Influencia do ciclo estral sobre as alterações de sensibilidade adrenergica induzidas por estresse agudo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Stress may change the sensitivity to catecholamines of many tissues. The aim of this study was to evaluate the sensitivity to noradrenaline and adrenaline of the right atria from female rats submitted to acute stress during the different phases of the estrous cycle.Wistar female rats at proestrus, estrus, metestrus and diestrus were submitted to one 50 min-swimming session, after which they were anesthetized and sacrificed. The right atria from these and trom control animais were isolated. Concentration-effect curves (CEC) to noradrenaline or adrenaline were obtained before and after the inhibition of the catecholamine uptake systems (phenoxibenzamine + estradiol). Data were analysed by Two-Way Anova or Student t test. Swimming stress did not change the sensitivity to noradrenaline of the right atria trom rats at estrus, metestrus and diestrus (p>0.05). However at proestrus, swimming induced supersensitivity to noradrenaline (p<0.05). Also at proestrus, the inhibition of the catecholamine uptake systems induced a lower shift to the left in the CEC to noradrenaline in the stressed group compared to the control group (1.74 x 2.45; p<0.05). Right atria from control rats at metestrus showed supersensitivity to adrenaline compared to the other estrous cycle phases. In the right atria from control rats at metestrus, the in vitro inhibition of the uptake systems did not shifted the CEC to adrenaline. Swimming stress also induced supersensitivity to adrenaline in the right atria from rats at metestrus, after the inhibition of uptake systems (p<0.05). Our results show that changes on the uptake systems are partially involved in the stress-induced supersensitivity to noradrenaline during proestrus. However other mechanisms seem also to be related to this effect. At metestrus, the supersensitivity to adrenaline seems not to be determined by alterations in the catecholamines uptake systems. In conclusion, the stress-induced alterations of the adrenergic sensitivity as well as their mechanisms are influence by the estrous cycle

ASSUNTO(S)

stress (fisiologia) beta adrenoreceptores

ACESSO AO ARTIGO

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