Vernon R G, Doris R, Finley E, Houslay M D, Kilgour E, Lindsay-Watt S
Hannah Research Institute, Scotland, U.K.
Biochem J. 1995 May 15;308 ( Pt 1)(Pt 1):291-6. doi: 10.1042/bj3080291.
The effect of lactation on the regulation of lipolysis by beta- and alpha 2-adrenergic agents and by adenosine has been investigated. When changes in adipocyte mean cell volume (which decreases with lactation) are allowed for, lactation increased the maximum response both to beta-adrenergic agents and to the adenosine analogue N6-phenylisopropyladenosine, but had no apparent effect on the responsiveness of the alpha 2-adrenergic system in both subcutaneous and omental adipocytes. For subcutaneous adipocytes, there was no significant change in the number of beta-adrenergic or alpha 2-adrenergic receptors, but the amount of Gs and the maximum (forskolin-stimulated) adenylate cyclase activity were increased by lactation. In contrast, in omental adipocytes, the number of beta- (but not alpha 2-) adrenergic receptors and the amount of Gs were increased, whereas forskolin-stimulated adenylate cyclase activity was unchanged by lactation. In both types of adipocyte, cyclic AMP phosphodiesterase and total protein kinase A activities were unchanged. Lactation had no effect on the number of adenosine receptors but increased the amounts of the Gi isoforms expressed in both types of adipocyte. These various adaptations differ markedly in a number of respects from those described previously in the rat. Lactation, then, while having a similar overall effect on the response to beta-adrenergic agonists of adipocytes, achieves this by depot-specific mechanisms. In contrast, changes in response to adenosine appear to involve the same mechanism in the two depots investigated.
研究了哺乳期对β-肾上腺素能药物、α2-肾上腺素能药物和腺苷调节脂肪分解的影响。考虑到脂肪细胞平均细胞体积的变化（哺乳期会减小），哺乳期增加了对β-肾上腺素能药物和腺苷类似物N6-苯基异丙基腺苷的最大反应，但对皮下和网膜脂肪细胞中α2-肾上腺素能系统的反应性没有明显影响。对于皮下脂肪细胞，β-肾上腺素能或α2-肾上腺素能受体的数量没有显著变化，但哺乳期会增加Gs的量和最大（福斯可林刺激的）腺苷酸环化酶活性。相反，在网膜脂肪细胞中，β-（而非α2-）肾上腺素能受体的数量和Gs的量增加，而哺乳期对福斯可林刺激的腺苷酸环化酶活性没有影响。在两种类型的脂肪细胞中，环磷酸腺苷磷酸二酯酶和总蛋白激酶A的活性均未改变。哺乳期对腺苷受体的数量没有影响，但增加了两种类型脂肪细胞中表达的Gi亚型的量。这些不同的适应性变化在许多方面与先前在大鼠中描述的值显著不同。因此，哺乳期虽然对脂肪细胞对β-肾上腺素能激动剂的反应具有类似的总体影响，但通过特定部位的机制实现这一点。相比之下，在所研究的两个部位中，对腺苷反应的变化似乎涉及相同的机制。
