European Journal of Anatomy

Official Journal of The Spanish Society of Anatomy
Cover Volume 5 - Number 1
Eur J Anat, 5 (1): 37-45 (2001)

Testosterone alters membrane binding of progesterone in male rat brains

Caldwell J.D., Gao G., Frasch M., Jirikowski G.F., Witt D.M.

Department of Biomedical Sciences, University of Illinois, College of Medicine Rockford, Rockford, IL 61107-1897, United States

ABSTRACT The steroid progesterone (P) is important in control of male sexual behaviors. In this study binding sites for P conjugated to bovine serum albumin (P-BSA) were analyzed in the brains of gonadectomized male rats that were implanted with silastic capsules either filled with testosterone or empty. Frozen brains were sliced, thaw mounted on microscope slides, and incubated with radiolabeled P-BSA (P-[125I-BSA]) alone or with 1000 fold P-BSA competitor. Microscope slides were then dried, dipped in photographic emulsion and placed in light-tight boxes for four days before being developed and counterstained. Grain densities over cells were then analyzed with an image analysis system. Testosterone treatment significantly increased specific binding of P-[125I-BSA] in the caudal medial basal hypothalamus, the paraventricular nucleus-anterior hypothalamus, and the medial preoptic area. Testosterone treatment significantly decreased P-[125I-BSA] binding in the amygdala. There was no significant effect of testosterone in the rostral medial basal hypothalamus. Testosterone treatment changes P-[125I-BSA] binding in several areas that are important for male sexual behavior suggesting a function for P-[125I-BSA] binding sites in endocrine systems and behavior.

Keywords: bovine serum albumin, estradiol benzoate, progesterone, sodium iodide i 125, testosterone, amygdaloid nucleus, animal experiment, animal tissue, article, autoradiography, central nervous system, gonadectomy, hormone action, hypothalamus, image analysis, male, medial preoptic area, membrane binding, nonhuman, radioiodination, rat, sexual behavior, thalamus midline nucleus

European Journal of anatomy
ISSN 2340-311X (Online)