Endocrinology, Vol 129, 2834-2844, Copyright © 1991 by Endocrine Society

ARTICLES

Immunocytochemical distribution of aromatase cytochrome P450 in the rat brain using peptide-generated polyclonal antibodies

MK Sanghera, ER Simpson, MJ McPhaul, G Kozlowski, AJ Conley and ED Lephart
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.

Estrogen formation is catalyzed by the aromatase cytochrome P450 (P450AROM) enzyme. Aromatase activity has been detected in several regions in the rat brain. In the present study, we used peptide- generated polyclonal antibodies raised against a 20-amino acid synthetic fragment of the rat P450AROM protein (as deduced from the nucleic acid sequence of the rat P450AROM complementary DNA), to determine the location of this enzyme in rat brain sections. Immunoreactive antisera were titered by means of an enzyme-linked immunosorbent assay and purified by diethylaminoethyl-Affigel Blue chromatography. Specific immunoreactivity was confirmed by Western blot analysis using known aromatase-containing tissue (rat ovary homogenates and microsomal fractions). Evaluation of the distribution of P450AROM immunoreactivity in brain sections of male and female rats (30 and 60 days of age) was performed using the avidin biotin peroxidase immunocytochemical technique and light microscopy. P450AROM immunoreactivity appeared to be localized to neurons, and was present in brain regions and nuclei where enzymatic activity has been reported. For example, intense immunoreactivity was observed in the amygdaloid structures and supraoptic nucleus, whereas moderate to light immunoreactivity was evident in the paraventricular and arcuate nuclei and hippocampus. Surprisingly, neurons in the bed nucleus stria terminalis, medial basal hypothalamic, and preoptic areas displayed little aromatase immunoreactivity. However, P450AROM immunoreactivity was detected in specific brain regions not previously recognized to contain the enzyme (i.e. intense staining was seen in the reticular thalamic nucleus, olfactory tract and piriform cortex, as well as other brain structures). The pattern, distribution, and intensity of P450AROM immunoreactivity was similar regardless of sex or age. In this study, microsomal preparations derived from a new brain area (i.e. the reticular thalamic nucleus; Rt) displaying P450AROM immunoreactivity were observed to contain detectable levels of aromatase enzymatic activity, as determined by the 3H2O-release assay. The activity in the Rt was inhibited by a known aromatase inhibitor, 4- hydroxyandrostenedione. These results confirm histologically the localization of P450AROM to brain regions where aromatase enzymatic activity has been detected and extend the knowledge of its location to areas previously unknown as sites of aromatase activity, which may be involved in the modulation of neuroendocrine function and reproductive behavior.

This article has been cited by other articles:

				S. J. Somponpun, A. K. Johnson, T. Beltz, and C. D. Sladek Estrogen receptor-{alpha} expression in osmosensitive elements of the lamina terminalis: regulation by hypertonicity Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2004; 287(3): R661 - R669. [Abstract] [Full Text] [PDF]

				A. Sierra-Ramirez, T. Morato, R. Campos, I. Rubio, C. Calzada, E. Mendez, and G. Ceballos Acute effects of testosterone on intracellular Ca2+ kinetics in rat coronary endothelial cells are exerted via aromatization to estrogens Am J Physiol Heart Circ Physiol, July 1, 2004; 287(1): H63 - H71. [Abstract] [Full Text] [PDF]

				O. Kretz, L. Fester, U. Wehrenberg, L. Zhou, S. Brauckmann, S. Zhao, J. Prange-Kiel, T. Naumann, H. Jarry, M. Frotscher, et al. Hippocampal Synapses Depend on Hippocampal Estrogen Synthesis J. Neurosci., June 30, 2004; 24(26): 5913 - 5921. [Abstract] [Full Text] [PDF]

				S. Somponpun and C. D. Sladek Role of Estrogen Receptor-{beta} in Regulation of Vasopressin and Oxytocin Release in Vitro Endocrinology, August 1, 2002; 143(8): 2899 - 2904. [Abstract] [Full Text] [PDF]

				F. Naftolin, T. L. Horvath, and J. Balthazart Estrogen Synthetase (Aromatase) Immunohistochemistry Reveals Concordance Between Avian and Rodent Limbic Systems and Hypothalami Experimental Biology and Medicine, September 1, 2001; 226(8): 717 - 725. [Abstract] [Full Text] [PDF]

				A. G. Mensah-Nyagan, J.-L. Do-Rego, D. Beaujean, V. Luu-The, G. Pelletier, and H. Vaudry Neurosteroids: Expression of Steroidogenic Enzymes and Regulation of Steroid Biosynthesis in the Central Nervous System Pharmacol. Rev., March 1, 1999; 51(1): 63 - 82. [Abstract] [Full Text] [PDF]

				V. Prevot, D. Croix, C. M. Rialas, P. Poulain, G. L. Fricchione, G. B. Stefano, and J.-C. Beauvillain Estradiol Coupling to Endothelial Nitric Oxide Stimulates Gonadotropin-Releasing Hormone Release from Rat Median Eminence Via a Membrane Receptor Endocrinology, February 1, 1999; 140(2): 652 - 659. [Abstract] [Full Text]

				R. W. Wang and A. Y. H. Lu Inhibitory Anti-Peptide Antibody Against Human CYP3A4 Drug Metab. Dispos., June 1, 1997; 25(6): 762 - 767. [Abstract] [Full Text]