GnRH mediates estrous behavior induced by ring A reduced progestins and vaginocervical stimulation.

Abstract

The present study was designed to assess the participation of gonadotropin-releasing hormone (GnRH) in the display of estrous behavior induced by application of vaginal-cervical stimulation (VCS) and by the intracerebroventricular (icv) administration of progesterone and its ring A-reduced metabolites to ovariectomized (ovx), estradiol benzoate (E2B) primed rats. Icv injection of Antide, a GnRH-1 receptor antagonist, significantly depressed lordosis behavior in ovx, E2B-primed rats treated with icv GnRH. Application of VCS to ovx, E2B-primed rats facilitated both lordosis and proceptivity. These behavioral responses were significantly depressed by the icv administration of Antide. Similarly, icv Antide blocked the stimulatory effect on both lordosis and proceptive behaviors elicited by progesterone and its ring A-reduced metabolites: 5alpha-pregnandione (5alpha-DHP), 5alpha-pregnan-3alpha-ol-20-one (5alpha,3alpha-Pgl) and 5beta-pregnan-3beta-hydroxy-20-one (5beta,3beta-Pgl) in ovx, E2B-primed rats. By contrast, icv injection of Antide failed to interfere with the facilitatory effect of the synthetic progestin megestrol acetate on lordosis and proceptive behaviors. This progestin is not reduced in ring A. The results suggest that GnRH release is an important process in the chain of events leading to the display of estrous behavior in response to progesterone, its ring A-reduced metabolites, and VCS in female rats.

• Authors: Porfirio Gómora-Arrati, Carlos Beyer, Francisco Javier Lima-Hernández, Maria Elena Gracia, Anne M Etgen, Oscar González-Flores
• Journal: Behavioural brain research (Behav Brain Res) Vol. 187 Issue 1 Pg. 1-8 (Feb 11 2008) ISSN: 0166-4328 [Print] Netherlands
• PMID: 17888527 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Hormone Antagonists
• Oligopeptides
• Progestins
• Gonadotropin-Releasing Hormone
• Estradiol
• iturelix
• Megestrol Acetate

Topics

• Animals
• Cervix Uteri (physiology)
• Estradiol (pharmacology)
• Estrous Cycle (drug effects)
• Female
• Gonadotropin-Releasing Hormone (antagonists & inhibitors, metabolism, pharmacology)
• Hormone Antagonists (pharmacology)
• Injections, Intraventricular
• Megestrol Acetate (antagonists & inhibitors, pharmacology)
• Oligopeptides (pharmacology)
• Ovariectomy
• Physical Stimulation
• Posture
• Progestins (chemistry, pharmacology)
• Rats
• Rats, Sprague-Dawley
• Sexual Behavior, Animal (drug effects)
• Vagina (physiology)