5-Hydroxytryptamine, 5-Hydroxytryptophan Decarboxylase and Monoamine Oxidase in Hearts of Normal, Thyroid-Fed and Propylthiouracil-Fed Male and Female Rats

Abstract

Male and female Wistar rats (125-175 g) were fed for 21 days ad lib. diets of a meal containing 0.15% strong desiccated thyroid, 0.15% prophylthiouracil (PTU), or meal alone. 5-Hydroxytryptamine (5-HT) contents, and 5-Hydroxytrypotophan decarboxylase (5-HTPD) and monoamine oxidase (MAO) activities of the hearts of these animals were determined. Normal male rats possessed significantly greater heart MAO activities than normal females; these animals showed no significant sex difference in heart 5-HT or 5-HTPD. Thyroid feeding of the males lowered heart 5-HTPD but did not alter heart 5-HT or MAO significantly. Thyroid-fed females showed decreased heart 5-HT and 5-HTPD and increased MAO. PTU-fed males showed elevated heart 5-HTPD, lowered MAO, and unchanged 5-HT. PTU feeding of the females produced no significant change in heart 5-HT or MAO but increased heart 5-HTPD.