Expression Of Receptor Subunits Research Articles

Profiling GABA(A) Receptor Subunit Expression in the Hippocampus of PMDD Rat Models Based on TCM Theories.

γ-Aminobutyric acid type A receptors (GABAARs) play an important role in cognitive and emotional regulation and are related to the hippocampus. However, little is known regarding patterns of hippocampal GABAAR subunit expression in rat models of premenstrual dysphoric disorder (PMDD). This study investigated the above changes by establishing two PMDD rat models based on Traditional Chinese Medicine (TCM) theories, namely, PMDD liver-qi invasion syndrome (PMDD-LIS) and PMDD liver-qi depression syndrome (PMDD-LDS). Behavioral tests were used to detect depression and irritability emotion. Western blot analysis was used to investigate protein levels of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits, whereas ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis was performed to determine gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in the hippocampus across each group. Concurrently, behavioral data indicated that the PMDD-LDS and PMDD-LIS rat models had been successfully established. GABAAR α2, α5, β2, and δ subunit was significantly upregulated, whereas α4 was significantly downregulated (P < 0.05) in PMDD-LDS rat models relative to controls. On the other hand, GABAAR α1, α2, and β3 were significantly downregulated while α4 and β2 were significantly upregulated in PMDD-LIS rat models relative to the control group (P < 0.05). Moreover, GABA levels significantly decreased, while Glu and the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conversely, GABA and Glu levels significantly decreased, whereas the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conclusively, our results revealed differential expression of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits between PMDD-LIS and PMDD-LDS rat models, suggesting that they may be biomarkers in the pathogenesis of PMDD.

Cognitive Flexibility in Mice: Effects of Puberty and Role of NMDA Receptor Subunits.

Cognitive flexibility refers to the ability to adapt flexibly to changing circumstances. In laboratory mice, we investigated whether cognitive flexibility is higher in pubertal mice than in adult mice, and whether this difference is related to the expression of distinct NMDA receptor subunits. Using the attentional set shifting task as a measure of cognitive flexibility, we found that cognitive flexibility was increased during puberty. This difference was more pronounced in female pubertal mice. Further, the GluN2A subunit of the NMDA receptor was more expressed during puberty than after puberty. Pharmacological blockade of GluN2A reduced the cognitive flexibility of pubertal mice to adult levels. In adult mice, the expression of GluN2A, GluN2B, and GluN2C in the orbitofrontal cortex correlated positively with performance in the attentional set shifting task, whereas in pubertal mice this was only the case for GluN2C. In conclusion, the present study confirms the observation in humans that cognitive flexibility is higher during puberty than in adulthood. Future studies should investigate whether NMDA receptor subunit-specific agonists are able to rescue deficient cognitive flexibility, and whether they have the potential to be used in human diseases with deficits in cognitive flexibility.

Intermittent treatment with Apremilast, a phosphodiesterase-4 inhibitor, ameliorates Alzheimer's-like pathology and symptoms through multiple targeting actions in aged T2D rats.

Apremilast (Apre), a novel phosphodiesterase-4 (PDE4) inhibitor, has been shown to have anti-inflammatory, immunomodulator, neuroprotective and senolytic properties, therefore, Apre like other PDE4 inhibitors may be a promising candidate for treatment of Alzheimer's disease (AD). To evaluate the effectiveness of Apre on Alzheimer's like pathology and symptoms in an animal model. The effects of Apre and cilostazol, a reference drug, on the behavioral, biochemical, and pathological features of Alzheimer's disease induced by a high-fat/high-fructose diet combined with low-dose streptozotocin (HF/HFr/l-STZ) were investigated. Apre 5mg/kg IP/day for 3 consecutive days per week for 8weeks attenuated memory and learning deficits tested by novel object recognition, Morris water maze and passive avoidance tests. Apre treatment significantly decreased the number of degenerating cells, and abnormal suppression of gene expression of AMPA and NMDA receptor subunits in the cortex and hippocampus of the AD rat model compared to rats that received vehicle. A significant decrease in elevated levels of hippocampal amyloid beta, tau-positive cell count, cholinesterase activity, and hippocampal caspase-3, a biomarker of neurodegeneration, was also observed after treatment with Apre in AD rats compared to rats that received placebo. Furthermore, a significant decrease in pro-inflammatory cytokines, oxidative stress, insulin resistance and GSK-3 was demonstrated in AD aged rats treated by Apre. Our findings demonstrate that intermittent treatment with Apre can enhance cognitive function in HF/HFr/l-STZ rats which may be related to decreased pro-inflammatory cytokines, oxidative stress, insulin resistance and GSK-3β.

Alterations in the properties of the glutamatergic system of the rat hippocampus in a lithium-pilocarpine model of temporal lobe epilepsy

Status epilepticus (SE) triggers many pathological changes in the nervous system that are not yet fully understood and may lead to the development of epilepsy. In this work, we studied the effects of SE on the properties of excitatory glutamatergic transmission in the hippocampus in a rat model of lithium-pilocarpine temporal lobe epilepsy. Studies were performed 1 day (acute phase of the model), 3 and 7 days (latent phase), and 30 to 80 days (chronic phase) after SE. Using real-time PCR, we found that in the latent phase there is a decrease in gene expression of GluA1 and GluA2 AMPA receptor subunits, which may also be accompanied by an increased proportion of calcium-permeable AMPA receptors, which play an essential role in the pathogenesis of many CNS diseases. In acute brain slices we found a decrease in the efficiency of excitatory synaptic neurotransmission in all phases of the model when recording field responses in the CA1 region of the hippocampus in response to stimulation of Schaffer collaterals by electric currents of different intensities. However, in the chronic phase we found an increase in the frequency of spontaneous excitatory postsynaptic potentials, indicating an increased background activity of the glutamatergic system in epilepsy. This is also supported by a decrease in the threshold of hind limb extension in the test of maximal electroshock seizure in rats with temporal lobe epilepsy compared to control animals. The results obtained indicate the presence of a number of functional alterations in the glutamatergic system related to epilepsy. These findings can be used to develop antiepileptogenic therapy.

RAGE signaling pathway is involved in CUS-induced depression-like behaviors by regulating the expression of NR2A and NR2B in rat hippocampus DG.

NMDA receptors play pivotal roles in the neurobiology of chronic stress-induced mood disorders. But the mechanism for chronic stress to disturb the expression of NMDA receptor subunits is still unclear. Recent researches indicated the involvement RAGE signaling pathway in regulation of glutamate system functions. In this study, we hypothesized RAGE signaling pathway mediated chronic stress-induced alteration in the expression of NMDA receptor subunits, leading to depressive-like behaviors. CUS decreased the expression of RAGE, NR2A, and NR2B, inhibited the phosphorylation of transcript factor ERK and CREB in rat hippocampus DG. RAGE knockdown in hippocampus DG by RAGE shRNA lentiviral particles induced depressive-like behaviors, reduced the mRNA and protein expression of NR2A and NR2B, and inhibited the phosphorylation of ERK and CREB. RAGE over-expression in hippocampus DG by RAGE adenovirus particles reversed the effects of CUS on depressive-like behaviors, ERK and CREB phosphorylation, and NR2A and NR2B expression. Our findings suggests that RAGE signaling pathway at least partially participates in the regulation of NR2A and NR2B expression, which mediates the effects of chronic stress on the depressive-like behaviors. These data provide evidence for RAGE signaling as a possible new pathway through which chronic stress results in the maladaptation of NMDA receptors.

Tebuconazole mediates cognitive impairment via the microbe-gut-brain axis (MGBA) in mice

Tebuconazole, one of the most widely used triazole fungicides, is reported to potentially pose a risk of inducing neurological disorders in human beings. Considering the increasing exposure, whether it could influence cognitive function remains to be elucidated. Herein, we used a mouse model to evaluate the potential cognitive risks and possible mechanisms from the continuous edible application of tebuconazole at low concentrations. Our study revealed that tebuconazole deteriorated spatial learning and memory and downregulated the expression of glutamate receptor subunits. Importantly, metagenomic analysis indicated that tebuconazole not only led to significant shifts in the composition and diversity of the gut microbiota but also changed intestinal homeostasis. Specifically, after exposure, tebuconazole circulated in the bloodstream and largely entered the gut–brain axis for disruption, including disturbing the Firmicutes/Bacteroidetes ratio, interrelated neurotransmitters and systemic immune factors. Moreover, pretreatment with probiotics improved immune factor expression and restored the deterioration of synaptic function and spatial learning and memory. The current study provides novel insights concerning perturbations of the gut microbiome and its functions as a potential new mechanism by which tebuconazole exposes cognitive function-related human health.

Sex differences in the neuroadaptations associated with incubated cocaine-craving: A focus on the dorsomedial prefrontal cortex.

Women have a shorter course from initial cocaine use to meeting the criteria for cocaine use disorder as compared to men. Preclinical findings similarly indicate that females develop key features of an addiction-like phenotype faster than males, including an enhanced motivation for cocaine and compulsive use, indicating that this phenomenon is biologically based. The goals of this study were to determine whether cocaine-craving, another key feature of addiction, also develops sooner during withdrawal in females than males and to determine whether there are sex differences in the molecular mechanisms associated with its development focusing on markers known to mediate cocaine-craving in males (i.e., dorsomedial prefrontal cortex, dmPFC, expression of brain-derived neurotrophic factor exon-IV, Bdnf-IV, and NMDA receptor subunits, Grin2a, Grin2b, and Grin1). Cocaine-craving was assessed following extended-access cocaine self-administration and 2, 7, or 14 days of withdrawal using an extinction/cue-induced reinstatement procedure. Tissue was obtained from the dmPFC immediately after reinstatement testing and gene expression changes were analyzed using real-time qPCR. In males, cocaine-craving (total extinction and cue-induced reinstatement responding) progressively increased from early to later withdrawal time-points whereas in females, cocaine-craving was already elevated during early withdrawal (after 2 days) and did not further increase at later withdrawal time-points. Levels of cocaine-craving, however, were similar between the sexes. Gene expression changes differed markedly between the sexes such that males showed the expected relapse- and withdrawal-associated changes in Bdnf-IV, Grin2a, Grin2b, and Grin1 expression, but females only showed a modest increase Grin1 expression at the intermediate withdrawal timepoint. These findings indicate that cocaine-craving is similarly expressed in males and females although the time-course for its incubation appears to be accelerated in females; the molecular mechanisms also likely differ in females versus males.

Profiling prefrontal cortex protein expression in rats exhibiting an incubation of cocaine craving following short-access self-administration procedures.

Incubation of drug-craving refers to a time-dependent increase in drug cue-elicited craving that occurs during protracted withdrawal. Historically, rat models of incubated cocaine craving employed extended-access (typically 6 h/day) intravenous drug self-administration (IV-SA) procedures, although incubated cocaine craving is reported to occur following shorter-access IV-SA paradigms. The notoriously low-throughput of extended-access IV-SA prompted us to determine whether two different short-access IV-SA procedures akin to those in the literature result in qualitatively similar changes in glutamate receptor expression and the activation of downstream signaling molecules within prefrontal cortex (PFC) subregions as those reported previously by our group under 6h-access conditions. For this, adult, male Sprague-Dawley rats were trained to intravenously self-administer cocaine for 2 h/day for 10 consecutive days (2-h model) or for 6 h on day 1 and 2 h/day for the remaining 9 days of training (Mixed model). A sham control group was also included that did not self-administer cocaine. On withdrawal day 3 or 30, rats were subjected to a 2-h test of cue-reinforced responding in the absence of cocaine and a time-dependent increase in drug-seeking was observed under both IV-SA procedures. Immunoblotting of brain tissue collected immediately following the cue test session indicated elevated phospho-Akt1, phospho-CaMKII and Homer2a/b expression within the prelimbic subregion of the PFC of cocaine-incubated rats. However, we failed to detect incubation-related changes in Group 1 metabotropic glutamate receptor or ionotropic glutamate receptor subunit expression in either subregion. These results highlight further a role for Akt1-related signaling within the prelimbic cortex in driving incubated cocaine craving, and provide novel evidence supporting a potential role also for CaMKII-dependent signaling through glutamate receptors in this behavioral phenomenon.

Prolonged zaleplon treatment affects NR2A receptor subunit expression in the prefrontal cortex of rats

Prolonged zaleplon treatment affects NR2A receptor subunit expression in the prefrontal cortex of rats

Maternal Hyperhomocysteinemia Produces Memory Deficits Associated with Impairment of Long-Term Synaptic Plasticity in Young Rats

Maternal hyperhomocysteinemia (HCY) is a common pregnancy complication caused by high levels of the homocysteine in maternal and fetal blood, which leads to the alterations of the cognitive functions, including learning and memory. In the present study, we investigated the mechanisms of these alterations in a rat model of maternal HCY. The behavioral tests confirmed the memory impairments in young and adult rats following the prenatal HCY exposure. Field potential recordings in hippocampal slices demonstrated that the long-term potentiation (LTP) was significantly reduced in HCY rats. The whole-cell patch-clamp recordings in hippocampal slices demonstrated that the magnitude of NMDA receptor-mediated currents did not change while their desensitization decreased in HCY rats. No significant alterations of glutamate receptor subunit expression except GluN1 were detected in the hippocampus of HCY rats using the quantitative real-time PCR and Western blot methods. The immunofluorescence microscopy revealed that the number of synaptopodin-positive spines is reduced, while the analysis of the ultrastructure of hippocampus using the electron microscopy revealed the indications of delayed hippocampal maturation in young HCY rats. Thus, the obtained results suggest that maternal HCY disturbs the maturation of hippocampus during the first month of life, which disrupts LTP formation and causes memory impairments.

Altered GABAA Receptor Expression in the Primary Somatosensory Cortex of a Mouse Model of Genetic Absence Epilepsy

Absence seizures are hyperexcitations within the cortico-thalamocortical (CTC) network, however the underlying causative mechanisms at the cellular and molecular level are still being elucidated and appear to be multifactorial. Dysfunctional feed-forward inhibition (FFI) is implicated as one cause of absence seizures. Previously, we reported altered excitation onto parvalbumin-positive (PV+) interneurons in the CTC network of the stargazer mouse model of absence epilepsy. In addition, downstream changes in GABAergic neurotransmission have also been identified in this model. Our current study assessed whether dysfunctional FFI affects GABAA receptor (GABAAR) subunit expression in the stargazer primary somatosensory cortex (SoCx). Global tissue expression of GABAAR subunits α1, α3, α4, α5, β2, β3, γ2 and δ were assessed using Western blotting (WB), while biochemically isolated subcellular fractions were assessed for the α and δ subunits. We found significant reductions in tissue and synaptic expression of GABAAR α1, 18% and 12.2%, respectively. However, immunogold-cytochemistry electron microscopy (ICC-EM), conducted to assess GABAAR α1 specifically at synapses between PV+ interneurons and their targets, showed no significant difference. These data demonstrate a loss of phasic GABAAR α1, indicating altered GABAergic inhibition which, coupled with dysfunctional FFI, could be one mechanism contributing to the generation or maintenance of absence seizures.

Antidepressant-induced increase in GluA2 expression does not translate in changes of AMPA receptor-mediated synaptic transmission at CA3/CA1 synapses in rats

Chronic treatment with serotonin selective reuptake inhibitors or tryciclic antidepressant drugs in rodents has been shown to increase the expression of GluA1 and/or GluA2 AMPA receptor (AMPAR) subunits in several brain areas, including the hippocampus. These changes in AMPAR composition have been suggested to result in increased glutamatergic neurotransmission and possibly underlie enhanced hippocampal synaptic plasticity through the increased availability of calcium-permeable AMPARs, specifically at CA3/CA1 synapses. However, the possibility that chronic treatment with antidepressants actually results in strengthened glutamatergic neurotransmission in CA1 has poorly been investigated. Here, we studied whether chronic treatment with the multimodal antidepressant drug trazodone mimicked the effect of paroxetine on the expression of AMPAR subunits in male wistar rat hippocampus and whether these drugs produced a parallel facilitation of field excitatory postsynaptic potentials (fEPSP) responses evoked by activation of CA3/CA1 synapses in dorsal hippocampal slices. In addition, we investigated whether the quality of glutamatergic AMPARs involved in basal neurotransmission was changed by altered subunit expression, e.g. leading to appearance of calcium-permeable AMPARs. We found a significant increase in GluA2 subunit expression following treatment with trazodone or paroxetine for twenty-one days, but not after seven-days treatment. In contrast, we did not find any significant changes in fEPSP responses supporting either a facilitation of glutamatergic neurotransmission in basal conditions or the appearance of functional calcium-permeable AMPARs at CA3/CA1 pyramidal neuron synapses. Thus, neurochemically-detected increases in the expression of AMPAR subunits cannot directly be extrapolated in increased number of functioning receptors and/or facilitated basal neurotransmission.

Effects of nicotine and lipopolysaccharide stimulation on adhesion molecules in human gingival endothelial cells.

Smoking is a risk factor for periodontitis, and the immune response of periodontal tissues in patients with periodontitis may be strongly affected by smoking. The purpose of this study was to elucidate the bioactivity and signal transduction of human gingival endothelial cells (HGECs) due to nicotinic stimulation using a cultured medium supplemented with lipopolysaccharide (LPS) as a model of periodontitis. HGECs were cultured in medium supplemented with LPS, nicotine, nicotine + LPS, and medium supplemented without nicotine or LPS (control). Cell proliferation was assessed using Alamar blue. Cytotoxicity was assessed by lactate dehydrogenase leakage. The expression of adhesion molecule-1 (ICAM-1, VCAM-1) was assessed by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay. The expression of nicotinic acetylcholine receptor (nAChR) subunits (α3, α5, α7, β2 and β4) was evaluated by RT-PCR. The involvement of p38 mitogen-activated protein kinase (p38MAPK) and protein kinase C (PKC) cell signaling pathways in ICAM-1 and VCAM-1 expression was investigated by RT-qPCR with specific inhibitors. HGECs stimulated with LPS, nicotine and nicotine + LPS showed inhibition of cell proliferation, increase of cell death, and increase of gene and protein expression of ICAM-1. Moreover, HGECs showed the presence of α5 and α7 nAChR subunits. The expression of ICAM-1 in HGECs stimulated with LPS, nicotine, and nicotine + LPS was significantly suppressed by p38MAPK inhibitor, but not by a PKC inhibitor. The nAChR subunits of HGECs are α5 and α7, and that HGECs stimulated with nicotine and LPS express ICAM-1 via p38MAPK pathway.

Cortical neuronal hyperexcitability and synaptic changes in SGCE mutation-positive myoclonus dystonia.

Myoclonus dystonia is a childhood-onset hyperkinetic movement disorder with a combined motor and psychiatric phenotype. It represents one of the few autosomal dominant inherited dystonic disorders and is caused by mutations in the ε-sarcoglycan (SGCE) gene. Work to date suggests that dystonia is caused by disruption of neuronal networks, principally basal ganglia-cerebello-thalamo-cortical circuits. Investigation of cortical involvement has primarily focused on disruption to interneuron inhibitory activity, rather than the excitatory activity of cortical pyramidal neurons. Here, we have sought to examine excitatory cortical glutamatergic activity using two approaches: the CRISPR/Cas9 editing of a human embryonic cell line, generating an SGCE compound heterozygous mutation, and three patient-derived induced pluripotent stem cell lines, each gene edited to generate matched wild-type SGCE control lines. Differentiation towards a cortical neuronal phenotype demonstrated no significant differences in either early- (PAX6, FOXG1) or late-stage (CTIP2, TBR1) neurodevelopmental markers. However, functional characterization using Ca2+ imaging and microelectrode array approaches identified an increase in network activity, while single-cell patch clamp studies found a greater propensity towards action potential generation with larger amplitudes and shorter half-widths associated with SGCE mutations. Bulk RNA sequencing analysis identified gene ontological enrichment for 'neuron projection development', 'synaptic signalling' and 'synaptic transmission'. Examination of dendritic morphology found SGCE mutations to be associated with a significantly higher number of branches and longer branch lengths, together with longer ion-channel dense axon initial segments, particularly towards the latter stages of differentiation (Days 80 and 100). Gene expression and protein quantification of key synaptic proteins (synaptophysin, synapsin and PSD95), AMPA and NMDA receptor subunits found no significant differences between the SGCE mutation and matched wild-type lines. By contrast, significant changes to synaptic adhesion molecule expression were identified, namely higher presynaptic neurexin-1 and lower postsynaptic neuroligin-4 levels in the SGCE mutation carrying lines. Our study demonstrates an increased intrinsic excitability of cortical glutamatergic neuronal cells in the context of SGCE mutations, coupled with a more complex neurite morphology and disruption to synaptic adhesion molecules. These changes potentially represent key components to the development of the hyperkinetic clinical phenotype observed in myoclonus dystonia, as well a central feature to the wider spectrum of dystonic disorders, potentially providing targets for future therapeutic development.

Molecular Identification of Pro-Excitogenic Receptor and Channel Phenotypes of the Deafferented Lumbar Motoneurons in the Early Phase after SCT in Rats.

Spasticity impacts the quality of life of patients suffering spinal cord injury and impedes the recovery of locomotion. At the cellular level, spasticity is considered to be primarily caused by the hyperexcitability of spinal α-motoneurons (MNs) within the spinal stretch reflex circuit. Here, we hypothesized that after a complete spinal cord transection in rats, fast adaptive molecular responses of lumbar MNs develop in return for the loss of inputs. We assumed that early loss of glutamatergic afferents changes the expression of glutamatergic AMPA and NMDA receptor subunits, which may be the forerunners of the developing spasticity of hindlimb muscles. To better understand its molecular underpinnings, concomitant expression of GABA and Glycinergic receptors and serotoninergic and noradrenergic receptors, which regulate the persistent inward currents crucial for sustained discharges in MNs, were examined together with voltage-gated ion channels and cation-chloride cotransporters. Using quantitative real-time PCR, we showed in the tracer-identified MNs innervating extensor and flexor muscles of the ankle joint multiple increases in transcripts coding for AMPAR and 5-HTR subunits, along with a profound decrease in GABAAR, GlyR subunits, and KCC2. Our study demonstrated that both MNs groups similarly adapt to a more excitable state, which may increase the occurrence of extensor and flexor muscle spasms.

Pharmacological characterization and differential expression of NMDA receptor subunits in the chicken vestibular system during development.

Previous studies demonstrated that in vitro preparations of the isolated vestibular system of diverse animal species still exhibit stable resting electrical activity and mechanically evoked synaptic transmission between hair cells and primary afferent endings. However, there are no reports related to their neurodevelopment. Therefore, this research aimed to examine whether NMDA receptors mediate these electrical signals in an isolated preparation of the chicken vestibular system at three developmental stages, E15, E18, and E21. We found that the spontaneous and mechanically evoked discharges from primary afferents of the posterior semicircular canal were modulated by agonists NMDA and glycine, but not by the agonist d-serine applied near the synapses. Moreover, the individually applied by bath perfusion of three NMDA receptor antagonists (MK-801, ifenprodil, and 2-naphthoic acid) or high Mg2+ decreased the resting discharge rate, the NMDA response, and the discharge rate of mechanically evoked activity from these primary afferents. Furthermore, we found that the vestibular ganglion shows a stage-dependent increase in the expression of NMDA receptor subunits GluN1, GluN2 (A-C), and GluN3 (A-B), being greater at E21, except for GluN2D, which was inversely related to the developmental stage. However, in the crista ampullaris, the expression pattern remained constant throughout development. This could suggest the possible existence of presynaptic NMDA receptors. Our results highlight that although the NMDA receptors are functionally active at the early embryonic stages of the vestibular system, NMDA and glycine reach their mature functionality to increase NMDA responses close to hatching (E21).

Spinal cord injury is associated with changes in synaptic properties of the mouse major pelvic ganglion.

Spinal cord injury (SCI) has substantial impacts on autonomic function. In part, SCI results in loss of normal autonomic activity that contributes to injury-associated pathology such as neurogenic bladder, bowel, and sexual dysfunction. Yet little is known of the impacts of SCI on peripheral autonomic neurons that directly innervate these target organs. In this study, we measured changes in synaptic properties of neurons of the mouse major pelvic ganglion (MPG) associated with acute and chronic SCI. Our data show that functional and physiological properties of synapses onto MPG neurons are altered after SCI and differ between acute and chronic injury. After acute injury excitatory postsynaptic potentials (EPSPs) show increased rise and decay time constants leading to overall broader and longer EPSPs, whereas in chronic-injured animals EPSPs are reduced in amplitude and show faster rise and decay leading to shorter EPSPs. Synaptic depression and low-pass filtering are also altered in injured animals. Finally, cholinergic currents are smaller in acute-injured animals but larger in chronic-injured animals relative to control animals. These changes in synaptic properties are associated with differences in nicotinic receptor subunit expression as well. MPG CHRNA3 mRNA levels decreased after injury, whereas CHRNA4 mRNAs increased. Furthermore, changes in the correlations of α- and β-subunit mRNAs suggest that nicotinic receptor subtype composition is altered after injury. Taken together, our data demonstrate that peripheral autonomic neurons are fundamentally altered after SCI, suggesting that longer-term therapeutic approaches could target these neurons directly to potentially help ameliorate neurogenic target organ dysfunction.NEW & NOTEWORTHY Spinal cord injury (SCI) has substantial impacts on autonomic function, yet little is known of the impacts of SCI on autonomic neurons that directly innervate effectors impacted by injury. Here we investigated changes at the cellular level associated with SCI in neurons that are "downstream" of the central injury. An understanding of these off-target impacts of SCI ultimately will be critical in the context of effective restoration of function through neuromodulation of pharmacological therapeutic approaches.

Short- and Long-Term Effects of Suboptimal Selenium Intake and Developmental Lead Exposure on Behavior and Hippocampal Glutamate Receptors in a Rat Model.

Selenium (Se) is an essential trace element required for normal development as well as to counteract the adverse effects of environmental stressors. Conditions of low Se intake are present in some European countries. Our aim was to investigate the short- and long-term effects of early-life low Se supply on behavior and synaptic plasticity with a focus on the hippocampus, considering both suboptimal Se intake per se and its interaction with developmental exposure to lead (Pb). We established an animal model of Se restriction and low Pb exposure; female rats fed with an optimal (0.15 mg/kg) or suboptimal (0.04 mg/kg) Se diet were exposed from one month pre-mating until the end of lactation to 12.5 µg/mL Pb via drinking water. In rat offspring, the assessment of motor, emotional, and cognitive endpoints at different life stages were complemented by the evaluation of the expression and synaptic distribution of NMDA and AMPA receptor subunits at post-natal day (PND) 23 and 70 in the hippocampus. Suboptimal Se intake delayed the achievement of developmental milestones and induced early and long-term alterations in motor and emotional abilities. Behavioral alterations were mirrored by a drop in the expression of the majority of NMDA and AMPA receptor subunits analyzed at PND 23. The suboptimal Se status co-occurring with Pb exposure induced a transient body weight increase and persistent anxiety-like behavior. From the molecular point of view, we observed hippocampal alterations in NMDA (Glun2B and GluN1) and AMPA receptor subunit trafficking to the post-synapse in male rats only. Our study provides evidence of potential Se interactions with Pb in the developing brain.

Chronic caffeine consumption improves the acute sleep deprivation-induced spatial memory impairment while altering N-methyl-D-aspartate receptor subunit expression in male rats.

Caffeine is a psychostimulant substance that is mostly used to prevent fatigue, increase alertness, and ameliorate sleep loss situations. In this study, we aimed to investigate the effect of chronic caffeine consumption on learning and memory functions and related genes in rapid eye movement (REM) sleep-deprived rats. During the neonatal period (postnatal day [PND] 28) Wistar albino male rats (n = 32) were randomly assigned into four groups: Control (C), caffeine application (Cf), acute REM sleep-deprivation (RD), and caffeine application + acute RD (Cf + RD). The 48 h of RD was executed when caffeine administration was completed. The learning and memory performance was evaluated by the Morris water maze test (MWMT). Following this, the rats were decapitated to isolate hippocampus tissues. In MWMT, time spent in the targeted quadrant decreased significantly in the RD group compared with the C and Cf + RD group. NR2A expression level increased in the RD group compared with C, Cf, and Cf + RD groups (p < 0.05). NR2B expression level increased in RD and Cf + RD groups compared with C and Cf groups (p < 0.05). BDNF and c-Fos expression levels did not differ significantly between the groups. RD impaired hippocampal spatial memory performance in the MWMT test. Our results indicated that chronic caffeine consumption has a therapeutic effect on spatial memory deterioration impairment caused by RD. Furthermore, it seems that the effect of caffeine RD on the hippocampus may be mediated by NR2A.

Mice lacking α4 nicotinic acetylcholine receptors are protected against alcohol-associated liver injury.

Chronic heavy alcohol consumption is a major risk factor for the development of liver steatosis, fibrosis, and cirrhosis, but the mechanisms by which alcohol causes liver damage remain incompletely elucidated. This group has reported that α4 nicotinic acetylcholine receptors (α4 nAChRs) act as sensors for alcohol in lung cells. This study tested the hypothesis that α4 nAChRs mediate the effects of alcohol in the liver. Expression of acetylcholine receptor subunits in mouse liver was determined by RNA sequencing (RNA-seq). α4 nAChR knockout (α4 KO) mice were generated in C57BL/6J mice by introducing a mutation encoding an early stop codon in exon 4 of Chrna4, the gene encoding the α4 subunit of the nAChR. The presence of the inactivating mutation was established by polymerase chain reaction and genomic sequencing, and the lack of α4 nAChR function was confirmed in primary fibroblasts isolated from the α4 KO mice. Wild-type (WT) and α4 KO mice were fed the Lieber-DeCarli diet (with 36% of calories from alcohol) or pair fed an isocaloric maltose-dextrin control diet for a 6-week period that included a ramping up phase of increasing dietary alcohol. Chrna4 was the most abundantly expressed nAChR subunit gene in mouse livers. After 6 weeks of alcohol exposure, WT mice had elevated serum transaminases and their livers showed increased fat accumulation, decreased Sirt1 protein levels, and accumulation of markers of oxidative stress and inflammation including Cyp2E1, Nos2, Sod1, Slc7a11, TNFα, and PAI1. All these responses to alcohol were either absent or significantly attenuated in α4 KO animals. Together, these observations support the conclusion that activation of α4 nAChRs by alcohol or one of its metabolites is one of the initial events promoting the accumulation of excess fat and expression of inflammatory mediators. Thus, α4 nAChRs may represent viable targets for intervention in chronic alcohol-related liver disease.