Reduced CaM Kinase II and CaM Kinase IV Activities Underlie Cognitive Deficits in NCKX2 Heterozygous Mice

Anxiolytic effects of Enterococcus faecalis 2001 on a mouse model of colitis

Ulcerative colitis (UC) is a refractory inflammatory bowel disease, which is known to cause psychiatric disorders such as anxiety and depression at a high rate in addition to peripheral inflammatory symptoms. However, the pathogenesis of these psychiatric disorders remains mostly unknown. While prior research revealed that the Enterococcus faecalis 2001 (EF-2001) suppressed UC-like symptoms and accompanying depressive-like behaviors, observed in a UC model using dextran sulfate sodium (DSS), whether it has an anxiolytic effect remains unclear. Therefore, we examined whether EF-2001 attenuates DSS-induced anxiety-like behaviors. Treatment with 2% DSS for seven days induced UC-like symptoms and anxiety-like behavior through the hole-board test, increased serum lipopolysaccharide (LPS) and corticosterone concentration, and p-glucocorticoid receptor (GR) in the prefrontal cortex (PFC), and decreased N-methyl-D-aspartate receptor subunit (NR) 2A and NR2B expression levels in the PFC. Interestingly, these changes were reversed by EF-2001 administration. Further, EF-2001 administration enhanced CAMKII/CREB/BDNF-Drebrin pathways in the PFC of DSS-treated mice, and labeling of p-GR, p-CAMKII, and p-CREB showed colocalization with neurons. EF-2001 attenuated anxiety-like behavior by reducing serum LPS and corticosterone levels linked to the improvement of UC symptoms and by facilitating the CAMKII/CREB/BDNF-Drebrin pathways in the PFC. Our findings suggest a close relationship between UC and anxiety.

Does the enriched environment alter memory capacity in malnourished rats by modulating BDNF expression?

Environmental factors interfere in the neural plasticity processes. Among these, malnutrition in the early stages of life stands out as one of the main non-genetic factors that can interfere in the morphofunctional development of the nervous system. Furthermore, sensory stimulation from enriched environments (EE) also interferes with neural development. These two factors can modify areas related to memory and learning as the hippocampus, through mechanisms related to the gene expression of brain-derived neurotrophic factor (BDNF). The BDNF may interfere in synaptic plasticity processes, such as memory. In addition, these changes in early life may affect the functioning of the hippocampus during adulthood through mechanisms mediated by BDNF. Therefore, this study aims to conduct a literature review on the effects of early malnutrition on memory and the relationship between the underlying mechanisms of EE, BDNF gene expression, and memory. In addition, there are studies that demonstrate the effect of EE reversal on exposure to changes in the functioning of hippocampal malnutrition in adult rats that were prematurely malnourished. Thereby, evidence from the scientific literature suggests that the mechanisms of synaptic plasticity in the hippocampus of adult animals are influenced by malnutrition and EE, and these alterations may involve the participation of BDNF as a key regulator in memory processes in the adult animal hippocampus.

DL0410 ameliorates cognitive disorder in SAMP8 mice by promoting mitochondrial dynamics and the NMDAR-CREB-BDNF pathway

Alzheimer's disease (AD) is a worldwide problem and there are no effective drugs for AD treatment. Previous studies show that DL0410 is a multi-target, anti-AD agent. In this study, we investigated the therapeutic effect of DL0410 and its action mechanism in SAMP8 mice. DL0410 (1-10 mg·kg^-1·d^-1) was orally administered to 8-month-old SAMP mice (SAMP8) for 8 weeks. We showed that DL0410 administration effectively ameliorated the cognitive deficits in the Morris water maze test, novel object recognition test, and nest building test. We revealed that DL0410 dose-dependently increased the expression levels of the mitochondrial proteins (PGC-1α, Mitofusin 2, OPA1, and Drp1), and subsequently ameliorated the processes of mitochondrial biosynthesis, fusion, and fission in the cortex and hippocampus of SAMP8 mice. Furthermore, DL0410 administration promoted the expression of synaptic proteins (synaptophysin and PSD95) in the brain of SAMP8 mice, and upregulated the protein phosphorylation in NMDAR-CAMKII/CAMKIV-CREB pathway responsible for the synaptic plasticity. DL0410 administration dose-dependently increased the expression of BDNF and TrkB, and the neurotrophic effect was mediated via the ERK1/2 and PI3K-AKT-GSK-3β pathways. DL0410 administration upregulated Bcl-2, increased the Bcl-2/Bax ratio and the level of caspase 3 and PARP-1, alleviating neuronal apoptosis. We proposed that the NMDAR-CREB-BDNF pathway might establish a positive feedback loop between synaptic plasticity and neurotrophy, with CREB at the center. In summary, DL0410 promotes synaptic function and neuronal survival, thus ameliorating cognitive deficits in SAMP8 mice via improved mitochondrial dynamics and increased activity of the NMDAR-CREB-BDNF pathway. DL0410 is a promising candidate to treat aging-related AD, and deserves more research and development in future.

The Calcium/Calmodulin-Dependent Kinases II and IV as Therapeutic Targets in Neurodegenerative and Neuropsychiatric Disorders

CaMKII and CaMKIV are calcium/calmodulin-dependent kinases playing a rudimentary role in many regulatory processes in the organism. These kinases attract increasing interest due to their involvement primarily in memory and plasticity and various cellular functions. Although CaMKII and CaMKIV are mostly recognized as the important cogs in a memory machine, little is known about their effect on mood and role in neuropsychiatric diseases etiology. Here, we aimed to review the structure and functions of CaMKII and CaMKIV, as well as how these kinases modulate the animals’ behavior to promote antidepressant-like, anxiolytic-like, and procognitive effects. The review will help in the understanding of the roles of the above kinases in the selected neurodegenerative and neuropsychiatric disorders, and this knowledge can be used in future drug design.

Kir6.1 Heterozygous Mice Exhibit Aberrant Amygdala-Dependent Cued Fear Memory

ATP-sensitive K⁺ (K_ATP) channels are predominantly expressed in the brain and consist of four identical inward-rectifier potassium ion channel subunits (Kir6.1 or Kir6.2) and four identical high-affinity sulfonylurea receptor subunits (SUR1, SUR2A, or SUR2B). We previously observed that chronic corticosterone-treated (CORT) mice exhibited enhanced anxiety-like behaviors and cued fear memory. In the present study, the protein and mRNA expression levels of Kir6.1, but not Kir6.2, were decreased in the lateral amygdala (LA) of CORT mice. Heterozygous Kir6.1-null (Kir6.1^+/-) mice also showed enhanced tone (cued) fear memory and long-term potentiation (LTP) in the cortico-LA pathway compared to those in wild-type mice. However, LTP was not enhanced in the hippocampal CA1 regions of Kir6.1^+/- mice. Consistent with increased cued fear memory, both Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-regulated kinase (ERK) activities were significantly elevated in the LAs of Kir6.1^+/- mice after tone stimulation. Our results indicate that increased CaMKII and ERK activities may induce LTP in the LA in Kir6.1^+/- mice, leading to aberrant cued fear memory. The changes in neural plasticity in the LA of Kir6.1^+/- mice were associated with anxiety-like behaviors and may be related to the pathogenic mechanisms of anxiety disorders in human patients.

Clinical and microbiological characteristics of non-tuberculous mycobacteria diseases in Singapore with a focus on pulmonary disease, 2012-2016

Background

Information on non-tuberculosis mycobacterial (NTM) diseases remains limited in Singapore and other Southeast Asian countries. This study aimed to delineate epidemiological and clinical features of pulmonary NTM disease.

Methods

A retrospective review was performed on all NTM isolates identified in Singapore General Hospital from 2012 to 2016 using the 2007 ATS/IDSA diagnostic criteria.

Results

A total of 2026 NTM isolates from 852 patients were identified. M. abscessus-chelonae group (1010, 49.9%) was the most commonly isolated and implicated in pulmonary NTM disease. Pulmonary cases (352, 76%) had the highest prevalence among patients diagnosed with NTM diseases (465/852, 54.6%) with no gender difference. Male patients were older (68.5 years, P = 0.014) with a higher incidence of chronic obstructive pulmonary disease (COPD) (23.6%, P < 0.001) and recurrent cough with phlegm production (51.6%, P = 0.035). In contrast, more female patients had bronchiectasis (50%, P < 0.001) and haemoptysis (37.6%, P = 0.042). Age and COPD were associated with multiple NTM species isolation per patient.

Conclusions

M. abscessus-chelonae group was the commonest NTM species isolated in Singapore. Pulmonary NTM infection has the highest frequency with male and female patients associated with a higher incidence of COPD and bronchiectasis respectively. Age and COPD were associated with multiple NTM species isolation per patient.

Aberrant Amygdala-Dependent Cued Fear Memory in Na+/Ca2+ Exchanger 1 Heterozygous Mice

Na⁺/Ca²⁺ exchangers (NCXs) are mainly expressed in the plasma membrane and exchange one Ca²⁺ for three Na⁺, depending on the electrochemical gradients across the plasma membrane. NCXs have three isoforms, NCX1-3, encoded by distinct genes in mammals. Here, we report that heterozygous mice lacking NCX1 (NCX1^+/-) exhibit impaired amygdala-dependent cued fear memory. NCX1^+/- mice showed significant impairment in fear-related behaviors measured with the elevated-plus maze, light-dark, open-field, and marble-burying tasks. In addition, NCX1^+/- mice showed abnormality in cued fear memory but not in contextual fear memory in a fear-conditioning task. In immunohistochemical analyses, NCX1^+/- mice had significantly increased number of c-Fos-positive cells in the lateral amygdala (LA) but not in the central amygdala following fear-related tone stimuli. c-Fos expression peaked at 1 h. In concordance with the aberrant fear-related behaviors in NCX1^+/- mice, enhanced long-term potentiation was also observed in the LA of these mice. Furthermore, enhancement of CaMKII or CaMKIV activity in the LA was observed in NCX1^+/- mice by immunoblot analyses. In contrast, CaMKII^+/- but not CaMKIV^-/- mice insufficiently exhibited tone-induced cued fear memory and there was no increase in the number of c-Fos-positive cells in the LA. Altogether, the increased CaMKII activity and consequent c-Fos expression likely account for the dysregulation of amygdala-dependent cued fear memory in NCX1^+/- mice.

High salt induced hypertension leads to cognitive defect

Although increasing evidences suggest a relationship between hypertension and brain function for years, it is still unclear whether hypertension constitutes a risk factor for cognitive decline and its underlying mechanism. In the present study, an experimental animal model of hypertension simply by feeding rats with high salt diet was employed. We found that long-term high salt intake caused a marked increase of systolic blood pressure linked to a declined regional cerebral blood flow. Fear conditioning and morris water maze behavioral test revealed that high salt diet induced hippocampal dependent spatial reference memory deficits, while a decreased synaptogenesis without neuronal loss in hippocampus was observed in high salt treated rats. Furthermore, we found that high salt induced a decrease of intracellular calcium, which inactivated CaMK II and resulted in dephosphorylation of CREB at Ser133. These findings suggest a novel etiopathogenic mechanism of cognitive deficit induced by hypertension, which is initiated by high salt diet.