Influences of bradykinin and substance P on the met-enkephalin-like peptide content in the rat incisor pulp.
The present study was aimed to examine possible influences of bradykinin (BK) and substance P (SP) on met-enkephalin (ME)-like peptide content in the rat incisor pulp. Des-Arg9-[Leu8]-BK, a potent BK-antagonist, significantly reduced the increased content of ME-like peptides induced by noxious stimulation, while the effect of BK-antagonist was reversed in combination with BK. Morphine decreased the increased content of ME-like peptides. Ethylketocyclazocine, a kappa-agonist, also decreased the increased content of the peptides. From these results, it was suggested that BK might be a trigger in the increase of ME-like peptide content induced by noxious stimulation and, in contrast, ME-like peptides in the pulp might inhibit BK release from the pulp in a negative feedback mechanism. On the other hand, [D-Pro2,D-Trp7,9]-SP, a potent SP-antagonist, did not show any significant influence to ME-like peptide content in the pulp. Furthermore, the content was not changed following cutting of inferior alveolar nerve. From these results, it was suggested that ME-like peptides in the pulp cells might be independent on SP-containing nerves in the pulp.
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D003714:Denervation; D003782:Dental Pulp / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000378:metabolism*; D016314:Ethylketocyclazocine; D007180:Incisor; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009474:Neurons / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000494:pharmacology*
D013373:Substance P; D004744:Enkephalin, Methionine; D016314:Ethylketocyclazocine; D009020:Morphine; D003907:Dexamethasone; D003496:Cyclazocine; D001920:Bradykinin; D007213:Indomethacin