NEURAL PATHWAYS FROM PHOTORECEPTORS TO THE PITUITARY

总的具体目标是定义光周期条件，该条件 允许表达生殖活动的内源周期节律 (根据血孕酮定义的动情周期与动情周期)和 催乳素分泌和确定神经结构参与 以绵羊为实验对象的这些节律的产生和控制 模特。具体目标是： 1.完成一项正在进行的研究，以检验内生性假设 绵羊繁殖活动的节律只有在一定的条件下才能表现出来 恒定的光周期。生殖周期节律的表达 将比较饲养在以下环境中的母羊的活动和催乳素分泌 12L：12D与8L：16D光周期。 2.检验特定信号(光周期)的影响的假设 方案)对内源昼夜节律表达的影响取决于 应用该信号的年度节奏的阶段。母羊将会是 放置在12L：12D下，处于其年度周期的4个不同阶段。 随后的生殖活动和催乳素分泌模式将 被监视。 3.检验内生节律表达的假设 卵巢完整的母羊的生殖活动被掩盖在12L：12D以下 光周期。将比较发病时间和发病时间的变化。 正常母羊发情周期的终止与黄体生成素的变化 12L：12D和8L：16D饲养条件下去卵巢雌激素处理的母羊 光周期。 4.检验去除嗅球不会 影响光周期变化改变黄体生成素和催乳素的能力 母羊的分泌物。嗅球切除对基础分泌物的影响 黄体生成素和卵泡刺激素及其对光周期变化的反应 将会受到监控。 5.检验视交叉上核损伤的无效假设 (SCN)、下丘脑前区病变(AHA)或嗅觉 球茎切除不会影响生殖节律的表达 在恒定的光周期下，绵羊的活动和催乳素分泌。 在三个单独的实验中，绵羊将受到SCN损伤，AHA 损伤、嗅球切除或假手术，然后放置在8L：16D下 以确定假定的内源性节律的表达是否改变。

The overall specific aims are to define the photoperiod conditions which permit expression of endogenous circannual rhythms of reproductive activity (anestrus versus estrous cycles as defined by blood progesterone) and prolactin secretion and to define the neural structures involved in generation and control of these rhythms using the sheep as the experimental model. Specific aims are: 1. To complete a study in progress testing the hypothesis that endogenous rhythms of reproductive activity in sheep are expressed only under certain constant photoperiods. Expression of circannual rhythms of reproductive activity and prolactin secretion will be compared in ewes housed under 12L:12D versus 8L:16D photoperiods. 2. To test the hypothesis that the effect of a specific signal (photoperiod regimen) on expression of endogenous circannual rhythms depends on the stage of the annual rhythm at which that signal is applied. Ewes will be placed under 12L:12D at 4 distinct stages of their annual cycle. Subsequent patterns of reproductive activity and prolactin secretion will be monitored. 3. To test the hypothesis that expression of an endogenous rhythm of reproductive activity is masked in ovary-intact ewes kept under a 12L:12D photoperiod. Comparison will be made of temporal changes in onset and cessation of estrous cycles in intact ewes versus changes of LH in ovariectomized estrogen-treated ewes housed under 12L:12D and 8L:16D photoperiods. 4. To test the null hypothesis that removal of the olfactory bulbs will not affect the ability of photoperiod changes to alter LH and prolactin secretion in ewes. The effect of olfactory bulbectomy on basal secretion of LH and FSH and on responses of these hormones to changes in photoperiod will be monitored. 5. To test the null hypotheses that lesions of the suprachiasmatic nucleus (SCN), lesions of the anterior hypothalamic area (AHA), or olfactory bulbectomy will not affect expression of circannual rhythms of reproductive activity and prolactin secretion in ewes kept under a constant photoperiod. In 3 separate experiments ewes will be subjected to either SCN lesions, AHA lesions, olfactory bulbectomy, or sham surgery and then housed under 8L:16D to determine if expression of the putative endogenous rhythm is altered.