The Inhibition Of Chronic Stress To Basolateral Amygdala 5-HT₂ Receptors Long-time Potentation In Rats

Objective In this study the chronic stress animal model was produced by electric foot shock which can not escape. The basolateral amygdala as the point of the research,using the technology of electrophysiology,behavior test and western blot,to clarify the inhibition of chronic stress to basolateral amygdala 5-HT2 receptors long-term potentiation in rats and its mechanism, which could supply such as anxiety, fear, and post-traumatic stress disorder, the amygdala mediated mood emotion anomalies some new treatment ideas.Methods ① Preparation of amygdale slice :Quickly remove the brain tissue to the low temperature oxygen saturation in artificial cerebrospinal fluid after anesthesia in rats, then contain the amygdala portion of the brain into brain slice thickness of 500μm.② To record the field potential: with a dissecting microscope, a bipolar stainless steel stimulating electrodes placed in the basolateral amygdala area, the brain slices placed under the tip surface at about 200μm. Providing the stimulus and recorded on the RM6240 system.③STP / LTP : the application of theta burst stimulation(TBS) to induce LTP, each string is 20 stimulation a short high-frequency pulses, with stimulus intensity conventional stimulation.④ The chronic stress model and behavioral test : rats were administered sequentially 5 days foot shock, electric shock with 0.8m A, the random 15 seconds every 60 seconds, last 40 min.Open field test and Morris water maze were used to test after chronic stress. ⑤The drug intervention : To adding DOI which is the agonist of 5-HT2 A /2C into ACSF and their antagonist ritanserin, respectively.To make it clear about chronic stress to basolateral amygdala 5-HT2 receptors long-time potentation in rats.⑥Western blot: Western blot was used to show the 5-HT2 A, 5-HT2 C,PKC protein expression of normal rats and rats with chronic stress in amygdala.Results ① The effects of DOI could induce LTP and synaptic facilitation significantly in BLA(p <0.05). ②DOI antagonists RS10221 can inhibit DOI facilitatory effect on LTP(p <0.05). ③The chronic stress has a significant effect on motor function and emotions in rats. ④ The 5-HT2 agonist DOI made no significant effect on LTP of chronic stress rats(p> 0.05).⑤Expression of BLA 5-HT2A、5-HT2 C not increased in rats with chronic stress when compared with those in control rats(p> 0.05), but in PKC significant increased(p <0.05).Conclusion Chronic stress can inhibit long-term potentiation in rat basolateral amygdala 5-HT2receptor-mediated and PKC is a key mechanism.This study suggests that 5-HT receptors, PKC may be involved in anxiety, fear and post- traumatic stress disorder,such as the amygdala-mediated abnormal process emotion.