Altered theta and beta oscillatory synchrony in a genetic mouse model of pathological anxiety.

While the neural circuits mediating normal, adaptive defensive behaviors have been extensively studied, substantially less is currently known about the network mechanisms by which aberrant, pathological anxiety is encoded in the brain. Here we investigate in mice how deletion of Neuroligin-2 (Nlgn2), an inhibitory synapse-specific adhesion protein that has been associated with pathological anxiety and other psychiatric disorders, alters the communication between key brain regions involved in mediating defensive behaviors. To this end, we performed multi-site simultaneous local field potential (LFP) recordings from the basolateral amygdala (BLA), centromedial amygdala (CeM), bed nucleus of the stria terminalis (BNST), prefrontal cortex (mPFC) and ventral hippocampus (vHPC) in an open field paradigm. We found that LFP power in the vHPC was profoundly increased and was accompanied by an abnormal modulation of the synchrony of theta frequency oscillations particularly in the vHPC-mPFC-BLA circuit. Moreover, deletion of Nlgn2 increased beta and gamma frequency synchrony across the network, and this increase was associated with increased center avoidance. Local deletion of Nlgn2 in the vHPC and BLA revealed that they encode distinct aspects of this avoidance phenotype, with vHPC linked to immobility and BLA linked to a reduction in exploratory activity. Together, our data demonstrate that alterations in long-range functional connectivity link synaptic inhibition to abnormal defensive behaviors, and that both exaggerated activation of normal defensive circuits and recruitment of fundamentally distinct mechanisms contribute to this phenotype. Nlgn2 knockout mice therefore represent a highly relevant model to study the role of inhibitory synaptic transmission in the circuits underlying anxiety disorders.

Comparison of real-ear insertion gains in Japanese-speaking individuals wearing hearing aids with DSLv5 and NAL-NL2.

OBJECTIVE: We used real-ear insertion gain (REIG), with the international speech test signal (ISTS), to evaluate the amplifying characteristics of hearing aids, set for patients who have been wearing such aids for a long time in a stable manner. We further compared this to the target values of the DSLv5 and NAL-NL2 methods. METHODS: The subjects were adults with moderate sensorineural hearing loss. We examined 40 ears in 25 individuals (15 people wearing hearing aids in both ears and ten people wearing aid in only one ear). Fit assessments were performed based on the speech performance-intensity functions and tolerance of environmental noise, and the ears studied were categorized as either ears with sufficient benefit or ears with insufficient benefit. Additionally, we evaluated the REIG for international speech test signals at 65-dB and 80-dB sound pressure level (SPL). We compared the REIG and target values for voice input at 65-dB and 80-dB SPL, calculated from the DSLv5 and NAL-NL2 methods. RESULTS: Among the 40 ears, 34 received sufficient benefit and six received an insufficient benefit from hearing aids. The REIG for ISTS at 65-dB in the sufficient benefit ears, at frequencies of 1,000 Hz and 2,000 Hz, were similar to the target values of NAL-NL2 and DSLv5 but were significantly lower at 250 Hz, 500 Hz, and 4,000 Hz frequencies. The compression ratio of REIG for sufficient benefit ears was similar to that of DSLv5. The REIG for ISTS at 65-dB in the insufficient benefit ears was smaller than that in the sufficient benefit ears at frequencies of 2,000 Hz and 4,000 Hz. CONCLUSION: This study suggested that the target values of NAL-NL2 and DSLv5 are appropriate, even for Japanese-speaking individuals, at mid-pitch sounds. Although it is necessary to investigate the necessity for low-pitch and high-pitch gains further in the future, this study provides meaningful data regarding the amplifying characteristics in Japanese-speaking individuals who have been wearing hearing aids in a stable manner.

A quantitative LC-MS/MS method for determination of thiazolidinedione mitoNEET ligand NL-1 in mouse serum suitable for pharmacokinetic studies.

Thiazolidinedione (TZD) compounds have shown promise as antidiabetic, antibiotics, antifungal and neuroprotective agents. The mitochondrial effect of a novel mitoNEET ligand, NL-1 {5-[(3,5-di-tert-butyl-4-hydroxyphenyl)methyl]-1,3-thiazolidine-2,4-dione}, and other TZD compounds, is a newly proposed mechanism for the neuroprotective action of these TZD compounds. In this work, a sensitive LC-MS/MS assay has been developed and validated for quantification of NL-1 in mouse serum. Sample preparation involved an acetonitrile protein precipitation procedure with addition of an internal standard NL-2 {5-[(4-hydroxy-3,5-dimethyl-phenyl)methyl]thiazolidine-2,4-dione}. LC-MS/MS analysis utilized a Columbus C-18 HPLC column (2mm×50mm, 5µm). Chromatography employed a multiple step gradient program that featured a steep linear gradient (25-95% in 0.5min) of 15µM ammonium acetate (additive for eliminating carry-over) in 2% methanol mixing with increasing proportions of 100% methanol. The HPLC was interfaced to a QTrap 5500 mass spectrometer (AB Sciex) equipped with an electrospray ionization source used in a negative ionization mode. Multiple reaction monitoring (MRM) of m/z 334→263 for NL-1 and m/z 250→179 for NL-2 was done. The method had a linear range of at least 1-100ng/mL in serum. The intra-assay and inter-assay percent coefficient of variation (%CV) were less than 4% and accuracies (%RE) ranged from -2.7% to 2.0%. The analytical procedure gave 96-115% absolute extraction recovery of NL-1. The relative matrix effect was measured and found to be insignificant. The analyte in serum was confirmed to be stable during storage and treatment. The method is suitable for pharmacokinetic (PK) studies of the parent drug NL-1 based on the preliminary serum results from dosed NL-1 mouse studies.