Scarpace P J, Nicolson M, Matheny M
Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, Gainesville, Florida 32608-1197, USA.
J Endocrinol. 1998 Nov;159(2):349-57. doi: 10.1677/joe.0.1590349.
To determine the effects of food restriction and leptin administration on several transcripts involved in energy homeostasis, we examined leptin, uncoupling proteins (UCP) 1, 2 and 3, lipoprotein lipase (LPL), beta3-adrenergic receptors (beta3AR) and hormone-sensitive lipase (HSL) mRNA levels in brown adipose tissue (BAT) and epididymal (EWAT) and perirenal (PWAT) white adipose tissue in three groups of rats. The groups were administered leptin for 1 week, or had food restricted to the amount of food consumed by the leptin-treated animals, or had free access to food. Leptin administration increased serum leptin concentrations 50-fold and decreased food consumption by 43%, whereas serum insulin and corticosterone concentrations were unchanged. Leptin increased LPL mRNA by 80%, UCP1 mRNA twofold, and UCP3 mRNA levels by 62% in BAT, and increased UCP2 mRNA levels twofold in EWAT. In contrast, UCP2 mRNA levels were unchanged in PWAT and BAT. In WAT from food-restricted rats, leptin gene expression was diminished by 40% compared with those fed ad libitum. With leptin administration, there was a further 50% decrease in leptin expression. LPL mRNA levels were decreased by food restriction but not by leptin in WAT, whereas beta3AR and HSL mRNA levels were unchanged with either food restriction or leptin treatment. The present study indicates that leptin increases the gene expression of UCP2 in EWAT and that of UCP1, UCP3 and LPL in BAT, whereas reduced food consumption but not leptin, decreases LPL expression in WAT. In addition, with leptin administration there is a decrease in leptin gene expression in WAT, independent of food intake and serum insulin and corticosterone concentrations.
为了确定食物限制和瘦素给药对能量平衡相关的几种转录本的影响，我们检测了三组大鼠棕色脂肪组织（BAT）、附睾白色脂肪组织（EWAT）和肾周白色脂肪组织（PWAT）中瘦素、解偶联蛋白（UCP）1、2和3、脂蛋白脂肪酶（LPL）、β3 - 肾上腺素能受体（β3AR）和激素敏感性脂肪酶（HSL）的mRNA水平。这些组分别接受了为期1周的瘦素给药，或者食物量被限制为瘦素处理组动物的食量，或者可以自由获取食物。给予瘦素使血清瘦素浓度增加了50倍，食物摄入量减少了43%，而血清胰岛素和皮质酮浓度没有变化。瘦素使BAT中的LPL mRNA增加了80%，UCP1 mRNA增加了两倍，UCP3 mRNA水平增加了62%，并使EWAT中的UCP2 mRNA水平增加了两倍。相比之下，PWAT和BAT中的UCP2 mRNA水平没有变化。在食物受限大鼠的白色脂肪组织中，与自由进食的大鼠相比，瘦素基因表达减少了40%。给予瘦素后，瘦素表达进一步降低了50%。在白色脂肪组织中，食物限制使LPL mRNA水平降低，但瘦素没有此作用，而β3AR和HSL mRNA水平在食物限制或瘦素处理时均未改变。本研究表明，瘦素增加EWAT中UCP2以及BAT中UCP1、UCP3和LPL的基因表达，而食物摄入量减少而非瘦素，会降低白色脂肪组织中LPL的表达。此外，给予瘦素会使白色脂肪组织中的瘦素基因表达降低，且与食物摄入量、血清胰岛素和皮质酮浓度无关。
