Metformin treatment of juvenile mice alters aging-related developmental and metabolic phenotypes in sex-dependent and sex-independent manners.

Metformin has attracted increasing interest for its potential benefits in extending healthspan and longevity. This study examined the effects of early-life metformin treatment on the development and metabolism of C57BL/6 J (B6) mice, with metformin administered to juvenile mice from 15 to 56 days of age. Metformin treatment led to decreased body weight in both sexes (P < 0.05, t-test). At 9 weeks of age, mice were euthanized and organ weights were recorded. The relative weight of retroperitoneal fat was decreased in females, while relative weights of perigonadal and retroperitoneal fat were decreased, and relative liver weight was increased in males (P < 0.05, t-test). Glucose and insulin tolerance tests (GTT and ITT) were conducted at the age of 7 weeks. ANOVA revealed a significant impairment in insulin sensitivity by the treatment, and a significantly interactive effect on glucose tolerance between sex and treatment, underscoring a disparity in GTT between sexes in response to the treatment. Metformin treatment reduced circulating insulin levels in fasting and non-fasting conditions for male mice, with no significant alterations observed in female mice. qRT-PCR analysis of glucose metabolism-related genes (Akt2, Glut2, Glut4, Irs1, Nrip1, Pi3k, Pi3kca, Pkca) in the liver and skeletal muscle reveals metformin-induced sex- and organ-specific effects on gene expression. Comparison with previous studies in heterogeneous UM-HET3 mice receiving the same treatment suggests that genetic differences may contribute to variability in the effects of metformin treatment on development and metabolism. These findings indicate that early-life metformin treatment affects development and metabolism in both sex- and genetics-dependent manners.

Single-Cell Transcriptomics Identifies Pituitary Gland Changes in Diet-Induced Obesity in Male Mice.

Obesity is a chronic disease with increasing prevalence worldwide. Obesity leads to an increased risk of heart disease, stroke, and diabetes, as well as endocrine alterations, reproductive disorders, changes in basal metabolism, and stress hormone production, all of which are regulated by the pituitary. In this study, we performed single-cell RNA sequencing of pituitary glands from male mice fed control and high-fat diet (HFD) to determine obesity-mediated changes in pituitary cell populations and gene expression. We determined that HFD exposure is associated with dramatic changes in somatotrope and lactotrope populations, by increasing the proportion of somatotropes and decreasing the proportion of lactotropes. Fractions of other hormone-producing cell populations remained unaffected. Gene expression changes demonstrated that in HFD, somatotropes became more metabolically active, with increased expression of genes associated with cellular respiration, and downregulation of genes and pathways associated with cholesterol biosynthesis. Despite a lack of changes in gonadotrope fraction, genes important in the regulation of gonadotropin hormone production were significantly downregulated. Corticotropes and thyrotropes were the least affected in HFD, while melanotropes exhibited reduced proportion. Lastly, we determined that changes in plasticity and gene expression were associated with changes in hormone levels. Serum prolactin was decreased corresponding to reduced lactotrope fraction, while lower luteinizing hormone and follicle-stimulating hormone in the serum corresponded to a decrease in transcription and translation. Taken together, our study highlights diet-mediated changes in pituitary gland populations and gene expression that play a role in altered hormone levels in obesity.

FOXO1 regulates expression of Neurod4 in the pituitary gland.

Pituitary gland function is regulated by the activity of various transcription factors that control cell fate decisions leading to cellular differentiation and hormone production. FOXO1 is necessary for normal somatotrope differentiation and function. Recent in vivo data implicate FOXO1 in the regulation of genes important for somatotrope differentiation including Gh1, Neurod4, and Pou1f1. In the current study, the somatotrope-like cell line GH3 was treated with a FOXO1 inhibitor, resulting in significant reduction in Neurod4 and Gh1 expression. Consistent with these findings, CRISPR/Cas9-mediated deletion of Foxo1 in GH3 cells significantly reduced expression of Gh1 and Neurod4. Chromatin immunoprecipitation sequencing identifies novel FOXO1 binding sites associated with the Neurod4, Gh1, and Pou1f1 genes. The FOXO1 binding site in the Neurod4 gene exhibits enhancer activity in somatotrope-like cells but not in gonadotrope-like cells. These data strongly suggest FOXO1 directly contributes to the transcriptional control of genes important for somatotrope differentiation.

Interaction of flavonols with human serum albumin: a biophysical study showing structure-activity relationship and enhancement when coated on silver nanoparticles.

Binding affinities of flavonols namely quercetin, myricetin, and kaempferol to human serum albumin (HSA) were determined fluorimetrically and the order was observed to be myricetin > quercetin > kaempferol demonstrating structure-activity relationship. Quercetin-coated silver nanoparticles (AgNPs) show higher binding affinity to HSA compared to free quercetin with binding constants 6.04 × 107 M-1 and 4.2 × 106 M-1, respectively. Using site-specific markers it is concluded that free quercetin and that coated on AgNPs bind at different sites. Significant structural changes in circular dichroism (CD) spectra of HSA were recorded with quercetin-coated AgNPs compared to free quercetin. These results were further substantiated by time-resolved fluorescence spectroscopy where fluorescence life time of the tryptophan residue in HSA-quercetin-coated AgNPs complex decreased to 3.63 ns from 4.22 ns in HSA-quercetin complex. Isothermal calorimetric studies reveal two binding modes for quercetin-coated AgNPs and also higher binding constants compared to free quercetin. These higher binding affinities are attributed to altered properties of quercetin when coated on AgNPs enabling it to reach the binding sites other than site II where free quercetin mainly binds.