Mitofusin-2 mediates cannabidiol-induced neuroprotection against cerebral ischemia in rats.

Cannabidiol (CBD) reportedly exerts protective effects against many psychiatric disorders and neurodegenerative diseases, but the mechanisms are poorly understood. In this study, we explored the molecular mechanism of CBD against cerebral ischemia. HT-22 cells or primary cortical neurons were subjected to oxygen-glucose deprivation insult followed by reoxygenation (OGD/R). In both HT-22 cells and primary cortical neurons, CBD pretreatment (0.1, 0.3, 1 µM) dose-dependently attenuated OGD/R-induced cell death and mitochondrial dysfunction, ameliorated OGD/R-induced endoplasmic reticulum (ER) stress, and increased the mitofusin-2 (MFN2) protein level in HT-22 cells and primary cortical neurons. Knockdown of MFN2 abolished the protective effects of CBD. CBD pretreatment also suppressed OGD/R-induced binding of Parkin to MFN2 and subsequent ubiquitination of MFN2. Overexpression of Parkin blocked the effects of CBD in reducing MFN2 ubiquitination and reduced cell viability, whereas overexpressing MFN2 abolished Parkin's detrimental effects. In vivo experiments were conducted on male rats subjected to middle cerebral artery occlusion (MCAO) insult, and administration of CBD (2.5, 5 mg · kg-1, i.p.) dose-dependently reduced the infarct volume and ER stress in the brains. Moreover, the level of MFN2 within the ischemic penumbra of rats was increased by CBD treatment, while the binding of Parkin to MFN2 and the ubiquitination of MFN2 was decreased. Finally, short hairpin RNA against MFN2 reversed CBD's protective effects. Together, these results demonstrate that CBD protects brain neurons against cerebral ischemia by reducing MFN2 degradation via disrupting Parkin's binding to MFN2, indicating that MFN2 is a potential target for the treatment of cerebral ischemia.

Roflupram protects against rotenone-induced neurotoxicity and facilitates α-synuclein degradation in Parkinson's disease models.

We have previously shown that roflupram (ROF) protects against MPP+-induced neuronal damage in models of Parkinson's disease (PD). Since impaired degradation of α-synuclein (α-syn) is one of the key factors that lead to PD, here we investigated whether and how ROF affects the degradation of α-syn in rotenone (ROT)-induced PD models in vivo and in vitro. We showed that pretreatment with ROF (10 µM) significantly attenuated cell apoptosis and reduced the level of α-syn in ROT-treated SH-SY5Y cells. Furthermore, ROF significantly enhanced the lysosomal function, as evidenced by the increased levels of mature cathepsin D (CTSD) and lysosomal-associated membrane protein 1 (LAMP1) through increasing NAD+/NADH and the expression of sirtuin 1 (SIRT1). Pretreatment with an SIRT1 inhibitor selisistat (SELI, 10 µM) attenuated the neuroprotection of ROF, ROF-reduced expression of α-syn, and ROF-increased expression levels of LAMP1 and mature CTSD. Moreover, inhibition of CTSD by pepstatin A (20 µM) attenuated ROF-reduced expression of α-syn. In vivo study was conducted in mice exposed to ROT (10 mg·kg-1·d-1, i.g.) for 6 weeks; then, ROT-treated mice received ROF (0.5, 1, or 2 mg·kg-1·d-1; i.g.) for four weeks. ROF significantly ameliorated motor deficits, which was accompanied by increased expression levels of tyrosine hydroxylase, SIRT1, mature CTSD, and LAMP1, and a reduced level of α-syn in the substantia nigra pars compacta. Taken together, these results demonstrate that ROF exerts a neuroprotective action and reduces the α-syn level in PD models. The mechanisms underlying ROF neuroprotective effects appear to be associated with NAD+/SIRT1-dependent activation of lysosomal function.

Chronic unpredictable mild stress induced depression-like behaviours and glutamate-glutamine cycling dysfunctions in both blood and brain of mice.

CONTEXT: Currently, there is no cure or early preclinical diagnostic assay available for depression. Recently, depression has been observed in association with metabolic abnormalities of the glutamate (Glu)-glutamine (Gln) cycling, which is regulated by Glu, Gln and γ-aminobutyric acid (GABA) amino acids. OBJECTIVE: The purpose of this study is to determine the changes of Glu, Gln and GABA in blood and brain of chronic unpredictable mild stress (CUMS) induced mice and to clarify the depression biomarkers in the Glu-Gln cycling. MATERIALS AND METHODS: Male Kunming mice were divided into model group and control group randomly (n = 12). The depression model of mice was established by CUMS stimulation for 56 days. The liquid chromatography-fluorescence method was used for simultaneous determination of Glu, Gln and GABA in the plasma and brain of mice. o-Phthalaldehyde and ß-mercaptoethanol were used as pre-column derivatization reagents. Neurotransmitters were analysed on high performance liquid chromatography (HPLC) on an HPH C18 column in combination with a fluorescence detector. RESULTS: The method was simple, highly sensitive and showed excellent linearity with regression coefficients higher than 0.999, good accuracy (95-108%) and good inter-day precision (RSD <15%) for all analytes. Limit of quantification (LOQ) values were established as 0.01, 0.01 and 0.005 µg/mL for Glu, Gln and GABA. The GABA in the CUMS mouse brain (p < 0.01) was significantly increased and Gln in plasma (p < 0.01) and brain (p < 0.01) were both decreased. CONCLUSIONS: Our study demonstrates that the Gln in plasma can be used as a biological marker of depression.

Novel Phosphodiesterase 4 Inhibitor FCPR03 Alleviates Lipopolysaccharide-Induced Neuroinflammation by Regulation of the cAMP/PKA/CREB Signaling Pathway and NF-κB Inhibition.

Overactivation of microglia contributes to the induction of neuroinflammation, which is highly involved in the pathology of many neurodegenerative diseases. Phosphodiesterase 4 (PDE4) represents a promising therapeutic target for anti-inflammation; however, the dose-limiting side effects, such as nausea and emesis, have impeded their clinic application. FCPR03, a novel selective PDE4 inhibitor synthesized in our laboratory, shows little or no emetic potency; however, the anti-inflammatory activities of FCPR03 in vitro and in vivo and the molecular mechanisms are still not clearly understood. This study was undertaken to delineate the anti-inflammatory effects of FCPR03 both in vitro and in vivo and explore whether these effects are regulated by PDE4-mediated signaling pathway. BV-2 microglial cells stimulated by lipopolysaccharide (LPS) and mice injected i.p. with LPS were established as in vitro and in vivo models of inflammation. Our results showed that FCPR03 dose dependently suppressed the production of tumor necrosis factor α, interleukin-1ß, and iinterleukin-6 in BV-2 microglial cells treated with LPS. The role of FCPR03 in the production of proinflammatory factors was reversed by pretreatment with protein kinase A (PKA) inhibitor H89. In addition, FCPR03 reduced the levels of proinflammatory factors in the hippocampus and cortex of mice injected with LPS. Our results further demonstrated that FCPR03 effectively increased the production of cAMP, promoted cAMP response element binding protein (CREB) phosphorylation, and inhibited nuclear factor κB (NF-κB) activation both in vitro and in vivo. Our findings suggest that FCPR03 inhibits the neuroinflammatory response through the activation of cAMP/PKA/CREB signaling pathway and NF-κB inhibition.

Catecholic amides as potential selective phosphodiesterase 4D inhibitors: Design, synthesis, pharmacological evaluation and structure-activity relationships.

In this study, a series of catechol-based amides (8a-n) with different amide linkers linking the catecholic moiety to the terminal phenyl ring was designed and synthesized as potent phosphodiesterase (PDE) 4D inhibitors. The inhibitory activities of these compounds were evaluated against the core catalytic domains of human PDE4 (PDE4CAT), full-length PDE4B1 and PDE4D7 enzymes, and other PDE family members. The results indicated the majority of compounds 8a-n displayed moderate to good inhibitory activities against PDE4CAT. Among these compounds, compound 8 j with a short amide linker (-CONHCH2-) displayed comparable PDE4CAT inhibitory activity (IC50=410 nM) with rolipram. More interestingly, compound 8 g, a potent and selective PDE4D inhibitor (IC50=94 nM), exhibited a 10-fold selectivity over the PDE4B subtypes and an over 1000-fold selectivity against other PDE family members. Docking simulations suggested that 8 g forms three extra H-bonds with the N-H of residue Asn487 and two water molecules.

Involvement of norepinephrine and serotonin system in antidepressant-like effects of hederagenin in the rat model of unpredictable chronic mild stress-induced depression.

CONTEXT: Previous studies from our laboratory indicated that both acute and subchronic administration of Fructus Akebiae (FAE) [the fruit of Akebiae quinata (Thunb.) Decne, (Lardizabalaceae)] produce antidepressant-like effects in animal depressive behavior tests. FAE contains approximately 70% of hederagenin (HG) as its main chemical component. OBJECTIVE: This study compared the antidepressant ability of FAE with that of HG in mice and further investigated the antidepressant-like effects and potential mechanisms of HG in rats subjected to unpredictable chronic mild stress (UCMS). MATERIALS AND METHODS: Mice received FAE (50 mg/kg) and HG (20 mg/kg) once a day via intragastric administration (i.g.) for 3 weeks. The anxiolytic and antidepressant activities of FAE and HG were compared using elevated plus maze (EPM) and behavioral despair tests including tail suspension test (TST) and forced swimming test (FST), respectively. Antidepressant effects of HG (5 mg/kg) were assessed using the UCMS depressive rat model. Moreover, the levels of monoamine neurotransmitters and relevant gene expression in UCMS rats' hippocampi were determined through high-performance liquid chromatography with electrochemical detection and real-time polymerase chain reaction techniques. RESULTS: The results of our preliminary screening test suggest that HG at 20 mg/kg, while not FAE at 50 mg/kg, significantly decreased the immobility in both TST and FST compared with the vehicle group when administered chronically; however, there were no significant differences observed between the HG and the FAE group. Chronic administration of HG failed to significantly reverse the altered crossing and rearing behavioral performance, time spent in the open arm and closed entries in the EPM, even if they showed an increased tendency, but HG significantly increased the percent of sucrose preference in the sucrose preference test (SPT) and decreased the immobility time in the FST. HG showed that significant increases of norepinephrine and serotonin levels and exhibited a tendency to increase the expression of 5-hydroxytryptamine (serotonin) 1A receptor mRNA, and to significantly decrease the expression of the mRNA for the serotonin transporter (5-HTT). However, there were no significant differences in the expression of the brain-derived neurotrophic factor. CONCLUSION: These findings confirm the antidepressant-like effects of HG in a behavioral despair test and UCMS rat model, which may be associated with monoamine neurotransmitters and 5-HTT mRNA expression.

Anxiolytic-like effects of YL-IPA08, a potent ligand for the translocator protein (18 kDa) in animal models of post-traumatic stress disorder.

Recently, the translocator protein (18 kDa) (TSPO), previously called peripheral benzodiazepine receptor (PBR) and both the starting point and an important rate-limiting step in neurosteroidogenesis, has received increased attention in the pathophysiology of post-traumatic stress disorder (PTSD) because it affects the production of neurosteroids, reinforcing the hypothesis that selective TSPO ligands could potentially be used as anti-PTSD drugs. As expected, we showed that chronic treatment with YL-IPA08 [N-ethyl-N-(2-pyridinylmethyl)-2-(3,4-ichlorophenyl)-7-methylimidazo [1,2-a] pyridine-3-acetamide hydrochloride], a potent and selective TSPO ligand synthesized by our institute, caused significant suppression of enhanced anxiety and contextual fear induced in the inescapable electric foot-shock-induced mouse model of PTSD and the time-dependent sensitization (TDS) procedure. These effects were completely blocked by the TSPO antagonist PK11195. Furthermore, YL-IPA08 could increase the level of allopregnanolone in the prefrontal cortex and serum of post-TDS rats, and these effects were antagonized by PK11195. In summary, the findings from the current study showed that YL-IPA08, a potent and selective TSPO ligand, had a clear anti-PTSD-like effect, which might be partially mediated by binding to TSPO and the subsequent synthesis of allopregnanolone.

Advances in the development of phosphodiesterase 7 inhibitors.

Phosphodiesterase 7 (PDE7) specifically hydrolyzes cyclic adenosine monophosphate (cAMP), a second messenger that plays essential roles in cell signaling and physiological processes. Many PDE7 inhibitors used to investigate the role of PDE7 have displayed efficacy in the treatment of a wide range of diseases, such as asthma and central nervous system (CNS) disorders. Although PDE7 inhibitors are developed more slowly than PDE4 inhibitors, there is increasing recognition of PDE7 inhibitors as potential therapeutics for no nausea and vomiting secondary. Herein, we summarized the advances in PDE7 inhibitors over the past decade, focusing on their crystal structures, key pharmacophores, subfamily selectivity, and therapeutic potential. Hopefully, this summary will lead to a better understanding of PDE7 inhibitors and provide strategies for developing novel therapies targeting PDE7.

The phosphodiesterase-4 inhibitor rolipram reverses Aß-induced cognitive impairment and neuroinflammatory and apoptotic responses in rats.

ß-amyloid (Aß) peptides play an important role in cognition deficits, neuroinflammation, and apoptosis observed in Alzheimer's disease (AD). Activation of cyclic AMP (cAMP) signalling enhances memory and inhibits inflammatory and apoptotic responses. However, it is not known whether inhibition of phosphodiesterase-4 (PDE4), a critical controller of intracellular cAMP concentrations, affects AD-associated neuroinflammatory and apoptotic responses and whether these responses contribute to deficits of memory mediated by cAMP signalling. We addressed these issues using memory tests and neurochemical measures. Specifically, rats microinfused with aggregated Aß25-35 (10 µg/side) into bilateral CA1 subregions displayed deficits in learning ability and memory, as evidenced by decreases in escape latency during acquisition trials and exploratory activities in the probe trial in the water-maze task and 24-h retention in the passive avoidance test. These effects were reversed by rolipram (0.1, 0.25 and 0.5 mg/kg.d i.p.), a prototypic PDE4 inhibitor, in a dose-dependent manner. Interestingly, Aß25-35-treated rats also displayed decreases in expression of phosphorylated cAMP response-element binding protein (pCREB) and Bcl-2, but increases in expression of NF-κB p65 and Bax in the hippocampus; these effects were also reversed by rolipram in a dose-dependent manner. Similar neurochemical results were observed by replacing Aß25-35 with Aß1-42, a full-length amyloid peptide that quickly forms toxic oligomers. These results suggest that PDE4 inhibitors such as rolipram may reverse Aß-induced memory deficits at least in part via the attenuation of neuronal inflammation and apoptosis mediated by cAMP/CREB signalling. PDE4 could be a target for treatment of memory loss associated with AD.

Piperphentonamine (PPTA) attenuated cerebral ischemia-induced memory deficits via neuroprotection associated with anti-apoptotic activity.

The calcium sensitizers levosimendan and piperphentonamine hydrochloride (PPTA) are used as cardiovascular drugs for treatment of heart failure. Given that levosimendan has been reported to exhibit a neuroprotective profile in a model of traumatic brain injury, it was interesting to know whether PPTA, a new calcium sensitizer recently developed in China, exerts a similar effect. The objective of this study was to determine whether PPTA exhibited neuroprotective effects and whether these properties were associated with memory. Four-vessel occlusion (4-VO) was used to induce global cerebral ischemia/reperfusion injury in rats treated with or without PPTA (5, 10 mg/kg, i.p., 2 h after the onset of reperfusion and then once a day for 15 consecutive days). Memory was measured using the step-through passive avoidance test. Neurochemical changes were examined in rat PC12 cells treated with oxygen-glucose deprivation (OGD) for 4 h followed by reoxygenation (OGD-R) for 24 h, in the absence or presence of PPTA. In vehicle-treated animals, 4-VO for 10 min produced memory deficits, as demonstrated by decreased retention in step-through passive avoidance, and massive neuron loss in the hippocampal CA1 subregion. These effects were attenuated by PPTA. The results were consistent with those observed in PC12 cells. PPTA treatment increased cell viability, as indicated by MTT assay, inhibited apoptosis, and decreased extracellular lactate dehydrogenase levels in Na(2)S(2)O(4)-treated PC12 cells. These results provide novel demonstration for the ability of PPTA to attenuate cerebral ischemia-induced memory deficits via neuroprotection in the hippocampus. The neuroprotective effect of PPTA appears to be associated with its anti-apoptotic activity. PPTA has the therapeutic potential for ischemic stroke.

Discovery of novel 2,3-dihydro-1H-inden-1-ones as dual PDE4/AChE inhibitors with more potency against neuroinflammation for the treatment of Alzheimer's disease.

Recently, the discovery of multifunctional molecules that target different factors in the treatment of dementia is a significant research area. Both PDE4 and AChE inhibitors display improvement in cognitive and memory function. In this study, twenty-eight novel 2,3-dihydro-1H-inden-1-ones were designed, synthesized, and evaluated as catechol ether-based dual PDE4/AChE inhibitors to treat Alzheimer's disease (AD). Among these compounds, 12C bearing a 2-(piperidin-1-yl)ethoxy group at the 6-position of indanone ring displayed satisfactory inhibitory activities and selectivity against AChE (IC50 = 0.28 µM) and PDE4D (IC50 = 1.88 µM). Compared with donepezil, 12C revealed a comparable neuroprotective effect. Moreover, 12C exhibited comparable AChE inhibitory activity with donepezil in the hippocampus of AD model mice. Interestingly, 12C displayed more potent anti-neuroinflammation than the donepezil and drug combination (donepezil + rolipram) groups. These results suggest that 12C is a promising multifunctional agent for the treatment of AD.

Discovery of Novel 3-Amino-4-alkoxyphenylketones as PDE4 Inhibitors with Improved Oral Bioavailability and Safety against Spatial Memory Impairments.

To realize PDE4 inhibitors with good developmental potentiality for the treatment of dementia, structure-based optimizations of lead compound FCPR03 resulted in novel aminophenylketones 9c and 9H with low nanomolar potency, which displayed comparable activity to rolipram, satisfactory bioavailability (F% = 36.92 and 42.96% respectively), and good blood-brain barrier (BBB) permeability switching from the cyclopropyl methoxy group to the cyclopropyl methylamine and the amide group to the corresponding ketone. Emetogenicity evaluation on a combined ketamine/xylazine anesthesia mice alternative model demonstrated that 9H displays no emetogenicity even at an oral dose of 5 mg/kg. In contrast, rolipram and roflumilast displayed emetogenicity at an oral dose of 0.5 mg/kg. In acute toxicological evaluation, 9H showed no obvious toxicological effect on mice when administered at oral doses below 625 mg/kg. Further investigations revealed that 9H improves the memory and cognitive impairment of Alzheimer's disease (AD) model mice induced by Aß25-35.

Prevention of cerebral ischemia-induced memory deficits by inhibition of phosphodiesterase-4 in rats.

Inhibition of phosphodiesterase-4 (PDE4) by rolipram, a prototypical PDE4 inhibitor, reverses memory impairment produced pharmacologically or genetically. Comparably, much less is known about the effect of rolipram on cerebral ischemia-induced memory deficits. The objective of this study was to determine the effects of rolipram on ischemia-induced memory deficit, neuronal damage, and alteration of PDE4 activity in the hippocampus. Memory was examined using Morris water-maze and step-through passive avoidance tests in rats subjected to global cerebral ischemia with or without repeated treatment with rolipram (0.3 or 1 mg/kg, i.p.); neuronal damage in the hippocampus and PDE4 activity in hippocampal tissues were determined using Nissl staining and HPLC, respectively. In the water-maze test, cerebral ischemia significantly increased the escape latency to reach the platform during acquisition training and decreased the exploration time in the target quadrant in the probe trial test; these were blocked by rolipram in a dose-dependent manner. Rolipram also reduced the distracted platform searches induced by cerebral ischemia. In the passive avoidance test, ischemia decreased the 24-h latency to the dark compartment, which was also blocked by rolipram treatment. In addition, Nissl staining revealed ischemia-induced neuron loss in hippocampal CA1; this was blocked by rolipram. Further, cerebral ischemia led to increases in activity of PDE, primarily PDE4, in the hippocampus, which also was antagonized by rolipram. These results suggest that rolipram prevents cerebral ischemia-induced memory deficits via inhibition of increased PDE4 activity and attenuation of hippocampal, neuronal damages induced by ischemia. PDE4 may be a target for treatment of cognitive disorders associated with cerebral ischemia.

[Effect of Cordyceps sinensis sporocarp on learning-memory in mice].

OBJECTIVE: To study the effect of extracts of Cordyceps sinensis sporocarp on learning-memory in scopolamine treated mice and the possible mechanism. METHODS: ICR mice were randomly divided into five groups: sham control, model, piracetam and CSE 0.5, 1 g/kg. Lotomotor activity was assessed. Morris water maze was used to evaluate the memory ability of mice 30 min later after ip scopolamine 1.0 mg/kg BW. Then acitivity of AchE was measured after behavioral test. RESULTS: CSE had no influence on lotomotor activity. However, CSE 0.5, 1 g/kg both shortened escape latency and increased times of come-crossing platform in Morris water maze, meanwhile activity of AchE in the brain was decreased by CSE. CONCLUSION: CSE can significantly improve the learning and memory impairment in mice induced by scopolamine, which may be correlated with the inhibition of activity of AchE.

Discovery of novel trimethoxyphenylbenzo[d]oxazoles as dual tubulin/PDE4 inhibitors capable of inducing apoptosis at G2/M phase arrest in glioma and lung cancer cells.

To discover PDE4/tubulin dual inhibitors with novel skeleton structures, 7-trimethoxyphenylbenzo[d]oxazoles 4a-u and 4-trimethoxyphenylbenzo[d]oxazoles 5a-h were designed and synthesized by migrating the trimethoxyphenyl group of TH03 to the benzo[d]oxazole moiety. Among these compounds, approximately half of them displayed good antiproliferative activities against glioma (U251) and lung cancer (A549 and H460) cell lines. The structure-activity relationships of trimethoxyphenylbenzo[d]oxazoles led to the identification of 4r bearing indol-5-yl side-chain as a novel dual PDE4/tubulin inhibitor, which exhibited satisfactory antiproliferative activities against glioma (IC50 = 300 ± 50 nM) and lung cancer (average IC50 = 39.5 nM) cells. Further investigations revealed that 4r induced apoptosis at G2/M phase arrest and disrupted the microtubule network. The preliminary mechanism of action showed that 4r down-regulated the expression of cyclin B1 and its upstream regulator gene cdc25C in A549.

Protective effect of gui zhi (Ramulus Cinnamomi) on abnormal levels of four amino acid neurotransmitters by chronically ma huang (Herb Ephedra) intoxicated prefrontal cortex in rats treated with a ma huang-gui zhi herb pair.

ETHNOPHARMACOLOGICAL RELEVANCE: The Herb Ephedra (Ma Huang in Chinese)-Ramulus Cinnamomi (Gui Zhi in Chinese) herb pair is a classic traditional Chinese herb pair used to treat asthma, nose and lung congestion, and fever with anhidrosis. In previous study, we found that chronic administration of ma huang induced obvious neurodegeneration in rat brains, with the prefrontal cortex showing the greatest effect. Gui zhi decreased hyperactivity produced by repeated ma huang administration, and attenuated oxidative stress in rat prefrontal cortex induced by ma huang. AIM OF THE STUDY: The study was aimed to investigate the protective effect of gui zhi on ma huang-induced abnormal levels of four amino acid neurotransmitters in rat prefrontal cortex. MATERIALS AND METHODS: All ma huang and ma huang-gui zhi herb pair extracts were prepared using methods of traditional Chinese medicine and were normalized based on the ephedrine content. Two-month-old male Sprague-Dawley rats (6 rats/group) were administered ma huang or ma huang-gui zhi herb pair extracts for 1, 3, 5 or 7 days (ephedrine = 48 mg/kg). The contents of ephedrine, glutamate (Glu), aspartic acid (Asp), glycine (Gly), and gamma-aminobutyric acid (GABA) in the prefrontal cortex were determined using ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) at 0.5, 1.0, 5.0 h after administration. RESULTS: Ma huang significantly enhanced the levels of GABA, Gly, Glu and Asp in the prefrontal cortex, while gui zhi partially abolished the effects. CONCLUSIONS: Ma huang-induced neurotoxicity may be associated with its effects on amino acid neurotransmitters. Gui zhi is a promising neuroprotective agent against for ma huang-induced neurotoxicity. The information presented in this study will help supplement the available data for future ma huang-gui zhi herb pair compatibility studies.

A new polyhydroxylated oleanane triterpenoid from the roots of Rhodomyrtus tomentosa.

A new oleanane triterpenoid, 2α,3ß,6ß,23,29-pentahydroxyolean-12-en-28- oic acid (1), was isolated from the roots of Rhodomyrtus tomentosa, together with four known oleanane triterpenoids (2-5) and two known ursane triterpenoids (6-7). The structure of compound 1 was determined by extensive NMR and HR-ESI-MS data analysis. Compounds 4-5 showed cytotoxicity against PC12 cell lines at a concentration of 50 µM, and compound 1 exhibited moderate neuroprotective activity against corticosterone induced PC12 cell death at the same concentration.

Reciprocal Substitution Between Methamphetamine and Heroin in Terms of Reinforcement Effects in Rats.

Heroin and methamphetamine are both popular illicit drugs in China. Previous clinical data showed that habitual users of either heroin or methamphetamine abuse the other drug for substitution in case of unavailability of their preferred drug. The present study aimed to observe whether heroin can substitute the methamphetamine reinforcement effect in rats, and vice versa. Rats were trained to self-administer heroin or methamphetamine (both 50 µg/kg/infusion) under an FR1 reinforcing schedule for 10 days. After having extracted the dose-effect curve of the two drugs, we administered methamphetamine at different doses (12.5-200 µg/kg/infusion) to replace heroin during the period of self-administration, and vice versa. The heroin dose-effect curve showed an inverted U-shaped trend, and the total intake dose of heroin significantly increased when the training dose increased from 50 to 100 or 200 µg/kg/infusion. Following replacement with methamphetamine, the total dose-effect curve shifted leftwards and upwards. By contrast, although the dose-effect curve of methamphetamine also showed an inverted U-shaped trend, the total dose of methamphetamine significantly decreased when the training dose decreased from 50 to 25 µg/kg/infusion; conversely, when the methamphetamine training dose increased, the total dose did not change significantly. The total dose-effect curve shifted rightwards after heroin was substituted with methamphetamine. Although heroin and methamphetamine had their own independent reward effects, low doses of methamphetamine can replace the heroin reward effect, while high doses of heroin can replace the methamphetamine reward effect. These results demonstrated that heroin and methamphetamine can substitute each other in terms of reinforcement effects in rats.

Synthesis, Biological Evaluation, and Molecular Docking of Arylpyridines as Antiproliferative Agent Targeting Tubulin.

Mimicking different pharmacophoric units into one scaffold is a promising structural modification tool to design new drugs with enhanced biological properties. To continue our research on the tubulin inhibitors, the synthesis and biological evaluation of arylpyridine derivatives (9-29) are described herein. Among these compounds, 6-arylpyridines (13-23) bearing benzo[d]imidazole side chains at the 2-position of pyridine ring displayed selective antiproliferative activities against HT-29 cells. More interestingly, 2-trimethoxyphenylpyridines 25, 27, and 29 bearing benzo[d]imidazole and benzo[d]oxazole side chains displayed more broad-spectrum antitumor activities against all tested cancer cell lines. 29 bearing a 6-methoxybenzo[d]oxazole group exhibited comparable activities against A549 and U251 cells to combretastatin A-4 (CA-4) and lower cytotoxicities than CA-4 and 5-Fu. Further investigations revealed 29 displays strong tubulin polymerization inhibitory activity (IC50 = 2.1 µM) and effectively binds at the colchicine binding site and arrests the cell cycle of A549 in the G2/M phase by disrupting the microtubules network.

Acute EPA-induced learning and memory impairment in mice is prevented by DHA.

Eicosapentaenoic acid (EPA), an omega-3 fatty acid, has been widely used to prevent cardiovascular disease (CVD) and treat brain diseases alone or in combination with docosahexaenoic acid (DHA). However, the impact of EPA and DHA supplementation on normal cognitive function and the molecular targets of EPA and DHA are still unknown. We show that acute administration of EPA impairs learning and memory and hippocampal LTP in adult and prepubescent mice. Similar deficits are duplicated by endogenously elevating EPA in the hippocampus in the transgenic fat-1 mouse. Furthermore, the damaging effects of EPA are mediated through enhancing GABAergic transmission via the 5-HT6R. Interestingly, DHA can prevent EPA-induced impairments at a ratio of EPA to DHA similar to that in marine fish oil via the 5-HT2CR. We conclude that EPA exhibits an unexpected detrimental impact on cognitive functions, suggesting that caution must be exercised in omega-3 fatty acid supplementation and the combination of EPA and DHA at a natural ratio is critical for learning and memory and synaptic plasticity.