The effects of imipramine on nociceptive behavior induced by intrathecal injection of substance P or N-methyl-D-aspartate in capsaicin pretreated mice

• Published in: Japanese Journal of Pharmacology Vol. 67; no. suppl.1; p. 138
• Main Authors: Shimizu, Takao, Iwasita, Tatsuro, Masuyama, Takashi, Ikeda, Kouzi, Nomoto, Masahiro, Fukuda, Takeo
• Format: Journal Article
• Language: English
• Published: The Japanese Pharmacological Society 1995
• ISSN: 0021-5198; 1347-3506
• DOI: 10.1016/S0021-5198(19)46518-9

Intrathecal administration of substance P (SP：6pmol) or N-methyl-D-aspartate (NMDA：0.25nmol) elicited nociceptive behavior such as licking, biting and scratching in mice. Both SP and NMDA-induced nociceptive behavior were dose-dependently reduced by simultaneous injection of imipramine. Intrathecal pretreatment with capsaicin before 1 day reduced SP concentration in spinal cord by 64% of control. This administration of capsaicin kept in suppression of SP-induced nociceptive behavior by imipramine (10μg), whereas inhibited the suppression of NMDA-induced nociceptive behavior by imipramine (5μg). NMDA-induced nociceptive behavior was suppressed by coadministration of SP (1pmol), whereas was potentiated by coadministration of SP (6pmol). These findings indicate a functional interaction between SP containing neurons and glutamate containing neurons in the dorsal horn of the spinal cord in mice.