| 其他摘要 | Part 1. Mechanism study on the anti-stress-like and anti-depressant-like effects of KMBZ-009. Although the acute response to stress (e.g., heightened cognition) is an adaptive mechanism, excessive stress, in particular uncontrollable stress induces many psychological and physiological problems. Specially, hippocampus- or prefrontal cortex-dependent learning and memory are dramatically impaired by stress. And its mechanism was associated with stress-induced release changes of stress hormone (corticorsterone etc.) and neurotransmitters and deficit of synaptic plasticity (such as LTP and LTD). Many studies have proved that several psychiatric disorders such as depression were related to stress, and the functions of HPA axis and monoamine neurotransmitters system were its underline mechanisms. Previous works of our Lab have proved that KMBZ-009 (a novel compound of pyrrolidone derivatives. It was named phenchlobenpyrrone) changed neurotransmitters release in brain by modulating intracellular Ca2+ concentration, and as a consequence, the higher functions of the brain such as learning and memory were changed by KMBZ-009. However, they are unclear so far whether KMBZ-009 ameliorates stress-induced memory deficit and whether it has anti-depressant-like effect. In the present study, using Morris water maze tasks, operant box paradigm, forced-swim test, patch-clamp in vitro recording and in vivo electrophysiological techniques, we study the effect of KMBZ-009 on acute stress-induced spatial memory deficit and depressive behaviors, as well as its underlining mechanisms. The data showed that acute inescapable stress or a dose of exogenous corticosterone (CORT, 10 mg kg-1) significantly decreased the search times in the target quadrant during retest period. Protective doses of KMBZ-009 (20, 40 mg kg-1), administrated 30 min before acute inescapable stress or CORT injection, abolished memory retrieval deficits seen in untreated rats. Memory is believed to dependent on synaptic plasticity. Here, it was showed that long-term depression (LTD) in the CA1 region of the hippocampus in vivo was facilitated by acute inescapable stress, sub-acute footshock stress and CORT. Pretreatment with KMBZ-009 (10, 20, 40 mg kg-1) inhibited that facilitation. In addition, acute inescapable stress also blocked induction of hippocampal long-term potentiation (LTP), pretreatment with 20 mg kg-1 KMBZ-009 30 min before acute inescapable stress normalized hippocampal LTP induction. Immunoassay results revealed an expected stress-induced CORT increase, and stress-increased CORT level was significantly diminished by KMBZ-009 (10, 20 and 40 mg kg-1) administration. Moreover, KMBZ-009 modulates the functions of AMPARs and GABAARs. The results showed that KMBZ-009 had no effect on NMDARs-mediated EPSCs, but it increased the amplitude of AMPARs-mediated EPSCs without changing of its kinetics at 400μmol L-1 concentration. KMBZ-009 did not change the amplitude of GABAARs-mediated IPSCs, however, the decay time of GABAARs-mediated IPSCs were prolonged by KMBZ-009 at the dose of 100μmol L-1. For GABAARs-mediated miniature IPSCs (mIPSCs), the decay time was also significantly prolonged by KMBZ-009 (100μmol L-1), but it had no effects on the rise time, amplitude and frequency of mIPSCs. The effect of KMBZ-009 on both excitatary and inhibitary currents contributes maintaining normal functions of pyramidal neurons in hippocampus when underdoing stress. Exposure to stress has been linked to the pathophysiology of depression and anxiety disorders. The ameliorating effect of KMBZ-009 on stress suggests that it may be useful in clinical treatment for stress and stress-related psychiatric disorders such as PTSD, depression/anxiety. Data showed that Treatments of animals with KMBZ-009 (5, 10, 20mg kg -1 p.o.) dose-dependent reduced the time of immobility and increased the latency to immobility of mice in FST, without any significant effect on locomotor activity of mice. The dose of 20 mg kg -1 of KMBZ-009 significantly increased the reinforcement rate and decreased the response rate of rats in DRL-72s. DL-propranolol (2 mg kg -1 i.p.; a β-adrenoceptor antagonist) and phentolamine (1 mg kg -1 i.p.; an α-adrenoceptor antagonist) significantly attenuated the KMBZ-009- induced antidepressant-like effect in FST. These data suggests that KMBZ-009 may possess an antidepressant-like effect, mediated by increase of brain norepinephrine. Part 2. KMBZ-009 attenuates oxidative stress-induced deficiency of neuron viability, mitochondria potential and hippocampal long-term potentiation of mice in vitro It is known that the free radicals are involved in neurodegeneration and the cognitive dysfunction, as seen in Alzheimer's disease (AD) and aging. Aniracetam, a compound of pyrrolidone derivatives, was reported to antagonize the ischemia-induced astrocytes degeneration at least in part by reducing the ROS production. Primary cell cultures and electrophysiological technique were used to examine the protective effects of aniracetam or KMBZ-009 against H2O2-induced toxicity to neuron viability, mitochondria potential and hippocampal long-term potentiation (LTP). Data showed that H2O2 exposure impaired the viability of neurons, reduced mitochondria potential and decreased LTP in the CA1 region of hippocampus. These deficient effects were significantly rescued by pre-treatment with aniracetam or KMBZ-009. Part 3. The in vivo synaptic plasticity mechanism of Chinese-Tranditional- Medicin-Fufang- or EGb 761-induced enhancement of spatial learning and memory in aged rats It has not been uniform to date that the Ginkgo biloba extracts enhance cognitive function in aged animals, and the mechanisms of action remain difficult to elucidate. In this study, the Morris water maze task and electrophysiological methods were used to study the effects of repeated daily administration of EGb 761, a standardized extract from G. biloba leaves, or Chinese-Tranditional-Medicin-Fufang (CTMF) on hippocampal-dependent spatial learning and memory and synaptic plasticity of aged rats. It was found that The aged subjects perform the Morris water maze task worse than adult rats, as a cellular mechanism, the hippocampal long-term potentiation (LTP) of aged animals is impaired. In addition, the spatial learning and memory of aged rats that had been fed on an EGb 761- or an CTMF-supplemented diet (60 mg kg-1) for 30 days were significantly better than those of control aged rats. The magnitude of LTP recorded in vivo from the hippocampus CA1 area of aged rats was significantly enhanced by EGb 761 or by CTMF(60 mg kg-1). Part 4. Memory acquisition in one trial step-through test was impaired by tail-hanging stress via dopamine D1 receptors over stimulation in mice Although it is well known that dopamine system is sensitive to stress, and leads to changes in the working memory function that is dependent on prefrontal cortex, it is unclear whether stress via dopamine system impairs emotion memory that is mainly dependent on amygdala and hippocampus. In the current study, the one trial step-through test is adopted to examine the effects of tail-hanging stress on acquisition of emotion memory and the mechanisms of dopamine in mice. The results show that the tail-hanging stress, and a dopamine D1 receptor antagonist SCH23390 significantly impair the memory acquisition, respectively. However, SCH23390 effectively reversed the memory deficit caused by the tail-hanging stress. The present data suggest that the acquisition of emotional memory related to amygdala, hippocampus or associated neural circles was impaired by stress due to the over stimulation of D1 receptors. |
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