Effects of dicholine salt of succinic acid on insulin-stimulated insulin receptor autophosphorylation in cerebellar granule neurons. CGN cultures were pre-incubated for 30 min in Hepes-buffered salt solution and then exposed to insulin (100 nmol/L), insulin (5 nmol/L), CS (50 μmol/L), or a combination of insulin (5 nmol/L) and CS (50 μmol/L) for 20 min. Autophosphorylation of insulin receptor was measured as described in Materials and Methods. In each experiment, amount of phosphorylated insulin receptor β-subunit (pYpY-IR) was normalized to total amount of insulin receptor β-subunit and expressed as a percentage of the response produced to 100 nmol/L insulin. Columns represent the means ± SD of pYpY-IR values obtained from four to nine culture dishes. *P < 0.05 vs. control.†P < 0.05 vs. insulin (100 nmol/L). #P < 0.05 vs. insulin (5 nmol/L).