A functional cell surface type receptor is required for the early action of 1,25-dihydroxyvitamin D3 on the phosphoinositide metabolism in rat enterocytes.
1,25-Dihydroxyvitamin D3 (1,25-(OH)2-D3) (0.1 pM to 2 nM) induces a concomitant very rapid (within 5 s) and transient release of inositol trisphosphate and diacylglycerol in enterocytes from 3-month-old rats. This high level is not maintained but declines to a lower level 60 s after stimulation. The stimulating effect is dose-dependent and biphasic with a maximum effect at 10 pM. 1,25-(OH)2-D3 induces a rapid (within 10 s) accumulation of inositol bisphosphate and its effect on inositol monophosphate is delayed (120 s). The primary action of 1,25-(OH)2-D3 is to initiate hydrolysis of phosphatidyl 4,5-bisphosphate to yield inositol trisphosphate and diacylglycerol. In contrast, 1,25-(OH)2-D3, for any of the concentrations and the incubation time periods tested, has no effect on inositol trisphosphate and diacylglycerol formation in enterocytes from 16-day-old rats at a time when specific binding sites for 1,25-(OH)2-D3 cannot be detected. In conclusion, the early (within 5-60 s) effects of 1,25-(OH)2-D3 on small intestinal epithelium may be mediated via the phosphoinositide transduction system and require the presence of functioning cell membrane-type receptors.
Lieberherr
M
M
Centre National de la Recherche Scientifique URA 583, Université Paris V, France.
Grosse
B
B
Duchambon
P
P
Drüeke
T
T
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002117:Calcitriol / Q000378:metabolism / Q000494:pharmacology*; D002478:Cells, Cultured; D004075:Diglycerides / Q000378:metabolism; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000502:physiology*
D001095:Arachidonic Acids; D004075:Diglycerides; D007295:Inositol Phosphates; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D016718:Arachidonic Acid; D002117:Calcitriol