.2 - (¦¡-hydroxy-pentyl) Benzoic Acid, The Antidepressant Effect Of The Potassium Salt, And The Bouguer Furan Anxiolytic And Depression Electrophysiological Mechanism

PartⅠ Antidepressant-like effects of potassium2-(1-hydroxypentyl)-benzotate(PHPB) in depression-like animal modelsMajor depressive disorder (MDD) is one of the most important mental diseases, characterized by high incidence and suicidal tendency, and brins great economic and spirit burden to our society. The pathogenesis of MDD is very complex and still unclear. Recent studies indicate that there is a close relationship between potassium channels especially two pore domain potassium and MDD, and potassium channel may through regulate the excitability of neurons to participate the pathogenesis of MDD. Studies demonstrated that TREK-1channels might be a new drug targets for antidepressant treatments in the future.Potassium2-(1-hydroxypentyl)-benzotate(dl-PHPB), which structure is derived from3-n-butylphathlide (NBP), is a completely novel compound independently designed by Institute of Material, Chinese Academy of Medical Sciences. Previous studies in our laboratory have show that TREK-1currents can be significantly blocked by L-NBP, the main active ingredient of PHPB. Based on previous studies, we first investigate the antidepressant effect and mechanisms of PHPB on force swim test (FST), tail suspension test (TST) and chronic mild stress (CMS) depression animal models. Relationships between potassium channels (such as TREK-1) and MDD were also investigated.FST and TST are widely used as a screening method for antidepressant activity. Our results showed that, immobility time was significantly reduced by acute treatment with PHPB both in FST and TST, and the antidepressant behavior was similar to that observed in fluoxetine treated group. Antidepressant behavior of Sub-chronic (5day) and chronic (12day) treatment with PHPB were also observed in FST. We alos test the antidepressant effect of L-NBP, which is the Prototype of PHPB, on FST. Immobility time was significantly reduced by L-NBP. In the end, we investigate the possible contribution of the serotonergic system in the antidepressant-like effect of PHPB in mice. The results showed that the anti-immobility effect of PHPB in the forced swim test and tail suspension test was not completely abolished by pre-treating the mice with pCPA (an inhibitor of5-HT synthesis). The results indicate that the anti-immobility effect of PHPB may not mainly dependent on serotonergic system.CMS, originally developed by Willner et al, is one of the best validated rodent models to study depression in animals, for its good etiological, face and predictive validity. It is also the animal depression model for analyzing cellular and molecular mechanisms underlying the pathophysiology of depression. In the present study, it has been shown that the CMS procedure induced depression-like symptoms in rats, including: decrease of sucrose consumption, reduction of the locomotor activity and drop of the body weight, and chronic treatment with PHPB(50and100mg/kg) effectively reversed CMS-induced aforementioned changes.It is believed that monoamine neurotransmitters (NE, DA and5-HT) and their metabolites in the central nervous system involved in the pathogenesis and were the main biochemical cause of depression. After21-day CMS, using HPLC-ECD analysis, our data demonstrated an elaborate monoaminergic profile with chronic PHPB treatment. The stress induced significant decrease of5-HT and NE level in the hippocampus and prefrontal cortex. PHPB administration regulated these changes to normal level in both prefrontal cortex and hippocampus.In order to further investigate the relationship between potassium channels and MDD, differential expressions of potassium channel subunit in CMS rats were observed. Our results indicated that the expression of TREK-1and Kv2.1were significantly increased in the prefrontal cortex but not changed in hippocampus by CMS procedure. TREK-1and Kv2.1was significantly down regulated after21-days treatment with fluoxetine and PHPB respectively in the prefrontal cortex. The expression of Kv4.2channel was significantly decreased both in the frontal cortex and hippocampus of depression rats, but Kv3.1channel was just significantly decreased in hippocampus and not changed in the prefrontal cortex. However, both Kv4.2and Kv3.1channels expression in CMS rats were not affected by chronic treatment with PHPB and fluoxetine. Inaddition, the expression of5HTla receptor was significantly decreased in the frontal cortex by PHPB or Fluoxetine treatment, but PKA-c expression was not changed both in the frontal cortex and hippocampus of depression rats.In conclusion, our results demonstrated that PHPB exerts antidepressant-like effects in two highly specific and predictive animal models of depression. The activity of PHPB in antidepression may be mediated partly through increase the monoamine neurotransmitter concentration and enhancing the excitability of neurons by down-regulated the function of TREK-1and Kv2.1channel in the prefrontal cortex. The relationship between TREK-1and MDD was also futher confirmed in our research, and supply the new evidence for the TREK-1channel as a new drug targets for antidepressant treatments in the future. Part Ⅱ The electrophysiology mechanisms of Anxiolytic and antidepressant effects of4-butyl-alpha-agarofuran(AF-5)4-Butyl-a-agarofuran (AF-5), one of the a-agarofuran derivatives from the Chinese traditional medicine Gharu-wood (Aquillaria agallocha Roxb.), is a completely new compound synthesized in our institute. In preclinical pharmacological research, AF-5has shown specific and significant antianxiety activity in several animal models. However, its mechanisms of action have not been elucidated yet. Given the important role of voltage-dependent sodium and potassium channels in the regulation of neuron excitability and emotional function, the aim of our study is to study the effects of AF-5on voltage-dependent potassium channel, voltage-dependent calcium channel and other depression and anxiolytic related channels in neurons.Patch clamp-recording was used to test the effects of AF-5on voltage-dependent potassium channel, voltage-dependent calcium channel and GABA related Cl-currents in primary cultured rat cortical neurons, and Kv2.1, Kv1.5, TREK-1currents in HEK293,LTK,and CHO cells.Our results showed that (1)Ik(DR) currents both in the primary cultures of cortex and hippocampal neurons was significantly inhibited by AF-5with the IC50of6.17μM and10.7μM respectively, but Ik(A)was not largely affected at that concentration.(2)IL-Ca currents both in the primary cultures of cortex and hippocampal neurons were significantly inhibited by AF-5with the IC50of4.41μM and1.29μM respectively. AF-5can also delay the activation and accelerate the inactivation of the IL-Ca both in the primary cultures of cortex and hippocampal neurons.(3) The currents of Kv2.1were also largely blocked by AF-5with the IC50of5.27μM, but Kv1.5and TREK-1currents were not significantly affected by AF-5at the concentration of10μM.(4)INa and IGABA(Cl-) both in the primary cultures of cortex and hippocampal neurons were not affected by AF-5at the concentration of10μM.In conclusion, our results demonstrated that The anxiolytic and antidepression effect of AF-5may through enhancing the excitability of neurons by block the Kv2.1and affect the monoamine neurotransmitter release by inhibit IL-ca currents in neurons, but the precise mechanisms still need further research.