Abstract
The attainment of a critically high core temperature has been proposed as an important factor limiting endurance performance in the heat. We have recently reported that an acute ingestion of a dual dopamine (DA)/noradrenaline (NA) reuptake inhibitor (bupropion) improved time trial performance with a high core temperature and without any change in the subjective sensations of fatigue and thermal stress (2005). We attempted to identify the effects of an acute injection of bupropion on exercise performance, thermal responses and neurotransmitters in the preoptic area and anterior hypothalamus (PO/AH) during exercise in the heat of the rat. A telemetry device was implanted into the peritoneal cavity and two intracerebral guides were implanted, one in the left PO/AH for the microdialysis probe, and one in the right frontal cortex for measuring brain temperature. On the day of the experiments, the animals were exercised at a speed of 26 m/min until exhaustion in a warm environment. Exercise performance was significantly improved by an acute injection of bupropion. The final brain and core temperatures in bupropion were significantly higher than the control. Both NA and DA in the PO/AH increased during exercise in both conditions, being higher in bupropion than control. These results suggest that DA and NA in the PO/AH might be responsible in the increase in exercise performance and body temperature. [J Physiol Sci. 2007;57 Suppl:S182]
