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.