Hutchison R E, Wozniak A W, Hutchison J B
MRC Neuroendocrine Development and Behaviour Group, Institute of Animal Physiology, Babraham, Cambridge, U.K.
J Endocrinol. 1992 Sep;134(3):385-96. doi: 10.1677/joe.0.1340385.
Oestrogen is formed in the female dove brain. The aim of this study was to determine whether (a) the catalytic properties of the brain aromatase are similar to the ovarian enzyme and (b) aromatase activity in the female brain changes during the reproductive cycle and is influenced by steroids and environmental stimuli. The results show that female preoptic aromatase has a higher substrate affinity than the enzyme in ovarian follicles (apparent Km: preoptic area, 7 nmol/l; ovarian follicles, 29 nmol/l), but a lower activity in the preoptic area (Vmax: preoptic area, 290 fmol/mg tissue per h; ovarian follicles, 843 fmol/mg tissue per h). In intact females with developing follicles, oestradiol-17 beta formation was higher in the posterior hypothalamus than the preoptic area. Females in a later stage of reproductive development (yolked follicles) had a different distribution of oestrogen formation with increased aromatase activity in the preoptic area. Preoptic and posterior hypothalamic aromatase activity of females paired with males for 10 days was positively correlated (r = 0.84, P = 0.0001; r = 0.75, P = 0.001 respectively) with ovarian development. Females with undeveloped ovaries which interacted with males had higher preoptic aromatase activity than visually isolated females with similar ovarian development, suggesting that behavioural stimuli have direct effects on brain aromatase activity which are independent of the ovary. Oestradiol benzoate treatment increased preoptic and posterior hypothalamic aromatase activity in intact and ovariectomized females, and testosterone propionate treatment increased anterior hypothalamic aromatase activity, but did not affect other areas, indicating that the distribution of induced aromatase activity is steroid-specific. Oestrogen treatment in ovariectomized or intact females did not replicate the maximal hypothalamic aromatase activity seen when the ovary contained yolked follicles. We conclude that brain aromatase activity is related directly to ovarian condition during the reproductive cycle of the female dove. As in the male, steroids have a role in the regulation of oestrogen formation in the female hypothalamus; behavioural stimuli are also likely to be involved in the control of the brain enzyme.
雌激素在雌性鸽子的大脑中合成。本研究的目的是确定：（a）大脑芳香化酶的催化特性是否与卵巢酶相似；（b）雌性大脑中的芳香化酶活性在生殖周期中是否发生变化，以及是否受类固醇和环境刺激的影响。结果表明，雌性视前区芳香化酶比卵巢卵泡中的酶具有更高的底物亲和力（表观 Km：视前区，7 nmol/l；卵巢卵泡，29 nmol/l），但视前区的活性较低（Vmax：视前区，290 fmol/mg组织每小时；卵巢卵泡，843 fmol/mg组织每小时）。在卵泡发育的完整雌性中，下丘脑后部的雌二醇-17β形成高于视前区。处于生殖发育后期（有卵黄卵泡）的雌性雌激素形成分布不同，视前区芳香化酶活性增加。与雄性配对10天的雌性视前区和下丘脑后部的芳香化酶活性与卵巢发育呈正相关（分别为r = 0.84，P = 0.0001；r = 0.75，P = 0.001）。卵巢未发育但与雄性互动的雌性比卵巢发育相似但视觉隔离的雌性具有更高的视前区芳香化酶活性，这表明行为刺激对大脑芳香化酶活性有直接影响，且这种影响独立于卵巢。苯甲酸雌二醇处理增加了完整和去卵巢雌性视前区和下丘脑后部的芳香化酶活性，丙酸睾酮处理增加了下丘脑前部的芳香化酶活性，但不影响其他区域，这表明诱导的芳香化酶活性分布具有类固醇特异性。去卵巢或完整雌性的雌激素处理并未重现卵巢含有卵黄卵泡时所见的最大下丘脑芳香化酶活性。我们得出结论，在雌性鸽子的生殖周期中，大脑芳香化酶活性与卵巢状况直接相关。与雄性一样，类固醇在雌性下丘脑雌激素形成的调节中起作用；行为刺激也可能参与大脑酶的控制。
