(F) U0126 (0.5 M) can abolish the inhibition of BER (5 M) around the production of A42, *P< 0.01 compared with vehicle-treated group, #P< 0.05 compared with vehicle-treated group LY310762 (n = 5). == Effects of BER and U0126 around the expression of BACE == We assayed the expression of BACE in HEK293 cells by WB. BER around the production of beta-amyloid40/42and the expression of BACE. == Conclusion == Our data show that BER decreases the production of beta-amyloid40/42by inhibiting the expression of BACE via activation of the ERK1/2 pathway. Keywords:Alzheimer’s disease, berberine, beta-amyloid40/42, beta-secretase, extracellular signal-regulated kinase1/2 == Background == Alzheimer’s disease (AD) is the most prominent form of senile dementia. In the pathogenesis of AD, amyloid- peptide (A) plays a critical and primary role [1]. The aggregation and accumulation of extracellular and intracellular A40/42impairs synaptic plasticity and memory [2,3]. A40/42is generated by -secreatase- (beta-site amyloid precursor protein cleaving enzyme, BACE) and -secretase-mediated sequential cleavages of amyloid precursor protein (APP). Inhibition of the production of A40/42can be expected to delay the development of AD [4]. In fact, some nonsteroidal anti-inflammatory drugs (NSAIDs), including sulindac sulfide, S-ibuprofen, R-ibuprofen and indomethacin, have been shown to inhibit the production of A40/42by inhibiting the expression of BACE and the activity of -secretase via activating peroxisome proliferator-activated receptor (PPAR ) and inhibiting Rho-Rho associated kinase (Rho-ROCK) pathway [5,6]. Additionally, some statins, including sinvastatin, rosuvastatin, and lovastatin, the cholesterol-lowering drugs, have been found to reduce levels of A40/42by promoting the expression of -secretase and inhibiting BACE activity [7-9]. Berberine (BER), an isoquinoline alkaloid existing inCortex phellodendri(Huangbai) andRhizoma coptidis(Huanglian), has a long history in China as a nonprescription drug for the treatment of diarrhea LY310762 and gastrointestinal disorders. In recent years, many studies have indicated that BER has multiple pharmacological effects. BER is usually a novel cholesterol-lowering drug unique from your statin family. It works by increasing the expression of low-density lipoprotein receptors (LDLR) and inhibiting lipid synthesis [10,11]. BER can also improve insulin resistance and exerts an insulin-independent glucose-lowering effect, stimulating insulin secretion and sensitizing insulin activity, inducing glycolysis, and increasing glucose transport and uptake activity [12-17]. At the same time, some studies have found that BER exerts anti-inflammatory effects by inhibiting arachidonic acid metabolism and the production of some inflammatory factors including cyclooxygenase-2 (COX-2), interleukin-1 beta (IL-1), tumor necrosis factor-alpha (TNF-), Interleukin-1 (IL-6) and inductible nitric oxide synthase (iNOS)[18-23]. BER can pass through the blood-brain barrier and reach the brain parenchyma in a dose- and time-dependent manner [24], and has multiple neuropharmacological properties including neuroprotective and neurotrophic effects. It also stimulates anti-neuronal apoptosis, improves cerebral microcirculation, reduces depressive disorder, and inhibits acetylcholinesterase [25-27]. Notably, one study [28] has reported that BER can decrease the production of A40/42, but the mechanism remains LKB1 unclear. LY310762 Further investigation of how BER inhibits the expression of BACE may have significant impact on the treatment of AD. In this study, we therefore focused on the mechanism of BER on BACE and A40/42inhibition, using LY310762 HEK293 cells stably transfected with APP695 made up of the Swedish mutation. == Results == == Effects of BER and U0126 around the proliferation and cytotoxicity of HEK293 cells == The MTT assay was used to detect the treatments around the proliferation of HEK293 cells. Relative to the vehicle group, no significant declines were observed in the cells receiving treatments (P> 0.05) (Figure1A, Band1C). The LDH release of cultured medium was used to assay the treatments for the cytotoxicity of HEK293 cells. Compared with vehicle treatment, BER LY310762 and U0126 showed no significant effects around the release of LDH in the culture medium (P> 0.05) (Figure1D, Eand1F), but 3% H2O2significantly increased the release of LDH in the culture medium (P< 0.01). == Physique 1. == Evaluation of the treatments around the proliferation and the cytotoxicity of HEK293 cells by MTT assay and LDH assay. (A).
(F) U0126 (0
