title: Acute muscle inflammation enhances the monosynaptic reflexes and c-fos expression in the feline spinal cord.
abstract: The aim of this research was to study the changes of the motor reflex activity (monosynaptic reflex (MSR) of the flexor and extensor muscles) and Fos immunoreactivity in lumbo-sacral spinal cord after acute induced myositis of m. gastrocnemius-soleus (GS). The experiments were carried out on ischaemic decerebrated, spinalized in C1 cats. After infiltration of the GS muscle with carrageenan (2%) MSRs of flexors and extensors showed a significant increase in amplitude +127+/-24.5% and +155+/-28.5%, respectively, p<0.05. The exposed effect was initiated within 30 min and achieved a maximum 2.8h after the intramuscular injections of carrageenan. After analysis of dynamics of the MSRs, animals were perfused and c-fos expression in the spinal segments L6-S1 was evaluated. In comparison to sham-operated animals, the number of Fos-immunoreactive (Fos-ir) cells was noticeably increased in the lumbar cord of cats with carrageenan-induced myositis. The labeled cells were concentrated in the ipsilateral laminae I/II, neck of the dorsal horn (V/VI) and intermediate zone (VII), however, clear predominance of their concentration was found in the deep laminae. The effect of muscle inflammation was also expressed as a significant decline in the number of NADPH-d-reactive cells (p<0.05) in ipsilateral laminae I/II of L6/L7. The results show that the input from acutely inflamed muscles may induce an increase of the reflex responsiveness of flexors and extensors which is not mediated via the gamma-spindle-loop and which coincides with a significant increase in c-fos expression in the deep laminae of the lumbar spinal cord.
authors.affiliation: Zentrum Physiologie und Pathophysiologie, Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany.
authors.forename: Eike D
authors.initials: ED
authors.lastname: Schomburg
authors.forename: Heinz
authors.initials: H
authors.lastname: Steffens
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Maznychenko
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Pilyavskii
authors.forename: Fredrik
authors.initials: F
authors.lastname: Hellström
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Kostyukov
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Maisky
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D002351:Carrageenan / Q000494:pharmacology; D002415:Cats; D007839:Functional Laterality / Q000502:physiology; D018836:Inflammation Mediators / Q000494:pharmacology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009220:Myositis / Q000503:physiopathology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009475:Neurons, Afferent / Q000378:metabolism; D009619:Nociceptors / Q000502:physiology; D010525:Peripheral Nerves / Q000378:metabolism / Q000503:physiopathology; D020671:Posterior Horn Cells / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D012021:Reflex, Abnormal / Q000502:physiology*; D012023:Reflex, Monosynaptic / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism / Q000503:physiopathology*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D016760:Proto-Oncogene Proteins c-fos; D002351:Carrageenan; D009252:NADPH Dehydrogenase