Aluminum-Induced Cholinergic Deficits in Different Brain Parts and Its Implications on Sociability and Cognitive Functions in Mouse

Aluminum is associated with etiology of many neurodegenerative diseases specially Alzheimer’s disease. Chronic exposure to aluminum via drinking water results in aluminum deposition in the brain that leads to cognitive deficits. The study aimed to determine the effects of aluminum on cholinergic biomarkers, i.e., acetylcholine level, free choline level, and choline acetyltransferase gene expression, and how cholinergic deficit affects novel object recognition and sociability in mice. Mice were treated with AlCl₃ (250 mg/kg). Acetylcholine level, free choline level, and choline acetyltransferase gene expression were determined in cortex, hippocampus, and amygdala. The mice were subjected to behavior tests (novel object recognition and social novelty preference) to assess memory deficits. The acetylcholine level in cortex and hippocampus was significantly reduced in aluminum-treated animals, as compared to cortex and hippocampus of control animals. Acetylcholine level in amygdala of aluminum-treated animals remained unchanged. Free choline level in all the three brain parts was found unaltered in aluminum-treated mice. The novel object recognition memory was severely impaired in aluminum-treated mice, as compared to the control group. Similarly, animals treated with aluminum showed reduced sociability compared to the control mice group. Our study demonstrates that aluminum exposure via drinking water causes reduced acetylcholine synthesis in spite of normal free choline availability. This deficit is caused by reduced recycling of acetylcholine due to lower choline acetyltransferase level. This cholinergic hypofunction leads to cognitive and memory deficits. Moreover, hippocampus is the most affected brain part after aluminum intoxication.     

Genetic background influences survival of infections with Salmonella enterica serovar Typhimurium in the Collaborative Cross

Salmonella infections typically cause self-limiting gastroenteritis, but in some individuals these bacteria can spread systemically and cause disseminated disease. Salmonella Typhimurium (STm), which causes severe systemic disease in most inbred mice, has been used as a model for disseminated disease. To screen for new infection phenotypes across a range of host genetics, we orally infected 32 Collaborative Cross (CC) mouse strains with STm and monitored their disease progression for seven days by telemetry. Our data revealed a broad range of phenotypes across CC strains in many parameters including survival, bacterial colonization, tissue damage, complete blood counts (CBC), and serum cytokines. Eighteen CC strains survived to day 7, while fourteen susceptible strains succumbed to infection before day 7. Several CC strains had sex differences in survival and colonization. Surviving strains had lower pre-infection baseline temperatures and were less active during their daily active period. Core body temperature disruptions were detected earlier after STm infection than activity disruptions, making temperature a better detector of illness. All CC strains had STm in spleen and liver, but susceptible strains were more highly colonized. Tissue damage was weakly negatively correlated to survival. We identified loci associated with survival on Chromosomes (Chr) 1, 2, 4, 7. Polymorphisms in Ncf2 and Slc11a1, known to reduce survival in mice after STm infections, are located in the Chr 1 interval, and the Chr 7 association overlaps with a previously identified QTL peak called Ses2. We identified two new genetic regions on Chr 2 and 4 associated with susceptibility to STm infection. Our data reveal the diversity of responses to STm infection across a range of host genetics and identified new candidate regions for survival of STm infection.     

Pathological and immunological evaluation of different regimens of praziquantel treatment in a mouse model of Schistosoma mansoni infection

BackgroundOne of the considerable challenges of schistosomiasis chemotherapy is the inefficacy of praziquantel (PZQ) at the initial phase of the infection. Immature schistosomes are not susceptible to PZQ at the curative dose. Here, we investigated the efficacy of different PZQ regimens administered during the initial stage of Schistosoma mansoni infection in mice.Methodology/Principal findingsTwo months-old mice were individually infected with 80 S. mansoni cercariae and divided into one infected-untreated control group (IC) and four PZQ-treated groups: PZQ at 100 mg/kg/day for five consecutive days (group PZQ1), PZQ at 100 mg/kg/day for 28 days (group PZQ2), PZQ at 18 mg/kg/day for 28 days (group PZQ3) and a single dose of PZQ at 500 mg/kg (group PZQ4). The treatment started on day one post-infection (p.i), and each group of mice was divided into two subgroups euthanized on day 36 or 56 p.i, respectively. We determined the mortality rate, the parasitological burden, the hepatic and intestinal granulomas, the serum levels of Th-1, Th-2, and Th-17 cytokines, and gene expression. The treatment led to a significant (p < 0.001) reduction of worm burden and egg counts in the intestine and liver in groups PZQ2 and PZQ3. On 56^th day p.i, there was a significant reduction (p < 0.001) of the number and volume of the hepatic granulomas in groups PZQ2 and PZQ3 compared to group PZQ1 or PZQ4. Moreover, in group PZQ3, the serum levels of IFN-γ, TNF-α, IL-13, and IL-17 and their liver mRNA expressions were significantly reduced while IL-10 and TGF-β gene expression significantly increased. The highest mortality rate (81.25%) was recorded in group PZQ2.Conclusion/SignificanceThis study revealed that the administration of PZQ at 18 mg/kg/day for 28 consecutive days was the optimal effective posology for treating S. mansoni infection at the initial stage in a murine model.     

Effect of lead stress on mineral content and growth of wheat (Triticum aestivum) and spinach (Spinacia oleracea) seedlings

Lead (Pb) is the most common heavy metal contaminant in the environment. Pb is not an essential element for plants, but they absorb it when it is present in their environment, especially in rural areas when the soil is polluted by automotive exhaust and in fields contaminated with fertilizers containing heavy metal impurities. To investigate lead effects on nutrient uptake and metabolism, two plant species, spinach (Spinacia oleracea) and wheat (Triticum aestivum), were grown under hydroponic conditions and stressed with lead nitrate, Pb(NO₃)₂, at three concentrations (1.5, 3, and 15 mM).Lead is accumulated in a dose-dependent manner in both plant species, which results in reduced growth and lower uptake of all mineral ions tested. Total amounts and concentrations of most mineral ions (Na, K, Ca, P, Mg, Fe, Cu and Zn) are reduced, although Mn concentrations are increased, as its uptake is reduced less relative to the whole plant’s growth. The deficiency of mineral nutrients correlates in a strong decrease in the contents of chlorophylls a and b and proline in both species, but these effects are less pronounced in spinach than in wheat. By contrast, the effects of lead on soluble proteins differ between species; they are reduced in wheat at all lead concentrations, whereas they are increased in spinach, where their value peaks at 3 mM Pb.The relative lead uptake by spinach and wheat, and the different susceptibility of these two species to lead treatment are discussed.     

Dopamine depletion and subsequent treatment with L-DOPA, but not the long-lived dopamine agonist pergolide, enhances activity of the Akt pathway in the rat striatum

Dysregulation of signaling pathways is believed to contribute to Parkinson's disease pathology and l-DOPA-induced motor complications. Long-lived dopamine (DA) agonists are less likely to cause motor complications by virtue of continuous stimulation of DA receptors. In this study, we compared the effects of the unilateral 6-hydroxydopamine lesion and subsequent treatment with l-DOPA and DA agonist pergolide on signaling pathways in rats. Pergolide caused less pronounced behavioral sensitization than l-DOPA (25 mg/kg, i.p., 10 days), particularly at lower dose (0.5 and 0.25 mg/kg, i.p.). Pergolide, but not l-DOPA, reversed lesion-induced up-regulation of preproenkephalin and did not up-regulate preprodynorphine or DA D3 receptor in the lesioned hemisphere. Pergolide was as effective as l-DOPA in reversing the lesion-induced elevation of ERK2 phosphorylation in response to acute apomorphine administration (0.05 mg/kg, s.c.). Chronic l-DOPA significantly elevated the level of Akt phosphorylation at both Thr(308) and Ser(473) and concentration of phosphorylated GSK3alpha, whereas pergolide suppressed the lesion- and/or challenge-induced supersensitive Akt responses. The data indicate that l-DOPA, unlike pergolide, exacerbates imbalances in the Akt pathway caused by the loss of DA. The results support the hypothesis that the Akt pathway is involved in long-term actions of l-DOPA and may be linked to l-DOPA-induced dyskinesia.     

Transactivation of the epidermal growth factor receptor mediates parathyroid hormone and prostaglandin F2 alpha-stimulated mitogen-activated protein kinase activation in cultured transgenic murine osteoblasts

Recent data suggest that G protein-coupled receptors (GPCRs), including those for PTH and prostaglandins (PGs), contribute to the proliferation and differentiation of osteoblasts in vivo. To understand how these signals are transduced, we studied activation of the ERK1/2 MAPK cascade in cultures of differentiating TMOb murine osteoblasts. In TMOb cells, stimulation of endogenous Gs/Gq-coupled PTH receptors, Gq-coupled PGF2 alpha receptors, and Gi/Gq-coupled lysophosphatidic acid receptors, but not Gs-coupled PGE2 receptors, caused a rapid 5- to 10-fold increase in ERK1/2 phosphorylation. GPCR-stimulated ERK1/2 activation coincided with increased tyrosine phosphorylation of epidermal growth factor (EGF) receptors and was blocked by the EGF receptor inhibitor, tyrphostin AG1478, and the metalloprotease inhibitor, batimastat, suggesting that the response involved transactivation of EGF receptors through the proteolytic release of an EGF receptor ligand. To further examine the mechanism of PTH-stimulated EGF receptor transactivation, we employed COS-7 cells expressing the rat PTH receptor. Here, stimulation with PTH(1-34) caused proteolysis of hemagglutinin epitope-tagged heparin binding-EGF, increased tyrosine autophosphorylation of EGF receptors, and AG1478-sensitive ERK1/2 activation. When PTH receptor-expressing COS-7 cells were placed in a mixed culture with cells lacking the PTH receptor but expressing a green fluorescent protein-tagged ERK2, stimulation with PTH(1-34) induced phosphorylation of green fluorescent protein-ERK2 that was abolished by either batimastat or tyrphostin AG1478. These data suggest that autocrine/paracrine cross-talk between EGF receptors and Gi- or Gq/11-coupled GPCRs represents the predominant mechanism of GPCR-mediated activation of ERK1/2 in cultured TMOb osteoblasts.     

Functional analysis and structure determination of alkaline protease from Aspergillus flavus

Proteases are one of the highest value commercial enzymes as they have broad applications in food, pharmaceutical, detergent, and dairy industries and serve as vital tools in determination of structure of proteins and polypeptides. Multiple application of these enzymes stimulated interest to discover them with novel properties and considerable advancement of basic research into these enzymes. A broad understanding of the active site of the enzyme and of the mechanism of its inactivation is essential for delineating its structure-function relationship. Primary structure analysis of alkaline protease showed 42% of its content to be alpha helix making it stable for three dimensional structure modeling. Homology model of alkaline protease has been constructed using the X-ray structure (3F7O) as a template and swiss model as the workspace. The model was validated by ProSA, SAVES, PROCHECK, PROSAII and RMSD. The results showed the final refined model is reliable. It has 53% amino acid sequence identity with the template, 0.24 Å as RMSD and has -7.53 as Z-score, the Ramachandran plot analysis showed that conformations for 83.4 % of amino acid residues are within the most favored regions and only 0.4% in the disallowed regions.     

Amelioration of cognitive impairment and neurodegeneration by catechin hydrate in rat model of streptozotocin-induced experimental dementia of Alzheimer’s type

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder resulting in cognitive decline and enhancement of oxidative loads in the brain. Flavonoids have been considered to exert human health benefits by anti-oxidant and anti-inflammatory properties. The present study is aimed to elucidate the neuroprotective effect of catechin hydrate (CH), a natural flavanoid with potential antioxidant and anti-inflammatory properties, on intracerebroventricular streptozotocin (ICV-STZ) induced neuronal loss and memory impairment. To test this hypothesis, male Wistar rats were pretreated with CH (10 and 20 mg/kg bwt) orally once daily for 21 days and then bilaterally injected with ICV-STZ (3 mg/kg bwt), while sham group rats receive the same volume of vehicle. After 2 weeks of ICV-STZ infusion, rats were tested for cognitive performance using Morris water maze (MWM) test and then sacrifice for biochemical and histopathological assays. CH was found to be successful in upregulating the antioxidant status and prevented the memory loss. The expression of choline acetyl transferase (ChAT) was decreased in ICV-STZ group and CH pretreatment increases the expression of ChAT. Moreover, inflammatory mediators like TNF-α, IL-1β levels and expression of iNOS were significantly attenuated by CH pretreatment. The study suggests that CH is effective in preventing memory loss, ameliorating the oxidative stress and might be beneficial for the treatment of sporadic dementia of Alzheimer’s type (SDAT).