Exendin fragment 9 39

Cells were pre‐treated for 1 hr with 200 nM of the GLP‐1r antagonist, exendin fragment (9‐39) (Sigma‐Aldrich) 36. It was previously verified that 200 nM exendin led to maximal inhibition of insulin secretion by Rin‐m5f after 24 hrs and 48 hrs incubation. The supernatant was withdrawn and exendin (9‐39) continuously applied with either cytokines or H₂O₂ in fresh medium during 6 hrs.

HSC were incubated with liraglutide (Novo Nordisk), or its vehicle PBS, at different concentrations (1 μM, 10 μM, 50 μM and 100 μM) and for different periods of time (24 h, 48 h and 72 h). In vitro dosing of liraglutide was based on previous literature^{41 (link)}. Considering that liraglutide exerted beneficial effects at 50 μM and after 72 h of treatment, all subsequent experiments were performed using these experimental conditions. Simvastatin was used in 10 µM dose alone and in combination with liraglutide. Exendin fragment 9–39 (Sigma-Aldrich; 10 nM–1 uM) was used as a GLP-1R antagonist^{41 (link)}.

Aβ_1–42 was from American Peptide (Sunnyvale, CA, USA). Ham's F12 media (HF12‐02) was from Caisson Labs (Smithfield, UT, USA). DMSO, bovine serum albumin (BSA), insulin, forskolin, 8‐bromoadenosine (8‐Br‐cAMP), exendin fragment 9‐39, and 3‐isobutyl‐1‐methylxanthine (IBMX) were from Sigma (St Louis, MO, USA). DAB was from DakoCytomation (Glostrup, Denmark). Prolong Gold Antifade, normal goat serum and DAPI were from Invitrogen (Carlsbad, CA, USA). Vectastain Elite ABC reagent was from Vector Laboratories Inc (Burlingame, CA, USA). Harris' hematoxylin and Entellan were from Merck (São Paulo, Brazil). In experiments in vitro and with Swiss mice, liraglutide was purchased from GL Biochem (Shanghai, China) and with NHPs, liraglutide was purchased from Novo Nordisk (Bagsværd, Denmark). PKI (14‐22) amide (myristoylated) and H89 were from Cell Signaling Technology (Danvers, MA, USA). ELISA kits for insulin and PKA activity were from Crystal Chem Inc (Elk Grove Village, IL, USA) and Enzo Life Sciences Inc (Farmingdale, NY, USA), respectively. All the antibodies used in this study are listed in the supplementary material, Tables S1 and S2.