复方柴归方超临界CO_2提取物调控cAMP信号通路的抗抑郁作用机制研究

目的从环磷酸腺苷(c AMP)信号通路角度探讨复方柴归方超临界CO_2提取物的抗抑郁作用机制。方法采用慢性温和不可预知应激(CUMS)程序对大鼠进行造模,以高、中、低剂量复方柴归方超临界CO_2提取物及文拉法辛为干预药物,检测各组大鼠海马组织中c AMP、蛋白激酶A(PKA)、环磷酸腺苷反应原件结合蛋白(CREB)、脑源性神经生长因子(BDNF)水平及其相应m RNA水平。结果与对照组比较,模型组大鼠海马组织中c AMP、PKA、p-CREB、BDNF水平显著下降(P0.05、0.01),复方柴归方干预后,与模型组比较,各剂量组c AMP、PKA、p-CREB、BDNF水平均出现回调(P0.05、0.01);同时,模型组大鼠海马组织中酪氨酸激酶B(TrkB)、PKA、p-CREB、BDNF的m RNA水平显著下降(P0.05、0.01),复方柴归方干预后,与模型组相比,各剂量组Trk B、PKA、p-CREB、BDNF的m RNA水平均出现回调(P0.05、0.01)。结论复方柴归方超临界CO_2提取物可通过调控c AMP-PKA-CREB-BDNF信号通路发挥抗抑郁作用。     

五子衍宗丸对少弱精子症模型大鼠睾丸组织Catsper1蛋白及其mRNA表达影响

目的 通过检测大鼠睾丸组织Catsper1蛋白及其mRNA表达水平,探讨五子衍宗丸治疗少弱精子症的作用机制。方法 将体质量200～220 g的雄性SD大鼠随机分成正常组,模型组,生精胶囊组,五子衍宗丸低剂量、中剂量、高剂量组。采用连续灌服雷公藤多苷8周的方法复制少弱精子症模型,模型复制成功后连续给药4周。采用Western blot法测定Catsper1蛋白含量,采用荧光定量PCR法测定Catsper1 mRNA表达水平,采用酶联免疫吸附试验检测睾丸组织中cAMP含量。结果 生精胶囊和高剂量五子衍宗丸能明显提高模型大鼠睾丸组织中降低的cAMP含量以及升高睾丸组织中降低的Catsper1蛋白及其mRNA表达水平（P<0.05）。结论 促进Catsper1蛋白表达并参与cAMP-Ca2+正反馈可能是五子衍宗丸提高精子质量的机制之一。     

Cerebellar cortical-layer-specific control of neuronal migration by pituitary adenylate cyclase-activating polypeptide

Migration of immature neurons is essential for forming the cortical layers and nuclei. Impairment of migration results in aberrant neuronal cytoarchitecture, which leads to various neurological disorders. Neurons alter the mode, tempo and rate of migration when they translocate through different cortical layers, but little is known about the mechanisms underlying this process. Here we show that endogenous pituitary adenylate cyclase-activating polypeptide (PACAP) has short-term and cortical-layer-specific effects on granule cell migration in the early postnatal mouse cerebellum. Application of exogenous PACAP significantly slowed the migration of isolated granule cells and shortened the leading process in the microexplant cultures of the postnatal day (P)0-3 cerebella. Interestingly, in the cerebellar slices of P10 mice, application of exogenous PACAP significantly inhibited granule cell migration in the external granular layer (EGL) and molecular layer (ML), but failed to alter the movement in the Purkinje cell layer (PCL) and internal granular layer (IGL). In contrast, application of PACAP antagonist accelerated granule cell migration in the PCL, but did not change the movement in the EGL, ML and IGL. Inhibition of the cAMP signaling and the activity of phospholipase C significantly reduced the effects of exogenous PACAP on granule cell migration. The PACAP action on granule cell migration was transient, and lasted for approximately 2 h. The duration of PACAP action on granule cell migration was determined by the desensitization of its receptors and prolonged by inhibiting the protein kinase C. Endogenous PACAP was present sporadically in the bottom of the ML, intensively in the PCL, and throughout the IGL. Collectively, these results indicated that PACAP acts on granule cell migration as "a brake (stop signal) for cell movement." Furthermore, these results suggest that endogenous PACAP slows granule cell migration when the cells enter the PACAP-rich PCL, and 2 h later the desensitization of PACAP receptors allows the cells to accelerate the rate of migration and to actively move within the PACAP-rich IGL. Therefore, endogenous PACAP may provide a cue that regulates granule cell migration in a cerebellar cortical-layer-specific manner.     

Prefrontal cortical network activity: Opposite effects of psychedelic hallucinogens and D1/D5 dopamine receptor activation

The fine-tuning of network activity provides a modulating influence on how information is processed and interpreted in the brain. Here, we use brain slices of rat prefrontal cortex to study how recurrent network activity is affected by neuromodulators known to alter normal cortical function. We previously determined that glutamate spillover and stimulation of extrasynaptic N-methyl-d-aspartic acid (NMDA) receptors are required to support hallucinogen-induced cortical network activity. Since microdialysis studies suggest that psychedelic hallucinogens and dopamine D1/D5 receptor agonists have opposite effects on extracellular glutamate in prefrontal cortex, we hypothesized that these two families of psychoactive drugs would have opposite effects on cortical network activity. We found that network activity can be enhanced by 2,5-dimethoxy-4-iodoamphetamine (DOI) (a psychedelic hallucinogen that is a partial agonist of 5-HT(2A/2C) receptors) and suppressed by the selective D1/D5 agonist SKF 38393. This suppression could be mimicked by direct activation of adenylyl cyclase with forskolin or by addition of a cAMP analog. These findings are consistent with previous work showing that activation of adenylyl cyclase can upregulate neuronal glutamate transporters, thereby decreasing synaptic spillover of glutamate. Consistent with this hypothesis, a low concentration of the glutamate transporter inhibitor threo-beta-benzoylaspartic acid (TBOA) restored electrically-evoked recurrent activity in the presence of a selective D1/D5 agonist, whereas recurrent activity in the presence of a low level of the GABA(A) antagonist bicuculline was not resistant to suppression by the D1/D5 agonist. The tempering of network UP states by D1/D5 receptor activation may have implications for the proposed use of D1/D5 agonists in the treatment of schizophrenia.     

Adenosine A2A receptors and basal ganglia physiology

Adenosine A2A receptors are highly enriched in the basal ganglia system. They are predominantly expressed in enkephalin-expressing GABAergic striatopallidal neurons and therefore are highly relevant to the function of the indirect efferent pathway of the basal ganglia system. In these GABAergic enkephalinergic neurons, the A2A receptor tightly interacts structurally and functionally with the dopamine D2 receptor. Both by forming receptor heteromers and by targeting common intracellular signaling cascades, A2A and D2 receptors exhibit reciprocal antagonistic interactions that are central to the function of the indirect pathway and hence to basal ganglia control of movement, motor learning, motivation and reward. Consequently, this A2A/D2 receptors antagonistic interaction is also central to basal ganglia dysfunction in Parkinson's disease. However, recent evidence demonstrates that, in addition to this post-synaptic site of action, striatal A2A receptors are also expressed and have physiological relevance on pre-synaptic glutamatergic terminals of the cortico-limbic-striatal and thalamo-striatal pathways, where they form heteromeric receptor complexes with adenosine A1 receptors. Therefore, A2A receptors play an important fine-tuning role, boosting the efficiency of glutamatergic information flow in the indirect pathway by exerting control, either pre- and/or post-synaptically, over other key modulators of glutamatergic synapses, including D2 receptors, group I metabotropic mGlu5 glutamate receptors and cannabinoid CB1 receptors, and by triggering the cAMP-protein kinase A signaling cascade.     

Recent discoveries in the genetics of melanoma and their therapeutic implications

The incidence of cutaneous malignant melanoma, tumors arising from melanocytes, has increased markedly over the past few years in many countries. Although early melanoma is curable through surgical excision, the prognosis of advanced melanoma is very poor, this tumor being resistant to current therapies. Thus there is a need for new therapies to improve the treatment of advanced melanoma. This review provides an overview of recent discoveries in the genetics of melanoma which could offer new therapeutic opportunities.     

Effects of chlorogenic acid on carbachol-induced contraction of mouse urinary bladder

Chlorogenic acid (CGA) is a polyphenol found in coffee and medicinal herbs such as Lonicera japonica. In this study, the effect of CGA-induced relaxation on carbachol (CCh)-induced contraction of mouse urinary bladder was investigated. CGA (30–300 μg/ml) inhibited CCh- or U46619-induced contraction in a concentration-dependent manner. SQ22536 (adenylyl cyclase inhibitor) recovered CGA-induced relaxation of CCh-induced contraction; however, ODQ (guanylyl cyclase inhibitor) did not have the same effect. In addition, 3-isobutyl-1-methylxanthine (IBMX) enhanced CGA-induced relaxation; however, forskolin or sodium nitroprusside did not have the same effect. Moreover, Ro 20–1724, a selective phosphodiesterase (PDE) 4 inhibitor, enhanced CGA-induced relaxation, but vardenafil, a selective PDE5 inhibitor, did not have the same effect. In the presence of CCh, CGA increased cyclic adenosine monophosphate (cAMP) level, whereas SQ22536 inhibited the increase of cAMP levels. Moreover, higher cAMP levels were obtained with CGA plus IBMX treatment than the total cAMP levels obtained with separate CGA and IBMX treatments. In conclusion, these results suggest that CGA inhibited CCh-induced contraction of mouse urinary bladder by partly increasing cAMP levels via adenylyl cyclase activation.