[Identification of chemical components in Qinggu San reference sample of classial prescription based on UHPLC-Q/Orbitrap HRMS combined with molecular network technology].

The method of ultra-high performance liquid chromatography-quadrupole-electrostatic field orbitrap high-resolution mass spectrometry(UHPLC-Q/Orbitrap HRMS)combined with molecular network was developed in this study for rapidly analyzing the chemical components of the Qinggu San reference sample of classical prescription. Firstly, an ACQUITY UPLC BEH Shield RP_(18) column(2.1 mm×100 mm, 1.7 µm)was used, and acetonitrile and 0.1% formic acid were taken as the mobile phases for gradient elution. The flow rate was 0.4 mL·min~(-1), and the column temperature was 30 ℃. Under these conditions, the mass spectrum data were collected in both positive and negative ion modes of the heated electrospray ionization source. Subsequently, the mass spectrum data of the Qinggu San reference sample were uploaded to the Global Natural Products Social Molecular Network(GNPS)platform for calculation and analysis, and a visual molecular network was built with Cytoscape 3.8.2 software. On this basis, the chemical components of the Qinggu San reference sample were identified by fragmentation regularity of standard compounds, retention time, accurate relative molecular weight of HR-MS, characteristic fragment ions information, literature, and databases. Finally, a total of 105 chemical components were identified and speculated in the Qinggu San reference sample, including 19 iridoid glycosides, 23 flavonoids, 15 phenylpropanoids, 11 triterpene saponins, and 37 other components. Meanwhile, two of these components are potential new compounds. The method used in this study not only achieved rapid and accurate identification of chemical components in the Qinggu San reference sample and provided a scie-ntific basis for the study of pharmacological substances and quality control of Qinggu San compound preparations but also provided a refe-rence for the rapid identification of chemical components in traditional Chinese medicine compound preparations.

Success rates of in vitro fertilization versus intracytoplasmic sperm injection in men with serum anti-sperm antibodies: a consecutive cohort study.

Antisperm antibodies (ASAs) are assumed to be a possible causative factor for male infertility, with ASAs detected in 5%-15% of infertile men but in only 1%-2% of fertile ones. It remains unclear whether ASAs have an adverse effect on the outcome of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). This study investigated differences in the rates of fertilization, pregnancy, and live births associated with serum ASA-positive and ASA-negative men following IVF or ICSI. Five hundred and fifty-four consecutive infertile couples undergoing IVF (n = 399) or ICSI (n = 155) were included. The two-sample two-sided t-test and Chi-square or Fisher's exact test was used for statistical analysis. Lower rates of fertilization (41.7% vs 54.8%, P = 0.03), good embryos (18.9% vs 35.2%, P = 0.00), pregnancy (38.5% vs 59.4%, P = 0.00), and live births (25.8% vs 42.5%, P = 0.00) were observed in men of the IVF group with a positive serum ASA than in those with a negative ASA. ASA positivity/negativity correlated with pregnancy rates (P = 0.021, odds ratio [OR]: 0.630, 95% confidence interval [CI]: 0.425-0.932) and live birth rates (P = 0.010, OR: 1.409, 95% CI: 1.084-1.831) after controlling for the female serum follicle-stimulating hormone level and the couple's ages at IVF. Women coupled with ASA-positive men had lower live birth rates with IVF than with ICSI (25.8% and 47.4%, respectively; P = 0.07). Women coupled with ASA-positive men had lower rates of pregnancy and live births following IVF than those coupled with ASA-negative men but had a similar outcome with ICSI.

HIV Tat causes synapse loss in a mouse model of HIV-associated neurocognitive disorder that is independent of the classical complement cascade component C1q.

Microglial activation, increased proinflammatory cytokine production, and a reduction in synaptic density are key pathological features associated with HIV-associated neurocognitive disorders (HAND). Even with combination antiretroviral therapy (cART), more than 50% of HIV-positive individuals experience some type of cognitive impairment. Although viral replication is inhibited by cART, HIV proteins such as Tat are still produced within the nervous system that are neurotoxic, involved in synapse elimination, and provoke enduring neuroinflammation. As complement deposition on synapses followed by microglial engulfment has been shown during normal development and disease to be a mechanism for pruning synapses, we have tested whether complement is required for the loss of synapses that occurs after a cortical Tat injection mouse model of HAND. In Tat-injected animals evaluated 7 or 28 days after injection, levels of early complement pathway components, C1q and C3, are significantly elevated and associated with microgliosis and a loss of synapses. However, C1qa knockout mice have the same level of Tat-induced synapse loss as wild-type (WT) mice, showing that the C1q-initiated classical complement cascade is not driving synapse removal during HIV1 Tat-induced neuroinflammation.

Corrigendum: Platelet Activating Factor Enhances Synaptic Vesicle Exocytosis Via PKC, Elevated Intracellular Calcium, and Modulation of Synapsin 1 Dynamics and Phosphorylation.

[This corrects the article on p. 505 in vol. 9, PMID: 26778968.].

Leucine-rich repeat kinase 2 modulates neuroinflammation and neurotoxicity in models of human immunodeficiency virus 1-associated neurocognitive disorders.

Leucine-rich repeat kinase 2 (LRRK2) is the single most common genetic cause of both familial and sporadic Parkinson's disease (PD), both of which share pathogenetic and neurologic similarities with human immunodeficiency virus 1 (HIV-1)-associated neurocognitive disorders (HAND). Pathologic LRRK2 activity may also contribute to neuroinflammation, because microglia lacking LRRK2 exposed to proinflammatory stimuli have attenuated responses. Because microglial activation is a hallmark of HIV-1 neuropathology, we have investigated the role of LRRK2 activation using in vitro and in vivo models of HAND. We hypothesize that LRRK2 is a key modulator of microglial inflammatory responses, which play a pathogenic role in both HAND and PD, and that these responses may cause or exacerbate neuronal damage in these diseases. The HIV-1 Tat protein is a potent neurotoxin produced during HAND that induces activation of primary microglia in culture and long-lasting neuroinflammation and neurotoxicity when injected into the CNS of mice. We found that LRRK2 inhibition attenuates Tat-induced pS935-LRRK2 expression, proinflammatory cytokine and chemokine expression, and phosphorylated p38 and Jun N-terminal kinase signaling in primary microglia. In our murine model, cortical Tat injection in LRRK2 knock-out (KO) mice results in significantly diminished neuronal damage, as assessed by microtubule-associated protein 2 (MAP2), class III ß-tubulin TUJ1, synapsin-1, VGluT, and cleaved caspase-3 immunostaining. Furthermore, Tat-injected LRRK2 KO animals have decreased infiltration of peripheral neutrophils, and the morphology of microglia from these mice were similar to that of vehicle-injected controls. We conclude that pathologic activation of LRRK2 regulates a significant component of the neuroinflammation associated with HAND.

Platelet Activating Factor Enhances Synaptic Vesicle Exocytosis Via PKC, Elevated Intracellular Calcium, and Modulation of Synapsin 1 Dynamics and Phosphorylation.

Platelet activating factor (PAF) is an inflammatory phospholipid signaling molecule implicated in synaptic plasticity, learning and memory and neurotoxicity during neuroinflammation. However, little is known about the intracellular mechanisms mediating PAF's physiological or pathological effects on synaptic facilitation. We show here that PAF receptors are localized at the synapse. Using fluorescent reporters of presynaptic activity we show that a non-hydrolysable analog of PAF (cPAF) enhances synaptic vesicle release from individual presynaptic boutons by increasing the size or release of the readily releasable pool and the exocytosis rate of the total recycling pool. cPAF also activates previously silent boutons resulting in vesicle release from a larger number of terminals. The underlying mechanism involves elevated calcium within presynaptic boutons and protein kinase C activation. Furthermore, cPAF increases synapsin I phosphorylation at sites 1 and 3, and increases dispersion of synapsin I from the presynaptic compartment during stimulation, freeing synaptic vesicles for subsequent release. These findings provide a conceptual framework for how PAF, regardless of its cellular origin, can modulate synapses during normal and pathologic synaptic activity.

Effect of trichostatin A on CNE2 nasopharyngeal carcinoma cells--genome-wide DNA methylation alteration.

Trichostatin A (TSA) is a histone deacetylase (HDAC) inhibitor. We here investigated its effects on proliferation and apoptosis of the CNE2 carcinoma cell line, and attempted to establish genome-wide DNA methylation alteration due to differentially histone acetylation status. After cells were treated by TSA, the inhibitory rate of cell proliferation was examined with a CCK8 kit, and cell apoptosis was determined by flow cytometry. Compared to control, TSA inhibited CNE2 cell growth and induced apoptosis. Furthermore, TSA was found to induce genome-wide methylation alteration as assessed by genome-wide methylation array. Overall DNA methylation level of cells treated with TSA was higher than in controls. Function and pathway analysis revealed that many genes with methylation alteration were involved in key biological roles, such as apoptosis and cell proliferation. Three genes (DAP3, HSPB1 and CLDN) were independently confirmed by quantitative real-time PCR. Finally, we conclude that TSA inhibits CNE2 cell growth and induces apoptosis in vitro involving genome-wide DNA methylation alteration, so that it has promising application prospects in treatment of NPC in vivo. Although many unreported hypermethylated/hypomethylated genes should be further analyzed and validated, the pointers to new biomarkers and therapeutic strategies in the treatment of NPC should be stressed.

The new small-molecule mixed-lineage kinase 3 inhibitor URMC-099 is neuroprotective and anti-inflammatory in models of human immunodeficiency virus-associated neurocognitive disorders.

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) is a significant source of disability in the HIV-infected population. Even with stringent adherence to anti-retroviral therapy, >50% of patients living with HIV-1 will develop HAND (Heaton et al., 2010). Because suppression of viral replication alone is not enough to stop HAND progression, there is a need for an adjunctive neuroprotective therapy in this population. To this end, we have developed a small-molecule brain-penetrant inhibitor with activity against mixed-lineage kinase 3 (MLK3), named URMC-099. MLK3 activation is associated with many of the pathologic hallmarks of HAND (Bodner et al., 2002, 2004; Sui et al., 2006) and therefore represents a prime target for adjunctive therapy based on small-molecule kinase inhibition. Here we demonstrate the anti-inflammatory and neuroprotective effects of URMC-099 in multiple murine and rodent models of HAND. In vitro, URMC-099 treatment reduced inflammatory cytokine production by HIV-1 Tat-exposed microglia and prevented destruction and phagocytosis of cultured neuronal axons by these cells. In vivo, URMC-099 treatment reduced inflammatory cytokine production, protected neuronal architecture, and altered the morphologic and ultrastructural response of microglia to HIV-1 Tat exposure. In conclusion, these data provide compelling in vitro and in vivo evidence to investigate the utility of URMC-099 in other models of HAND with the goal of advancement to an adjunctive therapeutic agent.

Ultrastructure of microglia-synapse interactions in the HIV-1 Tat-injected murine central nervous system.

The destruction of normal synaptic architecture is the main pathogenetic substrate in HIV-associated neurocognitive disorder (HAND), but the sequence of cellular events underlying this outcome is not completely understood. Our recent work in a mouse model of HAND using a single intraparenchymal injection of the HIV-1 regulatory protein trans-activator of transcription revealed increased microglial phagocytosis that was accompanied by an increased release of pro-inflammatory cytokines and elimination of dendritic spines in vivo, thus suggesting that microglia-synapse interactions could be dysregulated in HAND. Here, we further examine the relationships between microglia and synaptic structures in our mouse model, at high spatial resolution using immunocytochemical electron microscopy. Our ultrastructural analysis reveals the prevalence of putative microglial filopodial protrusions, which are targeting excitatory and inhibitory synapses, some of which contain phagocytic inclusions at various distances from their distal extremities to the microglial cell bodies. These observations thus suggest that cell-to-cell contacts mediated by microglial filopodia might be a crucial preliminary step in the elimination of synaptic structures in a neuroinflammatory milieu that occurs in HAND.

LRRK2 kinase inhibition prevents pathological microglial phagocytosis in response to HIV-1 Tat protein.

BACKGROUND: Human Immunodeficiency Virus-1 (HIV-1) associated neurocognitive disorders (HANDs) are accompanied by significant morbidity, which persists despite the use of combined antiretroviral therapy (cART). While activated microglia play a role in pathogenesis, changes in their immune effector functions, including phagocytosis and proinflammatory signaling pathways, are not well understood. We have identified leucine-rich repeat kinase 2 (LRRK2) as a novel regulator of microglial phagocytosis and activation in an in vitro model of HANDs, and hypothesize that LRRK2 kinase inhibition will attenuate microglial activation during HANDs. METHODS: We treated BV-2 immortalized mouse microglia cells with the HIV-1 trans activator of transcription (Tat) protein in the absence or presence of LRRK2 kinase inhibitor (LRRK2i). We used Western blot, qRT-PCR, immunocytochemistry and latex bead engulfment assays to analyze LRRK2 protein levels, proinflammatory cytokine and phagocytosis receptor expression, LRRK2 cellular distribution and phagocytosis, respectively. Finally, we utilized ex vivo microfluidic chambers containing primary hippocampal neurons and BV-2 microglia cells to investigate microglial phagocytosis of neuronal axons. RESULTS: We found that Tat-treatment of BV-2 cells induced kinase activity associated phosphorylation of serine 935 on LRRK2 and caused the formation of cytoplasmic LRRK2 inclusions. LRRK2i decreased Tat-induced phosphorylation of serine 935 on LRRK2 and inhibited the formation of Tat-induced cytoplasmic LRRK2 inclusions. LRRK2i also decreased Tat-induced process extension in BV-2 cells. Furthermore, LRRK2i attenuated Tat-induced cytokine expression and latex bead engulfment. We examined relevant cellular targets in microfluidic chambers and found that Tat-treated BV-2 microglia cells cleared axonal arbor and engulfed neuronal elements, whereas saline treated controls did not. LRRK2i was found to protect axons in the presence of Tat-activated microglia, as well as AnnexinV, a phosphatidylserine-binding protein. In addition, LRRK2i decreased brain-specific angiogenesis inhibitor 1 (BAI1) receptor expression on BV-2 cells after Tat-treatment, a key receptor in phosphatidylserine-mediated phagocytosis. CONCLUSION: Taken together, these results implicate LRRK2 as a key player in microglial inflammation and, in particular, in the phagocytosis of neuronal elements. These studies show that LRRK2 kinase inhibition may prove an effective therapeutic strategy for HANDs, as well as other neuroinflammatory conditions.

[Internal quality control of sperm concentrations in semen analysis: establishment of a method].

OBJECTIVE: To establish a method for internal quality control (IQC) of sperm concentration test in the laboratory. METHODS: We set the concentrations of frozen semen at 20 x 10(6) and 80 x 10(6) as low and high concentrations of putative IQC products, with QC-BEADSTM quality control beads (QCBs) as the control. Using the double-blind method, four technicians determined the sperm concentrations of the IQC products and QCBs by computer-assisted sperm analysis, and drew a quality control chart (Xbar chart and Sbar chart) for each product. Through a month of continuous detection, we calculated and compared the intra- and inter-batch coefficients of variation (CV%) of the quality control products of high and low concentrations. RESULTS: The intra-batch coefficients of variation of the assumed IQC products of high and low concentrations were CV3.5% and CV2.4%, and their inter-batch coefficients of variation were CV10.2% and CV9.6%. The intra-batch coefficients of variation of the QCBs of high and low concentrations were CV5.1% and CV7.1%, and their inter-batch coefficients of variation were CV7.1% and CV8%. The intra-batch coefficients of variation of both IQC products and QCBs of high and low concentrations were <10%, and their inter-batch coefficients of variation were <15%, which conformed to Levey-Jennings quality control principles and achieved IQC purposes. No significant differences were found in either intra- or inter-batch coefficients of variation between the IQC products and QCBs of high and low concentrations (P>0.05), indicating that assumed IQC products can replace QCBs for internal quality control in the laboratory. CONCLUSION: The IQC method we established for determining sperm concentration is simple, feasible and reliable.

HIV-1 Tat-induced microgliosis and synaptic damage via interactions between peripheral and central myeloid cells.

Despite the ability of combination antiretroviral treatment (cART) to reduce viral burden to nearly undetectable levels in cerebrospinal fluid and serum, HIV-1 associated neurocognitive disorders (HAND) continue to persist in as many as half the patients living with this disease. There is growing consensus that the actual substrate for HAND is destruction of normal synaptic architecture but the sequence of cellular events that leads to this outcome has never been resolved. To address whether central vs. peripheral myeloid lineage cells contribute to synaptic damage during acute neuroinflammation we injected a single dose of the HIV-1 transactivator of transcription protein (Tat) or control vehicle into hippocampus of wild-type or chimeric C57Bl/6 mice genetically marked to distinguish infiltrating and resident immune cells. Between 8-24 hr after injection of Tat, invading CD11b(+) and/or myeloperoxidase-positive leukocytes with granulocyte characteristics were found to engulf both microglia and synaptic structures, and microglia reciprocally engulfed invading leukocytes. By 24 hr, microglial processes were also seen ensheathing dendrites, followed by inclusion of synaptic elements in microglia 7 d after Tat injection, with a durable microgliosis lasting at least 28 d. Thus, central nervous system (CNS) exposure to Tat induces early activation of peripheral myeloid lineage cells with phagocytosis of synaptic elements and reciprocal microglial engulfment of peripheral leukocytes, and enduring microgliosis. Our data suggest that a single exposure to a foreign antigen such as HIV-1 Tat can lead to long-lasting disruption of normal neuroimmune homeostasis with deleterious consequences for synaptic architecture, and further suggest a possible mechanism for enduring neuroinflammation in the absence of productive viral replication in the CNS.

A thin-skull window technique for chronic two-photon in vivo imaging of murine microglia in models of neuroinflammation.

Traditionally in neuroscience, in vivo two photon imaging of the murine central nervous system has either involved the use of open-skull or thinned-skull preparations. While the open-skull technique is very versatile, it is not optimal for studying microglia because it is invasive and can cause microglial activation. Even though the thinned-skull approach is minimally invasive, the repeated re-thinning of skull required for chronic imaging increases the risks of tissue injury and microglial activation and allows for a limited number of imaging sessions. Here we present a chronic thin-skull window method for monitoring murine microglia in vivo over an extended period of time using two-photon microscopy. We demonstrate how to prepare a stable, accessible, thinned-skull cortical window (TSCW) with an apposed glass coverslip that remains translucent over the course of three weeks of intermittent observation. This TSCW preparation is far more immunologically inert with respect to microglial activation than open craniotomy or repeated skull thinning and allows an arbitrary number of imaging sessions during a time period of weeks. We prepare TSCW in CX3CR1 GFP/+ mice to visualize microglia with enhanced green fluorescent protein to ≤150 µm beneath the pial surface. We also show that this preparation can be used in conjunction with stereotactic brain injections of the HIV-1 neurotoxic protein Tat, adjacent to the TSCW, which is capable of inducing durable microgliosis. Therefore, this method is extremely useful for examining changes in microglial morphology and motility over time in the living brain in models of HIV Associated Neurocognitive Disorder (HAND) and other neurodegenerative diseases with a neuroinflammatory component.

[Use of L-carnitine before percutaneous epididymal sperm aspiration-intracytoplasmic sperm injection for obstructive azoospermia].

OBJECTIVE: To explore the use of L-carnitine before percutaneous epididymal sperm aspiration-intracytoplasmic sperm injection (PESA-ICSI) in the treatment of obstructive azoospermia. METHODS: Seventy-nine cases of obstructive azoospermia treated in our center from Sep 2008 to Aug 2009 were divided into an L-carnitine (n = 43) and a control group (n = 36), the former given oral L-carnitine at 1 g bid for 3 months before PESA-ICSI, while the latter left untreated. Comparisons were made between the two groups in the number of retrieved oocytes and fertilized oocytes as well as the number and rate of good embryos. RESULTS: There were no significant differences between the two groups in the number of retrieved oocytes and fertilized oocytes. But the number and rate of good embryos were significantly higher in the L-carnitine than in the control group (P < 0.05). CONCLUSION: Three-month oral medication of L-carnitine before PESA-ICSI can raise the number and rate of good embryos in obstructive azoospermia patients and therefore benefit the therapeutic outcome.

[Effects of two different cryoprotectants on the motility of post-thaw human sperm].

OBJECTIVE: To compare the effects of the cryoprotectant containing glucose and that containing sucrose on the motility of post-thaw human sperm. METHODS: The cryoprotectant containing glucose and that containing sucrose were applied to 50 semen samples and the motility of the post-thaw human sperm was compared before and after cryopreservation and between the study groups. RESULTS: The forward motility and total motility of the sperm were (58.4 +/- 5.7)% and (63.4 +/- 6.1)% before cryopreservation, (43.8 +/- 7.6)% and (48.4 +/- 7.6)% after thawing with the cryoprotectant containing glucose, and(42.6 +/- 8.9)% and (48.0 +/- 8.5)% after thawing with the cryoprotectant containing sucrose. Decreased sperm motility was observed after cryopreservation, with statistic significance (P < 0.01). There was no significant difference in the forward and total motility of the post-thaw sperm between the two cryoprotectants. CONCLUSION: Cryopreservation inflicts obvious damage on sperm. Sucrose is a feasible sperm cryoprotectant.

Early apoptotic changes in human spermatozoa and their relationships with conventional semen parameters and sperm DNA fragmentation.

AIM: To investigate whether early apoptotic changes in spermatozoa can be significant markers for sperm quality. METHODS: Two early apoptotic changes in the semen of 56 men were assessed using Annexin V (AN)/propidium iodide (PI) staining for phosphatidylserine externalization and JC-1 staining for mitochondrial membrane potential (MMP). The results were compared with conventional semen parameters and DNA fragmentation identified using the TUNEL assay. RESULTS: The different labeling patterns in the bivariate Annexin V/PI analysis identified four distinctive spermatozoa populations. The percentage of AN(-)/PI(-) spermatozoa positively correlated with conventional semen parameters and MMP, but negatively correlated with TUNEL (+) spermatozoa. As for the AN(-)/PI(+) fraction, we found an opposite result in comparison to AN(-)/PI(-) spermatozoa. The level of early apoptotic AN(+)/PI(+) spermatozoa negatively correlated with MMP and sperm motility. The level of late apoptotic AN+/PI+ spermatozoa negatively correlated with conventional semen parameters and MMP, and positively correlated with TUNEL (+) spermatozoa. MMP positively correlated with conventional semen parameters, but negatively correlated with TUNEL (+) spermatozoa. CONCLUSION: Although early apoptotic AN+/PI(-) spermatozoa only negatively correlates with sperm motility, the differences in proportion of each subpopulation of spermatozoa (especially, the percentage of AN(-)/PI(-) spermatozoa), and decreased MMP might be significant markers for diagnosing male infertility. They possibly bring additional information to predict the outcome of in vitro fertilization.

The phospholipid mediator platelet-activating factor mediates striatal synaptic facilitation.

The phospholipid mediator platelet-activating factor (PAF), an endogenous modulator of glutamatergic neurotransmission, can also be secreted by brain mononuclear phagocytes during HIV-1 infection. Platelet-activating factor can induce neuronal apoptosis by NMDA receptor-dependent and independent mechanisms. We now demonstrate that acute administration of sublethal doses of PAF to striatal slices augments synaptic facilitation in striatal neurons following high-frequency stimulation, which can be blocked by PAF receptor antagonists, suggesting that striatal synaptic facilitation can be augmented by PAF receptor agonism. We also demonstrate that repeated sublethal doses of PAF during tetanic stimulation can greatly increase the magnitude of postsynaptic potentials and action potentials, but a lethal dose of PAF destroys the capacity of corticostriatal synapses to achieve this augmented synaptic facilitation. Thus, the relative concentration and temporal pattern of PAF expression at glutamatergic synapses may govern whether it acts in a physiologic or pathophysiologic manner during striatal neurotransmission.

NF-kappaB/Rel regulates inhibitory and excitatory neuronal function and synaptic plasticity.

Changes in synaptic plasticity required for memory formation are dynamically regulated through opposing excitatory and inhibitory neurotransmissions. To explore the potential contribution of NF-kappaB/Rel to these processes, we generated transgenic mice conditionally expressing a potent NF-kappaB/Rel inhibitor termed IkappaBalpha superrepressor (IkappaBalpha-SR). Using the prion promoter-enhancer, IkappaBalpha-SR is robustly expressed in inhibitory GABAergic interneurons and, at lower levels, in excitatory neurons but not in glia. This neuronal pattern of IkappaBalpha-SR expression leads to decreased expression of glutamate decarboxylase 65 (GAD65), the enzyme required for synthesis of the major inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) in GABAergic interneurons. IkappaBalpha-SR expression also results in diminished basal GluR1 levels and impaired synaptic strength (input/output function), both of which are fully restored following activity-based task learning. Consistent with diminished GAD65-derived inhibitory tone and enhanced excitatory firing, IkappaBalpha-SR+ mice exhibit increased late-phase long-term potentiation, hyperactivity, seizures, increased exploratory activity, and enhanced spatial learning and memory. IkappaBalpha-SR+ neurons also express higher levels of the activity-regulated, cytoskeleton-associated (Arc) protein, consistent with neuronal hyperexcitability. These findings suggest that NF-kappaB/Rel transcription factors act as pivotal regulators of activity-dependent inhibitory and excitatory neuronal function regulating synaptic plasticity and memory.

Protecting the synapse: evidence for a rational strategy to treat HIV-1 associated neurologic disease.

Loss of synaptic integrity and function appears to underlie neurologic deficits in patients with HIV-1-associated dementia (HAD) and other chronic neurodegenerative diseases. Because synaptic injury often long precedes neuronal death and surviving neurons possess a remarkable capacity for synaptic repair and functional recovery, we hypothesize that therapeutic intervention to protect synapses has great potential to improve neurologic function in HAD and other diseases. We discuss findings from both HAD and Alzheimer's disease to demonstrate that the disruption of synaptic structure and function that can occur during excitotoxic injury and neuroinflammation represents a likely substrate for neurologic deficits. Based on available evidence, we provide a rationale for future studies aimed at identifying molecular targets for synaptic protection in neurodegenerative disease. Whereas patients with HAD beginning antiretroviral therapy have shown reversal of neurologic symptoms that is unique for patients with chronic neurodegenerative conditions, we propose that the potential for such reversal is not unique.

Synaptic activity becomes excitotoxic in neurons exposed to elevated levels of platelet-activating factor.

Neurologic impairment in HIV-1-associated dementia (HAD) and other neuroinflammatory diseases correlates with injury to dendrites and synapses, but how such injury occurs is not known. We hypothesized that neuroinflammation makes dendrites susceptible to excitotoxic injury following synaptic activity. We report that platelet-activating factor, an inflammatory phospholipid that mediates synaptic plasticity and neurotoxicity and is dramatically elevated in the brain during HAD, promotes dendrite injury following elevated synaptic activity and can replicate HIV-1-associated dendritic pathology. In hippocampal slices exposed to a stable platelet-activating factor analogue, tetanic stimulation that normally induces long-term synaptic potentiation instead promoted development of calcium- and caspase-dependent dendritic beading. Chemical preconditioning with diazoxide, a mitochondrial ATP-sensitive potassium channel agonist, prevented dendritic beading and restored long-term potentiation. In contrast to models invoking excessive glutamate release, these results suggest that physiologic synaptic activity may trigger excitotoxic dendritic injury during chronic neuroinflammation. Furthermore, preconditioning may represent a novel therapeutic strategy for preventing excitotoxic injury while preserving physiologic plasticity.