OBJECTIVES: The present study investigates the effect of a novel 5-HT3 receptor antagonist 3-methoxy-N-p-tolylquinoxalin-2-carboxamide (QCM-4) on several pathogenic markers of depression associated with obesity such as plasma insulin resistance, hippocampal cyclic adenosine monophosphate (cAMP), brain-derived neurotrophic factor (BDNF), serotonin (5-HT) concentrations, hippocampal neuronal damage, and p53 protein expression in high-fat-diet (HFD)-fed mice.
METHODS: Obesity was experimentally induced in mice by feeding with HFD for 14 weeks followed by administration of QCM-4 (1 and 2 mg/kg, p.o.)/standard escitalopram (ESC) (10 mg/kg, p.o.)/vehicle (10 ml/kg, p.o.) for 28 days. Behavioral assays such as sucrose preference test (SPT); forced swim test (FST); elevated plus maze (EPM); biochemical assays including oral glucose tolerance tests (OGTT), insulin, cAMP, BDNF, and 5-HT concentrations; and molecular assays mainly histology and immunohistochemistry (IHC) of p53 protein in the dentate gyrus (DG), CA1, and CA3 regions of hippocampus in HFD fed mice were performed.
RESULTS: Chronic treatment with QCM-4 in HFD-fed mice reversed the behavioral alterations in SPT, FST, and EPM. QCM-4 showed poor sensitivity for plasma glucose, improved insulin sensitivity, increased hippocampal cAMP, BDNF, and 5-HT concentrations. In the hippocampal DG, CA1, and CA3 regions, QCM-4 treatment improved the neuronal morphology in the histopathology and inhibited p53 protein expression in IHC assay in HFD-fed mice.
CONCLUSION: QCM-4 attenuated the depressive-like phenotype in HFD-fed mice by improving behavioral, biochemical, and molecular alterations through serotonergic neuromodulation.
MATERIALS AND METHODS: The antioxidant effect of these compounds was initially performed in vitro using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay methods before subjecting them to in vivo experiments. Compounds showing potent antioxidant activity (CS-1 and CS-2) were investigated further for their antidepressant activity using the forced swim test (FST) and tail suspension test (TST). Ascorbic acid (AA) and fluoxetine (20 mg/kg, p.o) were used as reference drugs for comparison in the antioxidant and antidepressant experiments, respectively.
RESULTS: It was observed that CS-2 and CS-3 exhibited highest DPPH (half maximal inhibitory concentration [IC50]: 16.22 and 25.18 μg/mL) and ABTS (IC50: 17.2 and 28.86 μg/mL) radical scavenging activity, respectively, compared to AA (IC50: 15.73 and 16.79 μg/mL) and therefore, both CS-2 and CS-3 were tested for their antidepressant effect using FST and TST as experimental models. Pretreatment of CS-2 and CS-3 (20 mg/kg) for 10 days considerably decreased the immobility time in both the FST and TST models.
CONCLUSION: The antioxidant and antidepressant effect of CS-2 and CS-3 may be attributed to the presence of azomethine linkage in the molecule.
Methods: Fifty male Sprague-Dawley rats were divided into (i) control, (ii) stress-exposed, (iii) stress-exposed and treated with TH (1 g/kg body weight twice daily via oral gavage), (iv) stress-exposed and treated with DHA-rich fish oil (450 mg/kg body weight twice daily via oral gavage), and (v) stress-exposed and treated with a combination of TH and DHA-rich fish oil. The chronic stress regimen consisted of a combination of restraint stress and a swim stress test for 28 days. The concentrations of selected pro-inflammatory cytokines in brain homogenates (TNF-α, IL6, and IFN-γ) were measured by ELISA.
Results: The concentrations of TNF-α, IL6, and IFN-γ in brain homogenates from the DHA, TH, and TH + DHA-treated groups were significantly lower compared to the control and stress-only-exposed groups (p