Table 2. Mechanical withdrawal thresholds for the bilateral hindpaws of rats.

Age/groups	Left hindpaw		Right hindpaw
	Tactile	Needle	Tactile	Needle
P8	1.72 ± 0.10	1.09 ± 0.13**	1.62 ± 0.10	1.17 ± 0.08**
P15	5.00 ± 0.33	3.95 ± 0.28**	4.80 ± 0.33	3.07 ± 0.42**
P22	4.97 ± 0.45	2.15 ± 0.40**	5.22 ± 0.43	1.78 ± 0.39**
P43	8.59 ± 0.78	4.19 ± 0.57**	6.85 ± 0.78	4.13 ± 0.48**
P57	18.83 ± 3.29	9.50 ± 0.88**	17.83 ± 2.70	9.25 ± 0.69**
P85	25.75 ± 4.90	9.94 ± 1.50**	25.92 ± 5.02	13.06 ± 1.84**

Two-way ANOVA was performed to determine the significance of differences in the mechanical withdrawal thresholds of the bilateral hindpaw between the two groups. The LSD post-hoc test was used to detect group differences at each age. Data are expressed as the mean ± SEM. *P < 0.05, **P < 0.01 for Needle vs. Tactile (n = 12).