Cold water swim stress inhibits the nociceptive responses to intrathecally administered somatostatin, but not substance P.
The effects of cold water swim stress (CWSS) on the nociceptive responses to i.t. administered substance P (SP) and somatostatin (SST) were examined. Male ICR mice, weighing about 30 g, were forced to swim in water at 20 degrees C for 3 min. In unstressed mice, i.t. injection of SP (0.1 nmol) and SST (1 nmol), respectively, produced nociceptive-related behaviors. Although CWSS had no effect on the intensity of the SP-induced nociceptive responses, CWSS significantly reduced the intensity of the SST-induced nociceptive responses. The effect of CWSS on the SST-induced nociceptive responses was blocked by naloxone (5 mg/kg, s.c.) and naltrindole (1 mg/kg, s.c.), a selective delta-opioid receptor antagonist, but not by beta-funaltrexamine (20 mg/kg, s.c.), a selective mu-opioid receptor antagonist. These results indicate that CWSS may selectively reduce the SST-induced nociceptive responses primarily through delta-opioid receptors.
Kamei
J
J
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
Hitosugi
H
H
Misawa
M
M
Nagase
H
H
Kasuya
Y
Y
D000818:Animals; D003080:Cold Temperature; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology*; D017465:Receptors, Opioid, delta / Q000502:physiology; D013004:Somatostatin / Q000008:administration & dosage*; D013312:Stress, Physiological / Q000503:physiopathology*; D013373:Substance P / Q000008:administration & dosage*; D013550:Swimming
D017465:Receptors, Opioid, delta; D013373:Substance P; D009270:Naloxone; D013004:Somatostatin