Effects of vitamin B 6 deficiency and repletion on the uptake of steroid hormones into uterus slices and isolated liver cells of rats

Abstract

1. In vitro, pyridoxal phosphate extracts steroid-hormone receptors from tight nuclear binding (Cidlowski & Thanassi, 1981); in vitamin B 6 -deficient rats there is increased and prolonged nuclear accumulation of oestradiol in the uterus and testosterone in the prostate, associated with enhanced biological responsiveness of these target tissues to steroid hormone action (Symes et al. 1984; Bowden et al. 1986). 2. Slices of uterus from vitamin B 6 -deficient rats accumulated more [ 3 H]oestradiol than did tissue from repleted animals. Acute repletion with vitamin B 6 (0.5–1 h before killing) further increased the uptake of the steroid. 3. Isolated hepatocytes from vitamin B 6 -deficient rats accumulated more [ 3 H]dexamethasone than did cells from repleted animals. Pre-incubation of the hepatocytes with pyridoxal phosphate resulted in a further increase in the uptake of the steroid. 4. The results suggest that in addition to the putative role of pyridoxal phosphate in releasing steroid-hormone-receptor complexes from tight nuclear binding (Cidlowski & Thanassi, 1981), vitamin B 6 deficiency may also increase the concentration of steroid-hormone receptors or enzymes and other steroid-binding proteins in target tissues.