Analgesic effect of α-cobratoxin on mice and its effect on protein kinase A activity of spinal dorsal root ganglion in mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To study the analgesic effect of α-cobratoxin (α-CbTX) on mice and its effect on protein kinase A (PKA) activity of spinal dorsal root ganglion (DRG) in mice.Methods:Healthy male ICR mice( n=102) were randomly divided into low-, medium-, and high-dose α-CbTX groups (1 mg/kg, 3 mg/kg, 9 mg/kg respectively, gavage, n=21), solvent control group (equivalent volume of 0.9% normal saline, gavage, n=21), morphine positive control group (3 mg/kg, intraperitoneal injection, n=6)or aspirin positive control group(300 mg/kg, gavage, n=12). The analgesic effect of α-CbTX was evaluated by hot plate test, acetic acid twisting test and formalin foot licking test. Formalin plantar injection was used to induce pain and then the L4-L6 DRG was taken 30 minutes later. The expression of PKA C-α in L4-L6 DRG of mice were detected by Western blot.SPSS 16.0 software was used for statistical analysis. Repeated measurement ANOVA was used to evaluate the hot plate experimental data, and one-way ANOVA was used for other experimental data. LSD- t test was used for further pairwise comparison. Results:In the hot plate test, the interaction between group and time of mice paw licking latency was significant ( F=8.902, P<0.05). At 0.5 h after administration, the paw licking latencies of α-CbTX medium-dose group ((11.83±1.47)s)and α-CbTX high-dose group (( 14.33±12.1)s) were both longer than that of solvent control group((8.17±0.75) s) ( t=4.461, 7.053, both P<0.05). The efficacy of α-CbTX medium dose group lasted until 1.5 h after administration (all P<0.05), and that of α-CbTX high dose group lasted until 2 h after administration(all P<0.05). In the acetic acid writhing test, the writhing times in the low-, medium- and high-dose α-CbTX group((34.50±3.62) times, (26.17±2.40) times, (13.83±3.76) times)) were significantly lower than that in solvent control group ((42.50±4.59) times) ( t=3.938, 8.040, 14.112, all P<0.05). In the period of the formalin test phase Ⅱ, the total licking time of α-CbTX low-, medium- and high-dose groups ((71.17±6.46) s), (54.67±6.41) s, (40.50±3.89)s) were significantly shorter than that of the solvent control group ((98.67±11.50) s)( t=6.950, 11.120, 14.700, all P<0.05). In the Western blot experiment, compared with solvent control group (0.22±0.01), the levels of PKA C-α in the DRG of mice in low-, medium- and high-dose α-CbTX groups ((0.31±0.02), (0.41±0.03), (0.44±0.02)) were up-regulated ( t=3.140, 6.471, 7.492, all P<0.05). Conclusion:α-CbTX has obvious analgesic effect, and its analgesic mechanism may be related to the activation of PKA.