Smart D, Jerman J C, Brough S J, Neville W A, Jewitt F, Porter R A
Neuroscience Research, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.
Br J Pharmacol. 2000 Apr;129(7):1289-91. doi: 10.1038/sj.bjp.0703257.
The pharmacology of the orexin-like peptides, hypocretin-1 and hypocretin-2, was studied in Chinese hamster ovary (CHO) cells stably expressing orexin-1 (OX(1)) or orexin-2 (OX(2)) receptors by measuring intracellular calcium (Ca(2+)) using Fluo-3AM. Orexin-A and orexin-B increased Ca(2+) in CHO-OX(1) (pEC(50)=7. 99+/-0.05 and 7.00+/-0.10 respectively, n=8) and CHO-OX(2) (pEC(50)=8.30+/-0.05 and 8.21+/-0.07 respectively, n=5). However, hypocretin-1 and hypocretin-2 were markedly less potent, with pEC(50) values of 5.31+/-0.04 and 5.41+/-0.04 respectively in CHO-OX(2) cells (n=5). In CHO-OX(1) cells 10 microM hypocretin-1 only elicited a 37.5+/-3.4% response whilst 10 microM hypocretin-2 elicited a 18.0+/-2.1% response (n=8). Desensitisation of OX(1) or OX(2) with orexin-A (100 nM) abolished the response to orexin-A (10 nM) and the hypocretins (10 microM), but not to UTP (3 microM). In conclusion, the hypocretins are only weak agonists at the orexin receptors.
通过使用Fluo-3AM测量细胞内钙（[Ca(2+)]i），在中国仓鼠卵巢（CHO）细胞中稳定表达食欲素-1（OX(1)）或食欲素-2（OX(2)）受体，研究了食欲素样肽（食欲素-1和食欲素-2）的药理学。食欲素-A和食欲素-B可增加CHO-OX(1)（pEC(50)分别为7.99±0.05和7.00±0.10，n = 8）和CHO-OX(2)（pEC(50)分别为8.30±0.05和8.21±0.07，n = 5）细胞中的[Ca(2+)]i。然而，食欲素-1和食欲素-2的效力明显较低，在CHO-OX(2)细胞中的pEC(50)值分别为5.31±0.04和5.41±0.04（n = 5）。在CHO-OX(1)细胞中，10μM食欲素-1仅引起37.5±3.4%的反应，而10μM食欲素-2引起18.0±2.1%的反应（n = 8）。用食欲素-A（100 nM）使OX(1)或OX(2)脱敏可消除对食欲素-A（10 nM）和食欲素（10μM）的反应，但对UTP（3μM）无影响。总之，食欲素在食欲素受体上只是弱激动剂。
