Gerhold Lynnette M, Sellix Michael T, Freeman Marc E
Department of Biological Science, Program in Neuroscience, Florida State University, Tallahassee 32306, USA.
J Comp Neurol. 2002 Aug 19;450(2):135-43. doi: 10.1002/cne.10307.
This study was designed to determine whether there is a functional relationship between cfos expression in vasoactive intestinal peptide (VIP) -containing neurons of the suprachiasmatic nucleus (SCN) and Fos-related antigens (FRAs) expression in neuroendocrine dopaminergic neurons of the arcuate (ARN) and periventricular (PeVN) nuclei of the hypothalamus. Brains were obtained from ovariectomized (OVX) female rats killed at 12:00 AM, 7:00 AM, 9:00 AM, 12:00 PM, and 7:00 PM (12 hours illumination beginning 6:00 AM). Antibodies against FRAs and tyrosine hydroxylase (TH) identified activated neuroendocrine dopaminergic neurons. Antibodies against cfos and VIP identified activated VIP-immunoreactive (IR) neurons in the SCN. The proportion of neuroendocrine dopaminergic neurons in the ARN and PeVN expressing FRAs was greatest and equivalent at 7:00 AM, 9:00 AM, 12:00 PM, and 12:00 AM. At 7:00 PM, the proportion of neuroendocrine dopaminergic neurons expressing FRAs was significantly lower than all other time points. In the SCN, a subpopulation of VIP-IR neurons maximally expressed cfos at 7:00 AM, which decreased through 9:00 AM. cFos was not expressed at 7:00 PM and 12:00 AM in VIP-IR neurons. Antisense VIP oligonucleotides were injected into the SCN to determine whether attenuation of VIP expression disturbs rhythms in neuroendocrine dopaminergic neuronal activity. OVX rats were infused with either antisense VIP oligonucleotides or scrambled sequence oligonucleotides bilaterally (0.5 microg in 0.5 microl of saline per side) in the SCN. Animals were killed 34 hours (7:00 PM) and 46 hours (7:00 AM) after receiving infusions, and brains were recovered. Administration of antisense VIP oligonucleotides decreased VIP protein expression in the SCN and prevented the decrease in the percentage of neuroendocrine dopaminergic neurons expressing FRAs at 7:00 PM but did not affect FRAs expression at 7:00 AM when compared with animals receiving scrambled oligonucleotides. These data suggest that VIP fibers from the SCN may relay time-of-day information to neuroendocrine dopaminergic neurons to inhibit their activity and, thus, initiate prolactin release in the evening.
本研究旨在确定视交叉上核（SCN）中含血管活性肠肽（VIP）的神经元中cfos表达与下丘脑弓状核（ARN）和室周核（PeVN）的神经内分泌多巴胺能神经元中Fos相关抗原（FRA）表达之间是否存在功能关系。实验用的大脑取自于在上午12:00、上午7:00、上午9:00、下午12:00和下午7:00处死的去卵巢（OVX）雌性大鼠（从上午6:00开始12小时光照）。抗FRA和酪氨酸羟化酶（TH）的抗体用于识别活化的神经内分泌多巴胺能神经元。抗cfos和VIP的抗体用于识别SCN中活化的VIP免疫反应性（IR）神经元。ARN和PeVN中表达FRA的神经内分泌多巴胺能神经元比例在上午7:00、上午9:00、下午12:00和上午12:00时最大且相当。在下午7:00时，表达FRA的神经内分泌多巴胺能神经元比例显著低于所有其他时间点。在SCN中，VIP-IR神经元的一个亚群在上午7:00时cfos表达最高，到上午9:00时下降。VIP-IR神经元在下午7:00和上午12:00时不表达cFos。向SCN注射反义VIP寡核苷酸，以确定VIP表达的减弱是否会扰乱神经内分泌多巴胺能神经元活动的节律。OVX大鼠双侧（每侧0.5微升盐水中含0.5微克）在SCN中注入反义VIP寡核苷酸或随机序列寡核苷酸。在接受注射后34小时（下午7:00）和46小时（上午7:00）处死动物并取出大脑。与接受随机寡核苷酸的动物相比，给予反义VIP寡核苷酸可降低SCN中VIP蛋白表达，并阻止下午7:00时表达FRA的神经内分泌多巴胺能神经元百分比的下降，但不影响上午7:00时的FRA表达。这些数据表明，来自SCN的VIP纤维可能将一天中的时间信息传递给神经内分泌多巴胺能神经元以抑制其活动，从而在傍晚引发催乳素释放。
