Association of cocaine- and amphetamine-regulated transcript-immunoreactive elements with thyrotropin-releasing hormone-synthesizing neurons in the hypothalamic paraventricular nucleus and its role in the regulation of the hypothalamic-pituitary-thyroid axis during fasting.

摘要: Because cocaine- and amphetamine-regulated transcript (CART) coexists with alpha-melanocyte stimulating hormone (alpha-MSH) in the arcuate nucleus neurons we have recently demonstrated that alpha-MSH innervates TRH-synthesizing hypothalamic paraventricular (PVN), raised possibility CART may also be contained fibers innervate hypophysiotropic thyrotropin-releasing (TRH) modulate TRH gene expression. Triple-labeling fluorescent situ hybridization immunofluorescence were performed to reveal morphological relationships between pro-TRH mRNA-containing CART- alpha-MSH-immunoreactive (IR) axons. CART-IR axons densely innervated majority of all parvocellular subdivisions PVN established asymmetric synaptic specializations neurons. However, whereas alpha-MSH-IR CART-IR, only a portion contact immunoreactive for alpha-MSH. In medial periventricular PVN, was co-contained approximately 80% neuronal perikarya, colocalization found TRH/CART accumulated Fluoro-Gold after systemic administration, suggesting serve as marker prevented fasting-induced suppression when administered intracerebroventricularly increased content cell cultures. These studies establish an anatomical association pro-TRH-producing demonstrate has stimulatory effect on by increasing expression biosynthesis TRH.