Anderson Brian M, Jacobson Lauren, Novakovic Zachary M, Grasso Patricia
Department of Medicine, Division of Endocrinology and Metabolism, Albany Medical College, Albany, NY 12208, USA; Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA.
Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY 12208, USA.
Brain Res. 2017 Jun 1;1664:1-8. doi: 10.1016/j.brainres.2017.03.020. Epub 2017 Mar 24.
This study describes the localization of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3, synthetic peptide leptin mimetics, in the hypothalamus of Swiss Webster and C57BL/6J wild-type mice, leptin-deficient ob/ob mice, and leptin-resistant diet-induced obese (DIO) mice. The mice were given [D-Leu-4]-OB3 or MA-[D-Leu-4]-OB3 in 0.3% dodecyl maltoside by oral gavage. Once peak serum concentrations were reached, the mice received a lethal dose of pentobarbital and were subjected to intracardiac perfusion fixation. The brains were excised, post-fixed in paraformaldehyde, and cryo-protected in sucrose. Free-floating frozen coronal sections were cut at 25-µm and processed for imaging by immunofluorescence microscopy. In all four strains of mice, dense staining was concentrated in the area of the median eminence, at the base and/or along the inner wall of the third ventricle, and in the brain parenchyma at the level of the arcuate nucleus. These results indicate that [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 cross the blood-brain barrier and concentrate in an area of the hypothalamus known to regulate energy balance and glucose homeostasis. Most noteworthy is the localization of [D-Leu-4]-OB3 immunoreactivity within the hypothalamus of DIO mice via a conduit that is closed to leptin in this rodent model, and in most cases of human obesity. Together with our previous studies describing the effects of [D-Leu-4]-OB3 and MA-[D-Leu-4]-OB3 on energy balance, glucose regulation, and signal transduction pathway activation, these findings are consistent with a central mechanism of action for these synthetic peptide leptin mimetics, and suggest their potential usefulness in the management of leptin-resistant obesity and type 2 diabetes in humans.
本研究描述了合成肽瘦素模拟物[D-亮氨酸-4]-OB3和MA-[D-亮氨酸-4]-OB3在瑞士韦伯斯特和C57BL/6J野生型小鼠、瘦素缺乏的ob/ob小鼠以及瘦素抵抗的饮食诱导肥胖（DIO）小鼠下丘脑的定位。通过口服灌胃给小鼠施用溶于0.3%十二烷基麦芽糖苷的[D-亮氨酸-4]-OB3或MA-[D-亮氨酸-4]-OB3。一旦达到血清峰值浓度，给小鼠注射致死剂量的戊巴比妥并进行心脏灌注固定。取出大脑，在多聚甲醛中后固定，并在蔗糖中进行冷冻保护。将自由漂浮的冷冻冠状切片切成25微米厚，通过免疫荧光显微镜进行成像处理。在所有四株小鼠中，密集染色集中在正中隆起区域、第三脑室底部和/或沿其内壁，以及弓状核水平的脑实质中。这些结果表明，[D-亮氨酸-4]-OB3和MA-[D-亮氨酸-4]-OB3穿过血脑屏障并集中在下丘脑已知调节能量平衡和葡萄糖稳态的区域。最值得注意的是，在该啮齿动物模型以及大多数人类肥胖病例中，[D-亮氨酸-4]-OB3免疫反应性通过对瘦素封闭的管道定位在DIO小鼠的下丘脑内。连同我们之前描述[D-亮氨酸-4]-OB3和MA-[D-亮氨酸-4]-OB3对能量平衡、葡萄糖调节和信号转导途径激活作用的研究，这些发现与这些合成肽瘦素模拟物的中枢作用机制一致，并表明它们在治疗人类瘦素抵抗性肥胖和2型糖尿病方面具有潜在用途。
