Table 1.

Antinociceptive effects of acute nicotine in μ-opioid receptor knock-out and wild-type mice

Wild-type miceKnock-out mice
Hot-plate test
 Saline35.62 ± 1.5924.42 ± 2.39
 Nicotine (1 mg/kg)50.89 ± 3.5329.55 ± 2.36
 Nicotine (3 mg/kg)120.40 ± 20.7748.65 ± 4.44
Tail-immersion test
 Saline0.81 ± 0.050.88 ± 0.05
 Nicotine (1 mg/kg)0.92 ± 0.060.95 ± 0.04
 Nicotine (3 mg/kg)1.11 ± 0.071.00 ± 0.08
  • Data (mean ± SEM) obtained in the hot-plate test (jumping response in seconds) and the tail-immersion test (tail withdrawal latency in seconds) are shown.