Lehmann M L, Erskine M S
Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
Neuroscience. 2005;136(1):55-64. doi: 10.1016/j.neuroscience.2005.02.053. Epub 2005 Sep 23.
Neurons within the posterodorsal medial amygdala of female rats are known to process vaginocervical stimulation received during mating through N-methyl-D-aspartate channel activation, conveying information to downstream hypothalamic cell groups that modulate neuroendocrine function. Stimulation of these neurons with an excitatory amino acid cocktail of glutamate, aspartate and glycine initiates 10-12 days of prolactin surge secretion that normally are observed only after the receipt of vaginocervical stimulation. Posterodorsal medial amygdala neurons responsive to vaginocervical stimulation also contain estrogen and progesterone receptors. The present experiment examined which downstream sites involved in prolactin secretion show c-fos expression following glutamate receptor activation within the posterodorsal medial amygdala and whether ovarian steroids influence cellular activation in these areas. Ovariectomized female rats implanted with unilateral cannulas directed at the posterodorsal medial amygdala received injections of estradiol benzoate and progesterone or oil before infusion treatment with either excitatory amino acid or control PBS. An additional group of estradiol benzoate+progesterone-treated females was infused with 1.0 microM glycine alone in PBS. Infusions were administered three times at 30 min intervals. FOS induction 90 min after infusion was determined immunohistochemically on the sides ipsilateral and contralateral to the infusion. Of the examined regions, excitatory amino acid treatment and hormone treatment induced three patterns of c-fos expression: 1) responses to both excitatory amino acid and hormone treatment [posterodorsal medial amygdala, medial preoptic area, ventrolateral ventromedial hypothalamic nucleus, bed nucleus of the stria terminalis]; 2) responses to estradiol benzoate+progesterone treatment only [anteroventral periventricular nucleus and dorsomedial nucleus]; and 3) responses to excitatory amino acid only [arcuate nucleus, suprachiasmatic nucleus, and paraventricular nucleus]. These data identify possible circuits by which vaginocervical stimulation, via activation of posterodorsal medial amygdala glutamate-type receptors, initiates and coordinates a series of events within a larger neuroendocrine circuit important for pregnancy.
已知雌性大鼠后内侧杏仁核中的神经元通过N-甲基-D-天冬氨酸通道激活来处理交配过程中接收到的阴道宫颈刺激,将信息传递给调节神经内分泌功能的下游下丘脑细胞群。用谷氨酸、天冬氨酸和甘氨酸的兴奋性氨基酸混合物刺激这些神经元会引发10 - 12天的催乳素激增分泌,这种分泌通常只有在接收到阴道宫颈刺激后才会观察到。对阴道宫颈刺激有反应的后内侧杏仁核神经元也含有雌激素和孕激素受体。本实验研究了催乳素分泌所涉及的哪些下游位点在杏仁核后内侧谷氨酸受体激活后显示c-fos表达,以及卵巢类固醇是否影响这些区域的细胞激活。植入单侧套管并将其指向后内侧杏仁核的去卵巢雌性大鼠在接受兴奋性氨基酸或对照磷酸盐缓冲盐水灌注治疗之前,接受苯甲酸雌二醇和孕激素或油的注射。另一组接受苯甲酸雌二醇+孕激素治疗的雌性大鼠仅在磷酸盐缓冲盐水中注入1.0微摩尔甘氨酸。以30分钟的间隔进行三次灌注。灌注90分钟后,通过免疫组织化学方法确定灌注同侧和对侧的FOS诱导情况。在所检查的区域中,兴奋性氨基酸处理和激素处理诱导了三种c-fos表达模式:1)对兴奋性氨基酸和激素处理均有反应[后内侧杏仁核、内侧视前区、下丘脑腹内侧核外侧部、终纹床核];2)仅对苯甲酸雌二醇+孕激素处理有反应[室周前腹核和背内侧核];3)仅对兴奋性氨基酸有反应[弓状核、视交叉上核和室旁核]。这些数据确定了可能的神经回路途径,通过该途径,阴道宫颈刺激通过激活后内侧杏仁核谷氨酸型受体,在对妊娠至关重要的更大神经内分泌回路中启动并协调一系列事件。