Vasopressin and stress-induced antinociception in the mouse.

1. Arginine vasopressin produced antinociception in the hot-plate test after intracerebroventricular injection (0.5 micrograms) and in the acetic acid abdominal constriction test after intraperitoneal injection (0.1 mg kg-1). 2. The antinociception produced by arginine vasopressin was sensitive to deamino(CH2)5Tyr(Me) arginine vasopressin (0.5 micrograms i.c.v.; 0.1 mg kg-1 i.p.) but not to naloxone (5 micrograms i.c.v.; 2 mg kg-1 i.p.) 3. Arginine vasopressin when administered by the intracerebroventricular route, but not by the intraperitoneal route, produced characteristic behaviour which was sensitive to deamino(CH2)5Tyr(Me) arginine vasopressin (0.5 micrograms, i.c.v.). 4. A 3 min swim at 20 degrees C produced antinociception on the hot-plate which was sensitive to naloxone (0.4 mg kg-1, i.p.) but not to deamino(CH2)5Tyr(Me) arginine vasopressin (0.5 micrograms, i.c.v.). 5. The reduction in the number of acetic acid-induced abdominal constrictions produced by a 30 s swim at 30 degrees C was not sensitive to either naloxone (2 mg kg-1, i.p.) or deamino(CH2)5Tyr(Me) arginine vasopressin (0.1 mg kg-1, i.p.). 6. Arginine vasopressin, at high doses, is antinociceptive in the mouse but does not appear to mediate stress-induced antinociception in this species.