N3-phenacyluridine as a new type of antinociceptive compound in mice.

The antinociceptive activity of N3-phenacyluridine, a novel hypnotic, was examined with tail pinch, hot plate and acetic acid-induced abdominal constriction methods by intracerebroventricular (i.c.v.) injection to mice. In the first method, N3-phenacyluridine exerted antinociceptive activity after the i.c.v. injection at a dose of 0.5 micromol/mouse, although this activity was comparable to the activity of morphine (0.01 micromol/mouse, i.c.v.). In the second method, the activity of N3 -phenacyluridine was continued until 120 min after the injection at a dose of 0.5 micromol/mouse. In last, N3-phenacyluridine (0.1 micromol/mouse, i.c.v.) significantly decreased in the numbers of acetic acid-induced abdominal constriction as compared to the control (1% Tween 80 saline). The ED50 value of the antinociceptive activity of N3-phenacyluridine was 0.02 imol/mouse, i.c.v. The present paper demonstrated for the first time that N3-phenacyluridine belonging to oxopyrimidine nucleoside analogue possesses not only the hypnotic and sedative activities previously reported, but also antinociceptive activity.