title: A neurophysiological evidence of capsaicin-sensitive nerve components innervating interscapular brown adipose tissue.
abstract: Neurophysiological basis for the heterogeneity of the nerve components in the brown adipose tissue (BAT) was examined in this experiment. Efferent nerve signals were recorded from the central cut end of the small nerve filament dissected from the nerve fibers innervating the interscapular BAT (IBAT). By focusing on qualitative aspects of observed compound action potentials (spikes), we found two distinctive types of spikes exhibited by the intercostal nerves innervating IBAT. The spikes mainly appeared upon sympathetic stimulations (cold stimulation and glucose administration) were characterized by low amplitude with relatively short duration (small spike) and their sensitivity to the ganglion blocker, hexamethonium (C6). On the other hand, the spikes seen throughout the experiments were characterized by high amplitude with long duration (large spike) and their insensitivity to C6. Since BAT is activated by cold and feeding via sympathetic nervous system, the small spikes seemed to be exhibited by sympathetic fibers. On the other hand, appearance of the large C6-insensitive spikes was strongly attenuated in capsaicin-desensitized rats. Even though the functional link between IBAT and C6 insensitive fibers remains unanswered, our results suggest that IBAT is under control of various nerve types including capsaicin-sensitive fibers in addition to the control of sympathetic nervous system.
authors.affiliation: Department of Physiology and Pathogenetic Veterinary Sciences, The United Graduate School, Gifu University, 1-1 Yanagido, 501-1193 Gifu, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Takahiko
authors.initials: T
authors.lastname: Shiina
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Nishijima
authors.forename: Yasuro
authors.initials: Y
authors.lastname: Atoji
authors.forename: Hideki
authors.initials: H
authors.lastname: Nikami
authors.forename: Akira
authors.initials: A
authors.lastname: Niijima
authors.forename: Tadashi
authors.initials: T
authors.lastname: Takewaki
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000294:innervation* / Q000502:physiology*; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D004525:Efferent Pathways / Q000187:drug effects / Q000502:physiology; D018738:Hexamethonium / Q000494:pharmacology; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012540:Scapula / Q000187:drug effects / Q000294:innervation* / Q000502:physiology*
chemical_list: D018738:Hexamethonium; D002211:Capsaicin