Antidepressant-like activity of (4-phenylpiperazin-1-yl) (quinoxalin-2-yl) methanone (4a), a novel 5-HT(3) receptor antagonist: an investigation in behaviour-based rodent models of depression

Repeated reserpine treatment induces depressive-like behaviors accompanied with hippocampal impairment and synapse deficit in mice

Depression remains a significant public health concern, and current animal models of depression are limited in their ability to accurately mimic human depression. However, studying the new development of antidepressants requires the use of progressive animal models. In this study, the mice were exposed to a low dose of reserpine (0.5 mg/kg) once daily for 14 days, followed by a 14-day period to allow for the development of spontaneous depression. We have successfully established a repeated reserpine-induced depressive animal model, which was characterized by emotional symptoms (anhedonia), cognitive symptoms, and psychomotor agitation or retardation. Our study demonstrated that repeated treatment with low-dose reserpine increased immobility time in the TST and FST. It also decreased the sucrose consumption ratio and induced anxiety-like behaviors. These anxiety-like behaviors were evidenced by decreased time spent in the center zone, longer first latency to center zone, and fewer entries into the center zone in the open field test. These findings support the utility of the low-dose reserpine repeated injection animal model for studying the pathogenesis of depression and the development of novel antidepressant treatments. Additionally, this study provides valuable insights into the potential of low-dose reserpine as a tool for modeling chronic depression in animals. Furthermore, our findings suggest that prolonged low-dose reserpine treatment could result in chronic depression. These findings have significant implications for the use of reserpine as a therapeutic agent for various conditions and emphasize the importance of closely monitoring patients' mental health.

1,8-Naphthyridine Derivatives: A Privileged Scaffold for Versatile Biological Activities

1, 8- Naphthyridine nucleus belongs to significant nitrogen-containing heterocyclic compounds which has garnered the interest of researchers due to its versatile biological activities. It is known to be used as an antimicrobial, anti-psychotic, anti-depressant, anti-convulsant, anti- Alzheimer's, anti-cancer, analgesic, anti-inflammatory, antioxidant, anti-viral, anti-hypertensive, antimalarial, pesticides, anti-platelets, and CB2 receptor agonist, etc. The present review highlights the framework of biological properties of synthesized 1, 8-naphthyridine derivatives developed by various research groups across the globe.

Role of central serotonin and noradrenaline interactions in the antidepressants' action: Electrophysiological and neurochemical evidence

The development of antidepressant drugs, in the last 6 decades, has been associated with theories based on a deficiency of serotonin (5-HT) and/or noradrenaline (NA) systems. Although the pathophysiology of major depression (MD) is not fully understood, numerous investigations have suggested that treatments with various classes of antidepressant drugs may lead to an enhanced 5-HT and/or adapted NA neurotransmissions. In this review, particular morpho-physiological aspects of these systems are first considered. Second, principal features of central 5-HT/NA interactions are examined. In this regard, the effects of the acute and sustained antidepressant administrations on these systems are discussed. Finally, future directions including novel therapeutic strategies are proposed.

Neuroprotective influence of sitagliptin against cisplatin-induced neurotoxicity, biochemical and behavioral alterations in Wistar rats

Cisplatin has been extensively used as a chemotherapeutic agent since around 40 years, though its usage is limited due to severe adverse effects like neurotoxicity that might be because of oxidative stress. Hence, the present study was planned to investigate the possible protective role of sitagliptin against cisplatin-associated neurotoxic, biochemical, and behavioral alterations in male Wistar rats. Sitagliptin is a dipeptidyl peptidase-4 inhibitor that shows dual effects by improving the control on metabolism as well as decreasing the debility in cognitive function that is associated with increased insulin sensitivity and antioxidant property. For the in vitro assay, cultured rat pheochromocytoma (PC12) cells were exposed to different concentrations (10, 20, and 50 mM) of sitagliptin for 24 h. Cisplatin at 5 mM concentrations was added and cell viability was assessed using MTT assay. For in vivo study, animals were divided into four groups. Group I (Vehicle control): animals were administered 0.9% (w/v) of normal saline (1 mL/100 g; p.o.). Group II (Cisplatin): animals were treated with cisplatin (2 mg/kg; i.p.). Group III (Cisplatin + sitagliptin): animals were administered cisplatin along with sitagliptin. Group IV (Sitagliptin): animals were given sitagliptin (10 mg/kg; p.o.). All the treatments were administered for 8 weeks. On last day of treatment, behavioral evaluations including locomotor and rotarod studies were performed. In addition, several antioxidant enzymes were also estimated from cerebellum tissues; such as levels of thiobarbituric acid reactive substance (TBARS) were determined as a marker of lipid peroxidation, reduced glutathione (GSH) and catalase (CAT) were also estimated. Histological study of cerebellum tissue was also performed after performing the behavioral study. Exposure to cisplatin decreased cell viability in PC12 cells which were significantly increased by co-treatment with sitagliptin. In in vivo study, cisplatin significantly elevated the level of TBARS and reduced the level of antioxidant enzymes such as GSH and CAT which were significantly restored in sitagliptin + cisplatin group of rats. In addition, cisplatin impaired performance on the locomotor and rotarod activities, whereas sitagliptin significantly improved the performance of both activities. These results suggested the neuroprotective influence of sitagliptin by protecting cerebellum part of brain against cisplatin-induced toxicity.

Depression mediates impaired glucose tolerance and cognitive dysfunction: A neuromodulatory role of rosiglitazone

Comorbidity of depression and diabetes is a serious risk factor worsening the complications such as cognitive function and locomotion. Treatment under this condition becomes extremely complicated. Insulin signaling and autophagy pathways are involved in modulation of learning and memory. Rosiglitazone (ROSI) ameliorate cognitive deficit associated with depression and insulin resistance. In the present study, we investigated the effect of ROSI against chronic unpredictable stress (CUS) induced depression as a risk factor for diabetes and behavioral dysfunctions. Adult male Swiss albino mice were exposed to CUS alongside ROSI (5mg/kg/day) treatment for 21days. Thereafter, animals were subjected to different behavioral studies to assess depressive like behavior, cognition and locomotion. The effect of ROSI on insulin signaling, autophagy and apoptosis were evaluated in the hippocampus. CUS resulted in depressive like behavior, cognitive impairment and hypolocomotion associated with oxidative stress, impaired glucose tolerance and hypercorticosteronemia. CUS significantly impaired hippocampal insulin signaling, membrane translocation of glucose transporter type 4 (GLUT4) as well as decreased the expression of autophagy5, autophagy7, B-cell lymphoma 2 and apoptosis inhibitory protein 2. ROSI significantly reduced depressive like behavior, postprandial blood glucose, hypercorticosteronemia, oxidative and inflammatory stress, and apoptosis in stressed mice. Moreover, ROSI treatment effectively improved hippocampal insulin signaling, GLUT4 membrane translocation and cognitive performance in depressed mice. ROSI administration might prove to be effective for neurological disorders associated with depressive like behavior and impaired glucose tolerance.

Urtica dioica leaves modulates muscarinic cholinergic system in the hippocampus of streptozotocin-induced diabetic mice

Diabetes mellitus is a chronic metabolic disorder and has been associated with cognitive dysfunction. In our earlier study, chronic Urtica dioica (UD) treatment significantly ameliorated diabetes induced associative and spatial memory deficit in mice. The present study was designed to explore the effect of UD leaves extract on muscarinic cholinergic system, which has long been known to be involved in cognition. Streptozotocin (STZ) (50 mg/kg, i.p., consecutively for 5 days) was used to induce diabetes followed by treatment with UD extract (50 mg/kg, oral) or rosiglitazone (5 mg/kg, oral) for 8 weeks. STZ-induced diabetic mice showed significant reduction in hippocampal muscarinic acetylcholine receptor-1 and choline acetyltransferase expressions. Chronic diabetes significantly up-regulated the protein expression of acetylcholinesterase associated with oxidative stress in hippocampus. Besides, STZ-induced diabetic mice showed hypolocomotion with up-regulation of muscarinic acetylcholine receptor-4 expression in striatum. Chronic UD treatment significantly attenuated the cholinergic dysfunction and oxidative stress in the hippocampus of diabetic mice. UD had no effect on locomotor activity and muscarinic acetylcholine receptor-4 expression in striatum. In conclusion, UD leaves extract has potential to reverse diabetes mediated alteration in muscarinic cholinergic system in hippocampus and thereby improve memory functions.

Pretreatment of Gymnema sylvestre revealed the protection against acetic acid-induced ulcerative colitis in rats

Background

Overproduction of free radicals and decreased antioxidant capacity are well-known risk factors for inflammatory bowel diseases. Gymnema sylvestre (GS) leaves extract is distinguished for its anti-diabetic, antioxidant and anti-inflammatory properties. Present study is designed to evaluate the preventative activities of GS against acetic acid (AA)-induced ulcerative colitis in Wistar rats.

Methods

Experimentally ulcerative colitis (UC) was induced by AA in animals pretreated with three different doses of GS leaves extract (50, 100, 200 mg/kg/day) and a single dose of mesalazine (MES, 300 mg/kg/day) for seven days. Twenty four hours later, animals were sacrificed and the colonic tissues were collected. Colonic mucus content was determined using Alcian blue dye binding technique. Levels of thiobarbituric acid reactive substances (TBARS), total glutathione sulfhydryl group (T-GSH) and non-protein sulfhydryl group (NPSH) as well as the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were estimated in colon tissues. Colonic nucleic acids (DNA and RNA) and total protein (TP) concentrations were also determined. Levels of pro-inflammatory cytokines including interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) as well as prostaglandin E₂ (PGE₂) and nitric oxide (NO) were estimated in colonic tissues. The histopathological changes of the colonic tissues were also observed.

Results

In AA administered group TBARS levels were increased, while colonic mucus content, T-GSH and NP-SH, SOD and CAT were reduced in colon. Pretreatment with GS inhibited TBARS elevation as well as mucus content, T-GSH and NP-SH reduction. Enzymatic activities of SOD and CAT were brought back to their normal levels in GS pretreated group. A significant reduction in DNA, RNA and TP levels was seen following AA administration and this inhibition was significantly eliminated by GS treatment. GS pretreatment also inhibited AA-induced elevation of pro-inflammatory cytokines, PGE₂ and NO levels in colon. The apparent UC protection was further confirmed by the histopathological screening.

Conclusion

The GS leaves extract showed significant amelioration of experimentally induced colitis, which may be attributed to its anti-inflammatory and antioxidant property.