Effect of Intermittent Hypoxia on the Exercise-induced Production of Testosterone and Lactate in Rats.

Abstract

Leydig cells locate in the interstitial compartment of the testis and are responsible for the testosterone production. It has been reported that the increased concentration of lactate in circulation during exercise is associated with the promoted testosterone. Moreover, the testosterone production in Leydig cells can be enhanced by hypoxia. It might be interesting to test if the administration of intermittent hypoxia affected the secretion of testosterone after exercise. The present study was to detect the effect of pretreatment of intermittent hypoxia on the secretion of testosterone in response to swimming both in vivo and in vitro. Male rats were housed in the hypoxic chambers (12% O2 + 88% N2) 8 h/day for 3 (H3) or 6 (H6) days. Normoxic rats were employed as control animals (C). In an in vivo experiment, pretreated rats were catheterized via the right jugular vein and blood samples were collected at different time intervals following swimming at 25°C for 30 min. Furthermore, purified rat Leydig cells (1 × 105 cells/ml) were in vitro incubated with or without hCG (0.05 IU/ml), forskolin (10−5 M) or sodium lactate (0-10 mM) at 34°C for 1 h to evaluate the effects of hypoxia or hypoxia plus lactate on testosterone production. The media were collected for measurement of testosterone by radioimmunoassay. The post-exercise concentrations of plasma lactate and testosterone were higher than those at resting levels in C and H3 groups. Although the basal level of testosterone increased by intermittent hypoxia for 6 days, the peak levels of both testosterone and lactate in response to swimming were prevented in H6 group. We confirmed that administration of intermittent hypoxia in vivo significantly increased testosterone release in vitro in response to hCG and forskolin in rat Leydig cells. Lactate at the 5 mM and 10 mM increased testosterone release by Leydig cells in control group. Pretreatment of intermittent hypoxia abolished the stimulatory effects of lactate on testosterone release in vitro. These results suggested that the chronic administration of intermittent hypoxia (e.g. 6 days) prevented the increase of testosterone secretion in response to exercise, which might be associated with the reduction of lactate generation induced by exercise in rats.