We analysed the sensitivity to β-adrenoceptor agonists in epididymal adipose cells from rats submitted to a stress protocol previously reported to induce alterations in sensitivity to catecholamines in cardiac tissue from rats. Food intake and body weight were lower, whereas adipocytes basal lipolysis was higher (control: 0.59 ± 0.04; stress: 1.00 ± 0.11, μmol glycerol/100 mg total lipids/100 min) in stressed compared to control rats. The responses 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) were sensitized, and the lipolytic responses 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) were desensitized. Responses to the higher concentration (100 μM) of isoprenaline (control: 1.80 ± 0.18; stress: 2.24 ± 0.10 μmol glycerol/100 mg total lipids/100 min), epinephrine (control: 1.64 ± 0.17; stress: 2.24 ± 0.14 μmol glycerol/100 mg total lipids/100 min), salbutamol (control: 0.65 ± 0.11; stress: 1.21 ± 0.41 μmol glycerol/100 mg total lipids/100 min), and d-butyryl-cAMP (control: 1.59 ± 0.17; stress: 2.72 ± 0.25) were significantly enhanced in adipocytes from stressed rats. pD2 or maximum response to CGP12177 were not altered. Supersensitivity to isoprenaline was abolished by 50 nM ICI118,551 but was not modified by 100 nM metoprolol. However, subsensitivity to norepinephrine and to BRL37344 was abolished by 100 nM metoprolol. Our results suggest that in epididymal adipocytes from stressed rats there is a desensitization of the response to adrenoceptor agonists mediated by β1-adrenoceptors together with a sensitization of the response mediated by β2-adrenoceptors. β3- adrenoceptors seem to be resistant to the stress effect.40917191727Hollenga, C.H., Zaasgma, J., Direct evidence for the atypical nature of functional beta-adrenoceptor in rat adipocytes (1989) Br. J. Pharmacol., 98, pp. 1420-1424Langin, D., Portillo, M., Saulnier-Blanche, J.-S., Lafontan, M., Coexistence of three beta-adrenergic receptor subtypes in white fat cells of various mammalian species (1991) Eur. J. Pharmacol., 199, pp. 191-301Carpéné, C., Castan, I., Collon, P., Galitzky, J., Moratinos, J., Lafontan, M., Adrenergic lipolysis in guinea pig is not a β3-adrenergic response: Comparison with human adipocytes (1994) Am. J. Physiol., 266, pp. R905-R913Gilman, A.G., G proteins: Transducers of receptor-generated signals (1987) Annu. Rev. Biochem., 56, pp. 615-649Langin, D., Holm, C., Lafontan, M., Adipocyte hormone-sensitive lipase: A major regulator of lipid metabolism (1996) Proc.Nutr. Soc., 55, pp. 93-109Lafontan, M., Berlan, M., Fat cell adrenergic receptors and the control of white and brown fat cell function (1993) J. Lipid Res., 34, pp. 1057-1091Lohse, M.J., Molecular mechanisms of membrane receptor desensitization (1993) Biochem. Biophys. Acta., 1179, pp. 171-188Axelrod, J., Reisine, T.D., Stress hormones: Their inter-action and regulation (1984) Science, 224, pp. 452-459Bassani, R.A., De Moraes, S., Subsensitivity of β-adrenoceptor agonists in right atria isolated from foot-shock-stressed rats (1987) Gen. Pharmacol., 18, pp. 473-477Bassani, R.A., De Moraes, S., Effects of repeated foot-shock stress on the chronotropic responsiveness of the isolated pacemaker of the rat: Role of β2-adrenoceptors (1988) J. Pharmacol. Exp. Ther., 246, pp. 316-321Nourani, F.R.R., Spadari, R.C., De Moraes, S., Foot-shock stress-induced supersensitivity to isoprenaline in the isolated pacemaker of rat: Effects of compounds RU-34886 and RU-28362 (1992) Gen. Pharmacol., 23, pp. 787-791Callia, M.L., De Moraes, S., Heterogeneity of beta adrenoceptors in right atria isolated from cold-exposed rats (1984) J. Pharmacol. Exp. Ther., 230, pp. 450-454Capaz, F.R., De Moraes, S., Reduction by acute restraint stress of norepinephrine sensitivity in isolated rat pacemaker (1988) Eur. J. Pharmacol., 147, pp. 295-298Spadari, R.C., De Moraes, S., Repeated swimming stress and responsiveness of the isolated rat pacemaker to the chronotropic effects of adrenaline and isoprenaline: Role of adrenal corticosteroids (1988) Gen. Pharmacol., 19, pp. 553-557Spadari, R.C., Bassani, R.A., De Moraes, S., Supersensitivity to isoprenaline and epinephrine in right atria isolated from rats submitted to a single swimming session (1988) Gen. Pharmacol., 19, pp. 129-135Hoffman, J.S., Flesher, M., A relay sequence device for scrambling grid shock (1962) J. Exp. Anim. Behav., 55, pp. 329-330Vanderlei, L.C.M., Marcondes, F.K., Lanza, L.L.B., Spadari-Bratfisch, R.C., Influence of the estrous cycle on the sensitivity to catecholamines in rat atria from rats submitted to foot-shock stress (1996) Can. J. Physiol. Pharmacol., 74, pp. 670-678Rodbell, M., Metabolism of isolated fat cells. I. Effects of hormones on glucose metabolism and lipolysis (1964) J. Biol. Chem., 239, pp. 375-380Wieland, O., Eine enzimatische methode zur bestimmung von glycerin (1957) Biochem. Z., 329, pp. 313-319Dole, V.P., Meinertz, H., Microdetermination of long-chain fatty cells in plasma and tissues (1960) J. Biol. Chem., 235, pp. 2595-2599Zar, J.H., (1984) Biostatistical Analysis. 2nd Ed., , Hall International, Upper Saddle River, NJSnedecor, G.W., Cochran, W.G., (1967) Statistical Methods, 6th Ed., pp. 342-343. , Iowa State University Press, Ames, IAGermack, R., Starzec, A.B., Vassy, R., Perret, G.Y., β-Adrenoceptor subtype expression and function in rat whte adipocytes (1997) Br. J. Pharmacol., 120, pp. 201-210Carpéné, C., Ambid, L., Lafontan, M., Predomminance of β3-adrenergic component in catecholamine activation of lipolysis in garden dormouse adipocytes (1994) Am. J. Physiol., 266, pp. R896-R904Blin, N., Camoin, L., Maigret, B., Strosberg, A.D., Structural and conformational features determining selective signal transduction in the β3-adrenergic receptor (1993) Mol. Pharmacol., 44, pp. 1094-1104Arch, J.R.S., Wilson, S., β3-adrenoceptors and the regulation of metabolism in adipose tissue (1996) Biochem. Soc. Trans., 24, pp. 412-418Van Liefde, I., Van Witzenburg, A., Vauquelin, G., Multiple beta adrenergic receptor mediated in the l-isoproterenol-induced lipolytic response in rat adipocytes (1992) J. Pharmacol. Exp. Ther., 262, pp. 552-558Boudot, J.P., Cavero, I., Fénard, S., Lefèvre-Borg, F., Manoury, P., Roach, A.G., Preliminary studies on SL 75212, a new potent cardioselective β-adrenoceptor agonist (1979) Br. J. Pharmacol., 66, p. 445Levin, B.E., Sullivan, A.C., Beta-1 receptor is the predominant beta-adrenoceptor on rat brown adipose tissue (1986) J. Pharmacol. Exp. Ther., 236, pp. 681-688Wagner, J., Nick, B., Rohm, N., Schümann, H.J., On the coexistence of β1- and β2-adrenoceptors in various organs (1981) Arch. Int. Pharmacodyn., 249, pp. 26-38Galitzky, J., Langin, D., Verwaerde, P., Montastruc, J.L., Lafontan, M., Berlan, M., Lypolytic effects of conventional β3-adrenoceptor agonists and of CGP 12177 in rat and human fat cells: Preliminary pharmacological evidence for a putative β4-adrenoceptor (1997) Br. J. Pharmacol., 122, pp. 1244-1250Kaumann, A.J., Molenaar, P., Modulation of human cardiac function through 4β-adrenoceptor population (1997) Naunyn-Schmiedeberg's Arch. Pharmacol., 135, pp. 667-681Molinowska, B., Schlicker, E., Further evidence for differences between cardiac atypical β-adrenoceptors and brown adipose tissue β3-adrenoceptors in the pithed rat (1997) Br. J. Pharmacol., 122, pp. 1303-1314Strosberg, A.D., Pietri-Rouxel, F., Function and regulation of the β3-adrenoceptor (1996) TIPS, 17, pp. 373-381Marcondes, F.K., Vanderlei, L.C.M., Lanza, L.L.B., Spadari-Bratfisch, R.C., Stress-induced subsensitivity to catecholamines depends on the estrous-cycle (1996) Can. J. Physiol. Pharmacol., 74, pp. 7-13Hadcock, J.R., Wang, H.-Y., Malbon, C.C., Agonist-induced destabilization of β-adrenergic receptor mRNA (1989) J. Biol. Chem., 264, pp. 19928-19933Granneman, J.G., Lahners, K.N., Differential adrenergic regulation of β1-and β3-adrenoceptor messenger ribonucleic acids in adipose tissues (1992) Endocrinology, 130, pp. 109-114Atgié, C., Faintrenie, G., Carpéné, C., Bukowiecki, L.J., Géloën, A., Effects of chronic treatment with noradrenaline or a specific β3-adrenergic agonist, CL 316 243, on energy expenditure and epididymal adipocyte lipolytic activity in rat (1998) Comp. Biochem. Physiol., 119 A, pp. 629-636Unelius, L., Bronnikov, G., Mohell, N., Nedergaard, J., Physiological desensitization of β3-adrenergic responses in brown fat cells: Involvement of a postreceptor process (1993) Am. J. Physiol., 265, pp. C1340-C1348Fève, B., Baude, B., Krief, S., Strosberg, A.D., Pairault, J., Emorine, L.J., Inhibition by dexamethasone of β3-adrenergic receptor 3T3-F442A adipocytes (1992) J. Biol. Chem., 267, pp. 15909-15915Fève, B., Emorine, L.J., Briend-Sutren, M.M., Lasnier, F., Strosberg, A.D., Pairault, J., Differential regulation of β1- and β2-adrenergic receptor protein and mRNA levels by glucocorticoids during 3T3-F442A adipose differentiation (1990) J. Biol. Chem., 265, pp. 16343-16349