Effect of infralimbic area H2S system on fear extinction of rats and its mechanism / 中国药理学通报

ABSTRACT

Dept of Physiology, School of Basic Medical Sciences, Bitehou Medical University, Yantai Shandong 264003, China Aim To explore the behavior and CBS/H2S levels in infralimbic (IL) medial prefrontal cortex (mPFC) in conditioned fear rats and study the effect of exogenous H2S on conditioned fear extinction of rats and the related mechanism. Methods The rat conditioned fear model was established with sound pairing with an aversive foot shock. Later the repeated single sound was used for extinction training. CBS/H2S con-tent in IL tissues was measured using Western blot and methylene blue method. In vivo extracellular single u-nit recordings were used to examine the frequency of spontaneous discharges of IL neurons. Results 1. CBS/H2S level in IL tissues of conditioned fear model (control group) decreased (P <0. 01) and the freezing level was aggravated (P < 0. 01) , while after extinction training CBS/H2 S level increased (P < 0.01, P < 0. 05) and the freezing level was alleviated (P < 0.01). 2. Freezing level decreased in NaHS group compared with extinction group (P <0. 01) . 3. L-cys-teine increased the frequency of spontaneous discharges of IL neurons (P < 0. 01). Conclusions Learning and memory ability decreases in PTSD model rats owing to the inhibition of CBS/H2S content in IL tissues. The mechanism of behavior improvement of H2S on PTSD model rats may be related to the excitation of H2S on frequency of spontaneous discharges of IL neurons.