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Capsaicin-sensitive nerves and endurance exercise in the rat
1Département des Sciences de l'Activité Physique, Université du Québec à Trois-Rivières, Canada.
Physiology & Behavior
|February 1, 1996
Summary
Capsaicin-sensitive nerves regulate exercise-induced increases in plasma catecholamines (epinephrine and norepinephrine) by signaling the adrenal medulla. Disrupting these nerves impairs this response without affecting exercise endurance or glucose levels.
Area of Science:
- Neuroscience
- Exercise Physiology
- Endocrinology
Background:
- Plasma catecholamines, including epinephrine (E) and norepinephrine (NE), increase during exercise.
- Capsaicin-sensitive nerves, particularly C-fibers, are known to play roles in various physiological responses.
Purpose of the Study:
- To investigate the role of capsaicin-sensitive nerves in controlling plasma catecholamine and glucose concentrations during exercise in rats.
Main Methods:
- Neonatal capsaicin treatment was used to impair capsaicin-sensitive nerves.
- Rats were subjected to exercise until exhaustion or studied at rest.
- Plasma catecholamine and glucose levels, as well as liver glycogen content, were measured.
Main Results:
- Vehicle-treated rats showed increased plasma E and NE during exercise, unlike capsaicin-treated rats.
- Capsaicinized rats exhibited lower plasma catecholamine levels during exercise compared to controls.
- Impaired catecholamine output in capsaicinized rats was not linked to altered exercise endurance or plasma glucose levels.
Conclusions:
- Capsaicin-sensitive C-fibers are involved in regulating adrenal medullary catecholamine secretion during exhaustive exercise.
- Substance P depletion in C-fibers likely contributes to the impaired catecholamine response.
- Adrenal medullary dysfunction alone does not significantly impact exercise performance or glucose homeostasis.