A: Detection of activated caspase-3 immunoreactivity in the dentate gyrus following MeHg and/or NAC exposure. P7 rats were injected with vehicle, 5.0 µg/gbw MeHg and/or 5×10µg/gbw NAC, sacrificed at 24 hrs and processed for immunostaining. Scale bar = 100 µm. B: Quantification revealed that the MeHg induced increase in caspase-3 positive cell number was completely blocked by NAC. Values are expressed as the means ± sem per section of 9 sections per animal, 3 animals per group. ***, P < 0.001 vs control; ###, P < 0.001 vs MeHg.