The effect of thyroid activity on adult rat spermatogenesis

Document Type: Full paper (Original article)

Authors

1 Department of Anatomical Sciences, School of Medicine, University of Medical Sciences of Fasa, Fasa, Iran

2 Department of Physiology, School of Medicine, University of Medical Sciences of Shiraz, Shiraz, Iran

3 Department of Biochemistry, School of Medicine, University of Medical Sciences of Fasa, Fasa, Iran

Abstract

The influence of hypo- and hyper-thyroidism on spermatogenesis was studied in 60-day-old adult male
Wistar rats. To confirm hypo- and hyper-thyroidism, the concentration of plasma thyroid hormones were
assayed by radioimmunoassay. The hypothyroid state, induced by administration of 25 mg/kg/day
methimazole for 5 successive days, resulted in significant decrease in the number of Sertoli cells, sperm
count, Leydig cells and the diameter of seminiferous tubules. The hyperthyroid state, induced by
administration of 1 mg/kg/day L-thyroxine for 10 successive days, increased the number of Sertoli cells,
sperm count, Leydig cells and the diameter of seminiferous tubules. Serum levels of FSH and LH and
testosterone were also evaluated. Hypo- and hyper-thyroidism had no effects on the concentrations of FSH
and LH, while the concentration of testosterone was significantly increased in hyperthyroid state; it decreased
in hypothyroid state in comparison with the control euthyroid rats. In conclusion, our data indicated that
hypo- and hyper-thyroidism affect spermatogenesis through their effects on germinal, interstitial and Sertoli
cells but not through the pituitary-gonadal axis.

Keywords