Oestradiol microimplants in the ventromedial preoptic area inhibit secretion of luteinizing hormone via dopamine neurones in anoestrous ewes
Oestradiol microimplants in the ventromedial preoptic area inhibit secretion of luteinizing hormone via dopamine neurones in anoestrous ewes
复制标题
DOI：
10.1046/j.1365-2826.2001.00726.x
复制
发表时间：
2001-12-01
影响因子：
3.2
通讯作者：
Goodman, RL
中科院分区：
文献类型：
--
作者：
Anderson, GM;Connors, JM;Goodman, RL
雌二醇对萨福克羊的GnRH/LH神经分泌系统产生季节特异性负反馈效应。这种神经内分泌抑制部分由多巴胺A15神经元介导，但这些神经元不具有雌激素受体。基于间接证据，我们假设，雌激素受体的神经元在腹内侧视前区（vmPOA）可能是在一个神经元系统的第一步，雌二醇抑制GnRH分泌在非繁殖季节。为了测试这一点，使用卵巢切除的母羊进行了三个实验，这些母羊接受了针对vmPOA或s.c.的空的或含雌二醇的双侧微植入物。皮下含雌二醇的植入物。在第一个实验中，在季节性不发情期间，在处理的第0、1、7和14天测量LH脉冲频率。在vmPOA中，雌二醇和s.c.仅雌二醇组，LH脉冲频率在第7天和第14天受到抑制，在第7天出现最大抑制。在第二个实验中，在繁殖季节重复该方案，在第0天和第7天检查LH脉冲; LH脉冲频率在任何组中都没有变化。第三个实验测试了在乏情期期间vmPOA雌二醇的作用是否可以通过注射多巴胺-D-2受体拮抗剂（-）-舒必利来克服。vmPOA微植入物和s.c.雌二醇植入物再次抑制LH脉冲频率，这在vmPOA雌二醇母羊中被舒必利逆转。我们的结论是，雌二醇作用于VMPOA中的细胞，以刺激涉及多巴胺神经元的系统，抑制GnRH/LH脉动在anestrous母羊。
Oestradiol exerts a season-specific negative feedback effect on the GnRH/LH neurosecretory system of the Suffolk ewe. This neuroendocrine suppression is mediated in part by dopamine A15 neurones, but these neurones do not possess the oestrogen receptor. Based on indirect evidence, we hypothesized that oestrogen receptor-containing neurones in the ventromedial preoptic area (vmPOA) may be the initial step in a neuronal system whereby oestradiol suppresses GnRH secretion during the non-breeding season. To test this, three experiments were conducted using ovariectomized ewes receiving either empty or oestradiol-containing bilateral microimplants directed at the vmPOA or s.c. subcutaneous oestradiol-containing implants. In the first experiment, LH pulse frequency was measured on days 0, 1, 7 and 14 of treatment during seasonal anoestrus. In vmPOA oestradiol and s.c. oestradiol groups only, LH pulse frequency was suppressed on days 7 and 14, with maximal suppression evident by day 7. In the second experiment, this protocol was repeated during the breeding season, with LH pulses examined on days 0 and 7; LH pulse frequency did not change in any group. The third experiment tested if the effect of vmPOA oestradiol during anoestrus could be overcome by an injection of the dopamine-D-2 receptor antagonist (-)-sulpiride. The vmPOA microimplants and s.c. oestradiol implants again suppressed LH pulse frequency and this was reversed by sulpiride in vmPOA oestradiol ewes. We conclude that oestradiol acts on cells in the vmPOA to stimulate a system involving dopamine neurones that inhibits GnRH/LH pulsatility in the anoestrous ewe.