A major component of our research in the Diabetes Section is to understand what controls beta cell function and mass in the pancreas. With age and type 2 diabetes failure of beta cells to respond to rising blood glucose levels (beta cell dysfunction) becomes evident and there appears to be a failure of expansion of beta cell mass. This is possibly due to increased apoptosis of existing beta cells as well as decreased neogenesis. We have been studying the mechanisms of action of GLP-1, a gut hormone, as they relate to insulin release. We found that not only is GLP-1 a potent insulinotropic agent, it upregulates insulin biosynthesis, increases translocation of pdx-1, a transcription factor necessary for maintenance of the beta cell phenotype, to the nucleus and it increases glucokinase protein levels (the essential glucose sensor in beta cells). We also found that it increases beta cell mass in rodents by increasing beta cell proliferation in islets of Langerhans. Other investigators demonstrated antiapoptotic effects of GLP-1 in beta cell lines and whole islets. A GLP-1 receptor agonist, exendin-4, is now available for treating type 2 diabetes. A component of our basic work is investigating how GLP-1 increases beta cell turnover. Of relevance to aging, we have found that the ability of GLP-1 receptor agonists to increase beta cell turnover is reduced in islets from old rodents: however, continuous, unremitting treatment of the animals with GLP-1 receptor agonists can overcome this. In addition to defective beta cell function and proliferation, we have found that alpha cells are increased. This led us to speculate that proper beta cell function is needed to control alpha cell function and numbers. Additionally, free fatty levels are increased in aging and type 2 diabetes. We are hypothesizing a unifying mechanism covering beta cell dysfunction, alpha cell hyperactivity, insulin resistance and increased cytokine levels. Eventually, we hope to outline novel therapeutic targets within this concept.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Investigator-Initiated Intramural Research Projects (ZIA)
Project #
Application #
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
National Institute on Aging
Zip Code
Dias, Jenny Pena; Veldhuis, Johannes D; Carlson, Olga et al. (2017) Effects of transdermal testosterone gel or an aromatase inhibitor on serum concentration and pulsatility of growth hormone in older men with age-related low testosterone. Metabolism 69:143-147
Dias, J P; Shardell, M D; Carlson, O D et al. (2017) Testosterone vs. aromatase inhibitor in older men with low testosterone: effects on cardiometabolic parameters. Andrology 5:31-40
Dias, Jenny Pena; Schrack, Jennifer A; Shardell, Michelle D et al. (2016) Association of abdominal fat with serum amylase in an older cohort: The Baltimore Longitudinal Study of Aging. Diabetes Res Clin Pract 116:212-7
Elahi, Dariush; Ruff, Dennis A; Carlson, Olga D et al. (2016) Does GLP-1 suppress its own basal secretion? Endocr Res 41:16-20
Galiatsatos, Panagis; Gibson, B Robert; Rabiee, Atoosa et al. (2014) The glucoregulatory benefits of glucagon-like peptide-1 (7-36) amide infusion during intensive insulin therapy in critically ill surgical patients: a pilot study. Crit Care Med 42:638-45
Elahi, Dariush; Angeli, Franca S; Vakilipour, Amin et al. (2014) GLP-1(32-36)amide, a novel pentapeptide cleavage product of GLP-1, modulates whole body glucose metabolism in dogs. Peptides 59:20-4
Rouse, Michael; Younès, Antoine; Egan, Josephine M (2014) Resveratrol and curcumin enhance pancreatic ?-cell function by inhibiting phosphodiesterase activity. J Endocrinol 223:107-17
Fiori, Jennifer L; Shin, Yu-Kyong; Kim, Wook et al. (2013) Resveratrol prevents ?-cell dedifferentiation in nonhuman primates given a high-fat/high-sugar diet. Diabetes 62:3500-13
Kalyani, Rita Rastogi; Egan, Josephine M (2013) Diabetes and altered glucose metabolism with aging. Endocrinol Metab Clin North Am 42:333-47
Chen, Hongyu; Martin, Bronwen; Cai, Huan et al. (2012) Pancreas++: automated quantification of pancreatic islet cells in microscopy images. Front Physiol 3:482

Showing the most recent 10 out of 17 publications