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.