Sigma-1R Overexpression In The PVN Deteriorated Heart Injury During Cardiopulmonary Bypass By Upregulating Sympathetic Nerve Tone

Objective:To observe the changes of sigma-1R expression in hypothalamus and heart during cardiopulmonary bypass（CPB）.To observe the effect of sigma-1R overexpression in PVN on the heart and brain during CPB through the detection of inflammatory factors,neurotransmitters and cardiac damage.To observe the effect of right stellate ganglion block on heart during CPB in S1R rats.Methods:Part 1 The changes of sigma-1R expression in the hypothalamus and heart during CPBSD rats were divided into Control group and CPB group（n=12）.The rats in Control group received all operations for CPB but did not receive CPB.CPB group continued cardiopulmonary bypass for 110 minutes.ECG and Mean arterial pressure（MAP）were recorded and arterial blood gas analysis during CPB.At the end of the experiment,Standard diviation of NN intervals（SDNN）was calculated,sigma-1R and inflammatory cytokines in the hypothalamus and heart were measured.Cardiac mitochondrial damage was observed by transmission electron microscopy,and cell morphology changes were observed with HE staining in the heart.Part 2 The effect of sigma-1R overexpression in PVN on the heart and brain during CPBVehicle virus or sigma-1R overexpression virus were microinjected in PVN（n=12）.Control virus were randomly divided into 2 groups:Vehicle group and Vehicle+CPB group,Sigma-1R group were randomly divided into 2 groups:S1R group and S1R+CPB group.（1）The effects of virus transfection in PVN on ratsVehicle group and S1R group rats were collected orbital blood,body weight and ECG after virus transfection for 10 days.SDNN was calculated,and the relative expression of sigma-1R m RNA and serum Noradrenaline（NE）were detected after virus transfection for21 days.（2）The effects of sigma-1R overexpression in PVN on CPB ratsIn Vehicle+CPB group and S1R+CPB group,rats were established CPB model after virus transfection for 21 days.SDNN was calculated after the process.Arterial blood,hypothalamus and cardiac tissue were collected after CPB.The following indexes were detected:（1）the concentration of inflammatory cytokines（IL-1β,IL-6,TNF-α,IL-10）,Cardiac troponin T（cTnT）,Angiotensin II（Ang II）and NE in serum with ELISA kits.（2）the concentration of sigma-1R,Dehydroepiandrosterone（DHEA）,inflammatory cytokines,Gamma-aminobutyric acid（GABA）,Glutamic acid（Glu）,Ang II and NE in the hypothalamus.Immunohistochemistry was used to observe the distribution of Tyrosine hydroxylase（TH）and Neuropeptide Y（NPY）.The type 1 angiotensin receptor（AT1R）observed by immunofluorescence.（3）the contents of NE,Ang II,Acetylcholine（Ach）and ATP,the relative expression of Bax and Bcl-2 m RNA in the cardiac tissue.Immunohistochemistry was used to observe the distribution of TH and NPY.The morphological changes of mitochondria and apoptosis Mitochondrial morphology was observed with transmission electron microscopy and the apoptosis rate was calculated by TUNEL staining in cardiac tissue.Part 3 The effect of right stellate ganglion block on the heart during CPB in S1R ratsAccording to the location of anesthetic injection,S1R rats were randomly divided into two groups（n=12）:subcutaneous injection group（S1R+IH group）and right stellate ganglion block（S1R+SGB group）.CPB model were established in both two groups.Arterial blood and cardiac tissue were taken at the end of the experiment.The following indexes were detected:cTnT in serum,NE,Ang II content and apoptosis rate in cardiac tissue.The distribution of TH and NPY were observed with immunohistochemistry.Results:Part 1 The expression of sigma-1R was decreased in the hypothalamus and heart during CPBMAP≥60mm Hg and HCT≥20%were maintained during CPB.There was no difference between CPB group and Control group on cell morphological in the heart.Compared with Control group,the expression of sigma-1R in CPB group were decreased,the mitochondrial injure were aggravated,the m RNA levels of inflammatory cytokines（IL-1β,IL-6,TNF-α,IL-10）were increased in the heart,and SDNN after CPB was significantly lower than that before CPB（P<0.05）.In the hypothalamus,the expression of sigma-1R were decreased,the concentration of DHEA,Ang II and the m RNA level of inflammatory cytokines（IL-1β,IL-6,TNF-α）were significantly increased（P<0.05）.Part 2 Overexpression of sigma-1R in PVN could aggravated inflammation in serum and hypothalamus,increased sympathetic output and cardiac sympathetic tension,aggravated cardiac injury.（1）Sigma-1R was overexpressed in PVN.There was no difference of rats’weight between Vehicle group and S1R group after virus transfection,the same as NE in serum and SDNN（P>0.05）.（2）Compared with Vehicle group and S1R group,the level of inflammatory cytokines（IL-1β,IL-6,TNF-α,IL-10）,NE and Ang II in serum were significantly increased in Vehicle+CPB group and S1R+CPB group.Compared with Vehicle+CPB group,the level of IL-1β,IL-6,TNF-αwere significant increased in S1R+CPB group（P<0.05）.While there were no statistical difference between Vehicle+CPB group and S1R+CPB group on IL-10,NE and Ang II（P>0.05）.（3）In the hypothalamus,compared with Vehicle group and S1R group,the inflammatory cytokines（IL-1β,IL-6,TNF-α）and excitatory neurotransmitter（Ang II,NE,Glu）were increased in Vehicle+CPB group and S1R+CPB group.Compared with Vehicle+CPB group,there were significant increase in S1R+CPB group（P<0.05）,while the inhibitory neurotransmitter GABA increased only in Vehicle+CPB group（P<0.05）.NPY,TH,and AT1R increased in PVN after CPB,and more significantly in the S1R+CPB group（P<0.01）.（4）Compared with Vehicle group and S1R group,cTnT,Bax,Bcl-2,mitochondrial Flameng score,and apoptosis rate in the heart were increased in Vehicle+CPB group and S1R+CPB group.（P<0.05）.Compared with Vehicle+CPB group,the SDNN values after CPB/before CPB(SDNN_a/b)was significantly reduced in S1R+CPB group（P<0.01）.Meanwhile the content of Ang II,NE,Ach and TH,NPY were increased in Vehicle+CPB group and S1R+CPB group compared with Vehicle group and S1R group（P<0.05）.Compared to the Vehicle+CPB group,the increase in the S1R+CPB group was more significant（P<0.01）.Part 3 Right stellate ganglion block decreased the cardiac damage caused by sigma-1R overexpression in PVN during CPBCompared with S1R+IH group,the content of cTnT in serum,apoptosis rate,NE,Ang II,TH and NPY in the heart were significantly decreased in S1R+SGB group（P<0.01）while SDNN_a/bwas increased（P<0.01）.Conclusion:（1）The expression of sigma-1R was decreased in the hypothalamus and heart during CPB.（2）Overexpression of sigma-1R in PVN could aggravated inflammation in serum and hypothalamus,increased sympathetic output and cardiac sympathetic tension and aggravated cardiac injury.（3）Right stellate ganglion block decreased the cardiac damage caused by sigma-1R overexpression in PVN during CPB.