Time course of flinching responses in PND13 rats (males and females combined) in response to an injection of 0.6%, 0.7%, and 0.8% formalin into the plantar surface of the right hindpaw.

<p>Data are presented as mean +/− SE. * <i>p</i><.05; **<i>p</i><.01, *** <i>p</i><.001, against other groups at the same time point.</p

Time course of flinching responses in PND82 rats (males and females combined) in response to an injection of 1.25%, 1.75%, and 2.25% formalin into the plantar surface of the right hindpaw.

<p>Data are presented as mean +/− SE. * <i>p</i><.05, against other groups at the same time point.</p

Time course of licking responses in PND22 male (A) and female (B) rats in response to an injection of 0.9%, 1%, and 1.1% formalin into the plantar surface of the left hindpaw.

<p>Data are presented as mean +/− SE. * <i>p</i><.05; **<i>p</i><.01, against other groups at the same time point.</p

Time course of licking responses in PND7 rats (males and females combined) in response to an injection of 0.3%, 0.4%, and 0.5% formalin into plantar surface of the left hindpaw.

<p>Data are presented as mean +/− SE. * <i>p</i><.05; **<i>p</i><.01; *** <i>p</i><.001, against other groups at the same time point.</p

Time course of licking responses in PND82 male (A) and female (B) rats in response to an injection of 1.25%, 1.75%, and 2.25% formalin into the plantar surface of the right hindpaw.

<p>Baseline is the time prior to formalin injection (10 min). Data are presented as mean +/− SE. * <i>p</i><.05, **<i>p</i><.01, against other groups at the same time point.</p