TABLE 1

Summary of the effects of the various drugs on the antinociception caused by α,β-amyrin assessed in the formalin test Each group represents means ± S.E.M. for 6 to10 animals.

Drug
Dose
Formalin Test
First Phase
Second Phase
mg/kg
Control 0 49 ± 2 155 ± 11
Naloxone 5 49 ± 4 165 ± 14
Morphine 5 9 ± 2** 22 ± 10**
Morphine + naloxone 5 + 5 41 ± 4+ 171 ± 14+
α,β-Amyrin 10 25 ± 2** 46 ± 8**
α,β-Amyrin + naloxone 10 + 5 28 ± 5N.S. 51 ± 7N.S.
Control 0 56 ± 3 152 ± 11
PCPA 100 48 ± 4 171 ± 13
α,β-Amyrin 10 29 ± 3** 51 ± 13**
α,β-Amyrin + naloxone 10 + 100 35 ± 7N.S. 29 ± 17N.S.
Control 0 55 ± 4 153 ± 16
l-Arginine 600 60 ± 5 144 ± 21
l-NOARG 75 47 ± 5N.S. 31 ± 11**
l-NOARG + l-arginine 75 + 100 58 ± 2N.S. 155 ± 16+
α,β-Amyrin 10 38 ± 3** 63 ± 16**
α,β-Amyrin + l-arginine 10 + 100 39 ± 2N.S. 43 ± 31N.S.
Control 0 55 ± 2 140 ± 12
Prazosin 0.15 51 ± 4 125 ± 10
Yohimbine 0.15 50 ± 3 113 ± 12
Phenylephrine 10 12 ± 5** 2 ± 0.5**
Phenylephrine + prazosin 10 + 0.15 48 ± 5+ 109 ± 14+
Clonidine 0.1 15 ± 3** 6 ± 2**
Clonidine + yohinbine 0.1 + 0.15 52 ± 4+ 138 ± 24+
α,β-Amyrin 10 18 ± 3** 20 ± 8**
α,β-Amyrin + prazosin 10 + 0.15 27 ± 5N.S. 23 ± 10N.S.
α,β-Amyrin + yohinbine
10 + 0.15
30 ± 4N.S.
65 ± 5N.S.

  • N.S., not significant.

  • ↵** P < 0.01 compared with control value

  • ↵+ P < 0.05 compared with morphine, l-NOARG, phenylephrine, or clonidine