Naloxone and initial estrogen action to induce lordosis in ovariectomized rats: the effect of a cut between the septum and preoptic area.
The effects of intra-third-ventricular (ITV) injection of naloxone (NLX), an opioid receptor antagonist, on lordosis behavior were studied in ovariectomized female rats given a horizontal half-circle cut located just above the anterior commissure (ARD) and subcutaneously (s.c.) treated with estradiol benzoate (EB) and progesterone (Prog). In ARD-sham control animals, lordosis quotient (LQ) was 78.8 +/- 4.2% (SE,n = 8). LQ (48.3 +/- 7.2%, SE, n = 8) in the ARD-sham rats significantly decreased with the ITV injection of NLX at the time of s.c. EB-priming. In contrast, lordosis reflex in the ARD-operated animals was maximally facilitated (sham versus ARD, P < 0.01). LQ in the ARD-operated rats did not decrease with the ITV injection of NLX at the s.c. EB-priming. The present results suggest that the opioidergic systems modulate an initial phase of estrogen action to induce lordosis and play a part in neural input from the forebrain structures to regulate female sexual receptivity.
Torii
M
M
Bioregulation and Physical Fitness Laboratory, Faculty of Engineering, Kyushu Institute of Technology, Fukuoka, Japan.
Kubo
K
K
Sasaki
T
T
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007276:Injections, Intraventricular; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010052:Ovariectomy; D011187:Posture / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology* / Q000601:surgery; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012686:Septal Nuclei / Q000502:physiology* / Q000601:surgery; D012726:Sexual Behavior, Animal / Q000187:drug effects*
D009292:Narcotic Antagonists; D009270:Naloxone; D011374:Progesterone; D004958:Estradiol