title: Dual projections of single orexin- or CART-immunoreactive, lateral hypothalamic neurons to the paraventricular thalamic nucleus and nucleus accumbens shell in the rat: Light microscopic study.
abstract: The paraventricular thalamic nucleus (PVT) is a major relay station to the limbic forebrain areas such as the nucleus accumbens shell (AcbSh). Both PVT and AcbSh are known to receive feeding/arousal-related peptidergic fibers including orexin (ORX) and cocaine- and amphetamine-regulated transcript (CART) peptide. In the first series of experiments, we examined the peptidergic fiber distribution in the AcbSh; the density of ORX (or CART) fibers in the AcbSh was substantially lower than that in the PVT. At the light microscopic level, ORX (or CART) terminals formed close appositions to choline acetyltransferase (ChAT)-, glutamate decarboxylase (GAD)-, or enkephalin (Enk)-immunoreactive neuronal elements in the AcbSh. In the second series of experiments, we addressed the question of whether single ORX (or CART) cells in the hypothalamus provided divergent axon collaterals to the PVT and AcbSh. ORX neurons with dual projections were found in the medial, central, and lateral subdivisions of the lateral hypothalamus (LH), which amounted to an average of 1.6% of total ORX cells. CART neurons with divergent axon collaterals were observed in the LH, zona incerta, dorsal hypothalamic area, and retrochiasmatic nucleus, which represented a mean of 2.5% of total CART cells. None of arcuate CART cells sent dual projections. These data suggested that a portion of ORX (or CART) neurons in the hypothalamus, via divergent axon collaterals, might concurrently modulate the activity of PVT and AcbSh cells to affect feeding and drug-seeking behaviors.
authors.affiliation: Department of Anatomy, School of Medicine, Konkuk University, 143-701 Seoul, South Korea.
authors.forename: Eun Y
authors.initials: EY
authors.lastname: Lee
authors.affiliation: Department of Anatomy, School of Medicine, Konkuk University, 143-701 Seoul, South Korea; Research Institute of Medical Science, School of Medicine, Konkuk University, 143-701 Seoul, South Korea. Electronic address: hyunsook.lee@kku.ac.kr.
authors.forename: Hyun S
authors.initials: HS
authors.lastname: Lee
mesh_terms: D000818:Animals; D007026:Hypothalamic Area, Lateral / Q000166:cytology* / Q000378:metabolism; D008297:Male; D008853:Microscopy; D020644:Midline Thalamic Nuclei / Q000166:cytology* / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D056347:Neuroanatomical Tract-Tracing Techniques; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009714:Nucleus Accumbens / Q000166:cytology* / Q000378:metabolism; D000068797:Orexins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D009419:Nerve Tissue Proteins; D000068797:Orexins; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
keywords: Cocaine- and amphetamine-regulated transcript (CART) peptide; Lateral hypothalamus (LH); Nucleus accumbens shell (AcbSh); Orexin (ORX); Paraventricular thalamic nucleus (PVT)