Horm Metab Res 2003; 35(2): 69-75
DOI: 10.1055/s-2003-39060
Original Basic
© Georg Thieme Verlag Stuttgart · New York

Testosterone and Sexual Experience Alter Levels of Plasma Membrane Binding Sites for Progesterone in the Male Rat Brain

D.  M.  Witt 1 , G.  Gao 2 , J.  D.  Caldwell 3
  • 1 Behavioral Neuroscience Program, Binghamton University (SUNY), Binghamton, NY, USA.
  • 2 Dept. of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, USA.
  • 3 Dept. Biomedical Sciences, University of Illinois School of Medicine, Rockford, IL USA.
Further Information

Publication History

Received 2 July 2002

Accepted after revision 16 October 2002

Publication Date:
07 May 2003 (online)

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Abstract

Physiological levels of progesterone act in conjunction with androgens to facilitate copulatory behavior in male rats, mice, and lizards. Radiolabeled progesterone conjugated to bovine serum albumin measured specific binding sites in membrane fractions from male rats that were gonadectomized and testosterone treated, or remained gonadally intact, to determine the role of gonadal steroids on mPR binding. To determine whether behavioral experience could alter binding levels, males either remained sexually naïve or became sexually experienced. In sexually naïve males, the highest levels of specific binding occurred in the dorsal portions of the medial preoptic area, with only moderate levels of binding in ventral portions of the medial preoptic area and the dorsal and ventral medial hypothalamus. However, conjugated progesterone binding in these brain regions did not change as a function of testosterone or behavioral manipulations. In contrast, the amygdala responded to behavioral experience with significantly (4-fold) increased binding in gonadectomized, T-treated males with sexual experience. These data indicate that the neuronal plasticity for membrane-associated progesterone binding is regionally specific, being regulated by sexual experience following the reinstatement of testosterone levels, thus suggesting a functional role for plasma membrane activity of progesterone in male rat reproduction.

References

J. D. Caldwell, Ph. D.

Department of Biomedical Sciences

University of Illinois · College of Medicine at Rockford · 1601 Parkview Avenue · Rockford, IL 61107-1897

Email: jackc@uic.edu