哺乳动物中雄性与雌性行为之间的巨大差别是怎样形成的？ 关于这个问题的主导理论是，性腺激素在脑发育早期诱导神经回路，让它们去诱导或抑制雄性或雌性特征。但新的研究工作表明，雄性或雌性的交配偏好并不是在发育过程中确定的。信息素感知已被发现能够改变成年雌性实验鼠的性行为。这一现象的关键是“犁鼻器”（vomeronasal organ），一种功能未知的辅助嗅觉器官，存在于鼻与嘴之间的犁骨（vomer bone）中。“犁鼻器”有缺陷的雌性会表现出雄性性行为，说明雄性和雌性行为的促动回路都存在于每个性别的脑中，是通过性别特异性的传感调控机制打开或关闭的。人类是在胎儿发育过程中失去“犁鼻器”的，但这一发现为研究人类的性别特异性行为开辟了新途径。
原始出处：
Nature 448, 1009-1014 (30 August 2007) | doi:10.1038/nature06089; Received 15 May 2007; Accepted 17 July 2007; Published online 5 August 2007
A functional circuit underlying male sexual behaviour in the female mouse brain
Tali Kimchi1, Jennings Xu1 & Catherine Dulac1
Department of Molecular and Cellular Biology, Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, USA
Correspondence to: Tali Kimchi1Catherine Dulac1 Correspondence and requests for materials should be addressed to C.D. (Email: dulac@fas.harvard.edu) or T.K. (Email: kimhi@fas.harvard.edu).
In mice, pheromone detection is mediated by the vomeronasal organ and the main olfactory epithelium. Male mice that are deficient for Trpc2, an ion channel specifically expressed in VNO neurons and essential for VNO sensory transduction, are impaired in sex discrimination and male–male aggression. We report here that Trpc2-/- female mice show a reduction in female-specific behaviour, including maternal aggression and lactating behaviour. Strikingly, mutant females display unique characteristics of male sexual and courtship behaviours such as mounting, pelvic thrust, solicitation, anogenital olfactory investigation, and emission of complex ultrasonic vocalizations towards male and female conspecific mice. The same behavioural phenotype is observed after VNO surgical removal in adult animals, and is not accompanied by disruption of the oestrous cycle and sex hormone levels. These findings suggest that VNO-mediated pheromone inputs act in wild-type females to repress male behaviour and activate female behaviours. Moreover, they imply that functional neuronal circuits underlying male-specific behaviours exist in the normal female mouse brain.
