Transdifferentiation of beta- to alpha-cells has been implicated in the pathogenesis of diabetes. To investigate the impact of contrasting aetiologies of beta-cell stress, as well as clinically approved
incretin therapies on this process, lineage tracing of beta-cells in transgenic Ins1 Cre/+/Rosa26-eYFP mice was investigated. Diabetes-like syndromes were induced by
streptozotocin (STZ), high fat feeding (HFF) or
hydrocortisone (HC), and effects of treatment with
liraglutide or
sitagliptin were investigated. Mice developed the characteristic metabolic features associated with beta-cell destruction or development of
insulin resistance.
Liraglutide was effective in preventing
weight gain in HFF mice, with both treatments decreasing energy intake in STZ and HC mice. Treatment intervention also significantly reduced
blood glucose levels in STZ and HC mice, as well as increasing either plasma or pancreatic
insulin while decreasing circulating or pancreatic
glucagon in all models. The recognised changes in pancreatic morphology induced by STZ, HFF or HC were partially, or fully, reversed by
liraglutide and
sitagliptin, and related to advantageous effects on alpha- and beta-cell growth and survival. More interestingly, induction of diabetes-like phenotype, regardless of pathogenesis, led to increased numbers of beta-cells losing their identity, as well as decreased expression of Pdx1 within beta-cells. Both treatment interventions, and especially
liraglutide, countered detrimental islet cell transitioning effects in STZ and HFF mice. Only
liraglutide imparted benefits on beta- to alpha-cell transdifferentiation in HC mice. These data demonstrate that beta- to alpha-cell transdifferentiation is a common consequence of beta-cell destruction or
insulin resistance and that clinically approved
incretin-based drugs effectively limit this.