Sim Yun-Beom, Park Soo-Hyun, Kim Sung-Su, Lim Su-Min, Jung Jun-Sub, Suh Hong-Won
Department of Pharmacology, Institute of Natural Medicine, College of Medicine Hallym University, 39 Hallymdaehak-gil, Chuncheon, Gangwon-do 200-702, Republic of Korea.
Department of Pharmacology, Institute of Natural Medicine, College of Medicine Hallym University, 39 Hallymdaehak-gil, Chuncheon, Gangwon-do 200-702, Republic of Korea.
Neuropeptides. 2014 Aug;48(4):207-12. doi: 10.1016/j.npep.2014.05.004. Epub 2014 May 27.
Alpha-melanocyte stimulating hormone (α-MSH) is known as a regulator of the blood glucose homeostasis and food intake. In the present study, the possible roles of α-MSH located in the spinal cord in the regulation of the blood glucose level were investigated in d-glucose-fed and immobilization stress (IMO) mouse models. We found in the present study that intrathecal (i.t.) injection with α-MSH alone did not affect the blood glucose level. However, i.t. administration with α-MSH reduced the blood glucose level in d-glucose-fed model. The plasma insulin level was increased in d-glucose-fed model and was further increased by α-MSH, whereas α-MSH did not affect plasma corticosterone level in d-glucose-fed model. In addition, i.t. administration with glucagon alone enhanced blood glucose level and, i.t. injection with glucagon also increased the blood glucose level in d-glucose-fed model. In contrasted to results observed in d-glucose-fed model, i.t. treatment with α-MSH caused enhancement of the blood glucose level in IMO model. The plasma insulin level was increased in IMO model. The increased plasma insulin level by IMO was reduced by i.t. treatment with α-MSH, whereas i.t. pretreatment with α-MSH did not affect plasma corticosterone level in IMO model. Taken together, although spinally located α-MSH itself does not alter the blood glucose level, our results suggest that the activation of α-MSH system located in the spinal cord play important modulatory roles for the reduction of the blood glucose level in d-glucose fed model whereas α-MSH is responsible for the up-regulation of the blood glucose level in IMO model. The enhancement of insulin release may be responsible for modulatory action of α-MSH in down-regulation of the blood glucose in d-glucose fed model whereas reduction of insulin release may be responsible for modulatory action of α-MSH in up-regulation of the blood glucose in IMO model.
α-黑素细胞刺激素（α-MSH）是一种已知的血糖稳态和食物摄入调节剂。在本研究中，我们在葡萄糖喂养和固定应激（IMO）小鼠模型中研究了脊髓中α-MSH在调节血糖水平方面的可能作用。我们在本研究中发现，鞘内（i.t.）单独注射α-MSH不会影响血糖水平。然而，在葡萄糖喂养模型中，鞘内给予α-MSH可降低血糖水平。在葡萄糖喂养模型中，血浆胰岛素水平升高，α-MSH可使其进一步升高，而α-MSH在葡萄糖喂养模型中不影响血浆皮质酮水平。此外，单独鞘内给予胰高血糖素可提高血糖水平，在葡萄糖喂养模型中鞘内注射胰高血糖素也会升高血糖水平。与在葡萄糖喂养模型中观察到的结果相反，在IMO模型中，鞘内给予α-MSH会导致血糖水平升高。IMO模型中血浆胰岛素水平升高。鞘内给予α-MSH可降低IMO导致的血浆胰岛素水平升高，而在IMO模型中，鞘内预先给予α-MSH不影响血浆皮质酮水平。综上所述，虽然脊髓中的α-MSH本身不会改变血糖水平，但我们的结果表明，脊髓中α-MSH系统的激活在葡萄糖喂养模型中对降低血糖水平起着重要的调节作用，而在IMO模型中，α-MSH则导致血糖水平上调。胰岛素释放的增强可能是α-MSH在葡萄糖喂养模型中下调血糖的调节作用的原因，而胰岛素释放的减少可能是α-MSH在IMO模型中上调血糖的调节作用的原因。
