Atgié C, Tavernier G, D'Allaire F, Bengtsson T, Marti L, Carpéné C, Lafontan M, Bukowiecki L J, Langin D
Department of Physiology, Medical School, Laval University, Quebec, Canada.
Am J Physiol. 1996 Dec;271(6 Pt 2):R1729-38. doi: 10.1152/ajpregu.1996.271.6.R1729.
In the guinea pig, cold acclimation induced a conversion of unilocular to multilocular adipocytes in interscapular (IS) and retroperitoneal (RP) fat depots but not in the epididymal (EP) fat pad. The conversion was associated with an increase in mitochondriogenesis and the appearance of the uncoupling protein. The maximal lipolytic responses to norepinephrine and dibutyryl adenosine 3',5'-cyclic monophosphate were decreased in IS cells, unchanged in RP cells, and increased in EP cells, suggesting a site-specific regulation of lipolysis at the postreceptor level. beta 3-Adrenergic agonists were not lipolytic regardless of the depot and the thermal environment of the animal. These agents did not inhibit glucose transport and lipogenesis, as was previously reported for rodents. Cloning and sequencing of the guinea pig beta 3-adrenoceptor gene revealed a slightly higher amino acid sequence similarity with the human than with the rodent beta 3-adrenoceptors. beta 3-Adrenoceptor transcripts were present at a very low level in guinea pig adipocytes, and mRNA levels did not increase to a significant extent after cold acclimation. The guinea pig thus differs from rodents by an absence of beta 3-adrenergic effects and by low beta 3-adrenoceptor expression in brown and white adipose tissues.
在豚鼠中，冷适应诱导肩胛间（IS）和腹膜后（RP）脂肪库中的单房脂肪细胞转变为多房脂肪细胞，但附睾（EP）脂肪垫中未出现这种转变。这种转变与线粒体生成增加和解偶联蛋白的出现有关。IS细胞中对去甲肾上腺素和二丁酰腺苷3'，5'-环磷酸的最大脂解反应降低，RP细胞中不变，EP细胞中增加，这表明在受体后水平存在脂解的位点特异性调节。无论动物的脂肪库和热环境如何，β3-肾上腺素能激动剂都不会引起脂解。这些药物不会抑制葡萄糖转运和脂肪生成，正如之前对啮齿动物的报道。豚鼠β3-肾上腺素能受体基因的克隆和测序显示，与人类β3-肾上腺素能受体相比，其氨基酸序列与啮齿动物β3-肾上腺素能受体的相似性略高。β3-肾上腺素能受体转录本在豚鼠脂肪细胞中的水平非常低，冷适应后mRNA水平也没有显著增加。因此，豚鼠与啮齿动物的不同之处在于缺乏β3-肾上腺素能效应，且棕色和白色脂肪组织中的β3-肾上腺素能受体表达较低。
