Enhancement of DNA polymerase beta activity in the pituitary gland by hormonal feedback

The activity of DNA polymerase beta (beta-enzyme) in bovine and rat pituitary glands was remarkably higher in the anterior than in the posterior lobe. In sucrose gradient centrifugation, the activity in the anterior lobe of the bovine pituitary gland appeared at the sedimentation constant, 3.3 S, while that of rat pituitary gland appeared at 3.3 S, 7.3 S and 12 S, respectively. The activity in each fraction increased in the anterior lobes of rat pituitaries that were stimulated to release TSH by decreased thyroid hormone levels induced by an antithyroid drug. These results suggest that the activity of the beta-enzyme is high in the cells of the anterior lobe which are hyperfunctioned to produce pituitary thyreotrophic hormone and may be controlled by hormonal feedback regulation.