Co-administration Of LY294002 Research Articles

Cognitive improving actions of tofacitinib in a mouse model of Alzheimer disease involving TNF-α, IL-6, PI3K-Akt and GSK-3β signalling pathway

Aim and Objective: This current study investigated the significance of tofactinib in improving memory functions in a memory model of β-amyloid (Aβ)-induced dementia.Material and Methods: Aβ1–42 was injected in the brain of mice using intracerebroventricular injection and after 14 days, the learning and memory was assessed on the Morris Water maze test. Mice were treated with tofactinib (10, 20, 30 mg/kg) two days prior to Aβ1–42 injection and 14 days after Aβ injection.Results: Treatment of tofactinib significantly improved the learning (decrease in day escape latency time [ELT]) and memory (increase in time spent in target quadrant). This drug also decreased the levels of T NF-α and IL-6 along with the rise in expression of p-Akt and p-GSK-3β/GSK-3β ratio in mice brain. Co-administration of LY294002 (P I3K inhibitor) or MK-2206 2HCl (Akt inhibitor) with tofactinib (30 mg/kg) obliterated the beneficial effects of the latter by increasing T NF-α and IL-6 levels along with decreasing the p-Akt expression and p-GSK-3β/GSK-3β ratio.Conclusion: It is concluded that tofactinib improves the condition of dementia of Alzheimer’s type, possibly through down regulation of T NF-α and IL-6 and instigation of P I3K-Akt-p-GSK-3β signalling system in the hippocampus of Aβ-treated mice.

Acylated Ghrelin Administration Inhibits Sleeve Gastrectomy - Induced Hippocampal Oxidative Stress, Apoptosis and Tau-Hyperphosphorylation by Activating the PI3K/Akt Pathway

This study investigated the impact of exogenous replacement therapy with acylated ghrelin (AG) post sleeve gastrectomy (SG) on the memory function in rats. In addition, we investigated the possible underlying mechanisms, including the effects on markers of oxidative stress, tau phosphorylation, and apoptosis. Adult male Wistar rats were divided into four groups (N = 18/group) as follows: sham (control), SG, SG+AG (100 μM), and SG+AG+LY294002 (0.25 μg/100 g). We continued all treatments daily for four weeks post-surgery. SG impaired the spatial, retention, and recognition memories as tested by the Morris water maze test, passive avoidance test, and novel object recognition test, respectively. Also, it enhanced the levels of reactive oxygen species and lipid peroxides, reduced glutathione and protein levels of Bcl-2, and increased the levels of Bax and cleaved caspase-3 in the hippocampus. In addition, SG reduced the hippocampal levels of acetylcholine and brain-derived neurotrophic factor. Concomitantly, it inhibited the hippocampal activity of Akt and increased the activity of glycogen synthase kinase 3β and tau protein phosphorylation. Exogenous administration of acylated ghrelin to rats that had undergone SG prevented memory deficits. Also, it prevented the alteration in the above-mentioned biochemical parameters, an effect that was abolished by co-administration of LY294002 (phosphoinositide 3-kinase inhibitor). In conclusion, AG replacement therapy after SG in rats protects them against memory deficits and hippocampal damage by suppressing tau protein phosphorylation, mediated by activating PI3K/Aktinduced inhibition of glycogen synthase kinase 3β.

A Novel Approach to Safer Glucocorticoid Receptor-Targeted Anti-lymphoma Therapy via REDD1 (Regulated in Development and DNA Damage 1) Inhibition.

Glucocorticoids are widely used for therapy of hematologic malignancies. Unfortunately, chronic treatment with glucocorticoids commonly leads to adverse effects including skin and muscle atrophy and osteoporosis. We found recently that REDD1 (regulated in development and DNA damage 1) plays central role in steroid atrophy. Here, we tested whether REDD1 suppression makes glucocorticoid-based therapy of blood cancer safer. Unexpectedly, approximately 50% of top putative REDD1 inhibitors selected by bioinformatics screening of Library of Integrated Network-Based Cellular Signatures database (LINCS) were PI3K/Akt/mTOR inhibitors. We selected Wortmannin, LY294002, and AZD8055 for our studies and showed that they blocked basal and glucocorticoid-induced REDD1 expression. Moreover, all PI3K/mTOR/Akt inhibitors modified glucocorticoid receptor function shifting it toward therapeutically important transrepression. PI3K/Akt/mTOR inhibitors enhanced anti-lymphoma effects of Dexamethasone in vitro and in vivo, in lymphoma xenograft model. The therapeutic effects of PI3K inhibitor+Dexamethasone combinations ranged from cooperative to synergistic, especially in case of LY294002 and Rapamycin, used as a previously characterized reference REDD1 inhibitor. We found that coadministration of LY294002 or Rapamycin with Dexamethasone protected skin against Dexamethasone-induced atrophy, and normalized RANKL/OPG ratio indicating a reduction of Dexamethasone-induced osteoporosis. Together, our results provide foundation for further development of safer and more effective glucocorticoid-based combination therapy of hematologic malignancies using PI3K/Akt/mTOR inhibitors.

Reconstituted High-Density Lipoprotein Stimulates Differentiation of Endothelial Progenitor Cells and Enhances Ischemia-Induced Angiogenesis

Plasma high-density lipoprotein (HDL) levels have an inverse correlation with incidence of ischemic heart disease as well as other atherosclerosis-related ischemic conditions. However, the molecular mechanism by which HDL prevents ischemic disease is not fully understood. Here, we investigated the effect of HDL on differentiation of endothelial progenitor cells and angiogenesis in murine ischemic hindlimb model. Intravenous injection of reconstituted HDL (rHDL) significantly augmented blood flow recovery and increased capillary density in the ischemic leg. rHDL increased the number of bone marrow-derived cells incorporated into the newly formed capillaries in ischemic muscle. rHDL induced phosphorylation of Akt in human peripheral mononuclear cells. rHDL (50 to 100 microg apolipoprotein A-I/mL) promoted differentiation of peripheral mononuclear cells to endothelial progenitor cells in a dose-dependent manner. The effect of rHDL on endothelial progenitor cells differentiation was abrogated by coadministration of LY294002, an inhibitor of phosphatidylinositol 3-kinase. rHDL failed to promote angiogenesis in endothelial NO-deficient mice. rHDL directly stimulates endothelial progenitor cell differentiation via phosphatidylinositol 3-kinase/Akt pathway and enhances ischemia-induced angiogenesis. rHDL may be useful in the treatment of patients with ischemic cardiovascular diseases.

Phosphoinositide 3-kinase regulates excitation-contraction coupling in neonatal cardiomyocytes.

The phosphoinositide 3-kinase (PI3K) inhibitor LY-294002 decreased steady-state contraction in neonatal rat ventricular myocytes (NRVM). To determine whether the effect on steady-state contraction could be due to decreased intracellular Ca(2+) content, Ca(2+) content was assessed with fluorescent plate reader analysis by using the caffeine-releasable Ca(2+) stores as an index of sarcoplasmic reticulum (SR) Ca(2+) content. Caffeine-releasable Ca(2+) content was diminished in a dose-dependent manner with LY-294002, suggesting that the decrease in steady-state contraction was due to diminished intracellular Ca(2+) content. Activation of the L-type Ca(2+) channel by BAY K 8644 was attenuated by LY-294002, suggesting the effect of LY-294002 is to reduce Ca(2+) influx at this channel. To investigate whether additional proteins involved in excitation-contraction (EC) coupling are likewise regulated by PI3K activity, the effects of compounds acting at sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a), the ryanodine receptor, and the Na/Ca exchanger (NCX) were compared with LY-294002. Inhibition of SERCA2a by thapsigargin increased basal Ca(2+) levels in contrast to LY-294002, indicating that SERCA2a activity is sustained in the presence of LY-294002. Ryanodine decreased SR Ca(2+) content. The additive effect with coadministration of LY-294002 could be attributed to a decrease in Ca(2+) influx at the L-type Ca(2+) channel. The NCX inhibitor Ni(2+) was used to investigate whether the decrease in intracellular Ca(2+) content with LY-294002 could be due to inhibition of the NCX reverse-mode activity. The minimal effect of LY-294002 with Ni(2+) suggests that the primary effect of LY-294002 on EC coupling occurs through inhibition of PI3K-mediated L-type Ca(2+) channel activity.

Role of reactive oxygen species and phosphatidylinositol 3-kinase in cardiomyocyte differentiation of embryonic stem cells

Cardiotypic development in embryonic stem cell-derived embryoid bodies may be regulated by reactive oxygen species (ROS). ROS were generated by a NADPH oxidase-like enzyme which was transiently expressed during the time course of embryoid body development. Incubation with either H 2O 2 or menadione enhanced cardiomyogenesis, whereas the radical scavengers trolox, pyrrolidinedithiocarbamate and N-acetylcysteine exerted inhibitory effects. The phosphatidylinositol 3-kinase (PI-3-kinase) inhibitors LY294002 and wortmannin abolished cardiac commitment and downregulated ROS in embryoid bodies. Coadministration of LY294002 with prooxidants resumed cardiomyocyte differentiation, indicating a role for PI-3-kinase in the regulation of the intracellular redox state.