Impaired spatial memory in adult vitamin D deficient BALB/c mice is associated with reductions in spine density, nitric oxide, and neural nitric oxide synthase in the hippocampus

Vitamin D deficiency is prevalent in adults and is associated with cognitive impairment. However, the mechanism by which adult vitamin D (AVD) deficiency affects cognitive function remains unclear. We examined spatial memory impairment in AVD-deficient BALB/c mice and its underlying mechanism by measuring spine density, long term potentiation (LTP), nitric oxide (NO), neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS) in the hippocampus. Adult male BALB/c mice were fed a control or vitamin D deficient diet for 20 weeks. Spatial memory performance was measured using an active place avoidance (APA) task, where AVD-deficient mice had reduced latency entering the shock zone compared to controls. We characterised hippocampal spine morphology in the CA1 and dentate gyrus (DG) and made electrophysiological recordings in the hippocampus of behaviourally naive mice to measure LTP. We next measured NO, as well as glutathione, lipid peroxidation and oxidation of protein products and quantified hippocampal immunoreactivity for nNOS and eNOS. Spine morphology analysis revealed a significant reduction in the number of mushroom spines in the CA1 dendrites but not in the DG. There was no effect of diet on LTP. However, hippocampal NO levels were depleted whereas other oxidation markers were unaltered by AVD deficiency. We also showed a reduced nNOS, but not eNOS, immunoreactivity. Finally, vitamin D supplementation for 10 weeks to AVD-deficient mice restored nNOS immunoreactivity to that seen in in control mice. Our results suggest that lower levels of NO, reduced nNOS immunostaining contribute to hippocampal-dependent spatial learning deficits in AVD-deficient mice.

Endothelial Nitric Oxide Synthase 4a/B Polymorphism and Its Interaction with Enos G894T Variants in Type 2 Diabetic Pa-tients: Modifying the Risk of Diabetic Nephropathy

The article's abstract is not available.

Acute Liver Failure in Rats Induced Vasogenic Edema and Nitric Oxide Synthase-Nitric Oxide-cGMP Pathway after Differential Regulation of NMDA Receptors in Cerebral Cortex and Cerebellum

Acute liver failure (ALF) is a complication of severe liver dysfunction resulting from a wide range of factors including alcoholism, drug-abuse, improper medication, viral hepatitis etc., and present with high mortality rate among the human population. ALF led hyperammonemia (HA) induced cerebral dysfunction is considered to be the main cause of death in patients, however, the precise molecular mechanism is not completely understood. The aim of this study was to investigate the status of brain edema and modulation of N-methyl D-aspartate receptors (NMDAR)- Nitric oxide synthase (NOS)- Nitric oxide (NO)- cyclic guanosine monophosphate (cGMP) axis in the cerebral cortex and cerebellum of ALF rats. ALF was induced by intraperitoneal (IP) injection of thioacetamide (TAA). We observed significantly increased brain water content in ALF rats but absence of astrocytes swelling suggested induction of vasogenic edema. Except constant NR2B, down regulation of NR2A, 2C and 2D subunits containing NMDAR genes in cerebral cortex, however, constant NR2A-C but up-regulation of NR2D subunit in cerebellum suggested brain regions specific differential regulation of NMDAR in ALF rats. Significantly increased nNOS gene and protein level were found to be accompanied by the significantly increased level of NO and cGMP in both brain tissues; however, increased eNOS expression in cortex but increased iNOS expression and activity in cerebellum were observed in ALF rats. Together these findings suggested that ALF in rats may trigger differential regulation of NR2A-D subunits containing NMDAR, induction of NOS-NO-cGMP axis and vasogenic edema in cerebral cortex and cerebellum.

Maternal exposure to an enrichment environment promotes uterine vascular remodeling and prevents embryo loss in mice.

Aim: Implantation-related events are crucial for pregnancy success. In particular, defects in vascular remodeling at the maternal-fetal interface are associated with spontaneous miscarriage and recurrent pregnancy loss. Physical activity and therapies oriented to reduce stress improve pregnancy outcomes. In animal models, environmental stimulation and enrichment are associated with enhanced well-being, cognitive function and stress resilience. Here we studied whether exposure of BALB/c mice to an enriched environment (EE) regulates crucial events during early gestation at the maternal-fetal interface. Method: Pregnant BALB/c mice were exposed to the EE that combines non-invasive stimuli from the sensory pathway with voluntary physical activity. The pregnancy rate was evaluated. Implantation sites were investigated microscopically and macroscopically. Vascular adaptation parameters at the maternal-fetal interface were analyzed. Results: We found that exposure to the EE prevented pregnancy loss between gestational days 7 and 15. Also, it increased the diameter of the uterine artery and decreased the wall:lumen ratio of the mesometrial decidual vessels, suggesting that EE exposure promotes vascular remodeling. Moreover, it increased nitric oxide synthase activity and inducible nitric oxide synthase expression, as well as prostaglandin F2α production and endoglin expression in the implantation sites. Conclusion: Exposure of pregnant females to the EE regulates uterine physiology, promoting vascular remodeling during early gestation. These adaptations might contribute to preventing embryo loss. Our results highlight the importance of the maternal environment for pregnancy success. The design of an “EE-like” protocol for humans could be considered as a new non-pharmacologic strategy to prevent implantation failure and recurrent miscarriage.