Dimorfismo cerebral y preferencia sexual en una rata pseudohermafrodita
Resumen
Introducción: El cerebro es sexualmente dimórfico pues los machos tienen algunos núcleos cerebrales de mayor tamaño que las hembras. Tal dimorfismo ocurre en el periodo perinatal, mucho después de que se han formado los genitales y órganos accesorios. En general, es aceptada la idea de que la preferencia sexual de un individuo correlaciona con el dimorfismo cerebral y no con el fenotipo genital. Método: En el presente trabajo describimos a una rata macho pseudohermafrodita, la cual fenotípicamente parecía hembra. Se evaluó su preferencia de pareja sexual frente a machos y hembras en dos pruebas diferentes, y posteriormente se analizó el dimorfismo de algunos núcleos cerebrales y se describió la histología de genitales y algunos órganos accesorios. Resultados: mostraron que la preferencia de pareja fue bisexual y su cerebro también tenía una organización bisexual. Se discute el papel organizacional de las hormonas en el dimorfismo cerebral y el papel de los núcleos cerebrales en relación a la preferencia de pareja. Conclusión: El cerebro de un pseudohermafrodita puede tener un dimorfismo intermedio y correlacionar con conducta bisexual.
Abstract
Introduction: The brain is sexually dimorphic because males express bigger nuclei in certain regions as compared to females. Brain dimorphism occurs during the perinatal period, much later than the period when genitals and accesory organs are formed. In general, it is well accepted the idea that sexual preference correlates with brain dimorphism, and not with genital phenotype. Method: In the present study we describe a male pseudohermaphrodite rat, which looked like female. We assessed its sexual partner preference before males and females in two separate tests and then its brain dimorphism and histology of genitals and accesory organs were analyzed. Results: they indicated that its partner preference was bisexual and its brain was also organized bisexually. We discuss the role of hormones in the organization of the brain and also the role of some brain nuclei with regard to sexual partner preference. Conclusion: A pseudohermaphrodite brain may express an intermediate dimorphism and correlate with bisexual partner preference.
Keywords: Brain dimorphism; pseudohermaphrodite; partner preference; homosexual.
Palabras clave
Referencias
Androutsos G. Hermaphroditism in Greek and Roman antiquity. Hormones 2006 5: 214-7.
McEntee K. Reproductive pathology of domestic mammals. Academic Press, San Diego. 1990 pp 8-30.
Phoenix CH, Goy RW, Gerall AA, Young WC. Organizing action of prenatally administered testosterone propionate on the tissues mediating mating behavior in the female guinea pig. Endocrinology 1959 65: 369-82.
Davis EC, Shryne JE, Gorski RA. A revised critical period for the sexual differentiation of the sexually dimorphic nucleus of the preoptic area in the rat. Neuroendocrinology 1995 62: 579-85.
Gorski RA. Sexual differentiation of the brain. Hosp Pract 1978 13: 55-62.
Gorski RA. Sexual differenciation of the nervous system. En: Kandel ER y Jessell TM. (Ed.). Principles of Neural Science. 2000 pp 1131-1148.
Gorski RA, Gordon JH, Shryne JE, Southam AM. Evidence for a morphological sex difference within the medial preoptic area of the rat brain. Brain Res 1978 148: 333-46.
Gulia KK y Mallick HN. Homosexuality: a dilemma in discourse!. Indian J Physiol Pharmacol 2010 54: 5-20.
LeVay S. A difference in hypothalamic structure between heterosexual and homosexual men. Science 1991 253: 1034-7.
Roselli CE, Reddy RC, Kaufman KR. The development of male-oriented behavior in rams. Front Neuroendocrin 2011 32: 1034-1037.
Savic I, Berglund H, Lindstrom P. Brain response to putative pheromones in homosexual men. Proc Natl Acad Sci U S A 2005 102: 7356-61.
Swaab DF, Gooren LJ, Hofman MA. Brain research, gender and sexual orientation. J Homosexual 1995 28: 283-301.
Weinrich JD. Is homosexuality natural?. En: Paul W, Weinrich JD, Gonsiorek JC, Hotver ME (Ed.). Homosexuality: social, psychological and biological issues. Beverley Hills. 1982 pp 203.
Paxinos G y Watson C. The rat brain in stereotaxic coordinates. Academic Press, San Diego. 1998 pp 9-34.
Dugger BN, Morris JA, Jordan CL, Breedlove SM. Androgen receptors are required for full masculinization of the ventromedial hypothalamus (VMH) in rats. Horm Behav 2007 51: 195-201.
Zuloaga DG, Puts DA, Jordan CL, Breedlove SM. The role of androgen receptors in the masculinization of brain and behavior: what we've learned from the testicular feminization mutation. Horm Behav 2008 53: 613-26.
Bloch GJ y Gorski RA. Estrogen/progesterone treatment in adulthood affects the size of several components of the medial preoptic area in the male rat. J Comp Neurol 1988 275: 613-22.
Bodo C y Rissman EF. Androgen receptor is essential for sexual differentiation of responses to olfactory cues in mice. Eur J Neurosci 2007 25: 2182-90.
Olsen KL. Induction of male mating behavior in androgen-insensitive (tfm) and Normal (King-Holtzman) male rats: effect of testosterone propionate, estradiol benzoate, and dihydrotestosterone. Horm Behav 1979 13: 66-84.
Segovia S, Garcia-Falgueras A, Perez-Laso C, Pinos H, Carrillo B, Collado P, Claro F, Guillamon A. The effects of partial and complete masculinization on the sexual differentiation of nuclei that control lordotic behavior in the male rat. Behav Brain Res 2009 196: 261-7.
Paredes RG. Medial preoptic area/anterior hypothalamus and sexual motivation. Scand J Psychol 2003 44: 203-12.
Bielsky IF y Young LJ. Oxytocin, vasopressin, and social recognition in mammals. Peptides 2004 25: 1565-74.
Cooke BM, Tabibnia G, Breedlove SM. A brain sexual dimorphism controlled by adult circulating androgens. Proc Natl Acad Sci U S A, 1999 96: 7538-40.
Coopersmith C, Gans SE, Rowe DW, Erskine MS. Infusions of lidocaine into the amygdala, but not the preoptic area, block pseudopregnancy in the rat. J Neuroendocrinol 1996 8: 259-66.
Erskine MS. Mating-induced increases in FOS protein in preoptic area and medial amygdala of cycling female rats. Brain Res Bull 1993 32: 447-51.
Polston EK y Erskine MS. Excitotoxic lesions of the medial amygdala differentially disrupt prolactin secretory responses in cycling and mated female rats. J Neuroendocrinol 2001 13: 3-21.
Parada M, Chamas L, Censi S, Coria-Avila G, Pfaus JG. Clitoral stimulation induces conditioned place preference and Fos activation in the rat. Horm Behav 2010 57: 112-8.
Morris JA, Jordan CL, Dugger BN, Breedlove SM. Partial demasculinization of several brain regions in adult male (XY) rats with a dysfunctional androgen receptor gene. J Comp Neurol 2005 487: 217-26.
Cooke BM, Breedlove SM, Jordan CL. Both estrogen receptors and androgen receptors contribute to testosterone-induced changes in the morphology of the medial amygdala and sexual arousal in male rats. Horm Behav 2003 43: 336-46.
Matsumoto A y Arai Y. Sex difference in volume of the ventromedial nucleus of the hypothalamus in the rat. Endocrinol Jpn 1983 30: 277-80.
McClellan KM, Parker KL, Tobet S. Development of the ventromedial nucleus of the hypothalamus. Front Neuroendocrinol 2006 27: 193-209.
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