Lafontan M
J Lipid Res. 1979 Feb;20(2):208-16.
The aim of this study was to explain the unresponsiveness of rabbit perirenal adipose tissue to epinephrine. The in vitro lipolytic response to isoproterenol and to epinephrine alone or associated with alpha- or beta-adrenergic blocking agents, was studied in the adipocytes of rabbits of various ages. Epinephrine induces a large glycerol release in young rabbit adipocytes whereas an increase in the rate of lipolysis cannot be shown with adult rabbit fat cells. Moreover, an antilipolytic effect can be shown for low concentrations of epinephrine when the basal rate of lipolysis is high in older rabbit adipocytes. Isoproterenol (beta-adrenomimetic) always exerts a strong adipokinetic effect, thus revealing functional beta-receptor sites. The blockade of alpha-adreneoceptor sites by phentolamine, which has no effect on young rabbits, abolishes the antilipolytic effect and unmasks strong lipolytic effect of epinephrine on aged and normal rabbit adipocytes. The loss of beta-adrenergic responsiveness towards epinephrine in the aging rabbit is linked to the involvement of an increased alpha-adrenergic responsiveness. The stimulation of alpha receptor sites by epinephrine leads to a depressive effect on lipolysis (lack of adipokinetic effect or antilipolytic action).
本研究的目的是解释兔肾周脂肪组织对肾上腺素无反应的原因。研究了不同年龄兔脂肪细胞对异丙肾上腺素、单独使用肾上腺素或与α-或β-肾上腺素能阻断剂联合使用时的体外脂解反应。肾上腺素可使幼兔脂肪细胞释放大量甘油，而成年兔脂肪细胞则未表现出脂解速率增加。此外，当老年兔脂肪细胞的基础脂解速率较高时，低浓度肾上腺素可表现出抗脂解作用。异丙肾上腺素（β-肾上腺素能激动剂）始终具有强烈的脂肪分解作用，从而揭示了功能性β-受体位点。酚妥拉明对α-肾上腺素能受体位点的阻断对幼兔无影响，但可消除老年兔和正常兔脂肪细胞中肾上腺素的抗脂解作用，并使其脂解作用增强。老年兔对肾上腺素的β-肾上腺素能反应性丧失与α-肾上腺素能反应性增加有关。肾上腺素对α-受体位点的刺激导致脂解作用受到抑制（缺乏脂肪分解作用或抗脂解作用）。
