Reyes Beverly A S, Valentino Rita J, Xu Guangping, Van Bockstaele Elisabeth J
Department of Neurosurgery, Farber Institute for Neurosciences, Thomas Jefferson University, 900 Walnut Street, Suite 400, Philadelphia, PA 19107, USA.
Eur J Neurosci. 2005 Jul;22(1):93-106. doi: 10.1111/j.1460-9568.2005.04197.x.
Locus coeruleus (LC) neurons respond to autonomic and visceral stimuli and discharge in parallel with peripheral sympathetic nerves. The present study characterized the synaptic organization of hypothalamic afferents with catecholaminergic neurons in the LC using electron microscopy. Peroxidase labeling of axon terminals that were anterogradely labeled from the paraventricular nucleus (PVN) was combined with gold-silver labeling of tyrosine hydroxylase in the LC. Approximately 19% of the anterogradely labeled axon terminals formed synaptic specializations with tyrosine hydroxylase-immunoreactive dendrites in the LC. Retrograde transport from the LC combined with immunocytochemical detection of enkephalin and corticotropin-releasing factor (CRF) suggested that most of the LC-projecting PVN neurons (30%) were CRF immunoreactive and few (2%) were enkephalin immunoreactive. Finally, dual retrograde tracing from the LC and median eminence revealed that PVN neurons that project to the LC are a population distinct from that projecting to the median eminence. The present data suggest that a population of hypothalamic neurons is poised to directly modulate the activity of LC neurons and may integrate autonomic responses in brain by influencing LC neurons. Moreover, PVN neurons that use CRF as a neurohormone are distinct from those that use CRF as a neuromodulator to impact on the LC.
蓝斑（LC）神经元对自主神经和内脏刺激产生反应，并与外周交感神经平行放电。本研究利用电子显微镜对下丘脑传入纤维与LC中儿茶酚胺能神经元的突触组织进行了表征。将从室旁核（PVN）顺行标记的轴突终末的过氧化物酶标记与LC中酪氨酸羟化酶的金银标记相结合。在LC中，约19%的顺行标记轴突终末与酪氨酸羟化酶免疫反应性树突形成突触特化。从LC的逆行运输与脑啡肽和促肾上腺皮质激素释放因子（CRF）的免疫细胞化学检测相结合，表明大多数投射到LC的PVN神经元（30%）具有CRF免疫反应性，少数（2%）具有脑啡肽免疫反应性。最后，从LC和正中隆起进行双逆行追踪显示，投射到LC的PVN神经元与投射到正中隆起的神经元群体不同。目前的数据表明，一群下丘脑神经元准备直接调节LC神经元的活动，并可能通过影响LC神经元来整合大脑中的自主反应。此外，将CRF用作神经激素的PVN神经元与将CRF用作神经调节剂以影响LC的神经元不同。
