Hypothyroidism in reproductively inhibited prairie deer mice (Peromyscus maniculatus bairdi) from laboratory populations.

Abstract

Several thyroid function parameters were compared between reproductively inhibited prairie deer mice of both sexes taken from laboratory populations and corresponding reproductively capable controls. The results of these experiments indicated the following: 1) prairie deer mice females had a statistically significant daily variation in mean serum thyroxine concentration and males displayed a similar trend; 2) total serum thyroxine and triiodothyronine were significantly lower in both male and female reproductively inhibited population animals compared with reproductively capable controls; 3) several morphometric characteristics of the thyroid of male and female population prairie deer mice were significantly different from that of control males and females, suggesting functional hypothyroidism in both sexes; 4) thyroid histology of male population deer mice was different from that of female population animals. In males, the data suggested that thyroid-stimulating hormone (TSH) stimulation was deficient due to some undetermined secondary hypothyroidism. In females, reduced serum thyroxine and triiodothyronine concentrations were observed due to primary hypothyroidism of unknown origin. The interrelationship between thyroid and adrenal function is discussed here and it is concluded that each of the systems may contribute to the observed reproductive inhibition. In particular, it was noted that the mechanism of response between population males and females may be quite different. No conclusive data are available to suggest whether one or the other system is the primary controller of the reproductive inhibition.