Androgen and glucocorticoid receptors in porcine skeletal muscle.

The presence of free androgen and glucocorticoid receptors was demonstrated in the rectus femoris muscle of the pig. No detectable free androgen receptors were observed in intact male pigs. Androgen receptor characteristics in castrates and gilts were related to the growth rate of the lean meat in the ham. The amount of free androgen receptor was less (P less than .05) and the androgen was more tightly bound to its receptor (P less than .05) in pigs with above-average ham growth. Moreover, a higher DNA content (P less than .01) was also found in these pigs, giving a lower (P less than .05) protein to DNA ratio. The anabolic action of androgens is likely to be mediated via androgen receptors in skeletal muscle cytosol. The amounts of free glucocorticoid receptors found were influenced by the pH of the cytosolic fraction. The relationships between cytosolic pH and both the amount of glucocorticoid receptor (positive; P less than .01) and plasma levels of cortisol (negative; P less than .05) might reflect the stress to which the pigs are exposed at slaughter.