TNF-alpha hyperpolarizes membrane potential and potentiates the response to nicotinic receptor stimulation in cultured rat myenteric neurones.
OBJECTIVE
Tumour necrosis factor-alpha (TNF-alpha) plays a central role in the pathophysiology of inflammatory bowel disease. The present experiments were designed to characterize the action of this cytokine on enteric neurones.


METHODS
Myenteric ganglia from newborn rats were treated for 20 h with TNF-alpha (100 ng mL(-1)) and studied with the patch-clamp technique.


RESULTS
Control neurones showed a membrane potential of -34.6 +/- 2.2 mV (n = 22), whereas TNF-alpha-treated cells exhibited a membrane potential of -50.8 +/- 3.5 mV (n = 25). The depolarization evoked by carbachol (50 microm) was potentiated from 5.2 +/- 0.7 mV (n = 6) in control neurones to 27.5 +/- 2.0 mV (n = 10) in TNF-alpha-treated cells. This effect was mimicked by 1,1-dimethyl-4-phenylpiperazinium iodide, but not by bethanechol. The changes in basal membrane potential and in the nicotinic receptor response were suppressed by the non-selective cyclooxygenase (COX) inhibitor indomethacin (10 microm), and the COX II-specific inhibitor, nimesulide (100 microm), whereas the COX-I selective inhibitor SC-560 (5 microm) and the proteintyrosinekinase inhibitor genistein (50 microm) only partially inhibited the action of TNF-alpha. Staining of the ganglionic cells with an antibody against the transcription factor STAT5 revealed that TNF-alpha induced a nuclear translocation of STAT5 in non-neuronal cells.


CONCLUSIONS
TNF-alpha changes the electrophysiological properties of myenteric neurones via cyclooxygenase metabolites and protein tyrosine phosphorylation; the cells primarily responding to the cytokine seem to be non-neuronal cells in the ganglion culture, which respond with a nuclear STAT5 translocation suggesting an action on gene transcription.
Rehn
M
M
Institute for Veterinary Physiology, University of Giessen, Giessen, Germany.
Hübschle
T
T
Diener
M
M
D000818:Animals; D000831:Animals, Newborn; D018723:Bethanechol / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005725:Ganglia, Autonomic / Q000166:cytology / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D007213:Indomethacin / Q000378:metabolism; D007421:Intestine, Small / Q000166:cytology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008894:Milk Proteins; D018721:Muscarinic Agonists / Q000494:pharmacology; D009197:Myenteric Plexus / Q000166:cytology / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D011978:Receptors, Nicotinic / Q000502:physiology*; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D016861:Cyclooxygenase Inhibitors; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D008894:Milk Proteins; D018721:Muscarinic Agonists; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D018723:Bethanechol; D004246:Dimethylphenylpiperazinium Iodide; D002217:Carbachol; D019833:Genistein; D007213:Indomethacin