Long-Lasting Exendin-4-Loaded PLGA Nanoparticles Ameliorate Cerebral Ischemia/Reperfusion Evoked Brain Injury and Voiding Dysfunction in Diabetic Rats

Abstract

Exendin-4 (Ex-4) is an incretin mimetic agent approved for diabetes treatment and neuronal protection. However, the required frequent injections restrict its clinical application. We prepared Ex-4-loaded poly(d,l-lactide-co-glycolide) nanoparticles (PEx-4) and investigated the effect on cerebral ischemia/reperfusion (IR) injury associated with cystopathy in diabetic rats. Using ten minutes of bilateral carotid artery occlusion combined with hemorrhage-induced hypotension of IR model in streptozotocin-induced type 1 diabetic (T1DM) Wistar rats, we compared Ex-4 and PEx-4 effect on prefrontal cortex edema, voiding function and oxidative stress including cerebral spinal fluid (CSF) reference H2O2 (RH2O2) and HOCl (RHOCl) levels, endoplasmic reticulum (ER) stress, apoptosis, autophagy and pyroptosis signaling in brain and bladder by western blot and immunohistochemistry. Single injection of PEx-4 displayed higher CSF antioxidant activity and long-lasting hypoglycemic effect than Ex-4 in rats. T1DM enhanced CSF RH2O2, and pIRE-1/cleaved caspase-12/pJNK/ATF4/ATF6/CHOP-mediated ER stress, caspase 3/PARP mediated apoptosis, Beclin-1/LC3-II mediated autophagy and caspase 1/IL-1β mediated pyroptosis signaling in the prefrontal cortex and bladders. IR led to prefrontal cortex edema, impairment in micturition center and further increased CSF RH2O2 and HOCl level, ER stress, apoptosis, autophagy and pyroptosis signaling in the T1DM brains and bladders. PEx-4 were more efficient than Ex-4 in attenuating IR-evoked prefrontal cortex edema and oxidative stress in brains and improving voiding dysfunction in bladders of T1DM rats. In summary, PEx-4 with stronger antioxidant activity and long-lasting bioavailability confer efficiently therapeutic efficacy to ameliorate IR-evoked brain and bladder injury through inhibiting oxidative stress, ER stress, apoptosis, autophagy and pyroptosis signaling in diabetic rats.