Carpéné C, Ambid L, Lafontan M
Institut National de la Santé et de la Recherche Médicale, Université Paul Sabatier, France.
Am J Physiol. 1994 Mar;266(3 Pt 2):R896-904. doi: 10.1152/ajpregu.1994.266.3.R896.
The beta 3-adrenoceptor (AR) agonists are potent activators of lipolysis in white adipose tissue. beta-AR agonists were tested here on the lipolytic activity of a hibernator, the garden dormouse (Eliomys quercinus L.). All the agonists exhibited full intrinsic activity; the most potent was the beta 3-AR agonist BRL-37344 [half-maximal effective concentration (EC50) = 0.8 nM]. The beta-antagonist idocyanopindolol (ICYP) also stimulated lipolysis of white adipocytes with the same potency and intrinsic activity as BRL-37344. The blockade of lipolytic effects of epinephrine or norepinephrine was similar to that of BRL-37344: the beta 1- and the beta 2-antagonists were quite ineffective. Total blockade occurred only with 100 microM bupranolol whatever the beta-agonist tested. This argues for the presence of a beta 3-component in the adrenergic-induced lipolysis. (-)-[125I]ICYP and (-)-[3H]CGP-12177 both labeled two populations of binding sites. On adipocyte membranes, binding of 0.6 nM (-)-[3H]CGP-12177 was inhibited with the following order of potency: isoproterenol > BRL-37344 > epinephrine. This order was modified at 20 nM, arguing for the beta-atypical nature of the low-affinity sites. Thus garden dormouse adipocytes possess beta 3-ARs, which are involved to an important degree in the adrenergic activation of lipolysis.
β3肾上腺素能受体（AR）激动剂是白色脂肪组织中脂肪分解的强效激活剂。在此对β-AR激动剂在冬眠动物花园睡鼠（Eliomys quercinus L.）的脂肪分解活性上进行了测试。所有激动剂均表现出完全的内在活性；最有效的是β3-AR激动剂BRL-37344 [半数最大效应浓度（EC50）= 0.8 nM]。β拮抗剂吲哚氰心安（ICYP）也以与BRL-37344相同的效力和内在活性刺激白色脂肪细胞的脂肪分解。肾上腺素或去甲肾上腺素的脂肪分解作用的阻断与BRL-37344相似：β1和β2拮抗剂相当无效。无论测试何种β激动剂，仅用100μM布普洛尔可实现完全阻断。这表明在肾上腺素能诱导的脂肪分解中存在β3成分。（-）-[125I]ICYP和（-）-[3H]CGP-12177均标记了两类结合位点。在脂肪细胞膜上，0.6 nM（-）-[3H]CGP-12177的结合被以下效力顺序的物质抑制：异丙肾上腺素＞BRL-37344＞肾上腺素。在20 nM时该顺序发生改变，表明低亲和力位点具有β非典型性质。因此，花园睡鼠脂肪细胞具有β3-ARs，其在肾上腺素能激活的脂肪分解中起重要作用。
