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Stress-induced subsensitivity to catecholamines depends on the estrous cycle
F K Marcondes1, L C Vanderlei, L L Lanza
1Departamento de Fisiologia e Biofisica, Universidade Estadual de Campinas, São Paulo, Brazil.
Canadian Journal of Physiology and Pharmacology
|June 1, 1996
Summary
Stress impacts female rat heart rate responses to catecholamines differently depending on the stress type and estrous cycle phase. Diestrus phase showed subsensitivity, more so with foot-shock stress.
Area of Science:
- Cardiovascular physiology
- Neuroendocrinology
- Stress research
Background:
- The chronotropic effects of catecholamines (noradrenaline and adrenaline) are crucial for cardiac function.
- Stress can significantly alter cardiovascular responses, but its interaction with the female estrous cycle is not fully understood.
Purpose of the Study:
- To investigate how different stress types (swimming vs. foot-shock) affect the sensitivity of female rat right atria to noradrenaline and adrenaline.
- To determine the influence of the estrous cycle (diestrus vs. estrus) on these stress-induced modifications.
Main Methods:
- Isolation of right atria from female rats subjected to repeated swimming or foot-shock stress.
- Assessment of atrial sensitivity to noradrenaline and adrenaline at different phases of the estrous cycle (diestrus and estrus).
Main Results:
- Female rats stressed during diestrus exhibited subsensitivity to both noradrenaline and adrenaline, regardless of stress type.
- Subsensitivity to adrenaline was more pronounced in rats subjected to foot-shock stress compared to swimming stress.
- No alterations in atrial sensitivity to catecholamines were observed in rats stressed during estrus.
Conclusions:
- The impact of stress on catecholamine-mediated cardiac chronotropism in female rats is dependent on the severity of the stressor.
- The estrous cycle plays a significant role in modulating the cardiovascular response to stress.