Effects of multiple doses of montmorillonite, alone and in combination with activated charcoal, on the toxicokinetics of a single dose of digoxin in rats.

Objectives: A narrow margin between the therapeutic and toxic doses of digoxin can result in an increased incidence of toxicity. Since digoxin has an enterohepatic cycle, multiple oral doses of absorbents like montmorillonite may be useful in the treatment of digoxin toxicity. Materials and Methods: In this study, 4 groups of 6 rats received intraperitoneal digoxin (1 mg/kg), and half an hour later, distilled water (DW) or oral adsorbents, including montmorillonite (1 g/kg), activated charcoal (1 g/kg) (AC) alone or in combination in the ratio of 70:30. Half of the mentioned doses were also gavaged at 3 and 5.5 hr after digoxin injection. The serum level of digoxin, biochemical factors, and activity score were assessed during the experiment. Three control groups only received DW, montmorillonite, or AC. Results: All adsorbents were able to significantly decrease the serum level of digoxin compared to the digoxin+DW group (P<0.01). Only montmorillonite reversed the digoxin-induced hyperkalemia (P<0.05). Multiple dose administration of adsorbents also significantly reduced the digoxin area under the curve and half-life and increased digoxin clearance (P<0.05). However, there was no significant difference in the kinetic parameters between groups that received digoxin plus adsorbents. Conclusion: Multiple-dose of montmorillonite reversed digoxin toxicity and reduced serum digoxin levels by increasing the excretion and reducing the half-life. Montmorillonite has also corrected digoxin-induced hyperkalemia. Based on the findings, a multiple-dose regimen of oral montmorillonite could be a suitable candidate for reducing the toxicity issue associated with drugs like digoxin that undergo some degree of enterohepatic circulation.

The Fibrinogen-like Domain of ANGPTL3 Facilitates Lipolysis in 3T3-L1 Cells by Activating the Intracellular Erk Pathway.

BACKGROUND: ANGPTL3 stimulates lipolysis in adipocytes, but the underlying molecular mechanism is yet unknown. The C-terminal fibrinogen-like domain of ANGPTL3 (ANGPTL3-Fld) activates the AKT pathway in endothelial cells. Hence, we evaluated whether ANGPTL3-Fld stimulates lipolysis in adipocytes through the MAPK kinase pathway. MATERIALS AND METHODS: 3T3-L1 adipocytes were treated with isoproterenol (ISO), ANGPTL3-Fld, or both. Lipolysis was evaluated through the release of free fatty acids (FFAs) in the culture medium. The activation status of intracellular kinases was evaluated with and without the inhibition of the BRAF-ERK arm of the MAPK pathway. RESULTS: ANGPTL3-Fld alone was not able to activate lipolysis, while the combination of ANGPTL3-Fld and ISO determined a 10-fold enrichment of the FFA concentration in the culture medium with an incremental effect (twofold) when compared with ISO alone. ANGPTL3-Fld alone inhibited hormone-sensitive lipase (HSL), whereas the treatment with ISO induced the activation of HSL. The net balance of ANGPTL3-Fld and ISO cotreatment resulted in HSL activation. The results indicate that ANGPTL3-Fld generated an intracellular activation signal involving the MAPK-ERK pathway, possibly through the PDGFRß-PLCγ-AMPK axis. CONCLUSION: ANGPTL3-Fld appears to act as a facilitator of lipolysis in adipocytes, and this effect was driven by a signal mediated by a pathway that is different from the canonical ß-adrenergic stimulus.

Refinement of pathogenicity classification of variants associated with familial hypercholesterolemia: Implications for clinical diagnosis.

BACKGROUND: The lack of functional evidence for most variants detected during the molecular screening of patients with clinical familial hypercholesterolemia (FH) makes the definitive diagnosis difficult. METHODS: A total of 552 variants in LDLR, APOB, PCSK9 and LDLRAP1 genes found in 449 mutation-positive FH (FH/M+) patients were considered. Pathogenicity update was performed following the American College of Medical Genetics and Genomics (ACMG) guidelines with additional specifications on copy number variants, functional studies, in silico prediction and co-segregation criteria for LDLR, APOB and PCSK9 genes. Pathogenicity of LDLRAP1 variants was updated by using ACMG criteria with no change to original scoring. RESULTS: After reclassification, the proportion of FH/M+ carriers of pathogenic (P) or likely pathogenic (LP) variants, and FH/M+ carriers of likely benign (LB) or benign (B) variants, was higher than that defined by standard criteria (81.5% vs. 79.7% and 7.1% vs. 2.7%). The refinement of pathogenicity classification also reduced the percentage of FH with variants of uncertain significance (VUS) (17.7% vs. 11.4%). After adjustment, the FH diagnosis by refined criteria best predicted LDL-C levels (Padj <0.001). Notably, FH with VUS variants had higher LDL-C than those with LB (all Padj ≤ 0.033), but similar to those with LP variants. CONCLUSION: Accurate variant interpretation best predicts the increase of LDL-C levels and shows its clinical utility in the molecular diagnosis of FH.

The effects of vitamin B12 on the brain damages caused by methamphetamine in mice.

OBJECTIVES: Methamphetamine (METH) is a powerful stimulant drug that directly affects the brain and induces neurological deficits. B12 is a water-soluble vitamin (vit) that is reported to attenuate neuronal degeneration. The goal of the present study is to investigate the effect of vitamin B12 on METH's neurodegenerative changes. MATERIALS AND METHODS: Two groups of 6 animals received METH (10 mg/kg, interaperitoneally (IP)) four times with a 2 hr interval. Thirty mins before METH administration, vit B12 (1 mg/kg) or normal saline were injected IP. Animals were sacrificed 3 days after the last administration. Caspase proteins levels were measured by Western blotting. Also, samples were examined by TUNEL assay to detect the presence of DNA fragmentation. Reduced glutathione (GSH) was also determined by the Ellman method. RESULTS: The pathological findings showed that vit B12 attenuates the gliosis induced by METH. Vit B12 administration also significantly decreased the apoptotic index in the striatum and the cerebral cortex (P<0.001). It also reduced caspase markers compared to the control (P<0.01 and P<0.001, respectively). Interestingly, co-administration of METH and Vit B12 elevates the levels of GSH in both regions of the brain and returned it to normal levels compared to the METH group. CONCLUSION: The current study suggests that parenteral vit B12 at safe doses may be a promising treatment for METH-induced brain damage via inhibition of neuron apoptosis and increasing the reduced GSH level. Research focusing on the mechanisms involved in the protective responses of vit B12 can be helpful in providing a novel therapeutic agent against METH-induced neurotoxicity.

Cinnamaldehyde improves methamphetamine-induced spatial learning and memory deficits and restores ERK signaling in the rat prefrontal cortex.

OBJECTIVES: Methamphetamine is a stimulant compound that penetrates readily into the central nervous system. Repeated exposure to methamphetamine leads to damage in the dopaminergic and serotonergic axons of selected brain regions. Previous studies showed that cinnamaldehyde improved memory impairment in animals. In the present study, we aimed to elucidate the effects of cinnamaldehyde on methamphetamine-induced memory impairment in rats. MATERIALS AND METHODS: Male Wistar rats received methamphetamine (10 mg/kg, intraperitoneally) for 7 days. Thirty minutes before each injection, animals were given cinnamaldehyde (20, 40, or 80 mg/kg) or rivastigmine (1 mg/kg). The spatial learning and memory were examined using the Morris water maze test. The expression of extracellular signal-regulated kinase (ERK) phosphorylation in the frontal cortex and hippocampus was also detected by immunohistochemical method. RESULTS: Administration of methamphetamine increased the latency to find the platform in the learning phase, while administration of cinnamaldehyde (40 mg/kg) or rivastigmine before methamphetamine reversed the increased latency. Administration of cinnamaldehyde, at the dose of 40 mg/kg with methamphetamine, increased the time and distance traveled in the target quadrant in comparison with the amphetamine group. Moreover, the methamphetamine and cinnamaldehyde-treated group had higher expression of phosphorylated ERK1/2 in the prefrontal cortex in comparison with the methamphetamine-treated animals. CONCLUSION: The present data demonstrated that repeated METH administration impaired cognitive performance through the ERK pathway and decreased the phosphorylation of ERK1/2 in the prefrontal cortex while administration of cinnamaldehyde restored both effects. Accordingly, cinnamaldehyde may be a valuable therapeutic tool for the treatment of cognitive deficits associated with methamphetamine consumption.

Exploring the effect of intravenous lipid emulsion in acute methamphetamine toxicity.

OBJECTIVES: The increasing use of methamphetamine (METH) in the last decades has made it the second most abused drug. Advancs in the area of intravenous lipid emulsion (ILE) have led to its potential application in the treatment of poisoning. The present study aims to investigate the potential role of ILE as an antidote for acute METH poisoning. MATERIALS AND METHODS: Two groups of six male rats were treated by METH (45 mg/kg), intraperitoneally. Five to seven min later, they received an infusion of 18.6 ml/kg ILE 20% through the tail vein or normal saline (NS). Locomotor and behavioral activity was assessed at different time after METH administration. Body temperature and survival rates were also evaluated. Brain and internal organs were then removed for histological examination and TUNEL assay. RESULTS: ILE therapy for METH poisoning in rats could prevent rats mortalities and returned the METH-induced hyperthermia to normal rates (P<0.05). ILE reduced freezing and stereotyped behaviors and increased rearing responses (P<0.05). Locomotor activity also returned to control levels especially during the last hours of the experiment. ILE administration decreased the prevalence of pulmonary emphysema in the lungs (P<0.05 and P<0.01) and percentages of TUNEL positive cells in the brain (P<0.05), in comparison with the control group. CONCLUSION: ILE could reduce the severity of METH- induced toxicity as well as mortality rate in the animals. Intravenous infusion of lipid emulsion may save the life of patients with acute METH intoxication who do not respond to standard initial therapy.