University of Texas Southwestern Medical Center, Department of Physiology, 5323 Harry Hines Boulevard, Dallas, Texas 75235-9040, USA.
Mol Cell Neurosci. 1992 Aug;3(4):360-9. doi: 10.1016/1044-7431(92)90034-y.
Reproductive events in the female rat can be influenced by exposure to the odors of conspecific males. Much evidence indicates that these pheromonal effects are mediated by the accessory olfactory system (AOS); however, individual cells within the AOS that are stimulated following exposure to male odors have not yet been visualized. The present experiment was designed to determine the effect of exposure to conspecific males and male odors on signal transduction in central AOS neurons as measured by immunohistochemical detection of the induction of the fos-like protein. AOS structures examined included the accessory olfactory bulb (AOB), medial amygdala (mAMYG), and bed nucleus of the stria terminalis (BNST). Due to its importance in the control of reproductive activities and its direct link to the AOS, the ventromedial nucleus of the hypothalamus (VMH) was also examined. Adult, ovariectomized rats were injected with estradiol benzoate (EB) and 48 h later were placed in cages containing bedding material soiled by conspecific males or placed in cages containing clean bedding material. After exposure durations ranging from 10 to 180 min, the animals were sacrificed and the brains were immunohistochemically processed for detection of fos-like immunoreactivity. Another group of ovariectomized, EB-injected females was repeatedly paired with conspeciflc males for 15 min followed by 15 min of rest. Repeated matings were conducted over a 60-, 120-, or 180-min period while control animals were repeatedly exposed to clean bedding material. Quantitative analysis of the number of fos-immunopositive cells in the AOB revealed that continuous exposure to male-soiled bedding or repeated mating resulted in significant induction of foslike immunoreactivity compared to controls. Both treatments produced similar numbers of fos-like immunoreactive cells in the mitral and granule cell layers of the AOB. Fos induction was apparent after 60 min of treatment but was more prominent at 120 and 180 min. In the mAMYG, BLAST, and VMH, differences between the two treatments were noted. Exposure to male-soiled bedding for 60 min produced scattered staining in the mAMYG, BLAST, and VMH, whereas 60 min of repetitive mating resulted in a more dense distribution of fos-like immunoreactive cells in these areas. Strikingly distinct patterns of fos-like immunoreactive cells were observed in the mAMYG, BLAST, and VMH following 120 or 180 min of repetitive mating. These patterns were not present in animals exposed to male odors. The findings indicate that exposure of female rats to reproductively relevant stimuli resulted in induction of fos-like immunoreactivity within the AOS and that both olfactory and nonolfactory cues probably contributed to this effect.
雌性大鼠的生殖活动可受到同种雄性气味的影响。大量证据表明，这些信息素效应是由附属嗅觉系统（AOS）介导的；然而，暴露于雄性气味后，刺激 AOS 内的单个细胞尚未被可视化。本实验旨在通过免疫组织化学检测诱导的 fos 样蛋白的诱导，确定暴露于同种雄性和雄性气味对中枢 AOS 神经元信号转导的影响。检查的 AOS 结构包括附属嗅球（AOB）、内侧杏仁核（mAMYG）和终纹床核（BNST）。由于其在生殖活动控制中的重要性及其与 AOS 的直接联系，下丘脑腹内侧核（VMH）也进行了检查。成年、去卵巢大鼠注射苯甲酸雌二醇（EB），48 小时后放置在含有同种雄性污染垫料的笼子中或放置在含有清洁垫料的笼子中。暴露时间从 10 分钟到 180 分钟不等后，处死动物，并用免疫组织化学方法检测 fos 样免疫反应性。另一组去卵巢、注射 EB 的雌性大鼠与同种雄性动物进行 15 分钟的重复交配，然后休息 15 分钟。在 60、120 或 180 分钟的时间内进行重复交配，而对照动物则反复暴露于清洁的垫料中。AOB 中 fos 免疫阳性细胞数量的定量分析表明，与对照组相比，连续暴露于雄性污染的垫料或重复交配会导致 fos 样免疫反应性的显著诱导。两种处理方法在 AOB 的乳突和颗粒细胞层中产生相似数量的 fos 样免疫反应性细胞。在处理 60 分钟后即可观察到 fos 诱导，但在 120 和 180 分钟时更为明显。在 mAMYG、BLAST 和 VMH 中，两种处理方法之间存在差异。暴露于雄性污染的垫料 60 分钟会在 mAMYG、BLAST 和 VMH 中产生散在的染色，而重复交配 60 分钟会导致这些区域 fos 样免疫反应性细胞的分布更加密集。在重复交配 120 或 180 分钟后，在 mAMYG、BLAST 和 VMH 中观察到fos 样免疫反应性细胞的明显不同模式。在暴露于雄性气味的动物中没有出现这些模式。研究结果表明，雌性大鼠暴露于与生殖相关的刺激会导致 AOS 内 fos 样免疫反应性的诱导，嗅觉和非嗅觉线索可能都促成了这种效应。
