Experimental pharmacological study on partial sympathicotonia in restraint and water immersion stressed animals

In order to obtain evidences supporting the previous suggestion that restraint and water immersion stressed (RWIS) animals are possibly in the state of partial sympathicotonia, further investigations have been carried out. 1) In the experiment on the influence from the adrenal, the preadministration of dexamethasone, spironolactone or metopirone did not affect the enhancement of response to acetylcholine (ACh) of the duodenum isolated from RWIS mice, while adrenalectomy inhibited both the enhancement of response to ACh and the reduction of response to noradrenaline (NA) of isolated duodenum and vas deferens of RWIS mice. The potentiation of the response to ACh of the duodenum isolated from the adrenalectomized RWIS mouse, on the other hand, was little affected by the pretreatment of dexamethasone. These results suggest that in the RWIS animal the influence from the adrenal medulla is greater than that from the adrenal cortex. 2) In the experiment on the influence from the autonomic nervous system, the treatment of RWIS mice with an adrenergic neuron degenerating agent to cause chemical denervation was found to suppress the potentiation of the response to ACh of isolated duodenum and vas deferens, suggesting the participation of the adrenergic neuron. A vagotomy showed little effect on responses either to ACh or NA of isolated duodenum and vas deferens from RWIS mice. A sympathectomy, however, suppressed these changes in responses, particularly reduction of response to NA was markedly inhibited to the normal level. These findings indicate that the excessive sympathicotonic state in the RWIS animal was remitted by sympathectomy. It may be concluded that the results of present investigations utilizing adrenalectomy, vagotomy and sympathectomy may present evidences for the previous suggestion that the RWIS animal might be in the state of partial sympathicotonia.