Studies On Mechanism Of Herbs Of Regulating "Liver" Therapy' Resistance To The Injury Of Hippocampus Caused By Psychological Stress

Part One Theory Studies1. The chronic psychological stress and injury of hippocampus neurons The hippocampus contains many messenger receptors, especially the high-densitical corticosteroid receptors (CR). The density is higher than other encephalic regions. In the reaction of stress, the hippocampus is not only the accommodation centers of superior position of the hypothalamic-pituitary-adrenal (HPA) axis, but also the most sensorial area to stress-impaired.Studies found that the acute stress has no distinctive impact to the construction of hippocampus. But under the station of chronic stress, the neurons of hippocampus would be atrophy even to death. The concrete mechanism is still unknown, but maybe the neural pathway of HPA- glutamic acid (Glu)- N-methyl-D-aspartic acid receptors (NMDAR) -Ca²⁺- nitrogen monoxidum (NO)- cyclic guanosine monophosphate (cGMP) has played a significant role in the station. Under the physiological condition, the pathway can exert a sere of biological effect on maintaining the excitable transmit between neurons and the excitability of neurons and brain.Under the pathological station, the chronic stress can cause the hyperactivity of HPA axis and heighten the concentration of plasma GC, then the GC can make the release of Glu too much, the Glu can combine with the NMDARon the postsynaptic membrane and evoke the long-lasting depolarization of neurons and lead to the change of ionic osmotic pressure and chemical modification, Ca2+ inflow through the calcium channel or channels bind with NMDAR which increase the contents of Ca2+ in the cells. Ca2* and calmodulin (CaM) can activate the NOS in the endochylema which can catalyze the form of NO. On the one hand, NO can suppress the intake of Glu through the metabolic product 0N00" which can promote the release of Glu, on the other hand, NO can combine with Fe2+ which is the active center of guanylate cyclase by extending to the presynaptic membrane as flyback messenger, and change the stereo-configuration of the enzymes, lead to the enhancement of enzyme activity and synthesis of cGMP, which can promote the release of Glu too.Brain-derived neurotrophic factor (BDNF) is a main member of neurotrophic factor family;which has important trophic action to the hippocampus and plays an important role to the survival, differentiation, synapse growth and form maintenance of neurons in the development stage and adult stage, and in the learning and memory by participating the formation of LTP and synaptic plasticity. A lot of findings indicate that the down regulation of BDNF can injure the hippocampus and promote the apoptosis in the station of stress. The down regulation of BDNF can increase the toxic effect of excitatory amino acid (EAA) , induce the expression of calcium-binding protein, prevent the inflow the Ca2+, stable the concentration of Ca2+, decrease the synthesis and activity of NMDAR and NMDAR subunit, against cytotoxic effect of NO and Glu and protect the neurons from injury. That' s why we suppose the down regulation of BDNF can injury the hippocampus through the above-mentioned pathway.2. The research meaning and overview of resistant to the damage of hippocampus caused by psychological stressThe injury of hippocampus caused by stress and the hyper function of HPA axis are the stress reactive infernal circle results of neuroendocrine system reaction. The hippocampus is the main ingredient of the limbic system, which participate the regulation of emotion, learning and memory, behavior, immunity and etc. The injury of it can aggravate the neuroendocrine abnormality which exerts an important function to the diseases educed by all kinds of stress and relate closely to many kinds of mental disorders like depression, posttraumatic stress disorder and etc and accelerate the aged process.Although the mechanism of the hippocampus injury deduced by chronic stress is still unknown, but the related study and hippocampus injury resistant to the stress have become the hot spot in the science of the current brain research.Now most of the biosynthesis preparation can only aim directly at one path-link, some of which have difficulties in the synthesis technique, so the application is restrained inevitably. The formula of traditional Chinese medicine have the holo-regulation function, so its manifests favorable prospect of implication and exploitation. Our research team have been studying the regulating "liver" therapy formula- jiaweisinisan (JWSNS) to prevent and cure the injury caused by the chronic stress for a long time, we found that JWSNS have the favorable hol-regulation function on the disorder of the NIM net caused by the stress reactions.Part Two Exper i mentaI Stud i es1. Materials and Methods1.1 HerbsComposition and dosage of JWSNS: Bupleurum Root 15 gx White Peony Root 15 g> Bitter Orange 6 gx Wolfberry Fruit 15 gx Cape jasmine Fruit 5 gx Rehmannia Root 18 gx Concha haliotidis 30 g. The herbs are bought from the medical material company of Guang Zhou and appraised as pure crude herbs by the drug department, The concentration of crude herbs is 1. 69g/ml after being fried and concentrated and preserved in refrigerator at 4 centi-degree after being cooled under the common temperature.1.2 The subgroup and administration of ratsWistar rats, offered by animals' centre in the first army medical university (certification number: 2002-009) , grade SPF, male, 180 - 220g in weight. All rats were divided into 3 groups at random according to the weight: Normal group, without any stimulus;Model group, applied stimulus but no herbs;Adjusting Liver group (hereafter referred to as JWSNS group), offered herbs 1 hour before being stimulated. JWSNS group are given 2ml JWSNS concentration instead of saline to Normal group and Model group before being stimulated. 1. 3 The model of the chronic psychological stressThe model of the chronic psychological stress: electric attack(voltage 30V, electric current intensity 1. 0 mA, 1 stimulus each 1 min and last for10s, 30min), swimming in 4°C water(5min each time), clipping the tail (lmin), food or water deprivation (24h each time), and restraint(6h each time), all ways above were randomly arranged 21 days, one way every day, then psychological stress were copied. 2. Results2.1 Influence of herbs of regulating "liver" therapy on the apoptosis of the hippocampus neurons of rats injured by the chronic psychological stress.We took the model of the chronic psychological stress to study the change of the rats' of hippocampus neurons apoptosis, which revealed the relations between the chronic psychological stress and the apoptosis of the hippocampus neuron. From the result of the research, we find that the chronic psychological stress can deduce the hippocampus neurons apoptosis which maybe one of the mechanisms of the hippocampus injury caused by the chronic psychological stress. For the reasons of the apoptosis, it maybe related to the change of the GC and NO combined with other findings, so we inspected the change of GR mRNA and nNOS of the hippocampus under the station of stress, and find that JWSNS can decrease distinctively the apoptosis, which reveals that maybe JWSNS fulfill the task of preventing and curing the chronic psychological stress by decreasing the apoptosis of hippocampus, so this can provide the basic theoretical reference and new methods to the clinical prevention and treatment of depression.2.2 Influence of herbs of regulating "liver" therapy on the GR mRNA of the hippocampus neurons of rats injured by the chronic psychological stressThe result manifests that, compared with the model group, there are many positive staining neurons in the normal group and JWSNS group, the positive staining is mainly existed in the endochylema of the neurons, a small amount locates in the nucleus and the color is very distinctive. The expression of GR mRNA decrease in model group, the reason is that the long-term chronic psychological stress induces the counteract to the inverse feedback effects of HPA axis, the body can down regulates the GR on th CRH/AVP neurons and creates the tolerance of high levels of GR, the number of GR reduced can make the symbols weaken compared with the GC, which can deduce a further disorder of HPA axis action. JWSNS can increase the expression of the R, which manifests that the herbs of regulating "liver" therapy can exert function on the super position of stress-hippocampus, up regulate the expression of GR mRNA, recovery thefeedback mechanism of HPA axis and prevent the further damage of the construction and function of hippocampus.2.3 Influence of herbs of regulating "liver" therapy on the expression of nNOS of the hippocampus neurons of rats injured by the chronic psychological stressThe result manifests that all the 3 groups have the expression of nNOS on the CA3 zone of hippocampus especially the model group. The normal group has the expression of nNOS indicated that there were still nNOS on the CA3 zone of hippocampus under physiological condition, maybe just for the low-concentration NO providing the guarantees to maintain the excitability of neurons and promoting the forming of LTP. The model group has high-concentration expression of nNOS, which is one reason of the excess of NO caused by the chronic psychological stress. Compared with the model group, JWSNS group can decrease the expression of nNOS, which reveals that herbs of regulating "liver" therapy can depress the expression of nNOS to refrain the pyramidal cell from the damage of NO. Reagan etc also thought that all of the subregion of hippocampus had the expression of nNOS, but only the expression of nNOS on CA3 zone and dore zone neurons had relations with the chronic psychological stress.2.4 Influence of herbs of regulating "liver" therapy on the expression of BDNF and Trk B of the hippocampus neurons of rats injured by the chronic psychological stressAs key mediated factors, CREB and BDNF play core roles in the revival of neurons and regulation of plasticity, which is why we think they are the core-mediators between the chronic psychological stress and depression. The down regulation of BDNF can cause the atrophy of hippocampus neurons even to death. We find that the masculine cells decrease under the station of chronic psypsychological stress, while JWSNS can regulate the disorder. The main positions of function are dentate band and CA3 zone of the hippocampus. The dentate band is one position of which has the function of neurogenesis in adult brain and CA3 zone is the most important injury position of the chronic psychological stress station based on many findings. Above all, herbs of regulating " liver " therapy can protect the neurons from injury and aregeneratory under the station of chronic psychological stress to fulfill the function of preventing and treating the stress damage and depression.Part Three Conclusions1. The main damage of chronic psychological stress to the hippocampus is to cause the neuron apoptosis, the mechanism is related to the neural pathway of HPA-Glu-NMDAR-Ca2+-N0-cGMPThe chronic stress can cause the hyperactivity of HPA axis and heighten the concentration of plasma GC, then the GC can make the release of Glu too much, the Glu can combine with the NMDAR on the postsynaptic membrane and evoke the long-lasting depolarization of neurons and lead to the change of ionic osmotic pressure and chemical modification, Ca2+ inflow through the calcium channel or channels bind with NMDAR which increase the contents of Ca2+ in the cells. Ca2+ and calmodulin (CaM) can activate the NOS in the endochylema which can catalyze the form of NO. On the one hand, NO can suppress the intake of Glu through the metabolic product 0N00" which can promote the release of Glu, on the other hand, the NO can combine with Fe2+ as the active center of guanylate cyclase by extending to the presynaptic membrane as flyback messenger, and change the stereo-configuration of the enzymes, lead to the enhancement of enzyme activity and synthesis of cGMP, which can promote the release of Glu too.2. The counter-injury mechanism of the JWSNS to the chronic psychological stress is mainly related to the neural pathway of HPA-Glu-NMDAR-Ca2+-N0-cGMPJWSNS can effectively depress the excitability of HPA axis caused by the chronic psychological stress, regulate the levels of 5-HT? DA> NE in the plasma and the centre and the amino acids of the hippocampus, decrease the inflow of Ca2+ and expression of nNOS and content of cGMP and up regulate the expression of BDNF and Trk B, through which above to protect the neurons from damage.