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Activation of the hypothalamo‐anterior pituitary corticotropin‐releasing hormone, adrenocorticotropin hormone and β‐endorphin systems during the estradiol 17β‐induced plasma LH surge in the ovariectomized monkey
Author(s) -
Kerdelhué B.,
Jones G. S.,
Gordon K.,
Seltman H.,
Lenoir V.,
Parsadaniantz S. Mélik,
Williams R. F.,
Hodgen G. D.
Publication year - 1995
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490420210
Subject(s) - medicine , endocrinology , ovariectomized rat , corticotropin releasing hormone , radioimmunoassay , luteinizing hormone , chemistry , anterior pituitary , hypothalamus , hormone , pituitary gland , peptide hormone , estradiol benzoate , biology
The present work describes time‐dependent changes in the content of corticotropin‐releasing hormone (CRH), adrenocorticotropin (ACTH), and β‐endorphin (β ‐EP) in the hypothalamus (HT) and anterior pituitary (AP) and in the concentration of ACTH and β‐EP in the plasma during the 17β estradiol (E2) benzoate (E 2 B)‐induced luteinizing hormone (LH) surge in ovariectomized cynomolgus monkeys. Monkeys were euthanized at 0, 30, 48, 72, and 96 hr post‐E 2 B. HT and AP were rapidly dissected, extracted in 2 N acetic acid containing 1 mM phenylmethane sulfonyl fluoride at 4°C, and centrifuged at 18,000g for 30 min. Peptide concentrations were measured in the supernatant by specific radioimmunoassays (RIAs). In the HT, there were significant (P < 0.05) decreases in ACTH and β ‐EP content by 30 hr post‐E 2 B and a significant (P < 0.05) decrease in HT CRH content 48 hr post‐E 2 B. Thereafter, CRH, ACTH, and β‐EP content increased up to 72 hr post‐E 2 B. In the AP, there was an almost linear decrease in the CRH content through 48 hr post‐E 2 B followed by a marked 20‐fold (P< 0.01) increase in the AP CRH content at 72 hr post‐E 2 B, which corresponds to the time of the descending arm of the LH surge. The patterns of ACTH and β‐EP content were very similar in the AP, while that of CRH differed markedly. In contrast, in the HT CRH, ACTH, and β‐EP profiles were very similar. Significant (P< 0.05) increases in circulating levels of ACTH, β‐EP, and cortisol were evident at 30 hr (all 3 hormones), 48 hr (β‐EP and cortisol), and 72 hr (cortisol) post‐E 2 B, which corresponds with the time of decreased hypothalamic content of CR1I, ACTH, and β‐EP. These results suggest that there may be a marked activation of the hypothalamo‐anterior pituitary‐adrenal axis during the negative and positive feedback phases of the E 2 B‐induced LH surge in the ovariectomized monkey. © 1995 Wiley‐Liss, Inc.