Chronic pain exacerbates memory impairment and pathology of Aß and tau by upregulating IL-1ß and p-65 signaling in a mouse model of Alzheimer's disease.

BACKGROUND: Chronic pain is linked to cognitive impairment; however, the underlying mechanisms remain unclear. In the present study, we examined these mechanisms in a well-established mouse model of Alzheimer's disease (AD). METHODS: Neuropathic pain was modeled in 5-month-old transgenic APPswe/PS1dE9 (APP/PS1) mice by partial ligation of the sciatic nerve on the left side, and chronic inflammatory pain was modeled in another group of APP/PS1 mice by injecting them with complete Freund's adjuvant on the plantar surface of the left hind paw. Six weeks after molding, the animals were tested to assess pain threshold (von Frey filament), learning, memory (novel object recognition, Morris water maze, Y-maze, and passive avoidance), and depression-like symptoms (sucrose preference, tail suspension, and forced swimming). After behavioral testing, mice were sacrificed and the levels of p65, amyloid-ß (residues 1-42) and phospho-tau in the hippocampus and cerebral cortex were assayed using western blotting, while interleukin (IL)-1ß levels were measured by enzyme-linked immunosorbent assay. RESULTS: Animals subjected to either type of chronic pain showed lower pain thresholds, more severe deficits in learning and memory, and stronger depression-like symptoms than the corresponding control animals. Either type of chronic pain was associated with upregulation of p65, amyloid-ß (1-42), and IL-1ß in the hippocampus and cerebral cortex, as well as higher levels of phosphorylated tau. CONCLUSIONS: Chronic pain may exacerbate cognitive deficits and depression-like symptoms in APP/PS1 mice by worsening pathology related to amyloid-ß and tau and by upregulating signaling involving IL-1ß and p65.

ß-Glucan attenuates cognitive impairment of APP/PS1 mice via regulating intestinal flora and its metabolites.

BACKGROUND: The intestinal flora has been shown to be involved in the progression of Alzheimer's disease (AD) and can be improved by ß-glucan, a polysaccharide derived from Saccharomyces cerevisiae, which affects cognitive function through the intestinal flora. However, it is not known if this effect of ß-glucan is involved in AD. METHOD: This study used behavioral testing to measure cognitive function. After that, high-throughput 16 S rRNA gene sequencing and GC-MS were used to analyze the intestinal microbiota and metabolite SCFAs of AD model mice, and further explore the relationship between intestinal flora and neuroinflammation. Finally, the expressions of inflammatory factors in the mouse brain were detected by Western blot and Elisa methods. RESULTS: We found that appropriate supplementation of ß-glucan during the progression of AD can improve cognitive impairment and reduce A ß plaque deposition. In addition, supplementation of ß-glucan can also promote changes in the composition of the intestinal flora, thereby changing the flora metabolites in the intestinal content and reduce the activation of inflammatory factors and microglia in the cerebral cortex and hippocampus through the brain-gut axis. While reducing the expression of inflammatory factors in the hippocampus and cerebral cortex, thereby controlling neuroinflammation. CONCLUSION: The imbalance of the gut microbiota and metabolites plays a role in the progression of AD; ß-glucan blocks the development of AD by improving the gut microbiota and its metabolites and reducing neuroinflammation. ß-Glucan is a potential strategy for the treatment of AD by reshaping the gut microbiota and improving its metabolites.

Synergistic effects of two naturally occurring iridoids in eliciting a rapid antidepressant action by up-regulating hippocampal PACAP signalling.

BACKGROUND AND PURPOSE: Current mainstream antidepressants have limited efficacy with a delayed onset of action. Yueju, a herbal medicine, has a rapid antidepressant action. Identification of the active ingredients in Yueju and the mechanism/s involved was carried out. EXPERIMENTAL APPROACH: Key molecule/s and compounds involved in this antidepressant action was identified by transcriptomic and HPLC analysis, respectively. Antidepressant effects were evaluated using various behavioural experiments. The signalling involved was assessed using site-directed pharmacological intervention or optogenetic manipulation. KEY RESULTS: Transcriptomic analysis showed that Yueju up-regulated pituitary adenylate cyclase activating polypeptide (PACAP) expression in the hippocampus. Two iridoids, geniposide and shanzhiside methyl ester, were identified and quantified from Yueju. Only co-treatment with both, at an equivalent concentrations found in Yueju, increased PACAP expression and elicited a rapid antidepressant action, which were blocked by intra-dentate gyrus infusion of a PACAP antagonist or optogenetic inactivation of PACAP expressing neurons. Geniposide and shanzhiside methyl ester co-treatment rapidly inhibited CaMKII phosphorylation and enhanced mTOR/4EBP1/P70S6k/BDNF ignalling, while intra-dentate gyrus infusions of a CaMKII activator blunted the rapid antidepressant action and BDNF expression up-regulation induced by the co-treatment. A single co-treatment of them rapidly improved depression-like behaviours and up-regulated hippocampal PACAP signalling in the repeated corticosterone-induced depression model, further confirming the involvement of PACAP. CONCLUSION AND IMPLICATIONS: Geniposide and shanzhiside methyl ester co-treatment had a synergistic rapid onset antidepressant action by triggering hippocampal PACAP activity and associated CaMKII-BDNF signalling. This mechanism could be targeted for development of fast onset antidepressants.

Biochanin A alleviates cognitive impairment and hippocampal mitochondrial damage in ovariectomized APP/PS1 mice.

BACKGROUND: Estrogen deficiency leads to mitochondrial defects that precede Alzheimer's disease (AD)-associated pathological changes in a postmenopausal mouse model. Biochanin A (BCA) is a phytoestrogen isolated from Trifolium pratense L. used to relieve postmenopausal problems in women. In previous work, we observed that oral BCA treatment led to neuroprotection in an ovariectomized rat model. The objective of this study was to investigate whether and how BCA protects against hippocampal mitochondrial damage in a postmenopausal model of AD. METHOD: APP/PS1 mice underwent bilateral ovariectomy and then, seven days later, received oral BCA at 20 or 40 mg/kg, or oral estradiol at 0.5 mg/kg, daily for 90 days. Sham animals were not ovariectomized and received no additional treatments. Cognitive function was examined using the passive avoidance task, novel object recognition test, and Morris water maze test. The level of circulating estrogen in vivo was assessed indirectly by measuring the wet weight of the uterus. We detected Aß deposition and PGC-1α in brain by immunohistochemistry; p62, by immunofluorescence; and ERα, ERß, PGC-1α, NRF1, mtTFA, Drp1, OPA1, Mfn2, Beclin1, LC3B, Pink1, and Parkin by immunoblotting. RESULTS: BCA treatment rescued cognitive decline and reduced Aß deposition and BACE1 expression in the hippocampus of ovariectomized APP/PS1 mice. BCA reversed the imbalance of mitochondrial dynamics caused by ovariectomy by increasing the expression of phospho-Drp1 (ser637), OPA1, and Mfn2. BCA reversed abnormal mitophagy induced by ovariectomy by increasing the expression of Beclin1, LC3B, Pink1, and Parkin, as well as by reducing the expression of p62. CONCLUSIONS: BCA treatment enhances learning and memory abilities and alleviates AD symptoms in a postmenopausal model of AD. A possible mechanism is that BCA rescues the reduction of mitochondrial biogenesis, imbalance of mitochondrial dynamics, and abnormal mitophagy caused by ovariectomy. This study supports further research on BCA to develop treatments for postmenopausal women with AD.

Baicalin attenuates amyloid ß oligomers induced memory deficits and mitochondria fragmentation through regulation of PDE-PKA-Drp1 signalling.

RATIONALE: Mitochondrial fragmentation contributes to the initiation of Alzheimer's disease (AD) pathology. Baicalin plays a significant role in rescuing mitochondrial dysfunction. However, the effect of baicalin treatment on the modulation of mitochondrial fragmentation has not yet been assessed. OBJECTIVES: The present study was designed to evaluate the effect of baicalin on memory and understand its mechanism of action. RESULTS: Baicalin treatment significantly reversed the altered learning and memory behaviours in AD mouse model. We found that baicalin treatment significantly improved the levels of microtubule association protein-2 and enhanced the expression of synaptophysin and postsynaptic density protein 95 (PSD95). Moreover, treatment with baicalin reversed amyloid-ß oligomer (AßO)-induced abnormalities in the succinate dehydrogenase complex iron sulphur subunit B (SDHB) and cytochrome c oxidase components I (COXI) and mitochondrial fragmentation in the hippocampus. Further, we found that baicalin decreased the PDE4 levels and upregulated the levels of phosphorylated Ser157 site of vasodilator-stimulated phosphoprotein (pVASPs157) and phosphorylated Ser637 site of mitochondrial dynamin-related protein 1 (pDrp1S637). Moreover, in AßO-treated HT-22 cells, H89 inhibited the effect of baicalin on PSD95, mitochondrial fragmentation, SDHB and COXI, PDE4, pVASPs157, and pDrp1S637. CONCLUSION: The effect of baicalin on memory improvement may be due to improved synaptic plasticity, mitochondrial fragmentation, and rescue of dysfunction via the inhibition of PDE4, which leads to activation of pDrp1S637 in the AßO-induced model.

Inhibition of phosphodiesterase-4 in the spinal dorsal horn ameliorates neuropathic pain via cAMP-cytokine-Cx43 signaling in mice.

BACKGROUND: The spinal phosphodiesterase-4 (PDE4) plays an important role in chronic pain. Inhibition of PDE4, an enzyme catalyzing the hydrolysis of cyclic adenosine monophosphate AMP (cAMP), produces potent antinociceptive activity. However, the antinociceptive mechanism remains largely unknown. Connexin43 (Cx43), a gap junction protein, has been shown to be involved in controlling pain transduction at the spinal level; restoration of Cx43 expression in spinal astrocytes to the normal levels reduces nerve injury-induced pain. Here, we evaluate the novel mechanisms involving spinal cAMP-Cx43 signaling by which PDE4 inhibitors produce antinociceptive activity. METHODS: First, we determined the effect of PDE4 inhibitors rolipram and roflumilast on partial sciatic nerve ligation (PSNL)-induced mechanical hypersensitivity. Next, we observed the role of cAMP-Cx43 signaling in the effect of PDE4 inhibitors on PSNL-induced mechanical hypersensitivity. RESULTS: Single or repeated, intraperitoneal or intrathecal administration of rolipram or roflumilast significantly reduced mechanical hypersensitivity in mice following PSNL. In addition, repeated intrathecal treatment with either of PDE4 inhibitors reduced PSNL-induced downregulation of cAMP and Cx43, and upregulation of proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1ß. Furthermore, the antinociceptive effects of PDE4 inhibitors were attenuated by the protein kinase A (PKA) inhibitor H89, TNF-α, or Cx43 antagonist carbenoxolone. Finally, PSNL-induced upregulation of PDE4B and PDE4D, especially the PDE4B subtype, was reduced by treatment with either of the PDE4 inhibitors. CONCLUSIONS: The results suggest that the antinociceptive effect of PDE4 inhibitors is contributed by increasing Cx43 expression via cAMP-PKA-cytokine signaling in the spinal dorsal horn.

Base-Mediated Coupling Reactions of Benzenesulfonyl Azides with Proline: Synthesis of Proline-Derived Benzenesulfonamides.

Sulfonamides and lipids are widely found in natural products, bioactive substances, and pharmaceuticals. Here, we report N-sulfonylation and esterification of carboxylic acids in an environment-friendly one-pot tandem protocol involving 1,2-dichloroethane (DCE). Moreover, 1,8-diazabicyclo (5.4.0) undec-7-ene was necessary for this reaction as a strong base, which drives the reaction to completion. Although DCE is a very low activity reagent, it acts not only as a solvent but also as a reactant in the reaction. The ß-chloroester contained in the reaction product can be easily dissociated to react with N, S, and O atoms, increasing the possibility for subsequent synthesis.

Estrogen Deficiency Induces Mitochondrial Damage Prior to Emergence of Cognitive Deficits in a Postmenopausal Mouse Model.

Background: Estrogen deficiency contributes to the development of Alzheimer's disease (AD) in menopausal women. In the current study, we examined the impact of estrogen deficiency on mitochondrial function and cognition using a postmenopausal mouse model. Methods: Bilateral ovariectomy was conducted in adult females C57BL/6J. Cognitive function was examined using the Morris water maze (MWM) test at 2 weeks, 1, 2, and 3 months after ovariectomy. Neurodegeneration was assessed using an immunofluorescence assay of microtubule-associated protein 2 (MAP2) in the hippocampus and immunoblotting against postsynaptic density-95 (PSD95). Mitochondrial function in the hippocampus was assessed using immunoblotting for NDUFB8, SDHB, UQCRC2, MTCO1, and ATP5A1. Mitochondrial biogenesis was examined using immunoblotting for PGC-1α, NRF1, and mtTFA. Mitochondrion fission was assessed with immunoblotting for Drp1, whereas mitochondrion fusion was analyzed with immunoblotting for OPA1 and Mfn2. Mitophagy was examined with immunoblotting for PINK1 and LC3B. Mice receiving sham surgery were used as controls. Results: Ovariectomy resulted in significant learning and memory deficits in the MWM test at 3 months, but not at any earlier time points. At 2 weeks after ovariectomy, levels of Drp1 phosphorylated at Ser637 decreased in the hippocampus. At 1 month after ovariectomy, hippocampal levels of NDUFB8, SDHB, PGC-1α, mtTFA, OPA1, and Mfn2 were significantly reduced. At 2 months after ovariectomy, hippocampal levels of MAP2, PSD95, MTCO1, NRF1, and Pink1 were also reduced. At 3 months, levels of LC3B-II were reduced. Conclusions: The cognitive decline associated with estrogen deficiency is preceded by mitochondrial dysfunction, abnormal mitochondrial biogenesis, irregular mitochondrial dynamics, and decreased mitophagy. Thus, mitochondrial damage may contribute to cognitive impairment associated with estrogen deficiency.

Biochanin A Attenuates Ovariectomy-Induced Cognition Deficit via Antioxidant Effects in Female Rats.

Background: Impairment of memory and cognition is one of the major symptoms in women with postmenopausal disorders due to estrogen deficiency, which accounts for the much higher prevalence of Alzheimer's disease in females. Biochanin A (BCA), a natural phytoestrogen, has been reported to protect neurons against ischemic brain injury. However, the neuroprotective effects of BCA in the postmenopausal-like model of ovariectomized (OVX) rats remain to be investigated. Methods: All the rats except for the sham group underwent the resection of bilateral ovaries. Seven days after the OVX surgery, rats were randomly divided into six groups: sham, OVX, OVX + BCA (5 mg/kg), OVX + BCA (20 mg/kg), OVX + BCA (60 mg/kg), and OVX + estradiol (E2; 0.35 mg/kg), which were administrated daily by gavage for 12 weeks. Learning and memory were examined using the Morris water-maze test before the end of the experiment. Morphological changes of the rat hippocampus were observed by HE staining and electron microscopy. Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in the hippocampus were measured. The effect of BCA on cell viability was measured in the presence of hydrogen peroxide (H2O2) using CCK8. Flow cytometry was used to measure neuronal apoptosis and reactive oxygen species (ROS) induced by H2O2. Expression of Bcl-2, Bax, and Caspase-3 was determined by Western blotting using hippocampal tissues and primary cultures of hippocampal neurons. Results: Chronic treatment with BCA mimicked the ability of E2 to reverse the deficit of learning and memory in the Morris water-maze test in OVX rats. BCA normalized OVX-induced morphological changes as revealed by HE staining and electron microscopy. In addition, BCA significantly decreased the levels of MDA, the biomarker of oxidative damage, and increased the activity of the intracellular antioxidant enzymes SOD and GSH-Px in OVX rats. Further, in primary cultures of hippocampal neurons, BCA reversed H2O2-induced decreases in cell viability and accumulation of ROS. Finally, BCA reversed OVX- or H2O2-induced increases in Bax and Caspase-3 and decreases in Bcl-2 in the hippocampus and primary cultures of hippocampal neurons. Conclusion: These results suggest that BCA improves memory through its neuroprotective properties in the brain under the circumstance of estrogen deficiency and can be used for treatment of memory loss in postmenopausal women.

Attenuation of ethanol abstinence-induced anxiety- and depressive-like behavior by the phosphodiesterase-4 inhibitor rolipram in rodents.

RATIONALE: Withdrawal symptoms stand as a core feature of alcohol dependence. Our previous results have shown that inhibition of phosphodiesterase-4 (PDE4) decreased ethanol seeking and drinking in alcohol-preferring rodents. However, little is known about whether PDE4 is involved in ethanol abstinence-related behavior. OBJECTIVE: The objective of this study was to characterize the role of PDE4 in the development of anxiety- and depressive-like behavior induced by abstinence from ethanol exposure in different animal models. METHODS: Using three rodent models of ethanol abstinence, we examined the effects of rolipram, a prototypical, selective PDE4 inhibitor, on (1) anxiety-like behavior induced by repeated ethanol abstinence in the elevated plus maze test in fawn-hooded (FH/Wjd) rats, (2) anxiety-like behavior in the open-field test and light-dark transition test following acute ethanol abstinence in C57BL/6J mice, and (3) anxiety- and depressive-like behavior induced by protracted ethanol abstinence in the elevated plus maze, forced-swim, and tail-suspension tests in C57BL/6J mice. RESULTS: Pretreatment with rolipram (0.1 or 0.2 mg/kg) significantly increased entries and time spent in the open arms of the elevated plus maze test in rats with repeated ethanol abstinence. Similarly, in mice with acute ethanol abstinence, administration of rolipram (0.25 or 0.5 mg/kg) dose-dependently increased the crossings in the central zone of the open-field test and duration and transitions on the light side of the light-dark transition test, suggesting anxiolytic-like effects of rolipram. Consistent with these, chronic treatment with rolipram (0.1, 0.3, or 1.0 mg/kg) increased entries in the open arms of the elevated plus maze test; it also reduced the increased duration of immobility in both the forced-swim and tail-suspension tests in mice after protracted ethanol abstinence, suggesting antidepressant-like effects of rolipram. CONCLUSIONS: These results provide the first demonstration for that PDE4 plays a role in modulating the development of negative emotional reactions associated with ethanol abstinence, including anxiety and depression. PDE4 inhibitors may be a novel class of drugs for treatment of alcoholism.

[Effect of tanshitone on prevention and treatment of retinoic acid induced osteoporosis in mice].

OBJECTIVE: To observe the prevention and therapeutic effects of tanshitone (TAN) on retinoic acid induced osteoporosis in mice. METHOD: The mice osteoporosis was induced by given retinoic acid intragastrically for two weeks. The histomorphological features of bone were observed and biochemical indexes in serum (Ca, P, ALP, TRAP, E2, BGP) were determined after the mice were given TAN at the dose of 40, 80, 160 mg x kg(-1) respectly. RESULT: Tanshinone can induce high conversion of osteoporosis. The levels of P, ALP, TRAP and BGP in the TAN groups were lower than the model group, while the E2 level was higher than the model group. CONCLUSION: Tanshitone can prevent the loss bone in the experimental mice. The mechanism may be that it improves the level of estrogenic hormone and inhibits the high bone turnover.