Effects of hard tissue-related hormones on the intracellular calcium ion of the rat odontoblasts.
We examined the effects of PTH, calcitonin (CT) and parotin subunit on the intracellular Ca2+ of odontoblasts using a chelate reagent, FURA2-AM. Rat CT (rCT), at a final concentration of 0.01 microM, induced a gradual lowering of Ca2+, and addition of ATP, in the presence of CT, resulted in a partial and short-lasting recovery of Ca2+. At higher concentrations, it caused a rapid decrease of Ca2+. CTs of other animal species showed similar effects. Human PTH (hPTH) added at concentrations of 0.01, 0.1 and 1 microM, caused no significant changes in intracellular Ca2+. Parotin subunit caused a rapid lowering of Ca2+ which was seen already at 0.01 microM. rCT added after treatment with hPTH caused an immediate decrease of Ca2+ to zero level, showing that CT action was enhanced by pretreatment with hPTH. This enhancement was also confirmed by addition of hPTH after rCT, where at 1 microM, it caused further acute decrease in Ca2+. After intracellular Ca2+ was lowered by CT pretreatment, parotin, at 0.1 microM, induced a further but gradual decrease of Ca2+. The present results, together with our previous study indicating that hPTH increased cAMP production and that CT inhibited the PTH action, made it clear that all the hormones affect odontoblasts, and that CT and parotin act via Ca-related signal transduction system, while PTH acts via cAMP-PKA-related cascade. Possible crosstalk of both systems was also suggested.
Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan.
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Saitoh
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Wakabayashi
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002116:Calcitonin / Q000494:pharmacology*; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002614:Chelating Agents; D000242:Cyclic AMP / Q000096:biosynthesis; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D006801:Humans; D007700:Kinetics; D008297:Male; D009804:Odontoblasts / Q000187:drug effects* / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012471:Salivary Proteins and Peptides / Q000494:pharmacology*; D015398:Signal Transduction
D002614:Chelating Agents; D005456:Fluorescent Dyes; D010281:Parathyroid Hormone; D012471:Salivary Proteins and Peptides; C049925:fura-2-am; D000255:Adenosine Triphosphate; D002116:Calcitonin; D000242:Cyclic AMP; D002118:Calcium; D016257:Fura-2