新型黑皮质素4受体激动剂减肥作用研究

The Anti-obesity Effect Of a Novel Melanocortin-4 Receptor Agonist

目的筛选具有黑皮质素4受体(MC4R)高亲和活性的α-MSH类似化合物,分析其激动活性,并观察其对小鼠体质量的调控作用与可能机制。方法从大鼠下丘脑及周围组织中提取富含MC4R的膜蛋白,采用放射性配体受体结合分析,比较并找出与MC4R具有高亲和力的α-MSH类似化合物。用LANCETMcAMP384在稳定转染MC4R的HEK293细胞上测试α-MSH类似化合物对cAMP释放的影响,确定其激动活性。采用高脂饲料喂养的小鼠,将筛选出的化合物经脑室给药一定时间后,观察小鼠体质量、摄食量及血糖、血脂、瘦素及胰岛素的变化,在整体水平上分析药物效果。结果受试化合物中LK-SPL-024对脑内MC4R亲和力最高。cAMP释放实验证明LK-SPL-024与α-MSH性质相同,均为MC4R激动剂,且激动活性与α-MSH相当。脑室注射给药,与生理氯化钠溶液对照组相比能有效减少肥胖小鼠进食量,显著降低血糖、血脂浓度并提高瘦素、胰岛素浓度;具有明显降低肥胖小鼠体质量的作用。结论本研究从α-MSH类似化合物中筛选得到了与MC4R高亲和力结合的化合物LK-SPL-024,该化合物是MC4R的激动剂,具有明确的减肥效应,机制可能与其升高血清瘦素和胰岛素水平有关。

Aim To screen the agonist of melanocortin-4 receptor （MC4R） and investigate its anti-obesity effect and potential mechanism in mice. Methods Membrane proteins with a high-density of MC4R were prepared from hypothalamus of SD rats. [^125I]-NDP-α-MSH was used as radio ligand while competitive ligand binding assay was used to evaluate the binding affinity of the chemicals to MC4R. LANCE^TM cAMP384 Kit was used to determine the ability of the chemicals to stimulate the release of cAMP in HEK293 cell lines which were stably expressed with MC4R. After the high-lipid fed mice were intracerebroventricularly injected with the chemicals for days, the effect of the chemicals on body weight, the food taken, the total plasma glucose, triglyceride, leptin and insulin in the blood of the mice were determined. Results In the assayed chemicals, LK-SPL-024 was found to have high binding affinity to MC4R. Like α-MSH, LK-SPL-024 stimulated the release of cAMP from the cells with MC4R expression,indicating that LK-SPL-024 was the agonist of MC4R and the activity for MC4R was similar to α-MSH. When injected intracerebroventricularly in vivo, LK-SPL-024 could efficiently decrease the body weight, the food taken, the total plasma glucose, triglyceride and increase the leptin and insulin level in the blood of the mice, compared with the mice treated with normal saline. Conclusion LK-SPL-024 was proved to be the agonist for MC4R and could decrease the body weight of overweighted mice. The mechanism could be related to increase of the total plasma leptin and insulin. The therapeutic effects of LK-SPL-024 on obesity deserve further study.