Nervous Control of Thyroid Activity. I. Effect of Pilocarpin and Adrenalin on Metamorphic Action of Thyreoactivator

Abstract

In the experiments reported here we have used amphibian metamorphosis (in the larvae of Ambystoma tig&zunz) as a physiological sign of the effects of the thyroid hormone, pilocarpin and adrena h as stimulators of the parasympathetic and sympathetic nervous system respectively, and injections of thyreoactivator from the anterior lobe of the beef hypophy~is'~ as an activator of the thyroid function.When pilocarpin or adrenalin alone is injected intraperitoneally, no visible effect on metamorphosis is obtained. It will be shown here that the injection of either of these drugs together with thyreoactivator increases the sensitivity of the larvae to the metamorphic action of the thyreoactivator.In one representative experiment (CCCLVI, 1933) a number of the larvae of the tiger salamander were divided into 4 groups : Group "a", controls injected with Ringer solution; Gruup "b, c and d" received triweekly intraperitoneal injections of thyreoactivator extracted from approximately 30 mg. dried anterior lobe, per animal and injection ; group "c" received in addition triweekly injections of 2 mg. pilocarpin-hydrochloride ( Merck) per animal and injection ; group "d" received in addition triweekly injections of 0.05 mg. adrenalin-chloride, 1 :lo00 (Parke, Davis Company), per animal and injection.