Abstract
In the experiments reported here we have used amphibian metamorphosis (in the larvae of Ambystoma tigrinum) as a physiological sign of the effects of the thyroid hormone, pilocarpin and adrenalin as stimulators of the parasympathetic and sympathetic nervous system respectively, and injections of thyreoactivator from the anterior lobe of the beef hypophysis 1 - 4 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; Group “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, 1:1000 (Parke, Davis Company), per animal and injection.
Group “a” remained larval for the period of the experiment; Group “b” needed an average of 41 injections of thyreoactivator to metamorphose; Group “c” (pilocarpin) needed an average of 12 injections of thyreoactivator and Group “d” (adrenalin) an average of 20 injections of thyreoactivator.
Further work is in progress to show whether the sensitizing effect of pilocarpin and adrenalin is due to a stimulation of specific thyroid secretory nerves or to other effects.
Get full access to this article
View all access options for this article.