Title

Estradiol increases prolactin synthesis and prolactin messenger ribonucleic acid in selected brain regions in the hypophysectomized female rat

UMMS Affiliation

Division of Endocrinology; Department of Obstetrics & Gynecology

Publication Date

11-1-1992

Document Type

Article

Subjects

Animals; Base Sequence; Cerebral Cortex; Colchicine; DNA; Electrophoresis, Polyacrylamide Gel; Estradiol; Female; *Hypophysectomy; Hypothalamus; Methionine; Molecular Sequence Data; Polymerase Chain Reaction; Pons; Precipitin Tests; Prolactin; RNA, Messenger; Rats; Rats, Sprague-Dawley; Sulfur Radioisotopes

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Immunoreactive PRL which is not of pituitary origin, has been identified in many regions of the rat brain. We have previously demonstrated that estradiol increases hypothalamic immunoreactive PRL content in hypophysectomized female rats. To determine if estradiol stimulates PRL synthesis, we examined the effect of estradiol on the in vivo production of PRL, and on the expression of PRL messenger RNA (mRNA) in the hypothalamus, pons, and cerebral cortex. To examine the effect of estradiol on the in vivo production of PRL, [35S] methionine was injected into the lateral ventricle and its incorporation into immunoprecipitable PRL was determined by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In estradiol, but not vehicle-treated hypophysectomized rats, a 24,000 M(r) immunoprecipitable PRL protein was detected in the hypothalamus and pons-medulla, 2 and 4 h after methionine administration. No immunoprecipitable PRL proteins were detected in the amygdala, hippocampus, cortex, or serum at either time point. In addition, in the hypothalamus, but not the pons-medulla, a second PRL band was detected with an apparent mol wt of 16,000K. To determine if estradiol increased the expression of PRL mRNA, copy DNA was obtained by reverse transcription of poly(A+) mRNA prepared from intact and vehicle or estradiol-treated hypophysectomized rats and analyzed by polymerase chain reaction amplification. In tissues from hypophysectomized rats, there was little, or no, detectable levels of PRL mRNA. In contrast, in estradiol-treated hypophysectomized rats PRL mRNA was easily detected in the hypothalamus and pons-medulla by polymerase chain reaction amplification. These data suggest that estradiol increases the PRL content in the hypothalamus and pons-medulla by increasing PRL gene expression, in a manner similar to that reported in the pituitary.

Rights and Permissions

Citation: Endocrinology. 1992 Nov;131(5):2154-60.

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

Endocrinology

PubMed ID

1425416