Postnatal Ovary is Necessary for the Maturation of Estradiol-Induced Luteinizing Hormone and Prolactin Surges in Female Rats

Summary

The role of postnatal ovary in the maturation of estradiol (E₂)-induced luteinizing hormone (LH) and prolactin (PRL) surges was examined in female rats of Wistar-Imamichi strain. Animals were bilaterally ovariectomized at 24 h after birth, 1 week (w), 2 w, 3 w, 4 w or 6 w of age. At about 10 w of age, every group was primed with estradiol benzoate (E₂ B) for two days, and on the third day was decapitated at either 0900 h or 1900 h. Anterior pituitary (AP) LH and PRL content was determined in every group of no E₂B treatment. Surge-like secretions of LH and PRL were observed at 1900 h, only in rats ovariectomized on or after 4 w of age. AP LH and PRL content was the higher, as ovariectomy was delayed. These results indicate that postnatal ovary is necessary for the maturation of E₂-induced LH and PRL surges. Such an effect of ovary is mediated at least by its stimulation of AP LH and PRL content.

Key-Words

Estradiol - Surge - Luteinizing Hormone - Prolactin - Postnatal Ovary - Sexual Differentiation