In vitro production and release of opioid peptides in the tooth pulp induced by bradykinin.
A possible relationship between met-enkephalin (ME)-like peptides and bradykinin (BK) in the rat incisor pulp was examined in in vitro experiments using whole pulp. ME-like peptide content in the pulp was increased by BK at a concentration of 1 microM, but not in higher concentrations, while the release of ME-like peptides from the pulp into the incubation medium was increased dose-dependently by BK. These effects of BK were inhibited by Des-Arg9-[Leu8]-BK, a potent BK-antagonist, suggesting that the effects of BK were mediated through a specific BK-receptor in the pulp. On the other hand, high K+ did not induce any increased release of ME-like peptides from the pulp and the BK effects were influenced neither in Ca++-free medium nor in the presence of ouabain. These results suggested that ME-like peptide releasing effect of BK was not due to depolarization of the cell membrane and was not active. In addition, kyotorphin, and enkephalin-releaser, could not only elicit a release of ME-like peptides from the pulp, but also a marked increase of the peptide content in the pulp. However, a combination of BK and kyotorphin attenuated the effect of BK or kyotorphin each other. These results suggested that there might be two kinds of mechanisms of ME-like peptide production in the pulp and those mechanisms might interfere mutually.
D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology; D003782:Dental Pulp / Q000187:drug effects / Q000378:metabolism*; D004723:Endorphins / Q000096:biosynthesis / Q000378:metabolism* / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical
D000700:Analgesics; D004723:Endorphins; C019448:kyotorphin; D004744:Enkephalin, Methionine; D010042:Ouabain; D011188:Potassium; D001920:Bradykinin; D002118:Calcium