Sensitive and non-invasive method for the in vivo analysis of membrane permeability in small animals

Moderate aerobic training enhances the effectiveness of insulin therapy through hypothalamic IGF1 signaling in rat model of Alzheimer's disease

Alzheimer's disease (AD) is a neurological condition that is connected with a decline in a person's memory as well as their cognitive ability. One of the key topics of AD research has been the exploration of metabolic causes. We investigated the effects of treadmill exercise and intranasal insulin on learning and memory impairment and the expression of IGF1, BDNF, and GLUT4 in hypothalamus. The animals were put into 9 groups at random. In this study, we examined the impact of insulin on spatial memory in male Wistar rats and analyzed the effects of a 4-week pretreatment of moderate treadmill exercise and insulin on the mechanisms of improved hypothalamic glucose metabolism through changes in gene and protein expression of IGF1, BDNF, and GLUT4. We discovered that rat given Aβ25-35 had impaired spatial learning and memory, which was accompanied by higher levels of Aβ plaque burden in the hippocampus and lower levels of IGF1, BDNF, and GLUT4 mRNA and protein expression in the hypothalamus. Additionally, the administration of exercise training and intranasal insulin results in the enhancement of spatial learning and memory impairments, the reduction of plaque burden in the hippocampus, and the enhancement of the expression of IGF1, BDNF, and GLUT4 in the hypothalamus of rats that were treated with Aβ25-35. Our results show that the improvement of learning and spatial memory due to the improvement of metabolism and upregulation of the IGF1, BDNF, and GLUT4 pathways can be affected by pretreatment exercise and intranasal insulin.

Alleviation of Hepatic Steatosis: Dithizone-Related Gut Microbiome Restoration During Paneth Cell Dysfunction

Non-alcoholic fatty liver disease (NAFLD), the world’s most common chronic liver disease, is increasingly linked to gut dysbiosis. Paneth cells secrete antimicrobial peptides that regulate the gut microbiome, but their role in the pathogenesis of NAFLD remains unclear. Here, we determine the changes in NAFLD development and gut microbial composition and function via the injection of dithizone that can pharmacologically deplete the granules of Paneth cells. Eight-week-old C57BL/6J male mice (n = 31) were given a high-fat diet (HFD) or standard control diet for 12 weeks. Dithizone (10 mg/kg) was intravenously injected every 3 weeks during the period of diet feeding. Metagenomic DNA was extracted from fecal samples for PacBio Single-Molecule Real-Time sequencing to identify changes in microbial composition and predicted function. We observed dithizone-treated HFD mice, when compared to non-treated HFD mice, to have significant reductions in hepatic triglyceride content (28.98 vs. 53.52 mg/g, p = 0.0419); plasma insulin level (2.18 vs. 6.63 ng/ml, p = 0.0079); and relative mRNA levels of fatty acid synthase (0.52 vs. 1.57, p = 0.0428) and stearoyl-CoA desaturase-1 (0.43 vs. 1.20, p = 0.0121). Bacterial taxonomic profiling found dithizone-treated HFD mice, when compared to non-treated HFD mice, had a lower Firmicutes/Bacteroidetes ratio (2.53 vs. 5.26, p = 0.0541); a higher relative abundance of Bacteroides ASV21 and ASV42 (1.04 vs. 0.22%, p = 0.0277 and 0.96 vs. 0.09%, p = 0.0213); and a reduction in microbes belonging to Firmicutes (all p < 0.05). Bacteroides species correlated positively with predicted microbial functions such as L-methionine (r = 0.54, p = 0.0019) and tetrahydrofolate (r = 0.52, p = 0.0029) biosynthesis. Collectively, dithizone treatment was associated with alleviation in the severity of liver steatosis in HFD mice, possibly through gut microbiome modulation involving the increase in Bacteroides, suggesting microbiome-targeted therapies may have a role in the treatment of NAFLD.

Sex differences in stroke outcome correspond to rapid and severe changes in gut permeability in adult Sprague-Dawley rats

BACKGROUND

Sex differences in experimental stroke outcomes are well documented, such that adult males have a greater infarct volume, increased stroke-induced mortality, and more severe sensory-motor impairment. Based on recent evidence that the gut is an early responder to stroke, the present study tested the hypothesis that sex differences in stroke severity will be accompanied by rapid and greater permeability of the gut-blood barrier and gut dysbiosis in males as compared to females.

METHOD

Male and female Sprague-Dawley rats (5-7 months of age) were subject to endothelin (ET)-1-induced middle cerebral artery occlusion (MCAo). Sensory-motor tests were conducted pre- and 2 days after MCAo. Gut permeability was assessed in serum samples using biomarkers of gut permeability as well as functional assays using size-graded dextrans. Histological analysis of the gut was performed with H&E staining, periodic acid-Schiff for mucus, and immunohistochemistry for the tight junction protein, ZO-1. Fecal samples obtained pre- and post-stroke were analyzed for bacterial taxa and short-chain fatty acids (SCFAs).

RESULTS

After stroke, males displayed greater mortality, worse sensory-motor deficit, and higher serum levels of proinflammatory cytokines IL-17A, MCP-1, and IL-5 as compared to females. MCAo-induced gut permeability was rapid and severe in males as indicated by dextran extravasation from the gut to the blood in the hyperacute (< 2 h) and early acute (2 days) phase of stroke. This was accompanied by dysmorphology of the gut villi and dysregulation of the tight junction protein ZO-1 in the acute phase. Fecal 16s sequencing showed no differences in bacterial diversity in the acute phase of stroke. Predictive modeling indicated that markers of gut permeability were associated with acute sensory-motor impairment and infarct volume.

CONCLUSIONS

These data show that extensive leakiness of the gut barrier is associated with severe post-stroke disability and suggest that reinforcing this barrier may improve stroke outcomes.