Pituitary luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin from birth to puberty in female and male rats.

Pituitary content and concentration of LH, FSH and prolactin were measured by radioimmunoassay (RIA) at 2-day intervals from birth to puberty in female and male rats. During the first 2 to 3 weeks of life all hormones were low in pituitary content and concentration in both sexes. They all increased in females during the third and fourth week, but decreased sharply during the days before vaginal opening. During the first ovulatory cycle pituitary content and concentration of LH and prolactin increased again, FSH, however, remained low. In males, pituitary LH, FSH and prolactin content reached peak levels during puberty. Our results show a distinct sexual dimorphism for pituitary FSH. Pituitary LH and prolactin content and concentration patterns show similar tendencies in both sexes with a delay of several days in males. The dramatic changes in female pituitary hormone concentrations just before the first ovulation were not detected in males before the first occurrence of mature spermatozoa in the tubuli of the testes.