Effects of vitamin D. A comparison of 1 alpha OHD2 and 1 alpha OHD3 in rats.
The effect of 1 alpha OHD2 and 1 alpha OHD3 have been studied in rachitic, normal, and prednisolone-treated male rats. The healing of rickets, the stimulation of intestinal Ca and P transport, the effect on bone mineral, and the induction of renal calcifications have been examined. The two 1-hydroxylated compounds are equally potent in healing rickets, and by comparison with previous data are equivalent to 100-200 IU/micrograms. 1 alpha OHD2 and 1 alpha OHD3 stimulated intestinal Ca and P transport to the same extent and were antagonistic to prednisolone in this respect. 1 alpha OHD2 reduced the number of osteoclasts and increased bone mineral in normal rats in contrast to 1 alpha OHD3, which increased osteoclasts and slightly reduced bone mineral. Prednisolone-induced osteopenia was more effectively counteracted by 1 alpha OHD2 than by 1 alpha OHD3. Mortality rate was higher in rats intoxicated with 1 alpha OHD3 than for rats given 1 alpha OHD2. LD50 was estimated to be five to fifteen times higher for 1 alpha OHD2. Renal calcification were more pronounced after dosing with 1 alpha OHD3 than after treatment with 1 alpha OHD2. When prednisolone was given together with 1 alpha OHD2 or 1 alpha OHD3, renal calcifications were further increased. These observations demonstrate physiological dissimilarities between vitamin D2 and vitamin D3 in rats which are in accordance with a different metabolism of the two vitamins. The findings, in particular that 1 alpha OHD2 is less toxic than 1 alpha OHD3, are of potential clinical importance.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D012080:Chronic Kidney Disease-Mineral and Bone Disorder / Q000209:etiology; D004872:Ergocalciferols / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D007011:Hypoparathyroidism / Q000209:etiology; D007408:Intestinal Absorption / Q000187:drug effects; D007422:Intestines / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D010018:Osteomalacia / Q000209:etiology; D010024:Osteoporosis / Q000209:etiology; D010758:Phosphorus / Q000378:metabolism; D011239:Prednisolone / Q000494:pharmacology; D051381:Rats; D012279:Rickets / Q000188:drug therapy / Q000209:etiology; D012867:Skin / Q000378:metabolism; D014807:Vitamin D / Q000502:physiology / Q000633:toxicity
D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; D014807:Vitamin D; D010758:Phosphorus; C042533:1 alpha-hydroxyergocalciferol; D011239:Prednisolone; D002118:Calcium; C008088:alfacalcidol