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Hypothalamic adrenoceptors mediate sympathoadrenal activity in exercising rats
A J Scheurink1, A B Steffens, R P Gaykema
1Department of Animal Physiology, State University of Groningen, Haren, The Netherlands.
The American Journal of Physiology
|September 1, 1990
Summary
Hypothalamic adrenoceptors regulate exercise responses. Blocking alpha- and beta-adrenoceptors in the hypothalamus affects plasma norepinephrine and epinephrine levels during strenuous exercise in rats.
Area of Science:
- Neuroendocrinology
- Exercise Physiology
Background:
- Hypothalamic regulation of the autonomic nervous system is crucial for physiological responses to stress, including exercise.
- Adrenoceptors within the hypothalamus play a role in modulating catecholamine release.
Purpose of the Study:
- To investigate the role of hypothalamic alpha- and beta-adrenoceptors in exercise-induced changes in plasma norepinephrine (NE), epinephrine (E), and corticosterone.
- To determine if central nervous system interference can dissociate exercise-induced NE and E responses.
Main Methods:
- Rats underwent strenuous swimming exercise.
- Blood samples were collected via heart catheterization to measure plasma NE, E, and corticosterone.
- Alpha- (phentolamine) and beta- (timolol) adrenoceptor antagonists were infused into the ventromedial hypothalamus (VMH) and lateral hypothalamic area (LHA).
Main Results:
- Exercise increased plasma E, NE, and corticosterone in control rats.
- VMH alpha-adrenoceptor blockade reduced exercise-induced E increase but not NE.
- VMH beta-adrenoceptor blockade enhanced E and attenuated NE increases.
- LHA alpha-adrenoceptor blockade enhanced NE, while beta-adrenoceptor blockade potentiated E increase.
- Plasma corticosterone levels remained unaffected by the interventions.
Conclusions:
- Hypothalamic alpha- and beta-adrenoceptors significantly influence peripheral catecholamine release during exercise.
- Central nervous system modulation of hypothalamic adrenoceptors can dissociate exercise-induced epinephrine and norepinephrine responses.