| PrefaceThe deficiency of 5-HT is believed to be involved in the genesis of depression. Currently treatment on depression is mostly aimed at the disturbance of monoamines transmitters. But most of synthetic antidepressants were aimed at one or two neural transmitters and have many adverse effects. So the treatment effects are far from satisfaction.Some foreign studies showed that chronic stress is related to the genesis of depression. The abnormality of biochemistry metabolism in CNS will cause brain lesion when chronic stress is existed. So decreasing the neuron injury and protecting the brain from being damaged should be a new and important treatment target.The present study was aimed to observe the changes of hippocampus in the rats of depression model and study the protective effects of EGb and Venlafaxine on brain injury.Materials1 Subject: Male Wistar rats (n=84) weighing about 180-220 g.2 Experimental reagents: rabbit anti-nNOS, rabbit anti-BDNF, SABC kit, EGb, Venlafaxine.3 Instruments: ultrasound comminuter, centifuger, Meta Morph/ Cool Snapfx/Ax70 image analysis system.MethodsRats were divided into 6 groups. Groups A served as normal control. Group B, C, D, E, F received 21 days chronic stress. Group C,D, E, F were fed with normal food, EGb 40mg/kg, Venlafaxine 15mg/kg and EGb 40mg/kg + Venlafaxine 15mg/kg respectively for 28 days after 21 days chronic stress.Every rat had been observed open-field behavior before it was decapitated. One side of the brain was removed the hippocampus, then weighted and homogenized the tissue and stored them at -70 , the other side was stored at 4% formaldehydum polymerisatum. Meanwhile, the serum was stored at -70.Immunohistochemistry method was used to measure the expression of nNOS and BDNF in hippocampus.One-way ANOVA tested group differences for all datum.ResultsOpen field measures showed that stopping time in the centre of group B increased compared with group A(P<0.01). Stopping time was significant between group F and group C,D(P <0.01~0.05). Ambulations, rearings and groomings were significant between group B and group A(P <0.01). Group F increased ambulation, rearing and grooming compared with group C(P <0.01). Defecation of group B was significant increased (P<0.01).The average grey value of nNOS positive cells in hippocampus of group B was decreased compared with group A (P <0.01). The average grey values of nNOS positive cells were significant between group C and group D, F respectively^<0.01). The average grey valueof BDNF positive cells in hippocampus of group B was increased compared with group A (P <0.01). The area percentage of BDNF positive cells in group B2 was decreased significantly (P <0.05). The average grey values of BDNF positive cells were significant between group C and group E, F respectively(P<0.01).The concentrations of NO in serum and hippocampus were significant increased in group B (P <0.05). Comparing with NO of group C, NO in hippocampus of group D2, F and in serum of group F were decreased significantly(P<0.05).DiscussionAcute stress will increase the rodent activities while chronic stress will decrease their activities. In our study, the rats endured chronic and comprehensive stress showed decreasing activities, which indicated the rats of depression model were successful.Group C, D, E, F had changed their open field behavior after they were treated with different ways. Group F's behavior had changed a lot compared with group C. They showed increased exploring, grooming and reduced defecation and freezing. This indicated that EGb and Venlafaxine would ameliorate the behaviors of rats of depression model obviously.Nitric oxide is an unstable gas that functions as a neuron-transmitter in the brain. Nitric oxide is formed from L-arginine by the Ca2+/calmodulin-dependent enzyme nitric oxide synthase (NOS). There are 3 types NOS in CNS: nNOS, iNOS, eNOS. The NO formed from iNOS and nNOS has toxic effects while the NO formed from eNOS has protected eff... |
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