Pituitary-testicular Axis Dysfunction in Methimazole-induced Hypothyroidism in Rats.

INTRODUCTION: Thyroid hormones play a major role in the regulation of testicular maturation and growth and in the control of Sertoli and Leydig cell functions in adulthood. When naturally occurring, hypothyroidism causes male hypogonadotropic hypogonadism and Sertoli cell function disorders, but when iatrogenic and methimazole-induced its influence on the pituitary-testicular axis function with respect to Sertoli cells is poorly known. MATERIAL AND METHODS: Male adult Wistar rats (n = 14) were divided into two groups: E - taking methimazole orally for 60 days, and C - control animals. After 60 d, the concentrations in serum of testosterone, follicle-stimulating and luteinising hormones, and inhibins A and B were measured. Testicles were examined morphologically: the apoptotic Sertoli cell percentage (ASC%) and number of these cells functional per tubular mm(2) (FSCN/Tmm(2)) were calculated. RESULTS: In group E, inhibin A was higher while inhibin B was lower than in group C. ASC% was higher and FSCN/Tmm(2) lower in group E than in group C. CONCLUSION: A specific modulation of Sertoli cell function in the course of methimazole-induced hypothyroidism leads to a simultaneous concentration increase in inhibin A and decrease in B. Inhibin A might share responsibility for pituitary-testicular axis dysfunction and hypogonadotropic hypogonadism in this model of hypothyroidism.