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To determine the relative contribution of the brainstem to the CART innervation of the TRH neurons in the PVN, the major ascending brainstem axonal pathways to the PVN were unilaterally transected in the hypothalamus. After 2 weeks survival time, hypothalamic sections were prepared for immunocytochemistry. PNMT-IR axon density decreased 76.0 +/- 3.8% on the side of the knifecut compared to the contralateral side, demonstrating satisfactory disconnection of the ascending brainstem pathways. In contrast, the density of CART-IR axons in the PVN on the lesioned side was reduced by only 26.9 +/- 2.7%. Disconnection of brainstem pathways reduced the total number of TRH neurons contacted by CART from 99.4 +/- 0.9% on the intact side to 74.3 +/- 9.4% on the lesioned side, as well as the number of CART varicosities on the surface of TRH neurons from 6.0 +/- 0.9 to 2.3 +/- 0.4 CART-IR varicosities/cell. These data indicate that CART-IR neurons residing in the brainstem give rise to only approximately one third of the CART input to the PVN as a whole, but serve as a major source of the CART-IR innervation of hypophysiotropic TRH neurons. 相似文献
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The hypothalamic paraventricular nucleus (PVN) coordinates major neuroendocrine and behavioral mechanisms, particularly responses to homeostatic challenges. Parvocellular and magnocellular PVN neurons are richly innervated by pituitary adenylate cyclase-activating polypeptide (PACAP) axons. Our recent functional observations have also suggested that PACAP may be an excitatory neuropeptide at the level of the PVN. Nevertheless, the exact localization of PACAP-producing neurons that project to the PVN is not understood. The present study examined the specific contribution of various brain areas sending PACAP innervation to the rat PVN by using iontophoretic microinjections of the retrograde neuroanatomical tracer cholera toxin B subunit (CTb). Retrograde transport was evaluated from hypothalamic and brainstem sections by using multiple labeling immunofluorescence for CTb and PACAP. PACAP-containing cell groups were found to be retrogradely labeled from the PVN in the median preoptic nucleus; preoptic and lateral hypothalamic areas; arcuate, dorsomedial, ventromedial, and supramammillary nuclei; ventrolateral midbrain periaqueductal gray; rostral and midlevel ventrolateral medulla, including the C1 catecholamine cell group; nucleus of the solitary tract; and dorsal motor nucleus of vagus. Minor PACAP projections with scattered double-labeled neurons originated from the parabrachial nucleus, pericoeruleus area, and caudal regions of the nucleus of the solitary tract and ventrolateral medulla. These observations indicate a multisite origin of PACAP innervation to the PVN and provide a strong chemical neuroanatomical foundation for interaction between PACAP and its potential target neurons in the PVN, such as parvocellular CRH neurons, controlling physiologic responses to stressful challenges and other neuroendocrine or preautonomic PVN neurons. 相似文献
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Füzesi T Sánchez E Wittmann G Singru PS Fekete C Lechan RM 《Journal of neuroendocrinology》2008,20(9):1058-1066
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After injection of WGA-HRP-colloidal gold in the rat paraventricular nucleus (PVN), retrogradely labeled neurons were found mainly in the medial and commissural subnuclei of the nucleus tractus solitarius (NTS) around 0.5 mm caudal to the obex which is closely related to cardiovascular function. Electron microscopic immunohistochemistry in these areas demonstrated synaptic contacts between retrogradely labeled neurons and substance P-immunoreactive terminals. Innervation of NTS-PVN projection systems by substance P is suggested. 相似文献
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Ziegler DR Edwards MR Ulrich-Lai YM Herman JP Cullinan WE 《The Journal of comparative neurology》2012,520(11):2369-2394
Multiple lines of evidence document a role for glutamatergic input to the hypothalamic paraventricular nucleus (PVH) in stress-induced activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. However, the neuroanatomical origins of the glutamatergic input have yet to be definitively determined. We have previously shown that vesicular glutamate transporter 2 (VGLUT2) is the predominant VGLUT isoform expressed in the basal forebrain and brainstem, including PVH-projecting regions, and that the PVH is preferentially innervated by VGLUT2-immunoreactive terminals/boutons. The present study employed a dual-labeling approach, combining immunolabeling for a retrograde tract tracer, Fluoro-Gold (FG), with in situ hybridization for VGLUT2 mRNA, to map the brainstem and caudal forebrain distribution of glutamatergic PVH-projecting neurons. The present report presents evidence for substantial dual labeling in the periaqueductal gray, caudal portions of the zona incerta and subparafascicular nucleus, and the lateral parabrachial nucleus. The current data also suggest that relatively few PVH-projecting neurons in ascending raphe nuclei, nucleus of the solitary tract, or ventrolateral medulla are VGLUT2 positive. The data reveal multiple brainstem origins of glutamatergic input to PVH that are positioned to play a role in transducing a diverse range of stressful stimuli. 相似文献