Insulin signal transduction is impaired in the type 2 diabetic retina

Rates of type 2 diabetes are reaching epidemic levels.  Yet, the tissue specific alterations due to insulin resistance are only recently being investigated.  The goal of the present study was to evaluate retinal insulin signal transduction in a common mouse model of type 2 diabetes, the db/db mouse.  Retinal lysates from five month old male db/db and db/+ (control) mice were collected and processed for Western blotting or ELISA analyses for insulin receptor, insulin receptor substrate-1 (IRS-1), Akt, tumor necrosis factor alpha (TNFa) and caspase 3 levels.  Data demonstrate increased TNFa and IRS-1 phosphorylation on serine 307.  This led to decreased Akt phosphorylation on serine 473 and increased cleavage of caspase 3.   Taken together, the data suggest dysfunctional insulin signaling in the retina of the db/db mouse.