Evidence for the involvement of corticotropin-releasing factor in the inhibition of gonadotropin release induced by hyperprolactinemia.
The hypothesis was tested that corticotropin-releasing factor (CRF) is involved in the inhibition of gonadotropin secretion during chronic hyperprolactinemia. Two models of hyperprolactinemia were used, namely inoculation with the prolactin (PRL)-secreting tumor 7315b and implantation of isogenic pituitary glands. Gonadectomized, adrenalectomized male rats received a testosterone capsule and a corticosterone pellet and were inoculated subcutaneously with tumor 7315b. Similar rats without tumor served as controls. The rats were studied 3-4 weeks later while anesthetized with urethane. Plasma testosterone and corticosterone were similar in the two groups of rats. Compared to controls, the tumor-bearing rats had significantly higher plasma levels of PRL (100-fold increase) and adrenocorticotropin (ACTH; 3-fold increase), whereas plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) had significantly decreased to 15 and 40%, respectively. CRF release into hypophysial stalk plasma was higher in rats with tumor 7315b than in controls (298 +/- 23 vs. 197 +/- 28 pg/h), and hypothalamic CRF content had increased from 3.0 +/- 0.3 to 4.3 +/- 0.3 ng. Male rats received 3 pituitary glands under the kidney capsule. Sham-operated rats served as controls. They were studied 5-7 weeks later while anesthetized with urethane. Compared to controls, pituitary-grafted rats had larger adrenals (49 +/- 4 vs. 34 +/- 2 mg), higher plasma PRL (156 +/- 18 vs. 52 +/- 8 ng/ml), ACTH (0.46 +/- 0.05 vs. 0.22 +/- 0.02 ng/ml) and corticosterone (455 +/- 39 vs. 268 +/- 14 ng/ml), and lower plasma levels of LH (21 +/- 2 vs. 41 +/- 6 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
Kooy
A
A
Department of Endocrinology, Erasmus University, Rotterdam, The Netherlands.
de Greef
W J
WJ
Vreeburg
J T
JT
Hackeng
W H
WH
Ooms
M P
MP
Lamberts
S W
SW
Weber
R F
RF
D000315:Adrenalectomy; D000818:Animals; D002908:Chronic Disease; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D006966:Hyperprolactinemia / Q000209:etiology / Q000378:metabolism*; D008297:Male; D009368:Neoplasm Transplantation; D010902:Pituitary Gland / Q000637:transplantation; D010907:Pituitary Hormones / Q000097:blood; D051381:Rats; D011915:Rats, Inbred BUF; D016042:Transplantation, Heterotopic
D006065:Gonadotropins, Pituitary; D010907:Pituitary Hormones; D003346:Corticotropin-Releasing Hormone