AC－cAMP－PKA途径对淋巴细胞DNA合成的调节作用

以ＣＤ３ＭｃＡｂ为激动剂，以淋巴细胞体外ＤＮＡ合成为研究手段，探讨了ＡＣ－ｃＡＭＰ－ＰＫＡ信号途径在ＣＤ３ＭｃＡｂ诱导的淋巴细胞活化中的意义。研究结果表明ＡＣ、ｃＡＭＰ和ＰＫＡ在决定细胞对外界刺激的反应中起着重要作用。在淋巴细胞活化早期细胞内ｃＡＭＰ出现一过性升高，随着细胞活化增殖，ｃＡＭＰ降至正常水平以下。活化ＡＣ、升高细胞内ｃＡＭＰ水平可显著降低ＣＤ３ＭｃＡｂ诱导的淋巴细胞ＤＮＡ合成，而ＰＫＩ却能在一定程度上促进淋巴细胞活化增殖。     

Adenosine suppresses protein kinase A- and C-induced enhancement of glutamate release in the hippocampus

Cultured hippocampal neurons from neonatal rats were used to investigate the effect of adenosine on the release of glutamate. Spontaneous tetrodotoxin-resistant miniature excitatory postsynaptic currents (mEPSCs) through AMPA receptor channels were recorded by means of the whole-cell patch-clamp technique. Adenosine (50 microM) reversibly reduced the frequency of mEPSCs by approximately 50-60%, but did not change their amplitudes. The protein kinase A inhibitor Rp-cyclic adenosine monophosphate (100-150 microM) did not block the adenosine-dependent reduction of the mEPSC frequency, showing that adenosine is not depressing synaptic transmission via a protein kinase A (PKA)-dependent mechanism. The D1 dopamine agonist SKF-38393 (250 microM), forskolin (5 microM) and 8Br-cAMP (2 mM), known to activate the cAMP/PKA-dependent signalling pathway, all enhanced the mEPSC frequency. A subsequent application of adenosine (50 microM) strongly reduced the potentiation produced by any one of these three drugs. It also reversed protein kinase C (PKC)-dependent stimulation of glutamate release induced by phorbol myristate acetate (100 nM). Taken together, adenosine not only inhibits the spontaneous release of glutamate independently of protein kinases A and C but also reverses the enhancement of exocytosis produced by protein kinases A and C activators.     

Abnormalities of cAMP signaling in affective disorders: implication for pathophysiology and treatment

Objective: During the last decade, much attention has been given to the role of signal transduction pathways in affective disorders. This review describes the possible role of the cAMP signaling in such disorders.

Methods: Among the components of cAMP signaling, this review focuses on the cAMP-dependent phosphorylation system. We analyzed the basic components of the cAMP-dependent phosphorylation system and the preclinical evidence supporting their involvement in the biochemical action of antidepressants and mood stabilizers. The clinical data available until now, concerning the possible link between the cAMP-dependent phosphorylation system and the pathophysiology of affective disorders, are also reviewed.

Results: The studies herein presented demonstrated that the levels and the activity of cAMP-dependent protein kinase are altered by antidepressants and mood stabilizers. Furthermore, these medications are able to modify the phosphorylation state, as well as the levels of some of the cAMP-dependent protein kinase substrates. More recently, clinical studies have reported abnormalities in the cAMP-dependent phosphorylation system in both peripheral cells and the postmortem brain of patients with affective disorders.

Conclusions: Overall, these studies support an involvement of cAMP signaling in affective disorders. The precise knowledge of the findings has the potential to improve the understanding of pharmacotherapy and to provide directions for the development of novel biochemical and genetic research strategies on the pathogenesis of affective disorders.     

Targeting whole body metabolism and mitochondrial bioenergetics in the drug development for Alzheimer's disease

Aging is by far the most prominent risk factor for Alzheimer's disease (AD), and both aging and AD are associated with apparent metabolic alterations. As developing effective therapeutic interventions to treat AD is clearly in urgent need, the impact of modulating whole-body and intracellular metabolism in preclinical models and in human patients, on disease pathogenesis, have been explored. There is also an increasing awareness of differential risk and potential targeting strategies related to biological sex, microbiome, and circadian regulation. As a major part of intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been considered for AD therapeutic interventions. This review summarizes and highlights these efforts.     

特立帕肽通过cAMP/PKA/CREB信号通路调控高糖微环境下的成骨细胞分化

目的 探讨特立帕肽对高糖微环境下小鼠胚胎成骨细胞（MC3T3-E1）分化的影响及作用机制。方法 将MC3T3-E1细胞分为正常糖组（NG,5.5 mmol/L葡萄糖）、NG+特立帕肽组（5.5 mmol/L葡萄糖+10 nmol/L特立帕肽）、高糖组（HG,25 mmol/L葡萄糖）、HG+特立帕肽组（25 mmol/L葡萄糖+10 nmol/L特立帕肽）和HG+特立帕肽+PKA抑制剂组（25 mmol/L葡萄糖+10 nmol/L特立帕肽+20μmol/L H-89）。CCK-8法检测细胞增殖;ELISA实验检测各组cAMP水平;试剂盒检测碱性磷酸酶（ALP）活性;茜素红染色检测细胞矿化结节生成情况;鬼笔环肽染色后观察细胞骨架;Real-time PCR检测细胞中PKA、CREB、RUNX2和Osx的mRNA表达水平。结果 各组细胞增殖能力差异无统计学意义（P>0.05）。与NG组相比,NG+特立帕肽组细胞cAMP水平升高（P<0.05）,ALP活性增强（P<0.05）,茜素红矿化结节生成能力增强（P<0.05）,细胞骨架清晰程度有所提升,PKA、CREB、R...     

In vitro ex vivo assessment of Morinda citrifolia on drug metabolizing enzymes in spontaneously hypertensive rats

Morinda citrifolia Linn. (Rubiaceae), common name noni, has been used as a herbal medicine for over 2000 years. The consumption of noni, and especially the fruit, stresses the importance, urgency, and possibility of the examination of drug interaction when concomitantly administered with a drug. The objectives of this study were to determine the effects of noni juice (NJ) on aminopyrine N-demethylase (APND), uridine diphosphoglucuronosyl-transferase (UGT), and cytosolic glutathione S-transferase (GST) drug metabolizing enzymes and the molecular mechanism elucidation of NJ on APND using different inhibitors and stimulators. The in vitro results for APND showed that different concentrations of NJ significantly increased the activity in isolated hepatocytes at 1.0?ng/mL, 10?ng/mL, 10?μg/mL, 20?μg/mL, 50?μg/mL, and 100?μg/mL. The ex vivo results demonstrated that NJ (210?mg/kg) produced a statistically significant increase in APND activity following 1 day of NJ treatment. The results for UGT and GST showed a decrease in the activity of UGT at a dose of 21?mg/kg following 1 day of treatment, and at 2.1 and 21?mg/kg following 14 days of treatment. GST enzyme demonstrated an increase in activity by 100% for all doses following 1 day of treatment. Molecular mechanism elucidation of the ex vivo effect of NJ on phase I APND showed that KT5720 significantly reduced the activity as compared to control. A change in activity of APND, UGT, and GST following 1 day and 14 days of treatment suggests that all three metabolic pathways may play a role in herb–drug interaction by modulation of metabolic enzymes.     

Cocaine facilitates protein synthesis-dependent LTP: The role of metabotropic glutamate receptors

Cocaine addiction alters synaptic plasticity in many brain areas involved in learning and memory processes, including the hippocampus. Long-term potentiation (LTP) is one of the best studied examples of hippocampal synaptic plasticity and it is considered as one of the molecular basis of learning and memory. We previously demonstrated that in the presence of cocaine, a long lasting form of hippocampal LTP is induced by a single pulse of high frequency stimulation, which in normal conditions evokes only an early form of LTP. In this study, we further explore the molecular basis of this modulation of synaptic plasticity by cocaine. By performing pharmacological experiments on hippocampal slices, we were able to show that cocaine converts early LTP to a form of LTP dependent on protein synthesis, probably through the cAMP-dependent protein kinase and extracellular signal-regulated kinase signaling cascades. We also found that metabotropic glutamate receptors are involved in this phenomenon. These studies further clarify the molecular machinery used by cocaine to alter synaptic plasticity and modulate learning and memory processes.     

Hypothalamic insulin and glucagon-like peptide-1 levels in an animal model of depression and their effect on corticotropin-releasing hormone promoter gene activity in a hypothalamic cell line

Background

In depression, excessive glucocorticoid action may cause maladaptive brain changes, including in the pathways controlling energy metabolism. Insulin and glucagon-like peptide-1 (GLP-1), besides regulation of glucose homeostasis, also possess neurotrophic properties. Current study was aimed at investigating the influence of prenatal stress (PS) on insulin, GLP-1 and their receptor (IR and GLP-1R) levels in the hypothalamus. GLP-1 and GLP-1R were assayed also in the hippocampus and frontal cortex – brain regions mainly affected in depression. The second objective was to determine the influence of exendin-4 and insulin on CRH promoter gene activity in in vitro conditions.

The novel distribution of phosphodiesterase-4 subtypes within the rat retina

Phosphodiesterases (PDEs) are important regulators of signal transduction processes. While much is known about the function of cyclic GMP-specific PDEs in the retina, much less is known about the closely related, cyclic AMP-specific PDEs. The purpose of the present study is to characterize and localize PDE4 within the adult rat retina. We have used Western blotting, RT-PCR, and immunohistochemistry together with retrograde labeling to determine the presence and location of each PDE4 subtype. Western blot analysis revealed that multiple isoforms of PDE4A, B, and D subtypes are present within the retina, whereas the PDE4C subtype was absent. These data were confirmed by RT-PCR. Using immunohistochemistry we show that all three PDE4s are abundantly expressed within the retina where they all colocalize with retrograde-labeled retinal ganglion cells, as well as bipolar cells, horizontal cells, and cholinergic amacrine cells, whereas Müller cells lack PDE4 expression. Uniquely, PDE4B was expressed by the inner and outer segments of rod photoreceptors as well as their terminals within the outer plexiform layer. Collectively, our results demonstrate that PDE4s are abundantly expressed throughout the rodent retina and this study provides the framework for further functional studies.