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Neuroestradiol in regulation of GnRH release.
- Source :
-
Hormones & Behavior . Aug2018, Vol. 104, p138-145. 8p. - Publication Year :
- 2018
-
Abstract
- Abstract Contribution to Special Issue on Fast effects of steroids. The concept that the positive feedback effect of ovarian estradiol (E 2) results in GnRH and gonadotropin surges is a well-established principle. However, a series of studies investigating the rapid action of E 2 in female rhesus monkeys has led to a new concept that neuroestradiol, synthesized and released in the hypothalamus, also contributes to regulation of the preovulatory GnRH surge. This unexpected finding started from our surprising observation that E 2 induces rapid stimulatory action in GnRH neurons in vitro. Subsequently, we confirmed that a similar rapid stimulatory action of E 2 occurs in vivo. Unlike subcutaneous injection of E 2 benzoate (EB), a brief (10–20 min), direct infusion of EB into the median eminence in ovariectomized (OVX) female monkeys rapidly stimulates release of GnRH and E 2 in a pulsatile manner, and the EB-induced GnRH and E 2 release is blocked by simultaneous infusion of the aromatase inhibitor, letrozole. This suggests that stimulated release of E 2 is of hypothalamic origin. To further determine the role of neuroestradiol we examined the effects of letrozole on EB-induced GnRH and LH surges in OVX females. Results indicate that letrozole treatment greatly attenuated the EB-induced GnRH and LH surges. Collectively, neuroestradiol released from the hypothalamus appears to be necessary for the positive feedback effect of E 2 on the GnRH/LH surge. Highlights • Estradiol induces rapid changes in GnRH neuronal activity. • Neuroestradiol is synthesized and released in the hypothalamus. • Neuroestradiol contributes to the regulation of pulsatile GnRH release. • Hypothalamic neuroestradiol is obligatory for the full GnRH surge. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0018506X
- Volume :
- 104
- Database :
- Academic Search Index
- Journal :
- Hormones & Behavior
- Publication Type :
- Academic Journal
- Accession number :
- 132606198
- Full Text :
- https://doi.org/10.1016/j.yhbeh.2018.04.003