Cerebral excitability in pup rats prenatally exposed to 1-bromopropane is suppressed by bromide accumulated in the brain

Previously, we reported that prenatal exposure to 1-bromopropane (1-BP) causes the accumulation of bromide (Br(-)) in the brain of rat pups. Here, we aimed to investigate the effects of Br(-) accumulation in rat pups prenatally exposed to 1-BP vapor. Dam rats were exposed to 1-BP (400 or 700 ppm; 1-BP group) by inhalation, or to NaBr (20 mM; Br(-) group) in drinking water during gestation days 1–20. We also analyzed pentylenetetrazole (PTZ, 60 mg/kg, ip)-induced behavioral changes in pups prenatally exposed to 1-BP or Br(-) on postnatal day (PND) 14. PTZ-induced epileptic convulsions were inhibited in both 1-BP (700 ppm) and Br(-) groups. The inhibition of neuronal excitability induced by Br(-) was evaluated electrophysiologically using the hippocampal slices obtained from PND14–16 pups. PTZ (2 mM) failed to induce epileptiform discharge in the presence of 1.2 mM Br(-) in the slices obtained from the control group. However, it induced epileptiform discharge following the removal of Br(-), by perfusing artificial cerebrospinal fluid into the slices obtained from the Br(-) group. Our results indicate that Br(-) accumulates in the brain of neonatal rat pups prenatally exposed to 1-BP vapor suppressed neuronal excitability.