The influence of restraint water-immersion stress on firing activities of pyramidal neurons in the medial prefrontal cortex in rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To explore the effects of restraint water-immersion stress (RWIS) on the firing activities of pyramidal neurons in the medial prefrontal cortex (MPFC) of rats.Methods Multi-channel in vivo recording techniques were used to record firing activities of pyramidal neurons before and during 4-h RWIS in rats.Firing rates,inter-spike intervals and burst firing rates were taken as indices to study the influence of RWIS on neuronal firing activities.Results Twenty-five pyramidal neurons of 12 rats were recorded.The opposite patterns of firing activities were observed in two different classes of neurons,type A and type B neurons which account for 72％ and 28％,respectively.In type A neurons,inhibited firing activities were in direct proportion to the stress-exposure.Mean firing rates and mean burst firing rates were significantly reduced to (0.81 ± 0.11) Hz and (1.012 ± 0.50) counts/min after 4h constant RWIS compared with those before RWIS,(3.57 ± 0.63) Hz and (10.29 ± 3.04) counts/min.However,in type B neurons,firing activities were enhanced.After 2h constant RWIS,mean firing rates and mean burst firing rates were increased from (1.77±0.45) Hz and (2.01±0.73) counts/min to (2.67±0.74)Hz and (9.04±2.42) counts/min,respectively.Moreover,the percentage of spikes in bursts was significantly increased and mean inter-spike intervals were remarkably shortened.Interestingly,the effect of RWIS on type B neurons lasted for shorter time compared with its effect on type A neurons.Conclusion RWIS differentially affects the firing activity of pyramidal neuron in the MPFC,i.e.,inhibiting the firing activity of type A neurons,but enhancing the firing activity of type B neurons.