Presynaptic CRF1 Receptors Mediate the Ethanol Enhancement of GABAergic Transmission in the Mouse Central Amygdala

Corticotropin-releasing factor (CRF) is a 41-amino-acid neuropeptide involved in stress responses initiated from several brain areas, including the amygdala formation. Research shows a strong relationship between stress, brain CRF, and excessive alcohol consumption. Behavioral studies suggest that the central amygdala (CeA) is significantly involved in alcohol reward and dependence. We recently reported that the ethanol augmentation of GABAergic synaptic transmission in rat CeA involves CRF1 receptors, because both CRF and ethanol significantly enhanced the amplitude of evoked GABAergic inhibitory postsynaptic currents (IPSCs) in CeA neurons from wild-type (WT) and CRF2 knockout (KO) mice, but not in neurons of CRF1 KO mice. The present study extends these findings using selective CRF receptor ligands, gene KO models, and miniature IPSC (mIPSC) analysis to assess further a presynaptic role for the CRF receptors in mediating ethanol effects in the CeA. In whole-cell patch recordings of pharmacologically isolated GABAAergic IPSCs from slices of mouse CeA, both CRF and ethanol augmented evoked IPSCs in a concentration-dependent manner, with low EC50s. A CRF1 (but not CRF2) KO construct and the CRF1-selective nonpeptide antagonist NIH-3 (LWH-63) blocked the augmenting effect of both CRF and ethanol on evoked IPSCs. Furthermore, the new selective CRF1 agonist stressin1, but not the CRF2 agonist urocortin 3, also increased evoked IPSC amplitudes. Both CRF and ethanol decreased paired-pulse facilitation (PPF) of evoked IPSCs and significantly enhanced the frequency, but not the amplitude, of spontaneous miniature GABAergic mIPSCs in CeA neurons of WT mice, suggesting a presynaptic site of action. The PPF effect of ethanol was abolished in CeA neurons of CRF1 KO mice. The CRF1 antagonist NIH-3 blocked the CRF- and ethanol-induced enhancement of mIPSC frequency in CeA neurons. These data indicate that presynaptic CRF1 receptors play a critical role in permitting or mediating ethanol enhancement of GABAergic synaptic transmission in CeA, via increased vesicular GABA release, and thus may be a rational target for the treatment of alcohol abuse and alcoholism

Procalcitonin Is Not a Reliable Biomarker of Bacterial Coinfection in People With Coronavirus Disease 2019 Undergoing Microbiological Investigation at the Time of Hospital Admission

Abstract Admission procalcitonin measurements and microbiology results were available for 1040 hospitalized adults with coronavirus disease 2019 (from 48 902 included in the International Severe Acute Respiratory and Emerging Infections Consortium World Health Organization Clinical Characterisation Protocol UK study). Although procalcitonin was higher in bacterial coinfection, this was neither clinically significant (median [IQR], 0.33 [0.11–1.70] ng/mL vs 0.24 [0.10–0.90] ng/mL) nor diagnostically useful (area under the receiver operating characteristic curve, 0.56 [95% confidence interval, .51–.60]).</jats:p

Delayed mucosal anti-viral responses despite robust peripheral inflammation in fatal COVID-19

Background While inflammatory and immune responses to SARS-CoV-2 infection in peripheral blood are extensively described, responses at the upper respiratory mucosal site of initial infection are relatively poorly defined. We sought to identify mucosal cytokine/chemokine signatures that distinguished COVID-19 severity categories, and relate these to disease progression and peripheral inflammation. Methods We measured 35 cytokines and chemokines in nasal samples from 274 patients hospitalised with COVID-19. Analysis considered the timing of sampling during disease, as either the early (0-5 days post-symptom onset) or late (6-20 days post-symptom onset). Results Patients that survived severe COVID-19 showed IFN-dominated mucosal immune responses (IFN-γ, CXCL10 and CXCL13) early in infection. These early mucosal responses were absent in patients that would progress to fatal disease despite equivalent SARS-CoV-2 viral load. Mucosal inflammation in later disease was dominated by IL-2, IL-10, IFN-γ, and IL-12p70, which scaled with severity but did not differentiate patients who would survive or succumb to disease. Cytokines and chemokines in the mucosa showed distinctions from responses evident in the peripheral blood, particularly during fatal disease. Conclusions Defective early mucosal anti-viral responses anticipate fatal COVID-19 but are not associated with viral load. Early mucosal immune responses may define the trajectory of severe COVID-19

Electrophysiological Evidence for Expression of Glycine Receptors in Freshly Isolated Neurons from Nucleus Accumbens

ABSTRACT In the course of studying N-methyl-D-aspartate (NMDA) receptors of the nucleus accumbens (NAcc), we found that 20% of freshly isolated medium spiny neurons, as well as all interneurons, responded in an unexpected way to long (5-s) coapplication of NMDA and glycine, the coagonist of NMDA receptors. Whereas the reversal potential of the peak NMDA current of this subset of neurons was still around 0 mV, the desensitizing current became outward at hyperpolarized potentials around Ϫ30 mV. A Cl Ϫ -free solution shifted the equilibrium potentials of the desensitized currents to around 0 mV. This outward current was not blocked by a Ca 2ϩ -free, Ba 2ϩ -containing solution, suggesting that the anionic conductance was not activated by Ca 2ϩ influx through NMDA receptor channels. Interestingly, glycine alone also evoked a current with a similar hyperpolarized reversal potential in this subset of neurons. The glycine current reversed around Ϫ50 mV, rectified outwardly, and inactivated strongly. Its desensitization was best fitted with a double exponential. Only the slow desensitization showed clear voltage dependence. The glycine current was not blocked by 200 M picrotoxin and 10 M zinc, was weakly antagonized by 1 M strychnine, and was not enhanced by 1 M zinc. In addition, 1 mM taurine, but not GABA, inactivated glycine currents, and 1 mM glycine occluded 10 mM taurine-mediated currents. These data indicate that a subset of nucleus accumbens neurons expresses glycine receptors and that either glycine or taurine could be an endogenous agonist for these receptors. The nucleus accumbens (NAcc), an interface region between limbic structures (hippocampus, amygdala, and prefrontal cortex) and the extrapyramidal motor system, modulates cognitive and motivational aspects of behavior that are translated into motor activity Glycine receptors, along with GABA receptors, represent the primary fast inhibitory mechanisms in the central nervous system. Activation of glycine receptors opens anionic channels that hyperpolarize neurons. Until recently, it was generally believed that glycine receptors were almost exclusively found in the spinal cord and brainstem of adult rats Glycine receptors are heteromultimeric receptors. Molecular approaches have revealed a certain diversity of glycine receptor subunits. To date, four different ␣ and one ␤ subunit have been identifie

Interleukin-1 Interacts with Ethanol Effects on GABAergic Transmission in the Mouse Central Amygdala

Neuroinflammation is hypothesized to enhance alcohol consumption and contribute to the development of alcoholism. GABAergic transmission in the central amygdala (CeA) plays an important role in the transition to alcohol dependence. Therefore, we studied the effects of interleukin-1β (IL-1β) a proinflammatory cytokine mediating ethanol-induced neuroinflammation, and its interaction with ethanol on CeA GABAegic transmission in B6129SF2/J mice. We also assessed ethanol intake in B6129SF2/J mice. Intake with unlimited (24 hours) ethanol access was 9.2-12.7 g/kg (3-15% ethanol), while limited (2 hours) access produced an intake of 4.1±0.5 g/kg (15% ethanol). In our electrophysiology experiments, we found that recombinant IL-1β (50 and 100 ng/ml) significantly decreased the amplitude of evoked inhibitory postsynaptic potentials (eIPSPs), with no significant effects on paired-pulse facilitation (PPF). IL-1beta (50 ng/ml) had dual effects on spontaneous miniature inhibitory postsynaptic currents (mIPSCs): increasing mIPSC frequencies in most CeA neurons, but decreasing both mIPSC frequencies and amplitudes in a few cells. The IL-1β receptor antagonist (IL-1ra; 100 ng/ml) also had dual effects on mIPSCs and prevented the actions of IL-1β on mIPSC frequencies. These results suggest that IL-1β can alter CeA GABAergic transmission at pre- and postsynaptic sites. Ethanol (44 mM) significantly increased eIPSP amplitudes, decreased PPFs, and increased mIPSC frequencies. IL-1β did not alter ethanol’s enhancement of the eIPSP amplitude, but, in IL-1β-responsive neurons, the ethanol effects on mIPSC frequencies were lost. Overall, our data suggest that the IL-1 system is involved in basal GABAergic transmission and that IL-1β interacts with the ethanol-induced facilitation of CeA GABAergic transmission