[ Effects of cabergoline on pituitary- thyroid hormones in adult male rats]

ABSTRACT

Cabergoline is a strong dopaminergic agonist that is derived from Ergot fungus. Although, this drug can be so important in treating many disorders such as hyperprolactinemia, but its side effects are considerable on the endocrinal axis. The purpose of this study was to determine effects of cabergoline on serum levels of TSH, T[4] and T[3] hormones in adult male rats. In this experimental study, 40 adult male wistar rats were used in five groups of eight. The drug was subcutaneously injected for a period of 14 days. The experimental groups received 0.1, 0.5 and 1 mg/kg, respectively. The control group received no drug. The sham group received only distilled water. At the end of 14[th] day, blood samples were taken and the concentration of TSH, T[4] and T[3] were measured by RIA. The results were analyzed by ANOVA and TUKEY test between the control and experimental group. Serum levels of TSH and T4 hormones in the experimental groups with doses of 0.1, 0.5 and 1 mg/kg showed statistically significant decrease compared with control group [p<0.05]. Concentration of T[3] hormone showed significant increase in the experimental group with 0.1 mg/kg in comparison with control group [p<0.05]. Cabergoline probably decreases the release of TSH and T[4] by stimulating the D[2]-dopaminergic receptor existing in thyrotrophic cells. According to the increase of T[3] concentration with low dose of drug, cabergoline may have different physiological effects in different amounts, and alter the function of pituitary -thyroid axis