Studies on the pleiotropic effects of gaseous chemical compound on the function of the central nervous system.

点击翻译按钮获取中文摘要

In this research, we investigated the effects of 1-bromopropane (1-BP), a substitute for chlorofluorocarbons, on the function of the central nervous system (CNS). We found that 1-BP directly potentiated the function of GABA_A receptors, but inhibited neuronal nicotinic acetylcholine receptors, respectively, from the experiments using Xenopus oocytes expression system. 1-BP also enhanced paired-pulse inhibition (PPI) of population spike (PS) amplitudes in the study using rat hippocampal slice preparations, suggesting an anesthetic effect of 1-BP. However, when the rats were exposed to 1-BP vapor subchronically, the decrease in PPI of PS amplitudes, i.e.disinhibition which was opposite to the direct effect of 1-BP mentioned above, was observed in the hippocampus, and this disinhibition occurred in the dentate gyrus more predominantly than CA1 area. RT-PCR analysis indicated decreased mRNA levels of GABA_A receptor β3 and δ subunits - the components of extrasynaptic GABA_A receptors - in the hippocampus of 1-BP-exposed rats. Moreover, both in vitro and in vivo experiments revealed that 1-BP altered mRNA levels of BDNF, a neurotrophic factor and Bcl-xL, an anti-apoptotic molecule, which was probably due to the inhibition of CREB and NF-κB activation, respectively. These results demonstrate that 1-BP may alter neuronal excitability via different mechanisms, which requires further investigation to be clarified.On the other hand, we examined bromide (Br-) concentrations in the brain obtained from 1-BP-exposed rats, to determine the one compartment model for time-dependent changes of Br- concentrations caused by 1-BP inhalation. In consequence, this model, together with our experimental observations, would describe a risk assessment for the CNS neurotoxicity induced by 1-BP exposure, which also suggests that Br- concentration in the blood and/or urine sample would be a useful chemical-indicator of 1-BP inhalation.