Targeting Toll-like Receptor 4/Nuclear Factor-κB and Nrf2/Heme Oxygenase-1 Crosstalk via Trimetazidine Alleviates Lipopolysaccharide-Induced Depressive-like Behaviors in Mice.

Depression is a global psychiatric illness that imposes a substantial economic burden. Unfortunately, traditional antidepressants induce many side effects which limit patient compliance thus, exploring alternative therapies with fewer adverse effects became urgent. This study aimed to investigate the effect of trimetazidine (TMZ); a well-known anti-ischemic drug in lipopolysaccharide (LPS) mouse model of depression focusing on its ability to regulate toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) as well as nuclear factor erythroid 2 related factor 2 (Nrf2)/ heme oxygenase-1 (HO-1) signaling pathways. Male Swiss albino mice were injected with LPS (500 µg/kg, i.p) every other day alone or parallel with oral doses of either escitalopram (Esc) (10 mg/kg/day) or TMZ (20 mg/kg/day) for 14 days. Treatment with TMZ attenuated LPS-induced animals' despair with reduced immobility time inforced swimming test. TMZ also diminished LPS- induced neuro-inflammation via inhibition of TLR4/NF-κB pathway contrary to Nrf2/HO-1 cascade activation with consequent increase in reduced glutathione (GSH) and HO-1 levels whereas the pro-inflammatory cytokines; tumor necrosis factor-α (TNF-α) and interleukin (IL)-1ß were evidently reduced. Besides, TMZ replenished brain serotonin levels via serotonin transporter (SERT) inhibition. Thus, TMZ hindered LPS-induced neuro-inflammation, oxidative stress, serotonin deficiency besides its anti-apoptotic effect which was reflected by decreased caspase-3 level. Neuroprotective effects of TMZ were confirmed by the histological photomicrographs which showed prominent neuronal survival. Here we showed that TMZ is an affluent nominee for depression management via targeting TLR4/NF-κB and Nrf2/HO-1 pathways. Future research addressing TMZ-antidepressant activity in humans is mandatory to enroll it as a novel therapeutic strategy for depression.

SIRT1/PARP-1/NLRP3 cascade as a potential target for niacin neuroprotective effect in lipopolysaccharide-induced depressive-like behavior in mice.

Depression is a serious mood disorder characterized by monoamines deficiency, oxidative stress, neuroinflammation, and cell death. Niacin (vitamin B3 or nicotinic acid, NA), a chief mediator of neuronal development and survival in the central nervous system, exerts neuroprotective effects in several experimental models. AIMS: This study aimed to investigate the effect of NA in lipopolysaccharide (LPS) mouse model of depression exploring its ability to regulate sirtuin1/poly (ADP-ribose) polymerase-1 (PARP-1)/nod-likereceptor protein 3 (NLRP3) signaling. MAIN METHODS: Mice were injected with LPS (500 µg/kg, i.p) every other day alone or concurrently with oral doses of either NA (40 mg/kg/day) or escitalopram (10 mg/kg/day) for 14 days. KEY FINDINGS: Administration of NA resulted in significant attenuation of animals' despair reflected by decreased immobility time in forced swimming test. Moreover, NA induced monoamines upsurge in addition to sirtuin1 activation with subsequent down regulation of PARP-1 in the hippocampus. Further, it diminished nuclear factor-κB (NF-κB) levels and inhibited NLRP3 inflammasome with consequent reduction of caspase-1, interleukin-1ß and tumor necrosis factor-α levels, thus mitigating LPS-induced neuroinflammation. NA also reduced tumor suppressor protein (p53) while elevating brain-derived neurotrophic factor levels. LPS-induced decline in neuronal survival was reversed by NA administration with an obvious increase in the number of intact cells recorded in the histopathological micrographs. SIGNIFICANCE: Accordingly, NA is deemed as a prosperous candidate for depression management via targeting SIRT1/PARP-1 pathway.

Alogliptin Attenuates Lipopolysaccharide-Induced Neuroinflammation in Mice Through Modulation of TLR4/MYD88/NF-κB and miRNA-155/SOCS-1 Signaling Pathways.

BACKGROUND: Endotoxin-induced neuroinflammation plays a crucial role in the pathogenesis and progression of various neurodegenerative diseases. A growing body of evidence supports that incretin-acting drugs possess various neuroprotective effects that can improve learning and memory impairments in Alzheimer's disease models. Thus, the present study aimed to investigate whether alogliptin, a dipeptidyl peptidase-4 inhibitor, has neuroprotective effects against lipopolysaccharide (LPS)-induced neuroinflammation and cognitive impairment in mice as well as the potential mechanisms underlying these effects. METHODS: Mice were treated with alogliptin (20 mg/kg/d; p.o.) for 14 days, starting 1 day prior to intracerebroventricular LPS injection (8 µg/µL in 3 µL). RESULTS: Alogliptin treatment alleviated LPS-induced cognitive impairment as assessed by Morris water maze and novel object recognition tests. Moreover, alogliptin reversed LPS-induced increases in toll-like receptor 4 and myeloid differentiation primary response 88 protein expression, nuclear factor-κB p65 content, and microRNA-155 gene expression. It also rescued LPS-induced decreases in suppressor of cytokine signaling gene expression, cyclic adenosine monophosphate (cAMP) content, and phosphorylated cAMP response element binding protein expression in the brain. CONCLUSION: The present study sheds light on the potential neuroprotective effects of alogliptin against intracerebroventricular LPS-induced neuroinflammation and its associated memory impairment via inhibition of toll-like receptor 4/ myeloid differentiation primary response 88/ nuclear factor-κB signaling, modulation of microRNA-155/suppressor of cytokine signaling-1 expression, and enhancement of cAMP/phosphorylated cAMP response element binding protein signaling.

Escitalopram Ameliorates Cardiomyopathy in Type 2 Diabetic Rats via Modulation of Receptor for Advanced Glycation End Products and Its Downstream Signaling Cascades.

Type 2 diabetes mellitus (T2DM) has been recognized as a known risk factor for cardiovascular diseases. Additionally, studies have shown the prevalence of depression among people with diabetes. Thus, the current study aimed to investigate the possible beneficial effects of escitalopram, a selective serotonin reuptake inhibitor, on metabolic changes and cardiac complications in type 2 diabetic rats. Diabetes was induced by feeding the rats high fat-high fructose diet (HFFD) for 8 weeks followed by a subdiabetogenic dose of streptozotocin (STZ) (35 mg/kg, i. p.). Treatment with escitalopram (10 mg/kg/day; p. o.) was then initiated for 4 weeks. At the end of the experiment, electrocardiography was performed and blood samples were collected for determination of glycemic and lipid profiles. Animals were then euthanized and heart samples were collected for biochemical and histopathological examinations. Escitalopram alleviated the HFFD/STZ-induced metabolic and cardiac derangements as evident by improvement of oxidative stress, inflammatory, fibrogenic and apoptotic markers in addition to hypertrophy and impaired conduction. These results could be secondary to its beneficial effects on the glycemic control and hence the reduction of receptor for advanced glycation end products content as revealed in the present study. In conclusion, escitalopram could be considered a favorable antidepressant medication in diabetic patients as it seems to positively impact the glycemic control in diabetes in addition to prevention of its associated cardiovascular complications.