Protective effect of ISO‑1 against advanced glycation end product aggravation of PC12 cell injury induced by Aβ1‑40.

Advanced glycation end products (AGEs) are important pathogenic substances involved in diabetes mellitus (DM) and its complications. AGEs also serve important roles in promoting the development of Alzheimer's disease (AD). Macrophage migration inhibitory factor (MIF), an inflammatory stimulant and a pathogenic factor involved in DM, was previously reported to be present at increased levels in the cerebrospinal fluid of patients with AD and mild cognitive impairment compared with age‑matched healthy controls. By investigating the association between AGEs and MIF, and the effects of neuroinflammation on AD, the present study aimed to increase understanding of the specific molecular mechanisms involved in the pathogenesis of DM and AD, and the connection between these diseases. PC12 cells were cultured in vitro; the levels of MIF mRNA and protein were determined using reverse transcription‑quantitative (RT‑q)PCR and western blot analyses. The optimal concentrations of AGEs and amyloid β 1‑40 (Aβ1‑40) were also determined in the cell model of AD using Cell Counting Kit‑8 and MTT assays. Cell numbers and morphological changes were observed following the treatment of Aβ1‑40‑stimulated PC12 cells with AGEs and the MIF inhibitor (S,R)‑3‑(4‑hydroxyphenyl)‑4,5‑dihydro‑5‑isoxazole acetic acid methyl ester (ISO‑1). The mRNA expression levels of interleukin (IL)‑1β, IL‑6, tumor necrosis factor‑α (TNF‑α) and MIF were determined via RT‑qPCR analysis. The results showed that the levels of MIF mRNA and protein were significantly increased in cells treated with AGEs compared with the control group. In the AD model group, the inhibition of PC12 cell growth was significantly increased, and the mRNA expression levels of IL‑1β, IL‑6, TNF‑α and MIF were also increased. Compared with treatment with AGEs alone, the combination of AGEs treatment with ISO‑1 significantly improved the survival rate and resulted in the reduced expression of inflammatory mediators in the AD cell model. Thus, ISO‑1 reduced AGEs‑mediated damage in the AD cell model. This may be a consequence of AGEs‑mediated MIF expression promoting neuritis in the AD cell model, whereas ISO‑1 decreased the expression of neuroinflammatory mediators.