What Athletes Should Know About AICAR and Others
As shown in Table 1, the majority of the effects of AICAr on skeletal muscles are AMPK-dependent. AICAr-induced glucose uptake in skeletal muscle was abolished in the knockout of the α 2 [32,33,35] and α 3 isoforms of AMPK [34]. Both AICAr and treadmill exercise increased insulin sensitivity to stimulate glucose uptake, and these effects were not observed in mice with reduced or ablated AMPK activity in skeletal muscle [68,69].
Other AMPK modulators
However, in the setting of Ca2+-induced T cell activation and death, AICAR and Compound C can either promote or inhibit T cell survival in an AMPK-dependent manner. Taken together, our data clarify the role of AMPK in T cells, as well as shed light on the implications of chemical intervention of AMPK activity in different diseases in vivo. AICAR/Compound C is commonly used as an agonist/antagonist to study AMPK-dependent cellular pathways. By specific deletion of AMPK in T cells using CD4-Cre-AMPK fl/fl mice, we confirmed that AICAR and Compound C can indeed activate or inhibit AMPK, respectively, in T cells from WT mice (Figure (Figure1).1). Importantly, treatment with AICAR or Compound C has no impact on AMPK KO T cell death, but respectively promotes or inhibits the survival of AMPK WT T cells in response to high concentration Ionomycin-activated T cells death (Figure (Figure2).2).
We next explored whether inhibition of AMPK activation by CC could promote hepatic oxidative stress and inflammation levels in sodium taurocholate-induced SAP rats. We found that the increase in the nuclear translocation of Nrf2 in the hepatic tissues of SAP rats was markedly reduced after CC treatment (Figures 6A,B). We further measured MDA and SOD levels, which are indicators of oxidative damage, in the liver tissues of each group. The levels of hepatic MDA in rats treated with CC were significantly augmented compared to those in the SAP groups (Figure 6C). Alternatively, treatment with CC had a reduced effect on the magnitude of sodium taurocholate-induced decline in hepatic SOD levels (Figure 6D).
The β-subunit contains a domain that interacts with the α- and γ-subunits and was previously reported to mediate the assembly of the heterotrimeric AMPK complex [5]. The γ-subunit binds to AMP following the phosphorylation of threonine 172 in the α-subunit and kinase activation [7]. AMPK is a central energy-sensing master regulator of cellular metabolism and is activated when the cellular AMP/ATP ratio increases [8]. This allosteric regulatory system further promotes the phosphorylation of threonine 172 in the α-subunit by upstream kinases [9]. As early as day 7, the food intake in all HFD-treated groups was reduced compared to STD-treated groups (Table 4).
Methotrexate and its mechanisms of action in inflammatory arthritis
- In this study, our data has demonstrated that extrinsic AICAR treatment induces apoptosis and increases DNA damage in EGFR-mutant lung cancer cell lines.
- AICAR, introduced from the first day of the study, reduced the content of lipid inclusions in the cytoplasm.
- The white gastrocnemius muscle contains ~90 % type IIB and ~10 % of type IIX fibers, with low levels but a minimal amount of type I or IIA fibers in rats [37, 47].
- These results indicate treatment period-specific effects of AICAR that lead to the activation of AMPK and inconsistent SIRT1 expression patterns.
At the end of the study, at the end of the 13th week, during necropsy, the internal organs were assessed, the masses of the organs https://soupspooncafe.com/the-effective-use-of-steroids-to-improve-quality-12/ were recorded, and special attention was paid to visceral fat, assessing its amount and the mass of the fat surrounding epididymis. The biochemical parameters and histology of the internal organs and tissues were assessed. The AICAR treatment led to a decrease in body weight, a decrease in the amount and mass of abdominal fat, and an improvement in the pathomorphological picture of internal organs.
Baseline glucose values were measured in the animals on empty stomachs before insulin administration, as well as in dynamics 20, 40, 60, and 120 min after subcutaneous administration of insulin at a dose of 2 IU/kg. In C57BL/6 mice kept on HFD, the baseline hyperglycemia was recorded—the initial blood glucose levels in groups 3, 4, 5, and 6 were significantly higher relative to animals from group 1 kept on a standard diet (STD + vehicle) and group 2 (STD + AC). The introduction of insulin significantly reduced the level of glucose in the blood from the initial values in each of the groups after 20 min. Hypoglycemia compared with the baseline values persisted until the end of the experiment. In this experiment, all the animals showed sensitivity to insulin, since the glucose level was significantly reduced in all animals (Table 3).
AMPK-dependent and independent effects of AICAR and compound C on T-cell responses
After glucose administration to all the mice, hyperglycemia was observed after 30 min (relative to baseline values). Significantly elevated glucose concentrations persisted until the 120th minute in groups 2 (STD + AC), 3 (HFD + vehicle), 5 (HFD + AC 7), and 6 (HFD + AC + MTX), while in groups 1 (STD + vehicle) and 4 (HFD + AC 1) the glucose levels did not differ from the baseline by 120 min. In all the groups, the maximum glucose level was observed by the 30th minute and, from the 60th minute to the 120th minute, the glucose values were significantly reduced relative to this maximum value (Table 7). At the same time, only in groups 1 (STD + vehicle) and 4 (HFD + AC 1) did the values fully recover to the initial level by the 120th minute.
The AMPK-stimulating AICAR can also be synthesized in a lab and is being evaluated in preclinical research and human clinical trials as a therapeutic agent to treat certain metabolic disorders in humans.
In chronic myelogenous leukemia (CML) cell lines [12] and primary samples [111], AICAr had antiproliferative effects, but AMPK knock-down by shRNA failed to prevent the effect of AICAr, indicating an AMPK-independent mechanism [12]. In azacytidine (Aza)-resistant myelodysplastic syndrome and acute myeloid leukemia (MS/AML) cell lines and primary samples, 2 mM AICAr blocked proliferation, and these initial findings led to a phase I/II clinical trial using AICAr in 12 patients with Aza-refractory MDS/AML patients. Despite a very good response in one out of four patients, the trial was stopped because the highest dose of AICAr caused serious renal side effects in patients with severe comorbidities [10]. As a cell-permeable nucleotide, AICAr enters the cells through adenosine transporters [20] and becomes phosphorylated by adenosine kinase into AICAR [21]. AICAR or ZMP activates AMPK but it is 40- to 50- fold less potent than AMP in AMPK activation and accumulates in high concentrations in the cytoplasm [1], so that it was always likely that AICAr may have several AMPK-independent effects.
The procedures for patient samples and data collection were approved by Yale University Human Investigation Committee. H1975 cells were plated in a 6-well plate at 80% confluency in duplicates and were treated with AICAR (1 mM) for 15 min. The supernatant was removed, and the pellets were heated for three mins at their respective temperature (37–55 °C) in a mini dry bath incubator (Four E’s Scientific), followed by a three-min cool-down. Cell pellets were then resuspended in 80 μl of RIPA (radioimmunoprecipitation assay) buffer (Thermo Fisher Scientific) supplemented with protease and phosphatase inhibitor cocktail (Roche) to lyse the cells. The mixtures were shaken at 4 °C for 2 h, followed by centrifugation at 4 °C for 40 min at 14,000 RPM.
