Figure 2.

Decreased post-activation depression (PAD) performed in vitro in pups from P4 to P6 and in vivo in adult rats that both were submitted to mild intrauterine hypoperfusion (MIUH) at E17. (A) Mean (± SEM) relative amplitudes of the monosynaptic reflex at different stimulation frequencies in MIUH pups, compared to sham rats. In sham rats, the monosynaptic amplitude decreased with increasing frequencies (i.e., PAD) from 0.1 Hz (set as reference = 100%) to 5 Hz [(ANOVA of Friedman, x² = 40.1, df = 4; p < 0.0001) and Wilcoxon's post-hoc comparisons:^**p < 0.01; ^***p < 0.0001; ns, non-significant] while this amplitude decreased lesser in MIUH pups [(ANOVA of Friedman, x² = 21.1, df = 4; p < 0.003) and Wilcoxon's post-hoc comparisons:^*p < 0.05; ns, non-significant]. The comparison of the monosynaptic reflex amplitude between sham and MIUH rats showed significant reduction of the PAD at stimulation frequency (Wilcoxon: b, p < 0.01) from 0.1 Hz. (B) Depression of the H-reflex (PAD), expressed as percentages, over consecutive stimulations from 0.2 Hz (set as reference = 100%) to 5 Hz in sham rats [(ANOVA of Friedman, x² = 69.6, df = 4; p < 0.0001) and Wilcoxon's post-hoc comparisons:^**p < 0.01] while the H-reflex was increased at 0.5 and 1 Hz and did not reduce at higher frequencies of stimulation in MIUH rats [(ANOVA of Friedman, x² = 12.5, df = 4; p < 0.01) and Wilcoxon's post-hoc comparisons: ns, non-significant]. When we compared the H-reflex PAD between sham and MIUH rats, we found significant decreases of PAD at stimulation frequencies from 0.2 to 5 Hz (Wilcoxon: a, p < 0.05; b, p < 0.01) in the latter group.