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Pain, Itch and Their Disorders

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Hemokinin-1 (1-5) elicits the inhibitory effect on pruritic processing in rats

  • P2-186
  • 直野ー中山 留美 / Rumi Nakayama-Naono:1,2 船橋 英樹 / Funahashi Hideki:3 髙宮 考悟 / Takamiya Kogo:1 西森 利數 / Nishimori Toshikazu:3 
  • 1:宮崎大学・医・統合生理 / Dept of Neurosci, Fac of Med, Univ of Miyazaki, Miyazaki, Japan 2:日本学術振興会 特別研究員 / JSPS Research Fellow, Tokyo, Japan 3:宮崎大学・医・精神医学 / Dept of Psychiatry, Fac of Med, Univ of Miyazaki, Miyazaki, Japan 

Hemokinin-1 (HK-1) is a peptide encoded by the preprotachykinin gene, TAC-4, and shares the hydrophobic carboxyl-terminal (C-terminal) region common to mammalian tachykinin peptides, such as substance P (SP). It is generally believed that C-terminal fragments of SP elicit an excitatory effect, while pretreatment with amino-terminal (N-terminal) fragments of SP inhibits the function of SP; however, there is no available information on HK-1. Therefore, to clarify the characteristics of C-terminal and N-terminal fragments of HK-1, HK-1 was divided into HK-1 (1-5) as the N-terminal fragment and HK-1 (6-11) as the C-terminal fragment based on the similarity of amino acids between HK-1 and SP. Intrathecal administration of HK-1 (6-11) induced scratching behavior similar to HK-1, while HK-1 (1-5) hardly induced scratching. Pretreatment with HK-1 (1-5), however, attenuated scratching induced by HK-1 and SP, whereas pretreatment with SP (1-5) attenuated SP-induced scratching, but not HK-1. Furthermore, intrathecal administration of HK-1 (1-5) and SP (1-5) markedly attenuated the induction of flinching and enhancement of c-Fos expression in the spinal cord following intradermal administration of formalin, a noxious stimulant, while pretreatment with HK-1 (1-5), but not SP (1-5), markedly attenuated the induction of scratching behavior by subcutaneous administration of pruritic agents, such as serotonin or histamine. Taken together, these findings indicate that HK-1 (1-5) suppresses pruritic and nociceptive processing, while SP (1-5) suppresses nociceptive processing. Therefore, it is suggested that HK-1 (1-5) may be a useful tool for revealing pruritic processing and HK-1 may play a crucial role in pruritic processing.

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