Naono Rumi, Yoshioka Daisuke, Ikeda Tetsuya, Nakayama Tomohiro, Nishimori Toshikazu
Division of Neurobiology, Miyazaki Medical College, University of Miyazaki, Kiyotake, Miyazaki 889-1692, Japan.
Brain Res Bull. 2007 Mar 15;71(5):461-5. doi: 10.1016/j.brainresbull.2006.10.002. Epub 2006 Oct 19.
Some novel tachykinin peptides exhibiting homology with known members of the tachykinin family have been recently reported; however, little is known about the function of these peptides. Repeated intrathecal administration of substance P (SP) causes desensitization by binding SP to neurokinin 1 (NK1) receptor. Thus, to clarify the characteristics of the receptors involved in these novel peptides, we investigated whether desensitization is induced by intrathecal administration of these peptides in rats since desensitization is induced by binding these peptides to the receptor. Intrathecal administration of 10(-3) M hemokinin-1 (HK-1) and 10(-3) M decapeptide common in the carboxyl-terminal region of endokinin A and endokinin B (EKA/B) as well as SP evoked scratching behavior. When each peptide was administered twice with an interval of 15 min, remarkable desensitization of scratching behavior was produced. Furthermore, the first administration of EKA/B or SP produced clear cross-desensitization to SP, EKA/B and HK-1, whereas the first administration of HK-1 demonstrated weak cross-desensitization to EKA/B and SP. These results suggest that EKA/B and SP may bind to both the NK1 receptor and HK-1-preferred receptor, and HK-1 may preferentially bind to its preferred receptor.
最近有报道称一些与速激肽家族已知成员具有同源性的新型速激肽肽段；然而，关于这些肽段的功能知之甚少。反复鞘内注射P物质（SP）会通过使SP与神经激肽1（NK1）受体结合而导致脱敏。因此，为了阐明参与这些新型肽段的受体的特性，我们研究了鞘内注射这些肽段在大鼠中是否会诱导脱敏，因为这些肽段与受体结合会诱导脱敏。鞘内注射10⁻³ M的血激肽-1（HK-1）、10⁻³ M在内激肽A和内激肽B（EKA/B）羧基末端区域常见的十肽以及SP都会引发抓挠行为。当每种肽段以15分钟的间隔给药两次时，会产生明显的抓挠行为脱敏。此外，首次注射EKA/B或SP会对SP、EKA/B和HK-1产生明显的交叉脱敏，而首次注射HK-1对EKA/B和SP表现出较弱的交叉脱敏。这些结果表明，EKA/B和SP可能与NK1受体和HK-1偏好性受体都结合，而HK-1可能优先与其偏好性受体结合。
