title: Regulation of discrete sub-populations of transmitter-identified neurones after inhibition of electrical activity in cultures of mouse spinal cord.
abstract: The effects of blockade of electrical activity by tetrodotoxin in cultures of mouse spinal cord and dorsal root ganglion on immunohistochemically-identified neuronal sub-populations have been investigated. Some spinal cord neuronal types, such as those storing methionine-enkephalin, substance P or calcitonin gene-related peptide were almost totally depleted after inhibition of electrical activity for 4 days. By contrast, putative substance P- and calcitonin gene-related peptide-immunoreactive dorsal root ganglion neurones were not significantly affected by such treatment. Several other neuronal types were reduced by about 30-40% after exposure to tetrodotoxin. The decrement in methionine-enkephalin-, substance P- and calcitonin gene-related peptide-immunoreactive neurones caused by tetrodotoxin was reversible, and, in the case of methionine-enkephalin, could not be elicited after day 30 in culture. Radioimmunoassay of levels of methionine-enkephalin in cultures confirmed the immunohistochemical data. It is concluded, therefore, that exposure to tetrodotoxin selectively reduces peptide immunoreactivity in specific neuronal sub-populations, but that the selectivity is not based on a single known neuronal characteristic such as transmitter phenotype, or a particular structural protein. The action of tetrodotoxin on those cells most severely attenuated is an alteration in transmitter expression rather than a lethal effect. The diminution with time of the ability of tetrodotoxin to attenuate methionine-enkephalin levels may reflect a reduction in the activity-dependent regulation of peptide expression relative to other competing trophic influences.
authors: Department of Physiology, University College, Cardiff, United Kingdom.
authors: G A
authors: GA
authors: Foster
authors: L E
authors: LE
authors: Eiden
authors: D E
authors: DE
authors: Brenneman
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide; D002478:Cells, Cultured; D004744:Enkephalin, Methionine / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009479:Neuropeptides / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D013373:Substance P / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D009479:Neuropeptides; D013373:Substance P; D013779:Tetrodotoxin; D004744:Enkephalin, Methionine; D015740:Calcitonin Gene-Related Peptide