Soma Kiran K, Scotti Melissa-Ann L, Newman Amy E M, Charlier Thierry D, Demas Gregory E
Department of Psychology, Graduate Program in Neuroscience, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
Front Neuroendocrinol. 2008 Oct;29(4):476-89. doi: 10.1016/j.yfrne.2007.12.003. Epub 2008 Jan 3.
In 1849, Berthold demonstrated that testicular secretions are necessary for aggressive behavior in roosters. Since then, research on the neuroendocrinology of aggression has been dominated by the paradigm that the brain receives gonadal hormones, primarily testosterone, which modulate relevant neural circuits. While this paradigm has been extremely useful, recent studies reveal important alternatives. For example, most vertebrate species are seasonal breeders, and many species show aggression outside of the breeding season, when gonads are regressed and circulating testosterone levels are typically low. Studies in birds and mammals suggest that an adrenal androgen precursor-dehydroepiandrosterone (DHEA)-may be important for the expression of aggression when gonadal testosterone synthesis is low. Circulating DHEA can be metabolized into active sex steroids within the brain. Another possibility is that the brain can autonomously synthesize sex steroids de novo from cholesterol, thereby uncoupling brain steroid levels from circulating steroid levels. These alternative neuroendocrine mechanisms to provide sex steroids to specific neural circuits may have evolved to avoid the "costs" of high circulating testosterone during particular seasons. Physiological indicators of season (e.g., melatonin) may allow animals to switch from one neuroendocrine mechanism to another across the year. Such mechanisms may be important for the control of aggression in many vertebrate species, including humans.
1849年，贝托尔德证明睾丸分泌物是公鸡攻击行为所必需的。从那时起，对攻击行为神经内分泌学的研究一直受一种范式主导，即大脑接收性腺激素，主要是睾酮，这些激素调节相关神经回路。虽然这种范式极其有用，但最近的研究揭示了重要的其他可能性。例如，大多数脊椎动物是季节性繁殖者，许多物种在繁殖季节之外也表现出攻击性，此时性腺退化，循环睾酮水平通常较低。对鸟类和哺乳动物的研究表明，当性腺睾酮合成较低时，一种肾上腺雄激素前体——脱氢表雄酮（DHEA）——可能对攻击行为的表达很重要。循环中的DHEA可在大脑内代谢为活性甾体激素。另一种可能性是大脑可以从胆固醇自主合成新的甾体激素，从而使大脑甾体激素水平与循环甾体激素水平脱钩。这些为特定神经回路提供甾体激素的替代神经内分泌机制可能已经进化，以避免在特定季节高循环睾酮带来的“代价”。季节的生理指标（如褪黑素）可能使动物在一年中从一种神经内分泌机制切换到另一种。这种机制可能对包括人类在内的许多脊椎动物物种的攻击行为控制很重要。
