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Estrogen contributes to phenotypic differences in cardiac sympathetic tonus in adult female Dark Agouti and Copenhagen rats.
Author(s) -
Fuentes Evelyn,
Maag Adriane J.,
Rodenbaugh D. W.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a264-b
Subject(s) - estrogen , endocrinology , medicine , estrous cycle , cardiac function curve , sympathetic nervous system , ovariectomized rat , blood pressure , heart failure
The prevalence of cardiovascular disease in women starts to exceed that of men by 45 years of age. This disparity in the incidence of cardiovascular disease suggests a central role for estrogen on cardiovascular function. It has been reported that renal sympathetic nerve activity increases after central injections of estrogen. In addition, gender influences both exercise capacity and the responses of cardiac sympathetic tone (ST) and parasympathetic tone (PT) to exercise in the spontaneously hypertensive rat. Interestingly, higher cardiac sympathetic activity has been identified as an intermediate phenotypic difference contributing to differences in aerobic capacity between Copenhagen (COP) and Dark Agouti (DA) rats. Thus, the divergent exercise capacity phenotype of DA and COP rats may involve estrogen and its effect on the cardiovascular and autonomic nervous system. We predict estrogen levels will be higher in the DA rats respective to COP rats and that cardiac ST will be proportional to cyclical changes in estrogen during the rat estrous cycle. Intact and ovariectomized female DA and COP rats were used to compare cardiac ST in relation to estrogen levels. Vaginal smears and ELISA were used to evaluate estrous cycle phases and estrogen levels on the days cardiac ST was studied. Cardiac ST is higher in female DA rats respective to female COP rats. In addition, cardiac ST levels were directly related to phases of the estrous cycle. These results suggest estrogen levels may be a phenotypic mechanism affecting both exercise capacity and the intermediate phenotypic difference in cardiac ST in female DA and COP rats.