicited by a nerve stimulation. Intravenous injection of 1 mg/kg of Lyoniol-A produced contraction of the guinea-pig ileum in situ, whereas 5×10-6 g/ml of it did not have any effect on the responsiveness of the isolated Guinea-pig ileum, suggesting that the autonomic response to Lyoniol-A was via the central nervous system. A small dose of Lyoniol-A injected intraventricularly produced an immediate effect in mice. In the intact chicks as well as in the spinal ones, Lyoniol-A slightly enhanced the crossed extensor reflex. In evoked electromyogram in chicks, intravenous injection of 2 mg/kg of Lyoniol-A induced late responses, which seemed to be due to the interference with spinal and supraspinal structures. From these results the possible mode of action of Lyoniol-A is discussed.
