Efeito do estresse sobre a resposta lipolitica as catecolaminas em adipocitos de ratos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

We analysed the alterations in sensitivity to catecholamines in epididymal adipocytes from rats submitted to footshock stress. Adult Wistar male rats (200-350 g) were submitted to three footshock sessions. Each rat received during 30 min, 120 electric shocks (1.0 mA, 1,0 sec) at variable intervals of 5 to 25 seco After the last session, the animals were sacrificed and its epididymal adipose pad was rapidly dissected out. Lipolytic activity was analysed on isolated fat cells obtained according to the method of RODBELL (1964) with minor modifications. Concentration-response curves for agonists were obtained in the presence and the absence of antagonists. Glycerol released in the infranatant medium was taken as index of fat cells lipolysis. Half-maximal effective drug concentration (ECso) values were obtained and expressed as pD2 values (-log ECso). Data were compared by ANOV A, plus Fischer test or by Student t-test, as p <0.05. Adipocytes from stressed rats showed an increase in basallipolysis (control 0.59 + 0.04; stress 1.00 + 0.11), sensitisation of the response to isoprenaline (pD2 control 7.46 + 0.11; stress ,8.11 + 0.17), adrenaline (PD2 control 5.78 + 0.20; stress 6.13 + 0.18), and salbutamol (pD2 control 5.64 + 0.28; stress 5.92 + 0.34), and desensitization of the lipolytic response to norepinephrine (pD2 control 6.98 + 0.13; stress 6.41 + 0.12), and to BRL37344 (pD2 control 8.43 + 0.19; stress 7.54 + 0.21). Maximum responses to isoprenaline (control1.80+ 0.18; stress 2.24+ 0.10), epinephrine (control1.64+ 0.17; stress 2.24 + 0.14), salbutamol (control 0.65 + 0.11; stress 1.21 + 0.41), and d-butirilcAMP (control 1.59 + 0.17; stress 2.72 + 0.25), were significantly enhanced in adipocytes from stressed rats. Supersentivity to isoprenaline was cancelled by 50 nM ICI118,551 but was not modified by 100 nM metoprolol. However, subsensitivity to norepinephrine and to BRL37344 was cancelled by 100 nM metoprolol. Our results suggest that in epididymal adipocytes from stressed rats there is a desensitization of the response mediated by ? 3-/ ? 1-adrenoceptors together with a sensitization ofthe response mediated by ? 2-adrenoceptors

ASSUNTO(S)

rato como animal de laboratorio stress (fisiologia)

ACESSO AO ARTIGO

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