Houseknecht K L, Portocarrero C P
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907-1151, USA.
Domest Anim Endocrinol. 1998 Nov;15(6):457-75. doi: 10.1016/s0739-7240(98)00035-6.
Leptin is the adipocyte-specific product of the ob gene. Expression of leptin in fully fed animals reflects adipocyte size and body-fat mass. Leptin signals the status of body energy stores to the brain, where signals emanate to regulate food intake and whole-body energy expenditure. The leptin gene was identified in the leptin-deficient, obese ob/ob mouse by positional cloning techniques. Recently, leptin has been cloned in domestic species including pigs, cattle, and chickens. The leptin receptor has at least five splice variants; the long form of the receptor is primarily expressed in the hypothalamus and is thought to be the predominant signaling isoform. Leptin receptors are members of the cytokine family of receptors and signal via janus-activated kinases (JAK)/signal transducers and activators of transcription (STAT) and mitogen-activated protein kinase (MAPK) pathways. Mutations in the leptin or leptin receptor genes results in morbid obesity, infertility, and insulin resistance in rodents and humans. Leptin regulates food intake and energy expenditure via central and peripheral mechanisms. Leptin receptors are expressed in most tissues, and in vitro evidence suggests that leptin may have direct effects on some tissues such as adipose tissue, the adrenal cortex, and the pancreatic beta-cell. Leptin is thought to influence whole-body glucose homeostasis and insulin action. Studies are underway to determine the role that leptin plays in the biology of domestic animals.
瘦素是肥胖基因（ob基因）在脂肪细胞中特异性表达的产物。在饮食充足的动物体内，瘦素的表达反映了脂肪细胞的大小和体脂量。瘦素将机体能量储备状况的信号传递至大脑，大脑发出信号调节食物摄入量和全身能量消耗。通过定位克隆技术，在瘦素缺乏的肥胖ob/ob小鼠中鉴定出了瘦素基因。最近，在包括猪、牛和鸡在内的家畜中也克隆出了瘦素。瘦素受体至少有五种剪接变体；受体的长形式主要在下丘脑表达，被认为是主要的信号传导异构体。瘦素受体是细胞因子受体家族的成员，通过janus激活激酶（JAK）/信号转导子和转录激活子（STAT）以及丝裂原活化蛋白激酶（MAPK）途径进行信号传导。瘦素或瘦素受体基因的突变会导致啮齿动物和人类出现病态肥胖、不孕和胰岛素抵抗。瘦素通过中枢和外周机制调节食物摄入量和能量消耗。瘦素受体在大多数组织中都有表达，体外实验证据表明，瘦素可能对某些组织，如脂肪组织、肾上腺皮质和胰腺β细胞有直接影响。瘦素被认为会影响全身葡萄糖稳态和胰岛素作用。目前正在进行研究以确定瘦素在家畜生物学中所起的作用。
