Brain response to putative pheromones in lesbian women

Abstract

The progesterone derivative 4,16-androstadien-3-one (AND) and the estrogen-like steroid estra-1,3,5(10),16-tetraen-3-ol (EST) are candidate compounds for human pheromones. In previous positron emission tomography studies, we found that smelling AND and EST activated regions primarily incorporating the sexually dimorphic nuclei of the anterior hypothalamus, that this activation was differentiated with respect to sex and compound, and that homosexual men processed AND congruently with heterosexual women rather than heterosexual men. These observations indicate involvement of the anterior hypothalamus in physiological processes related to sexual orientation in humans. We expand the information on this issue in the present study by performing identical positron emission tomography experiments on 12 lesbian women. In contrast to heterosexual women, lesbian women processed AND stimuli by the olfactory networks and not the anterior hypothalamus. Furthermore, when smelling EST, they partly shared activation of the anterior hypothalamus with heterosexual men. These data support our previous results about differentiated processing of pheromone-like stimuli in humans and further strengthen the notion of a coupling between hypothalamic neuronal circuits and sexual preferences.hypothalamus ͉ olfaction ͉ positron emission tomography ͉ sexual orientation I n animals, the choice of sexual partner is highly influenced by signals from sex-specific pheromones. These signals are processed by specific nuclei located in the anterior hypothalamus, identified as male and female mating centers (1-5). A lesion of the respective mating center as well as impairment of pheromone transduction may alter the coital approach in a sex-specific way (3-5). For example, electrolytic lesion of the preoptic area is reported to shift the mean preference of male ferrets away from the estrous females to the stud males (3, 5). Male rats are found to reduce their coital behavior after destruction of the preoptic area and show more interest in stimulus males than receptive females (1). Female ferrets, however, preferred females after destruction of the ventromedial hypothalamic nucleus (2) and did not allow males to intromit (4), whereas female rats increased the proportion of female approaches after kindling of the preoptic area (6).In humans, reproductive functions are mediated by neuronal circuits of the anterior hypothalamus. There is reason to believe that these circuits also participate in the integration of the hormonal and sensory cues that are necessary for our sexual behavior and may also be involved in our sexual preferences (7). The preoptic area of the hypothalamus harbors cells releasing luteinic hormone-releasing hormone (8). These cells develop from the migrating neuroblasts of the olfactory mucosa (9) and mediate estrogen feedback. The estrogen feedback differs between males and females and also is reported to differ between homosexual men (HoM) and heterosexual men (HeM) (10). In addition, the anterior hypothalamus contains neuronal congl...

Sexual differentiation of the human brain in relation to gender identity and sexual orientation

“…Apparently heterosexual men are not stimulated by a male scent, which suggests that pheromones contribute to determining our behavior in relation to our sexual orientation (125). In a follow-up study (126), lesbian women, as compared to heterosexual women, reacted in a sexatypical, almost reciprocal way to pheromones. These observations, too, show that there are hypothalamic circuits that function in a way that depends on our sexual orientation.…”

Same-sex sexual behavior and evolution

“…In male homosexuals, regions of the brain that are associated with sexual activity activate in response to a testosterone derivative with pheromone-like properties [63]. An estrogen derivative similarly activated the same brain regions in homosexual women [64]. The responses are sex atypical, and researchers have begun to attribute such differences to anatomical features of the brain, for example amygdala connections, that are differentiated with respect to sexual orientation but not biological sex [65].…”

Sexual orientation and its basis in brain structure and function

“…Pheromones thus may play a part in our behavior related to sexual orientation. A follow-up study (3) showed that HoW reacted in a sex-atypical, almost reciprocal, way to pheromones as compared with HeW, again indicating that some hypothalamic circuits function in relation to sexual orientation. Kranz and Ishai (11) expanded this observation to cortical areas.…”

“…This sexual differentiation process is accompanied by many structural and functional brain differences among these groups (1). In previous studies (2,3), the Savic laboratory detected a sex-differentiated activation of the anterior hypothalamus in heterosexual men (HeM) and heterosexual women (HeW) and a sex-atypical, almost reversed, pattern of activation in homosexual men (HoM) and homosexual women (HoW). The hypothalamus (Fig.…”