| Depression is high incidence, high suicide, high recurrence and disability, however the Depression recognition, diagnosis and treatment need to improve. It has become a serious public health problem and social problem in the world. Modern treatment of depression is commonly use the drugs such as selective NE reuptake inhibitors and selective 5- HT reuptake inhibitors(SSRI). Although it is effective in depression, the chemical synthetic drug can appear serious side effects after long-term use. Therefore, the research and development of antidepressant drugs is an urgent need to find new targets.The translocator protein(18 k Da)(TSPO) is a five transmembrane domain protein. TSPO mainly exist in the glial cells in the brain, and after the ligand binding can promote cholesterol transport into the mitochondrial membrane, so as to promote the synthesis of neurosteroid. neurosteroid plays an important role in human emotions and stress adjustment, in the treatment of mental system diseases such as depression, anxiety, show the potential application value. TSPO specificity ligand AC- 5216 is developed by Japan’s Sankyo, which is currently in phase Ⅱ clinical stage. It has antidepressant and anxiolytic effect on the animal models, and has no side effects,such as sedative, myorelaxant and cognitive impairment, withdrawal and tolerance. However, AC-5216 is unsoluble, so the bioavailability is limited. Therefore, Beijing Institute of Pharmacology and Toxicology synthesis its derivative YL-IPA08, which has higher affinity and selectivity to TSPO and has anxiolytic and antidepressant effect in forced swimming and tail suspension model. Meanwhile it has no muscle relaxant, sedation and cognitive damage. The compound has high bioavailability(78%), with the prototype into the brain. Therefore, YL-IPA08 has a good future for being a medicine. However, antidepressant effects of YL-IPA08 remains to be fully evaluated, and its antidepressant mechanism remains to be explored deeply, which can provide a scientific and theoretical basis for being a new antidepressants with intellectual property rights.Based on clinical effectiveness of traditional Chinese medicine, screening active ingredients from traditional Chinese medicine is an important direction and approach for development of new antidepressant drugs in China. Albiflorin, a monoterpene glycoside, is a main component of Radix paeoniae Alba, which is a Chinese herbal medicine often used in the treatment of depression-like disorders. Radix paeoniae Alba, commonly known as the peony, is the Ranunculaceae peony root of Paeonia lactiflora Pall, which is often used in Chinese herbal formulas, including Sini-San and Xiaoyao-San, for the treatment of depression-like disorders. Among these components, the monoterpene glycosides extracts, such as paeoniflorin and albiflorin, are usually described as the most important active components of the peony. Reports have shown that paeoniflorin has antidepressant effects in rats and mice. However, the antidepressant effect of albiflorin, the other important component of the monoterpene glycosides extract, has not been reported.We studied the antidepressant effects and mechanisms of TSPO ligand YL-IPA08 and albiflorin. Our study includes two parts: 1. Antidepressant effects of novel 18 k D protein translocation(TSPO) ligand YL-IPA08 and its echanisms; 2. Antidepressant effects of albiflorin and its mechanisms.Part One Antidepressant effects and mechanisms of novel 18 k D protein translocation(TSPO) ligand YL-IPA08The cause of depression is complex, which is relevant to genetics, biochemistry, social, psychological, cultural and other factors. The pathogenesis of depression is relatively complex, the study shows that it may be related to the brain monoamine neural function imbalance, HPA axis excessive activation, low brain derived neurotrophic factor(BDNF) and other factors. So clinical antidepressants are mostly act by adjusting the brain monoamine neural function, inhibiting HPA axis and increase the expression of BDNF. The influence of the expression of BDNF can be regulated from different signal transduction pathways, mainly including c AMP, MAPK and Ca MK pathways. Activating these pathways can increase the expression of CREB, which can regulate the expression of BDNF. BDNF can affect the neuron survival, regeneration and neurons plasticity to play the role of antidepressants. The study is to explore the antidepressant effec of YL- IPA08 on the classic depression model- chronic unpredictable stress rat model in this part. And then, to study its mechanism on TSPO targets. Meanwhile, we also deteted its effect of HPA axis and c AMP pathways. The experiment mainly includes the following aspects:1. The effects of YL-IPA08 repeated treatment on behaviors of chronic unpredictable stress(CUS) ratsWe divided the rats into six parallel groups according to the sucrose preference(SP) baseline data: control(no stressor), stress-control, stress-AC-5216 and YL-IPA08(0.1, 0.3 and 1.0 mg/kg, i.g.). Rats were subjected to chronic unpredictable stress(CUS) for five weeks. AC-5216 and YL-IPA08 were administrated by oral per day for 35 days. Then the sucrose preference(d 35), open-field(d 37), novelty-suppressed feeding(d 39) and elevated plus maze(d 41) were tested. The five-week stress procedure caused a significant decrease in sucrose preference, number of crossings and rearings, entries and time spent into open arm, and caused significant increase of latency of feeding in the stress-control rats compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group, indicating YL-IPA08 has significant antidepressant effects.2. The antidepressant mechanisms of YL-IPA08After the behavior tests, following decapitation blood were cellected and then bilateral hippocampi and prefrontal cortex of rats were rapidly removed. Part of each group rats were perfused for immunofluorescence test, some whole brains is taken out to golgi experiments.We detected the expression of TSPO, p-CREB and BDNF in hippocampus via Western Blot to explore the relationship between the behavior effect of YL-IPA08 and the expression of TSPO, p-CREB and BDNF. We detected the levels of progesterone, allopregnanolone and 5α-reductase in serum, hippocampus and prefrontal cortex via ELISA to explore the relationship between the behavior effect of YL-IPA08 and neurosteroid and its synthase. We detected the levels of adrenocorticotropic hormone and corticosterone in serum via ELISA to explore the relationship between the behavior effect of YL-IPA08 and HPA axis. We detected the level of c AMP in hippocampus and prefrontal cortex via ELISA to explore the relationship between the behavior effect of YL-IPA08 and the level of c AMP. We detected the neurogenesis and the complexity of neural structures via immunofluorescence and golgi staining to explore the relationship between the behavior effect of YL-IPA08 and the neurogenesis and the complexity of neural structures.The five-week stress procedure caused a significant decrease in TSPO, p-CREB and BDNF in hippocampus compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group via Western Blot. The five-week stress procedure caused a significant decrease in progesterone in hippocampus and prefrontal cortex and increase in serum in the stress-control rats compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group; The five-week stress procedure caused a significant decrease in allopregnanolone in serum, hippocampus and prefrontal cortex in the stress-control rats compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group. The five-week stress procedure caused a significant increase in adrenocorticotropic hormone and corticosterone in serum compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group via ELISA. The five-week stress procedure caused a significant decrease in c AMP in hippocampus and prefrontal cortex compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group via ELISA.The five-week stress procedure caused a significant decrease in the total Brd U-positive cells, total dendritic length and total number of dendritic branching points in hippocampus compared with the control non-stressed rats, administration of AC-5216 and YL-IPA08 restored them to normal levels compared to the CUS group via immunofluorescence and golgi staining.The results suggested that YL-IPA08 have antidepressan effects in animal model of chronic unpredictable stress. The mechanism may be as follows: 1. Promoting the synthesis of neurosteroid by binding TSPO. 2. Suppressing activity of hypothalamus-pituitary-adrenal cortex(HPA) axis. 3. Enhancing c AMP-CREB-BDNF pathway. 4. Enhancing neurogenesis and plasticity.Part Two Antidepressant effects and mechanisms of albiflorinPreclinical and clinical lines of evidence suggest that disturbed monoaminergic neurotransmission is one of most important mechanisms underlying the pathophysiology of depression. The monoamine hypothesis has demonstrated that serotonin(5-HT), noradrenaline(NE) and dopamine(DA) are the important neurotransmitters involved in the etiology of depression. Indeed, most of the current antidepressants act on one or more mechanisms compatible with the monoamine hypothesis, such as inhibition of the reuptake of 5-HT and/ or NA. Brain-derived neurotrophic factor(BDNF), a type of nerve growth factor, is predominantly expressed in the central nervous system and related to the survival and maintenance of neuronal function. Elevating the expression of BDNF plays a crucial role in the treatment of depression. Based on this theory, firstly we chose two classic animal behavior despair tests, the forced swimming test(FST) and tail suspension test(TST), to evaluate the antidepressant-like activity of albiflorin in mice. We then used a chronic unpredictable stress model to further evaluate the antidepressant-like effects of albiflorin, and the hippocampal monoamine levels and BDNF expression were also measured. The experiment mainly includes the following aspects:1. The effects of albiflorin on depression models of mice and ratsMice were randomly divided into five groups: control, fluoxetine and albiflorin(3.5, 7.0 and 14.0 mg/kg, i.g.) for the forced swimming test(FST), tail suspension test(TST) and locomotor test after 7 days administration of albiflorin. Subchronic treatment with fluoxetine and albiflorin significantly decreased the immobility time in the FST and TST without affecting locomotor activity.We divided the rats into six parallel groups according to the sucrose preference(SP) baseline data: control(no stressor), stress-control, stress- fluoxetine and albiflorin(3.5, 7.0 and 14.0 mg/kg, i.g.). Rats were subjected to chronic unpredictable stress(CUS) for five weeks. Fluoxetine and albiflorin were administrated by oral per day. The sucrose preference, open-field were tested. The five-week stress procedure caused a significant decrease in sucrose preference, number of crossings and rearings in the stress-control rats compared with the control non-stressed rats, administration of fluoxetine and albiflorin restored them to normal levels compared to the CUS group.2. The antidepressant mechanisms of albiflorinWe detected the expression of BDNF in hippocampus via Western Blot in mice and rats to to explore the relationship between the behavior effect of albiflorin and the expression of BDNF. We detected the levels of DA,DOPAC,5-HT,5-HIAA,AD,HVA and NE in hippocampus via HPLC to explore the relationship between the behavior effect of albiflorin and the levels of monoamine neurotransmitter.After 7 d of subchronic treatment fluoxetine and albiflorin significantly increased the hippocampal BDNF expression compared to the control group. In the CUS protocol, hippocampal BDNF levels were decreased in the hippocampus of stress-control rats while albiflorin or fluoxetine restored the BDNF expression to normal levels.The five-week stress procedure caused a significant decrease in 5-HT, 5-HIAA and NA levels in the stress-control rats compared with the control non-stressed rats. The 5-HT, 5-HIAA and NA levels were increased after albiflorin treatment. Fluoxetine also induced elevations in 5-HT, 5-HIAA and NA levels.The results suggested that albiflorin displayed an antidepressant-like effect in mice and rats, and this effect may be partially mediated by regulating the central monoamine neurotransmitter system and increasing the levels of BDNF. |
PDF Full Text Request