Intrathecal administration of the common carboxyl-terminal decapeptide in endokinin A and endokinin B evokes scratching behavior and thermal hyperalgesia in the rat.
Endokinins are novel mammalian tachykinin peptides designated from a human preprotachykinin gene and consist of endokinin A (EKA), endokinin B (EKB), endokinin C (EKC) and endokinin D (EKD). A representative of the tachykinin peptide is substance P (SP), which functions as a pain modulator or transmitter and contributes to pain processing; however, little is known about the function of endokinins in pain processing. Therefore, we evaluated the effects of EKA/B (using the common C-terminal decapeptide in EKA and EKB) and EKC/D (using the common C-terminal duodecapeptide in EKC and EKD) on pain processing in rats. Intrathecal administration of 10(-3) M (10 nmol) EKA/B evoked pain-related behavior such as scratching while 10(-3) M EKC/D administration did not. This induction of scratching behavior following EKA/B administration was suppressed by pretreatment with an NK1 receptor antagonist. In addition to the induction of scratching behavior, intrathecal administration of 10(-7) - 10(-4) M (1 pmol-1 nmol) EKA/B decreased the latency of the paw withdrawal response to noxious thermal stimulation, whereas there was little effect of EKC/D administration on the latency of the withdrawal response. This effect of EKA/B was also suppressed by pretreatment with NK1 receptor antagonists. These results indicate that intrathecal administration of EKA/B but not EKC/D evokes scratching behavior and thermal hyperalgesia through the NK1 receptor.
Yoshioka
Daisuke
D
Division of Neurobiology, Miyazaki Medical College, University of Miyazaki, Kiyotake, Miyazaki 889-1692, Japan.
Takebuchi
Fumiko
F
Nishimori
Toshikazu
T
Naono
Rumi
R
Ikeda
Tetsuya
T
Nakayama
Tomohiro
T
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006930:Hyperalgesia / Q000139:chemically induced*; D007278:Injections, Spinal / Q000379:methods; D008297:Male; D010146:Pain / Q000139:chemically induced* / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods; D010455:Peptides / Q000008:administration & dosage*; D010803:Physalaemin / Q000008:administration & dosage / Q000031:analogs & derivatives; D011812:Quinuclidines / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D015320:Tachykinins / Q000737:chemistry*; D013997:Time Factors
D010455:Peptides; D011812:Quinuclidines; D015320:Tachykinins; C079014:GR 82334; C076851:L 703606; D010803:Physalaemin