Thirteen-weeks subcutaneous treatment with high dose of natural sex hormones in rats with special reference to their effect on the pituitary-gonadal axis. I. Oestradiol.

A high dose of oestradiol (0.3 mg/kg/day) was administrated subcutaneously to male and female rats daily for 13 weeks. The effects of hormonal treatment on various parameters were studied. The results revealed that treatment with oestradiol resulted in alopecia, retarded hair regrowth, decreased body weight and food consumption and reduced Hb, PCV and total RBCs. Neutrophilic leucocytosis, elevated ESR, and decreased blood glucose levels were also observed. Atrophy of the ovaries, testes and secondary sex organs was also recorded. The uterus of the oestradiol treated rats displayed endometrial epithelial cell hyperplasia and hypertrophy of the myometrium. The pituitary gland of the rats with oestradiol had a significant increase in the number of PRL and ACTH cells together with cytological criteria indicative of increased secretory activity; the gonadotropin-producing cells showed involutionary changes. The mammary glands of the oestradiol treated rats showed maximal stromal and ductal proliferation and minimal acinar proliferation.