Shen-Zhi-Ling oral liquid ameliorates cerebral glucose metabolism disorder in early AD via insulin signal transduction pathway in vivo and in vitro

Background Shen-Zhi-Ling oral liquid (SZL) is an herbal formula known for its efficacy of nourishing “heart and spleen”, and is used for the treatment and prevention of middle- and early-stage dementia. This study investigated the effects of SZL on amelioration of AD, and examined whether the underlying mechanisms from the perspective of neuroprotection are related to brain glucose metabolism. Methods Firstly, LC–MS/MS was used to analysis the SZL mainly enters the blood component. Then, the effects of SZL on cognitive and behavioral ability of APP/PS1 double transgenic mice and amyloid protein characteristic pathological changes were investigated by behavioral study and morphological observation. The effects of SZL on the ultrastructure of mitochondria, astrocytes, and micrangium related to cerebral glucose metabolism were observed using transmission electron microscopy. Then, micro-PET was also used to observe the effects of SZL on glucose uptake. Furthermore, the effects of SZL on insulin signaling pathway InR/PI3K/Akt and glucose transporters (GLUT1 and GLUT3) were observed by immunohistochemistry, Western-blot and RT-qPCR. Finally, the effects of SZL on brain glucose metabolism and key enzyme were observed. In vitro, the use of PI3K and/or GSK3β inhibitor to observe the effects of SZL drug-containing serum on GLUT1 and GLUT3. Results In vivo, SZL could significantly ameliorate cognitive deficits, retarded the pathological damage, including neuronal degeneration, Aβ peptide aggregation, and ultrastructural damage of hippocampal neurons, improve the glucose uptake, transporters and glucolysis. Beyond that, SZL regulates the insulin signal transduction pathway the insulin signal transduction pathway InR/PI3K/Akt. Furthermore, 15% SZL drug-containing serum increased Aβ42-induced insulin signal transduction-pathway related indicators and GLUT1 and GLUT3 expression in SH-SY5Y cells. The improvement of GLUT1 and GLUT3 in the downstream PI3K/Akt/GSK3β signaling pathway was reversed by the use of PI3K and/or GSK3β inhibitor. Conclusions In summary, our results demonstrated that improving glucose uptake, transport, and glycolysis in the brain may underlie the neuroprotective effects of SZL, and its potential molecular mechanism may be related to regulate the insulin signal transduction pathway.

Expression and Significance of Insulin Receptor Substrate 1 in Human Hepatocellular Carcinoma

Background. Insulin receptor substrate 1 (IRS-1) is an important molecule of the insulin signal transduction pathway and has been associated with the occurrence and development of many tumors, including hepatocellular carcinoma (HCC). Our study was designed to determine the expression and significance of IRS-1 in human HCC. Methods. Two hundred and forty specimens were drawn from 140 patients, including 100 HCC tissues and 100 paracancerous (PC) tissues from 100 HCC patients, 20 liver cirrhosis (LC) tissues from 20 LC patients, and 20 chronic hepatitis (CH) tissues from 20 CH patients. Baseline and pathological characteristics were included, and the expression of IRS-1 was examined by immunohistochemical (IHC) staining. Binary logistic regression model calculation was used for multivariate analysis. Results. The total positive rates of IRS-1 expression were 41.0%, 17.0%, 15.0%, and 10.0% in HCC, PC, LC and CH tissues, respectively. IRS-1-positive signals were brown in color and located in the nucleus and cytoplasm. Compared with PC, LC, and CH tissues, a significantly increased expression was observed in human HCC tissues (P<0.001, P=0.028, and P=0.008). Eight of the total 240 specimens had the strong immunostaining of IRS-1 expression, and all of them were HCC tissues. After control of the age, gender, and HBV and HCV infection, IRS-1 expression was independently associated with the diagnosis of HCC (OR 6.60, 95% CI 2.243-19.425, P=0.001). Conclusions. Positive expression of IRS-1 in HCC was increased significantly and may play an important role in the occurrence and development of human HCC.

Natural Alkaloids Intervening the Insulin Pathway: New Hopes for Anti-Diabetic Agents?

Background: Accumulating experimental data supports the capacity of natural compounds to intervene in complicated molecular pathways underlying the pathogenesis of certain human morbidities. Among them, diabetes is now a world’s epidemic associated with increased risk of death; thus, the detection of novel anti-diabetic agents and/or adjuvants is of vital importance. Alkaloids represent a diverse group of natural products with a range of therapeutic properties; during the last 20 years, published research on their anti-diabetic capacity has been tremendously increased. Purpose: To discuss current concepts on the anti-diabetic impact of certain alkaloids, with special reference to their molecular targets throughout the insulin-signaling pathway. Methodology: Upon in-depth search in the SCOPUS and PUBMED databases, the literature on alkaloids with insulin secretion/sensitization properties was critically reviewed. Results: In-vitro and in-vivo evidence supports the effect of berberine, trigonelline, piperine, oxymatrine, vindoneline, evodiamine and neferine on insulin-signaling and related cascades in beta-cells, myocytes, adipocytes, hepatocytes and other cells. Associated receptors, kinases, hormones and cytokines, are affected in terms of gene transcription, protein expression, activity and/or phosphorylation. Pathophysiological processes associated with insulin resistance, beta-cell failure, oxidative stress and inflammation, as well as clinical phenotype are also influenced. Discussion: Growing evidence suggests the ability of specific alkaloids to intervene in the insulin-signal transduction pathway, reverse molecular defects resulting in insulin resistance and glucose intolerance and improve disease complications, in-vitro and in-vivo. Future indepth molecular studies are expected to elucidate their exact mechanism of action, while large clinical trials are urgently needed to assess their potential as anti-diabetic agents.

Curcumin ameliorates insulin signalling pathway in brain of Alzheimer’s disease transgenic mice

Deficits in glucose, impaired insulin signalling and brain insulin resistance are common in the pathogenesis of Alzheimer’s disease (AD); therefore, some scholars even called AD type 3 diabetes mellitus. Curcumin can reduce the amyloid pathology in AD. Moreover, it is a well-known fact that curcumin has anti-oxidant and anti-inflammatory properties. However, whether or not curcumin could regulate the insulin signal transduction pathway in AD remains unclear. In this study, we used APPswe/PS1dE9 double transgenic mice as the AD model to investigate the mechanisms and the effects of curcumin on AD. Immunohistochemical (IHC) staining and a western blot analysis were used to test the major proteins in the insulin signal transduction pathway. After the administration of curcumin for 6 months, the results showed that the expression of an insulin receptor (InR) and insulin receptor substrate (IRS)-1 decreased in the hippocampal CA1 area of the APPswe/PS1dE9 double transgenic mice, while the expression of phosphatidylinositol-3 kinase (PI3K), phosphorylated PI3K (p-PI3K), serine-threonine kinase (AKT) and phosphorylated AKT (p-AKT) increased. Among the curcumin groups, the medium-dose group was the most effective one. Thus, we believe that curcumin may be a potential therapeutic agent that can regulate the critical molecules in brain insulin signalling pathways. Furthermore, curcumin could be adopted as one of the AD treatments to improve a patient’s learning and memory ability.

Antenatal corticosteroids alter insulin signaling pathways in fetal baboon skeletal muscle

We hypothesize that prenatal exposure to glucocorticoids (GCs) negatively alters the insulin signal transduction pathway and has differing effects on the fetus according to gestational age (GA) at exposure. Twenty-three fetal baboons were delivered from 23 healthy, nondiabetic mothers. Twelve preterm (0.67 GA) and 11 near-term (0.95 GA) baboons were killed immediately after delivery. Half of the pregnant baboons at each gestation received two doses of i.m. betamethasone 24 h apart (170 μg/kg) before delivery, while the other half received no intervention. Vastus lateralis muscle was obtained from postnatal animals to measure the protein content and gene expression of insulin receptor β (IRβ; INSR), IRβ Tyr 1361 phosphorylation (pIRβ), IR substrate 1 (IRS1), IRS1 tyrosine phosphorylation (pIRS1), p85 subunit of PI3-kinase, AKT (protein kinase B), phospho-AKT Ser473 (pAKT), AKT1, AKT2, and glucose transporters (GLUT1 and GLUT4). Skeletal muscle from preterm baboons exposed to GCs had markedly reduced protein content of AKT and AKT1 (respectively, 73 and 72% from 0.67 GA control, P<0.001); IRβ and pIRβ were also decreased (respectively, 94 and 85%, P<0.01) in the muscle of premature GC-exposed fetuses but not in term fetuses. GLUT1 and GLUT4 tended to increase with GC exposure in preterm animals (P=0.09), while GLUT4 increased sixfold in term animals after exposure to GC (P<0.05). In conclusion, exposure to a single course of antenatal GCs during fetal life alters the insulin signaling pathway in fetal muscle in a manner dependent on the stage of gestation.