The type 3 iodothyronine deiodinase (D3) metabolizes thyroid hormones to inactive metabolites in many tissues, including the brain. In the present studies, we have examined the mechanisms by which T3 (T3), retinoic acid, 12-O-tetradecanoyl phorbol 13-acetate (TPA), and basic fibroblast growth factor (bFGF) induce D3 expression in primary cultures of neonatal rat astrocytes. In untreated cells, ...

Serum 1,25-dihydroxyvitamin D3 concentration and renal 25-hydroxyvitamin D 1 a-hydroxylase activity were measured in rats fed various levels of calcium, phosphorus and vitamin D3. Both calcium deprivation and phosphorus deprivation greatly increased circulating levels of 1,25-dihydroxyvitamin D3. The circulating level of 1,25-dihydroxyvitamin D3 in rats on a low-calcium diet increased with incr...

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder caused by a complex interaction between genetic and environmental risk factors. Among the environmental factors, vitamin D3 (cholecaliferol) seems to play a significant role in the etiology of ASD because this vitamin is important for brain development. Lower concentrations of vitamin D3 may lead to increased brain size, alt...

The type 3 iodothyronine selenodeiodinase (D3) is an integral membrane protein that inactivates thyroid hormones. By using immunofluorescence cytochemistry confocal microscopy of live or fixed cells transiently expressing FLAG-tagged human D3 or monkey hepatocarcinoma cells expressing endogenous D3, we identified D3 in the plasma membrane. It co-localizes with Na,K-ATPase alpha, with the early ...

Ultraviolet radiation is known to be highly variable in aquatic ecosystems. It has been suggested that UV-exposed organisms may demonstrate enough phenotypic plasticity to maintain the relative fitness of natural populations. Our long-term objective is to determine the potential photoprotective effect of vitamin D3 on Daphnia pulex exposed to acute or chronic UV radiation. Herein we report our ...

Type I iodothyronine deiodinase (D1) and type II iodothyronine deiodinase (D2) catalyze the activation of the prohormone T4 to the active hormone T3; type III iodothyronine deiodinase (D3) catalyzes the inactivation of T4 and T3. D3 is highly expressed in brain, placenta, pregnant uterus, and fetal tissues and plays an important role in regulating thyroid hormone bioavailability during fetal de...

Despite differences in the phamacokinetics of 25-hydroxycholecalciferol (25(OH)D3) and 25-hydroxyergocalciferol (25(OH)D2) in man, the effects of these and their 1α-hydroxylated forms (1,25(OH)2D3 and 1,25(OH)2D2) on cellular activity of vitamin D-responsive cells have hardly been compared. We studied differences in the effects of these metabolites on cell number, gene transcription, protein ex...

Background: One strategy for improving population vitamin D status is consumption of fortified foods. However, the effects of dairy products fortified with different vitamin D isoforms on postprandial vitamin D status and metabolic outcomes have not been addressed.Objective: We investigated whether consumption of dairy drinks fortified with either 25-hydroxycholecalciferol [25(OH)D3] or choleca...

BACKGROUND & AIMS Vitamin D, best known to regulate bone mineralization, has numerous additional roles including regulation inflammatory pathways. Recently, an increased incidence of 25-hydroxyvitamin D3 (25(OH)D3) deficiency has been found in subjects suffering from liver diseases. We here investigated if low vitamin D levels might be associated with prognosis, inflammation and infectious comp...

Hypocalcemic vitamin D (D)-depleted rats were supplemented with calcium or 1,25(OH)2D3, and the metabolism of D3 to 25(OH)D3 was studied. Infusion with 7 or 65 pmol 1,25(OH)2D3. 24 h-' led to normal or slight hypercalcemia associated with physiological and supraphysiological plasma concentrations of the hormone while calcium supplementation normalized plasma calcium despite 1,25(OH)2D3 concentr...