title: Increased spinal monoamine concentrations after chronic thoracic dorsal rhizotomy in goats.
abstract: In goats, bilateral thoracic dorsal rhizotomy (TDR) causes severe ventilatory failure during exercise, followed by progressive functional recovery. We investigated spinal neurochemical changes associated with TDR and/or functional recovery by measuring spinal concentrations of the monoamines serotonin (5-HT), norepinephrine, and dopamine via HPLC. Changes in 5-HT and calcitonin gene-related peptide were visualized with immunohistochemistry. Goat spinal cords were compared 4-15 mo after TDR from T(2) to T(12) (n = 7) with sham-operated (n = 4) or unoperated controls (n = 4). TDR increased the concentration of cervical 5-HT (C(5)-C(6); 122% change), caudal thoracic norepinephrine (T(7)-T(11); 53% change), and rostral thoracic dopamine (T(3)-T(6); 234% change). TDR increased 5-HT-immunoreactive terminal density (dorsal and ventral horns) and nearly eliminated calcitonin gene-related peptide immunoreactivity in the superficial laminae of the dorsal horn in rostral thoracic segments; both effects became less pronounced in caudal thoracic segments. Thus TDR elevates monoamine concentrations in discrete spinal regions, including possible compensatory changes in descending serotonergic inputs to spinal segments not directly affected by TDR (i.e., cervical) but associated with functionally related motor nuclei (i.e., phrenic nucleus).
authors.affiliation: Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Mitchell
authors.forename: K B
authors.initials: KB
authors.lastname: Bach
authors.forename: P A
authors.initials: PA
authors.lastname: Martin
authors.forename: K T
authors.initials: KT
authors.lastname: Foley
authors.forename: E B
authors.initials: EB
authors.lastname: Olson
authors.forename: M S
authors.initials: MS
authors.lastname: Brownfield
authors.forename: V
authors.initials: V
authors.lastname: Miletic
authors.forename: M
authors.initials: M
authors.lastname: Behan
authors.forename: S
authors.initials: S
authors.lastname: McGuirk
authors.forename: H E
authors.initials: HE
authors.lastname: Sloan
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D006041:Goats; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D009919:Orchiectomy; D012016:Reference Values; D019051:Rhizotomy; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000502:physiology*; D013904:Thoracic Vertebrae; D013997:Time Factors
chemical_list: D012701:Serotonin; D015740:Calcitonin Gene-Related Peptide; D004298:Dopamine; D009638:Norepinephrine