Colocalization of P450 Aromatase and Oxytocin Immunostaining in the Rat Hypothalamus

Abstract

With combined immunoperoxidase and immu­nofluorescence, we observed colocalization of cytochrome P450 aromatase with the posterior lobe peptide oxytocin and its associated neurophysin 1 in adult male rats. P450 was most abundant in the anterior hypothalamus. Colocalization of OT with P450 was observed in the preoptic region, the periventricular nucleus of the hypothalamus, the lateral subcommissural nucleus, and in the zona incerta. Magnocellular perikarya in the supraoptic and in the paraventricular nuclei contained only occasionally both antigens. P450 immunostaining overlapped to a great extent with known estrogen target regions. Oxytocinergic functions are controlled by estradiol while androgen receptors are mostly absent in neuroendocrine hypothalamic nuclei. Our findings suggest that systemic androgens may be aromatized to estrogens in male oxytocinergic neurons linked to the limbic system.

Key words

hypothalamus - androgens - oxytocin - aromatase - limbic system - pituitary

• References

• 1 Caldwell JD, Suleman F, Chou SH, Shapiro RA, Herbert Z, Jirikowski GF. Emerging roles of steroid-binding globulins. Horm Metab Res 2006; 38: 206-218
• 2 Caldwell JD, Prange Jr AJ, Pedersen CA. Oxytocin facilitates the sexual receptivity of estrogen-treated female rats. Neuropeptides 1986; 7: 175-189
• 3 Insel TR. Oxytocin – A neuropeptide for affiliation: evidence from behavioral, receptor autoradiographic, and comparative studies. Psychoneuroendocrinology 1992; 17: 33-35
• 4 Tribollet E, Audigier S, Dubois-Dauphin M, Dreifuss JJ. Gonadal steroids regulate oxytocin receptors but not vasopressin receptors in the brain of male and female rats. An autoradiographical study. Brain Res 1990; 12: 129-140
• 5 Jirikowski GF, Caldwell JD, Stumpf WE, Pedersen CA. Oxytocinergic neuronal systems in the rat hypothalamus are influenced by estrogens. Neuroscience 1988; 25: 237-248
• 6 Baulieu EE. Neurosteroids: of the nervous system, by the nervous system, for the nervous system. Recent Prog Horm Res 1997; 52: 1-32
• 7 Huang CB. Immunohistochemical localization of cytochrome P450 enzymes 2C and 4A in the normal rat brain. Chin Med J (Engl) 1998; 111: 1007-1012
• 8 Simpson ER, Mahendroo MS, Means GD. Aromatase cytochrome P450, the enzyme responsible for estrogen biosynthesis. Endocr Rev 1994; 15: 342-355
• 9 Strobel HW, Thompson CM, Antonovic L. Cytochromes P450 in brain: function and significance. Curr Drug Metab 2001; 2: 199-214
• 10 Simpson ER, Clyne C, Rubin G, Boon WC, Robertson K, Britt K, Speed C, Jones M. Cytochromes P450 in brain: function and significance. Annu Rev Physiol 2002; 64: 93-127
• 11 Meyer RP, Hagemeyer CE, Knoth R, Kaufmann MR, Volk B. Anti-epileptic drug phenytoin enhances androgen metabolism and androgen receptor expression in murine hippocampus. J Neurochem 2006; 96: 460-472
• 12 Bhatnagar AS, Mfiller PH, Schenkel LS, Trunet PF, Beh I, Schieweck K. Inhibition of estrogen biosynthesis and its consequences on gonadotropins secretion in the male. J Steroid Biochem Mol Biol 1992; 41: 437-443
• 13 MacLusky NJ, Naftolin E. Sexual differentiation of the central nervous system. Science 1981; 211: 1294-1302
• 14 Roselli CE, Klosterman S, Resko JA. Anatomic relationships between aromatase and androgen receptor mRNA expression in the hypothalamus and amygdala of adult male Cynomolgus monkeys. J Comp Neurol 2001; 439: 208-223
• 15 Negri-Cesi P, Colciago A, Celotti F, Motta M. Sexual differentiation of the brain: Role of testosterone and its active metabolites. J Endocrinol Invest 2004; 27 (Suppl) 120-127
• 16 Engele J, Pilgrim C, Reisert I. Sexual differentiation of mesencephalic neurons in vitro: effects of sex and gonadal hormones. Int J Dev Neurosci 1989; 7: 603-611
• 17 Abdelgadir SE, Roselli CE, Choate JV, Resko JA. Distribution of aromatase cytochrome P450 messenger ribonucleic acid in adult rhesus monkey brains. Biol Reprod 1997; 57: 772-777
• 18 Steckelbroeck S, Heidrich DD, Stoffel-Wagner B, Hans VH, Schramm J, Bidlingmaier F, Klingmüller D. Characterization of aromatase cytochrome P450 activity in the human temporal lobe. J Clin Endocrinol Metab 1999; 84: 2795-2801
• 19 Gabor CS, Phan A, Clipperton-Allen AE, Kavaliers M, Choleris E. Interplay of oxytocin, vasopressin, and sex hormones in the regulation of social recognition. Behav Neurosci 2012; 126: 97-109
• 20 Filippi S, Luconi M, Granchi S, Vignozzi L, Bettuzzi S, Tozzi P, Ledda F, Forti G, Maggi M. Estrogens, but not androgens, regulate expression and functional activity of oxytocin receptor in rabbit epididymis. Endocrinology 2002; 143: 4271-4280
• 21 Horvath TL, Wikler KC. Aromatase in developing sensory systems of the rat brain. J Neuroendocrinol 1999; 11: 77-84
• 22 Goto-Kazeto R, Kight KE, Zohar Y, Place AR, Trant JM. Localization and expression of aromatase mRNA in adult zebrafish. Gen Comp Endocrinol 2004; 139: 72-84
• 23 Norris PJ, Hardwick JP, Emson PC. Regional distribution of cytochrome P450 2D1 in the rat central nervous system. J Comp Neurol 1996; 366: 244-258
• 24 Norris PJ, Hardwick JP, Emson PC. Localization of NADPH cytochrome P450 oxidoreductase in rat brain by immunohistochemistry and in situ hybridization and a comparison with the distribution of neuronal NADPH-diaphorase staining. Neuroscience 1994; 61: 331-350
• 25 Tsuruo Y. Topography and function of androgen metabolizing enzymes in the central nervous system. Anatomical Sci Int 2005; 80: 1-11
• 26 Riedl AG, Watts PM, Edwards RJ, Boobis AR, Jenner P. Brain cytochrome P450 in the rat. Biochem Soc Trans 1996; 24: 52-58
• 27 Watts PM, Riedl AG, Douek DC, Edwards RJ, Boobis AR, Jenner P, Marsden CD. Co-localization of P450 enzymes in the rat substantia nigra with tyrosine hydroxylase. Neuroscience 1998; 86: 511-519
• 28 Peruffo A, Giacomello M, Montelli S, Corain L, Cozzi B. Expression and localization of aromatase P450 AROM, estrogen receptor-α and estrogen receptor-β in the developing fetal bovine frontal cortex. Gen Comp Endocrinol 2011; 172: 211-217
• 29 Sar M, Parikh I. Immunohistochemical localization of estrogen receptor in rat brain, pituitary and uterus with monoclonal antibodies. J Steroid Biochem 1986; 24: 497-503
• 30 Sanghera MK, Simpson ER, McPhaul MJ, Kozlowski G, Conley AJ, Lephart ED. Immunocytochemical distribution of aromatase cytochrome P450 in the rat brain using peptide-generated polyclonal antibodies. Endocrinology 1991; 129: 2834-2844
• 31 Do-Rego JL, Acharjee S, Seong JY, Galas L, Alexandre D, Bizet P, Burlet A, Kwon HB, Luu-The V, Pelletier G, Vaudry H. Vasotocin and mesotocin stimulate the biosynthesis of neurosteroids in the frog brain. J Neurosci 2006; 21: 6749-6760
• 32 Naftolin F, Horvath TL, Jakab RL, Leranth C, Harada N, Balthazart J. Aromatase immunoreactivity in axon terminals of the vertebrate brain. An immunocytochemical study on quail, rat, monkey and human tissues. Neuroendocrinology 1996; 63: 149-155
• 33 Morse DC, Stein AP, Thomas PE, Lowndes HE. Distribution and induction of cytochrome P450 1A1 and 1A2 in rat brain. Toxicol Appl Pharmacol 1998; 152: 232-239
• 34 Kadioglu P, Oral G, Sayitoglu M, Erensoy N, Senel B, Gazioglu N, Sav A, Cetin G, Ozbek U. Aromatase cytochrome P450 enzyme expression in human pituitary. Pituitary 2008; 11: 29-35
• 35 Murray GI, Pritchard S, Melvin WT, Burke MD. Cytochrome P450 CYP3A5 in the human anterior pituitary gland. FEBS Lett 1995; 364: 79-82
• 36 Carretero J, Vázquez G, Rubio M, Blanco E, Juanes JA, Pérez E, Burks D, Vázquez R. Postnatal differentiation of the immunohistochemical expression of aromatase P450 in the rat pituitary gland. Histol Histopathol 2003; 18: 419-423
• 37 Carretero J, Vázquez G, Blanco E, Rubio M, Santos M, Martín-Clavijo A, Torres JL, Vázquez R. Immunohistochemical evidence of the presence of aromatase P450 in the rat hypophysis. Cell Tissue Res 1999; 295: 419-423
• 38 Galmiche G, Richard N, Corvaisier S, Kottler ML. The expression of aromatase in gonadotropes is regulated by estradiol and gonadotropin-releasing hormone in a manner that differs from the regulation of luteinizing hormone. Endocrinology 2006; 147: 4234-4244