Pyridoxine deficiency influences the behavior of the glucocorticoid receptor complex

Pyridoxine deficiency results in an increased number of activatable hepatic glucocorticoid.receptor complexes and an accelerated rate of translocation of the complexes to nuclei in vitro. After 15 min of heat activation at 25°C, 74% of the steroid.receptor complexes from pyridoxine-deficient cytosol were bound to nuclei compared to 29% from controls. Five minutes after an intraperitoneal injection of [³H]triamcinolone acetonide to control and pyridoxine-deficient rats the amount of [³H]steroid taken up into the liver of each group was 21 pmol/g of liver. However, 10 min after administration of [³H]steroid the concentration of triamcinolone acetonide fell to 16.2 pmol/g of liver in the pyridoxine-deficient animals while the concentration of steroid rose to a peak level of 25.6 pmol/g of liver in control animals. The control animals concentrated 1.6 times more steroid in the liver than the deficient animals. This concentration ratio was maintained at the 15- and 30-min time points. Supplementation of the deficient animals with pyridoxine partially restored the animals' ability to concentrate [³H]steroid in the liver. In vivo, the amount of [³H]steroid associated with nuclei from control and pyridoxine-deficient animals was not appreciably different, although the percentage of steroid associated with nuclei of the pyridoxine-deficient group was greater. At 5-, 10-, and 15-min time points, pyridoxine-deficient animals had 7, 11, and 17% of the total radioactivity associated with nuclei compared to 6, 9, and 10% for controls. These experiments indicate that pyridoxine deficiency affects the activation and translocation of the hepatic glucocorticoid receptor to nuclei as well as the uptake or retention, or both, of steroid into liver cells.