Effects of blood sampling technique and exercise on plasma androgens in female rats.

Plasma concentrations of testosterone, androstenedione, and dihydrotestosterone rise during exercise in women. The purpose of this study was to evaluate exercise-induced changes in these three androgens in female rats to see if the rat may be used as a model for studying these responses. Because some androgen originates in the adrenal cortex, and the adrenocortical axis is stress-responsive, blood samples taken by cardiac puncture under halothane anesthesia, a potentially stressful technique, were compared with those taken by decapitation, which should not elicit a stress response. Blood was collected from sedentary rats at rest and from exercise-trained rats after 30 min of running. Half the samples were taken by each technique. Sampling technique did not affect androgen levels. Combining data from both techniques, testosterone was similar in rats at rest (503 pmol.l-1 +/- 62 (SE), N = 20) and post-exercise (500 +/- 31, N = 17). Androstenedione was higher post-exercise (1648 pmol.l-1 +/- 248, N = 17) than at rest (866 +/- 115, N = 18; P less than 0.009). Dihydrotestosterone was also higher post-exercise (452 pmol.l-1 +/- 31, N = 17) than at rest (324 +/- 41, N = 20; P less than 0.05). It is concluded that: 1) cardiac puncture with halothane anesthesia is acceptable for studying androgens in female rats, and 2) the female rat may be useful for studying the androstenedione and dihydrotestosterone responses to exercise, but is not appropriate for studying testosterone exercise responses.