Neuroscience 2000 Abstract
| Presentation Number: | 472.15 |
|---|---|
| Abstract Title: | Mating-induced Fos in mu opioid receptor neurons in the medial preoptic area is not a result of binding of endogenous opioid peptides. |
| Authors: |
Coolen, L. M.*1
; Wells, A. B.1
1Neurosci Program, Univ. Cincinnati, Cincinnati, OH |
| Primary Theme and Topics |
I. Neural Basis of Behavior - 117. Reproductive behavior |
| Secondary Theme and Topics | I. Neural Basis of Behavior<br />- 119. Neuropeptides and behavior |
| Session: |
472. Reproductive behavior II Poster |
| Presentation Time: | Tuesday, November 7, 2000 10:00 AM-11:00 AM |
| Location: | Hall G-J |
| Keywords: | copulation, male sexual behavior, hypothalamus, c-fos |
Male sexual behavior results in induction of Fos-immunoreactivity (IR) in neurons in the medial preoptic nucleus (MPN) of the male rat. In addition, a recent finding from our laboratory demonstrated mating-induced activation of mu-opioid receptor (MOR) containing neurons, as indicated by internalization of this receptor (Coolen et al, SFN abstr. 420.4, 1999). This suggests that release and binding of endogenous opioid peptides (EOP) in MPN occurs as a result of male sexual behavior. The present study addressed two questions: (1) does mating induce Fos-IR in MOR-containing neurons, and (2) is Fos-induction a result of EOP binding to MORs? Male rats were injected s.c. with saline or the opioid receptor antagonist naloxone (5 or 10 mg/kg bodyweight), 30 minutes before mating which included one ejaculation. One hour after mating animals were sacrificed and brains immunostained for c-fos and MOR. Indeed, following mating approximately 50% of MOR containing neurons in MPN were Fos positive. However, naloxone did not block mating-induced expression of c-fos in MOR neurons, although naloxone did eliminate internalization and thus ligand-binding of this receptor. These results suggest that blockade of the receptor did not interfere with mating-induced c-fos expression in MOR neurons. In a second experiment, male rats received i.c.v. injections of DAMGO, an opioid agonist (0.1 or 1 μg/5 nl) or saline. Injections of DAMGO at either dose did not induce Fos-IR in MOR neurons in MPN, although DAMGO did induce internalization of MORs. Together, these results indicate that mating-induced Fos-IR in MOR neurons in MPN is not a result of EOP binding.
Supported by NSF IBN-9906430 to LMC
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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