[The role of vitamin E in metabolism and reception of vitamin D].
It was found that calcium exchange disturbances under vitamin E deficiency is due to changes in the metabolism of vitamin D. In vitamin E-deficient rats the serum blood levels of hydroxyvitamin D (25-OHD) showed no significant changes, whereas the concentration of the hormonal form of 1.25-hydroxyvitamin D [1.25(OH)2D], decreased by 40%. In vitro studies showed that the 25-hydroxylase D3 activity in the livers of rats with E-avitaminosis had a tendency to decrease (by 22%), whereas that of 24-hydroxylase dropped drastically (by 52%). The serum blood levels of the parathyroid hormone (PTH) and kidney levels of cAMP under E-avitaminosis were significantly lowered. Preincubation of kidney slices with the adenylate cyclase activator, forskolin, increased the activity of 1-OHase in about the same degree as that in vitamin E-rich rats. The free radical scavenger, BHT, added to kidney slices suppressed the activity of the both enzymes; this finding testifies to the low O2-binding affinity of these monooxygenases. The content of 1.25(OH)2D3 receptors occupied in vivo in the kidneys of vitamin E-deficient rats decreased 2.5-fold; however, the binding of 1.25(OH)2D3-receptor complexes to heterologous DNA was unaffected thereby. The vitamin deficiency in vivo results in the inhibition of vitamin D metabolism in the liver and kidney concomitant with the formation of active metabolites and decreases the concentration of hormone-receptor complexes in target tissues.
Sergeev
I N
IN
Arkhapchev
Iu P
IuP
Spirichev
V B
VB
D000818:Animals; D002112:Calcifediol / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D000242:Cyclic AMP / Q000032:analysis; D005609:Free Radicals; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D010281:Parathyroid Hormone / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism; D014807:Vitamin D / Q000378:metabolism*; D014810:Vitamin E / Q000502:physiology*
D002413:Cations, Divalent; D005609:Free Radicals; D010281:Parathyroid Hormone; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D014807:Vitamin D; D014810:Vitamin E; D000242:Cyclic AMP; D002112:Calcifediol; D002118:Calcium
Rol' vitamina E v obmene i retseptsii vitamina D.