INHIBITORY EFFECTS OF CYPROHEPTADINE ON PITUITARY-THYROID AXIS AND PANCREATIC BETA-CELLS IN RATS

ATM: To study the influences of cyproheptadine (Cyp) on the endocrine functions of pituitary-thyroid axis and pancreatic beta cells in rats. METHODS: The effects of Cyp on functions of pituitary-thyroid axis an d pancreatic beta cells were observed by radioimmunoassay, biochemical analysis, and electron microscope. RESULTS: Cyp 2.3 mg . kg(-1) ig fo r 10 d decreased serum thyroid stimulating hormone (TSH) from control groups (5.3 +/- 0.9) to (4.2 +/- 0.9) mU . L-1 and insulin levels from (64 +/- 8) to (50 +/- 9) kIU . L-1(P < 0.05 and 0.01). Cyp 4.6 mg . k g(-1) decreased serum TSH (3.8 +/- 0.5) mU . L-1, T-3 (1.2 +/- 0.2) mm ol . L-1, T-4 (62 +/- 7) mmol . L-1, and insulin levels (42 +/- 8) kIU . L-1 decreased (P <0.05 or 0.01). The retrograde changes of ultrastr ucture of pituitary TSH cells and pancreatic beta cells. CONCLUSION: C yp has an inhibiting action on endocrine functions of pituitary-thyroi d axis and pancreatic beta cells in rats.