The neuroprotective effects of carnosine against oAβ1-42-induced toxicity are mediated by TGF-β1. (A) Mixed neuronal cultures were challenged with oAβ1-42 (2 µM) for 48 h in the absence or presence of increasing concentrations of carnosine (1, 5, and 10 mM). (B) Effect of SB431542 (specific inhibitor of type-1 TGF-β receptor) treatment (10 µM) on the neuroprotective activity of carnosine against oAβ1-42-induced toxicity. oAβ1-42 toxicity in mixed neuronal cultures was assessed by cell counting after trypan blue staining. Cell counts were performed in three to four random microscopic fields/well. Data are the mean of 6 (A) or 5 (B) determinations and are expressed as the percent variation with respect to the cell death recorded in oAβ1-42-treated cells. Standard deviations are represented by vertical bars. * Significantly different from oAβ1-42-treated cells, p < 0.001, ω significantly different from oAβ1-42 + Car 1 mM, p < 0.001, # significantly different from oAβ1-42 + Car 10 mM.