Control of ventilation in androgenized hypogonadal male rats

We have previously shown that subcutaneous administration of aspartic acid (a dicarboxylic acidic amino acid) at a dose of 580 mg/kg causes long lasting depression of ventilation in adult intact and postpubertally castrated male rats, but not in intact female rats. The purpose of the present study was to determine if hypogonadism induced by perinatal administration of testosterone propionate (TP) will alter ventilation, oxygen consumption, and the ventilatory response to aspartic acid and to hypercapnia in adult males. TP treatment resulted in adult males who had lower body, prostate, heart, and testes weights than those of control male rats. Ventilation in air and oxygen consumption were comparable between the two groups as was the ventilatory response to aspartic acid. In contrast, TP-treated rats exhibited a significantly decreased ventilatory response to hypercapnia due predominantly to lower tidal volumes compared to control animals. Aspartic acid treatment did not affect oxygen consumption in either group. Thus, TP treatment results in the development of adult male rats who, although hypogonadal, retain a male-like ventilatory response to aspartic acid, but whose response to hypercapnia is more like that of hypogonadal men and rats.