Responses to exercise in the heat related to measures of hypothalamic serotonergic and dopmaninergic function
Research output: Contribution to journal › Article
Authors
Colleges, School and Institutes
Abstract
We have studied 12 recreationally active men to measure their responses to exercise in the heat and relate these to measures of hypothalamic function explored with a buspirone [5-hydroxytryptamine 1A (5-HT1A) agonist, dopaminergic D-2 antagonist] neuroendocrine challenge, with and without pretreatment with pindolol (5-HT1A antagonist). Pindolol treatment allowed the serotonergic and non-serotonergic components of prolactin release to be distinguished. Subjects exercised at 73 (5)% maximal rate of oxygen uptake ((V) over dot O-2max) until volitional fatigue at 35degreesC (relative humidity, 30%). On another two occasions they underwent a buspirone challenge [0.5 mg (kg body mass)(-1)], once with, and once without, pindolol [0.5 mg (ka body mass)(-1)] pretreatment and the circulating plasma concentrations of prolactin were measured for the next 2.5 h. Rectal temperature increased throughout exercise, whilst mean skin temperature remained constant. There was a wide inter-subject variation in prolactin response to the neuroendocrine challenges. The proportion of the prolactin response to buspirone attributable to a non-serotonergic component (most likely dopaminergic) correlated both with exercise duration (r=0.657, P=0.028), rectal temperature at fatigue (r=0.623, P=0.041) and the rate of temperature rise r=-0.669, P = 0.024). Our results suggest that high activity of the dopaminergic pathways in the hypothalamus is a predictor of exercise tolerance in the heat.
Details
Original language | English |
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Pages (from-to) | 451-459 |
Number of pages | 9 |
Journal | European Journal of Applied Physiology |
Volume | 89 |
Issue number | 5 |
Publication status | Published - 1 Jun 2003 |
Keywords
- serotonin, heat tolerance, dopamine, prolactin, fatigue