Involvement of nitric oxide-cyclic guanosine monophosphate pathway in the antidepressant-like effect of tropisetron and ondansetron in mice forced swimming test and tail suspension test

Ondansetron attenuates cisplatin-induced behavioral and cognitive impairment through downregulation of NOD-like receptor inflammasome pathway

Cisplatin is an effective and commonly used chemotherapeutic drug; however, its use is accompanied by several adverse effects, including chemobrain. Ondansetron is a 5-HT3 antagonist, commonly used in prophylactic against chemotherapy-induced nausea and vomiting. Moreover, it has been identified as a novel neuroprotective agent in different animal models. However, its protective role against chemotherapy-induced chemobrain has not been investigated. The current study was the first study that explored the potential neuroprotective effect of ondansetron against cisplatin-induced chemobrain in rats. Cisplatin (5 mg/Kg) was injected intraperitoneally, once weekly, for 4 weeks with the daily administration of ondansetron (0.5 and 1 mg/Kg). Compared to the cisplatin-treated group, ondansetron administration showed a significant decrease in the latency time and a significant increase in ambulation, rearing, and grooming frequency in the open field test (OFT). Moreover, a significant improvement in the latency time in the rotarod and passive avoidance tests, following ondansetron administration. In addition, ondansetron treatment increased the percentage of alternation in the Y-maze test. Also, ondansetron showed a remarkable enhancement in the biochemical parameters in the hippocampus. It increased the acetylcholine (Ach) level and decreased the level of the acetylcholine esterase enzyme (AchE). Ondansetron significantly decreased interleukin-1β (Il-1β), tumor necrosis factor-alpha (TNF-α), toll-like receptor-4 (TLR-4), NOD-like receptor-3 (NLRP3) inflammasome as well as caspase-1 and caspase-3 levels. Furthermore, ondansetron significantly decreased the levels of copper transporter-1(CTR1) expression in the hippocampus. Collectively, these findings suggest that ondansetron may exhibit a neuroprotective and therapeutic activity against cisplatin-induced chemobrain.

The Possible Protective Effects of Ondansetron and Tropisetron on Optic Nerve Crush Injury in Rats

BACKGROUND

This study aimed to evaluate the potential neuroprotective effect of cyclosporine - a calcineurin inhibitor-, ondansetron, and tropisetron-5-hydroxytryptamine (serotonin) 3 receptor (5-HT3R) antagonists-, on optic nerve crush (ONC) injury in rats. Moreover, underlying signaling activities of their beneficial neuroprotective effects were studied.

METHODS

Adult male rats were treated with the intravitreal administration of cyclosporine (1.6 mM), ondansetron (100 nM), and tropisetron (100 nM) immediately after the induction of ONC. Subsequently, on 7th day after surgery, the rats' retinas were extracted, and the expression of apoptotic regulators (Bax and Bcl-2) and calcineurin were studied by western blot analysis.

RESULTS

The induction of ONC injury was associated to higher expression of Bax and calcineurin, while Bcl-2 expression was considerably decreased in these animals. Intravitreal treatment with cyclosporine (1.6 mM), ondansetron (100 nM), and tropisetron (100 nM) significantly attenuated the increased expression of Bax and calcineurin. Moreover, the treatment with these agents resulted in an elevated expression of Bcl-2 in the retina.

CONCLUSION

Our findings indicate that cyclosporine, ondansetron, and tropisetron protect against ONC injury in rats, possibly via the suppression of apoptosis and modulation of calcineurin activity directly and via 5-HT3 receptors. Moreover, immunoblotting showed that tropisetron was more effective as opposed to ondansetron. Further studies are needed to evaluate the precise mechanism behind cyclosporine, ondansetron, and tropisetron activities.

Possible involvement of l-arginine-nitric oxide pathway in the antidepressant activity of Auraptene in mice

Background

Depression is one of the most common mental illnesses worldwide. Nitric oxide (NO) is involved in the pathophysiology of depression. Auraptene (a coumarin derivative) has been shown to possess pharmacological effects on neurological diseases.

Purpose

The present study aimed to investigate the possible role of the NO pathway in Auraptene antidepressant effects in male mice.

Methods

Behavioral tests were used to assess depression-like behaviors. The mice received Auraptene at 10, 30, and 100 mg/kg, the combination of the sub-effective (ineffective) dose of Auraptene (10 mg/kg) and L-NAME, and the combination of the effective dose of Auraptene (30 mg/kg) and L-arginine. Finally, OFT, TST, FST, brain, serum MDA level, antioxidant capacity, hippocampus, and serum NO level were measured.

Results

The data analysis showed that Auraptene (30 mg/kg) improved depression-like behaviors. Auraptene (30 mg/kg) also significantly reduced serum NO levels (P < 0.05) and significantly increased serum MDA (10 mg/kg, P < 0.05). Auraptene at 30 mg/kg also increased serum antioxidant capacity (P < 0.01). Co-administration of L-NAME and the sub-effective dose of Auraptene enhanced the effects of Auraptene. However, co-administration of the effective dose of Auraptene and L-arginine reduced the impacts of Auraptene.

Conclusions

The results showed that Auraptene causes antidepressant effects in a dose-dependent manner and acts as a prooxidant at 100 mg/kg, and exacerbates oxidative stress. The antidepressant effects of this active molecule are exerted by reducing the NO level in the hippocampus and serum, increasing the antioxidant capacity, and reducing the MDA level in the serum.

5-HT Receptors and the Development of New Antidepressants

Serotonin modulates several physiological and cognitive pathways throughout the human body that affect emotions, memory, sleep, and thermal regulation. The complex nature of the serotonergic system and interactions with other neurochemical systems indicate that the development of depression may be mediated by various pathomechanisms, the common denominator of which is undoubtedly the disturbed transmission in central 5-HT synapses. Therefore, the deliberate pharmacological modulation of serotonergic transmission in the brain seems to be one of the most appropriate strategies for the search for new antidepressants. As discussed in this review, the serotonergic system offers great potential for the development of new antidepressant therapies based on the combination of SERT inhibition with different pharmacological activity towards the 5-HT system. The aim of this article is to summarize the search for new antidepressants in recent years, focusing primarily on the possibility of benefiting from interactions with various 5-HT receptors in the pharmacotherapy of depression.

Adenylyl Cyclase (AC) Mediates the Antidepressant-Like Effects of Tropisetron on a Mouse Model of Maternal Separation Stress

The adenylyl cyclase (AC) pathway is involved in the pathophysiology of depression. Finding new antidepressants with high medicinal properties and low side effects is warranted. Therefore, this study was designed to determine the antidepressant-like effect of tropisetron on a maternal separation (MS) model in mice, considering the possible role of AC. NMRI male mice were divided into eleven groups. The control group was treated with saline and MS groups were treated with saline, tropisetron (a 5-HT3 receptor antagonist) at doses of 1, 3, and 5 mg/kg; forskolin (an activator of AC) at doses of 5, 10, and 25 mg/kg; a subeffective dose of forskolin with a subeffective dose of tropisetron; and an effective dose of tropisetron plus an effective dose of NB001 (3 mg/kg) (an AC inhibitor). After treatment, animals were subjected to behavioral tests including the forced swimming test (FST), splash test, and open field test (OFT). We showed that MS caused depressive-like behaviors determined as an increase in the immobility time in the forced swimming test (FST) and decreased grooming time in the splash test. Our results showed that administration of tropisetron, as well as forskolin, mitigated the depressive-like behaviors in MS mice. We found that coadministration of a subeffective dose of tropisetron plus a subeffective dose of forskolin potentiated the antidepressant-like effect of tropisetron. However, coadministration of an effective dose of NB001 with an effective dose of tropisetron did not significantly affect the antidepressant-like effect of tropisetron. We concluded that the antidepressant-like effects of tropisetron on MS mice are partially mediated through the adenylyl cyclase pathway.

Nitric oxide mediates the antidepressant-like effect of modafinil in mouse forced swimming and tail suspension tests

OBJECTIVES

Previous studies have suggested antidepressant properties for modafinil; however, the underlying mechanisms mediating the antidepressant effect of modafinil have not been well recognized in clinical and animal studies. Nitric oxide (NO) is involved in the pathophysiology of depression. We attempted to investigate the possible role of NO in the antidepressant-like effect of modafinil in mouse forced swimming test (FST) and tail suspension test (TST).

METHODS

The antidepressant-like effect of modafinil (25, 50 and 75 mg/kg), alone and in combination with l-arginine, l-arg, (100 mg/kg) and N^G-l-arginine methyl ester, l-NAME (5 mg/kg), was evaluated using FST and TST. Following behavioral tests, the hippocampi were dissected out to measure nitrite levels.

RESULTS

Findings suggested that administration of modafinil at doses of 50 and 75 mg/kg significantly reduced immobility time in the FST and TST. Furthermore, administration of l-arg and l-NAME increased and decreased, respectively, the immobility time in the FST and TST. We showed that co-administration of a sub-effective dose of modafinil (25 mg/kg) plus l-NAME potentiated the antidepressant-like effect of the sub-effective dose of modafinil. In addition, co-treatment of an effective dose of modafinil (75 mg/kg) with l-arg attenuated the antidepressant-like effect of the effective dose of modafinil. We showed that the antidepressant-like effect of modafinil is associated with decreased nitrite levels in the hippocampus.

CONCLUSIONS

Our findings for the first time support that the modulation of NO, partially at least, is involved in the antidepressant-like effect of modafinil in mouse FST and TST.

Yueju-Ganmaidazao Decoction confers rapid antidepressant-like effects and the involvement of suppression of NMDA/NO/cGMP signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Yueju-Ganmaidazao Decoction (YG) is a multiherbal medicine prescribed for treatment of mood disorder, consisting of two classical traditional Chinese herbal medicine Yueju and Ganmaidazao. Yueju and Ganmaidazao both are used for depression treatment. The combined decoction of Yueju and Ganmaidazao is prescribed to achieve optimal clinical outcomes by dealing with different symptoms of depression. Recent studies indicated ethanol extract of Yueju was capable to confer rapid antidepressant-like response. The antidepressant activity of YG decoction with fast-onset feature remains to be investigated.

AIM OF THE STUDY

Rapid and safe antidepressant treatment is urgently needed. This study aimed to assess the rapid antidepressant-like activity of YG and the underlying mechanism, focusing on NMDA/NO/cGMP signaling.

MATERIALS AND METHODS

The optimal doses for immediate and persistent antidepressant-like response were first screened using tail suspension test (TST) and forced swimming test (FST) post a single administration of YG. The rapid action was further confirmed by using the chronic mild stress (CMS) and learned helplessness (LH) paradigms. The expressions of NMDA receptor subunits were evaluated post stress and YG. The contributions of NMDA, NO, and cGMP signaling to the antidepressant effect of YG were investigated systematically using pharmacological interventions.

RESULTS

The optimal dose for immediate and persistent antidepressant potential, evidenced with reduced immobility times in TST or FST from 30 min to 7 days, was determined. The rapid antidepressant-like effect was confirmed in CMS and LH paradigms, including instant normalization of sucrose preference behavior. The expression of NMDA subunit NR1 in the hippocampus was reduced from 30 min to 5 days post YG. In animals subjected to CMS and LH, hippocampal NR1 expression increased, reversed by YG. YG's antidepressant-like effect was blunted by pretreatment with the agonists along the signalings including NMDA (75 mg/kg), L-arginine (750 mg/kg) and sildenafil (5 mg/kg) in TST or FST. Conversely, administration of subeffective dose of individual antagonists, including MK-801 (0.05 mg/kg), 7-nitroindazole (30 mg/kg), methylene blue (10 mg/kg), in combination with a subeffective dose of YG, elicited antidepressant effects.

CONCLUSION

YG conferred rapid antidepressant-like effects, and the antidepressant response was essentially dependent on suppression of NMDA/NO/cGMP signaling.

Revisiting the validity of the mouse tail suspension test: Systematic review and meta-analysis of the effects of prototypic antidepressants

Animal models in neuropsychiatric research need validation. One way to address external validity is systematic reviews and meta-analyses. The present study presents a meta-analysis of the effects of antidepressants in the mouse tail suspension test (TST). A PubMed search identified studies that examined imipramine and fluoxetine effects in the TST. Inclusion criteria were testing in the light phase; trial duration was six minutes; immobility time scored 6 or (last) 4 min; adult mice; acute intraperitoneal (IP) administration. Effect sizes (ES) were estimated using Cohen's d, heterogeneity of ES with Cochran's Q test, correlations between dose and ES with Pearson's correlation and differences between strains with Analysis of variance. Results show that antidepressants decrease immobility time in the TST and a correlation between drug dose and ES but no effects of strain. We suggest that the TST is a valid tool to quantitatively, consistently and reproducibly capture the immobility-reducing aspects of fluoxetine and imipramine and that the lack of strain effects is due to small number of experiments in many of the strains.

Antidepressant effect of the interaction of fluoxetine with granisetron

Selective serotonin reuptake inhibitors (SSRIs) may produce digestive side effects such as nausea and vomiting, diarrhoea and decreased appetite. These side effects are determined by the increase in serotonin availability at 5-HT3 receptors. Granisetron, a serotonin 5-HT3 receptor antagonist, is expected to antagonize the digestive adverse effects of serotonin reuptake inhibitors, but the question is to what extent granisetron influences the antidepressant effect of these substances. The aim of this study was to determine the dose of fluoxetine that has an antidepressant effect in the Porsolt test, and the interaction between fluoxetine and granisetron with respect to the antidepressant effect in this test. In experiment 1, fluoxetine was antidepressant only at 20 mg/kg body weight (bw). In experiment 2, granisetron 1 mg/kg bw had a statistically significant antidepressant effect vs. control. Fluoxetine 20 mg/kg bw associated with a small dose of granisetron (0.1 mg/kg bw) produced a significant antidepressant effect vs. control. This shows that low doses of granisetron associated to fluoxetine might produce a significant antidepressant effect, suggesting a potentiation between these two drugs used in sub-effective antidepressant doses. In conclusion, in our experimental conditions, we can assume that granisetron in low doses could be used to combat intestinal transit disorders produced by SSRI antidepressants. These low doses are preferred, because they increase the antidepressant effect of these SSRIs.

Minocycline Ameliorates Depressive-Like Behavior and Demyelination Induced by Transient Global Cerebral Ischemia by Inhibiting Microglial Activation

Global cerebral ischemia (GCI) commonly occurs in the elderly. Subcortical white matter lesions and oligodendrocyte (OLG) loss caused by cerebral ischemia have been implicated in the development of post-ischemic depression and cognitive impairment. OLGs are necessary for axonal myelination; the disrupted differentiation of OLG progenitor cells (OPCs) is associated with impaired remyelination. Evidence has indicated that increased levels of inflammatory cytokines released from activated microglia induce depression-like behaviors by affecting neurotransmitter pathways, but the mechanisms remain elusive. We explored the potential mechanisms that link microglia activation with GCI-induced depression and cognitive dysfunction by studying effects of minocycline on white matter damage, cytokine levels, and the monoaminergic neurotransmitters. An acute GCI animal model was generated through bilateral common carotid artery occlusion to induce ischemic inflammation and subcortical white matter damage. Minocycline, an inhibitor of microglia activation, was intraperitoneally administrated immediately after surgery and continued daily for additional six days. Minocycline shortened the immobile duration in tail suspension test and forced swimming test, while no improvement was found in Morris water maze test. The plasma levels of IL-1β, IL-6, TNF-α, HMGB1, and netrin-1 were significantly reduced with the treatment of minocycline. Minocycline treatment substantially reversed demyelination in corpus callosum and hippocampus, alleviated hippocampal microglia activation, and promoted OPCs maturation, while no effect was found on hippocampal neurodegeneration. Besides, the content of dopamine (DA) in the hippocampus was upregulated by minocycline treatment after GCI. Collectively, our data demonstrated that minocycline exerts an anti-depressant effect by inhibiting microglia activation, promoting OPCs maturation and remyelination. Increased DA in hippocampus may also play a role in ameliorating depressive behavior with minocycline treatment.

NMDA receptors and L-arginine/nitric oxide/cyclic guanosine monophosphate pathway contribute to the antidepressant-like effect of Yueju pill in mice

The present study aims to evaluate the involvement of N-methyl-d-aspartate receptor and nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) system in antidepressant-like effects of Yueju pill (YJ), a Chinese herbal medicine. The immobility time in tail suspension test (TST) and forced swim test (FST) was used to assess the antidepressant effects. Prior administration of L-arginine (750 mg/kg, intraperitoneal [i.p.]), a NO synthase substrate that enhances NO signaling or sildenafil (5 mg/kg, i.p.), a phosphodiesterase 5 inhibitor that enhances cGMP, blunted the antidepressant-like activity of YJ (2.7 g/kg, i.g.). Co-treatment of ineffective dose of YJ (1.35 g/kg, i.g.) with one of the reagents that suppress the NO/cGMP signaling, including methylene blue (10 mg/kg, i.p.), an inhibitor of NO synthase; 7-NI (7-nitroinidazole, 30 mg/kg, i.p.), an nNOS specific inhibitor; L-NAME (10 mg/kg, i.p.), a non-specific inhibitor of NO synthase; and MK-801 (0.05 mg/kg, i.p.), an NMDA receptor antagonist, reduced the immobility time in TST and FST, compared with those in vehicle or single drug treatment groups. Neither above drugs alone or co-administrated with YJ affected locomotor activity or anxiety behavior in open field test. Thus, our results suggest that the antidepressant-like action of YJ may depend on the inhibition of NMDA/NO/cGMP pathway.

Coenzyme Q10 Alleviated Behavioral Dysfunction and Bioenergetic Function in an Animal Model of Depression

Coenzyme Q₁₀ (CoQ₁₀) is a natural compound, is involved in the mitochondrial electron transfer chain (ETC) and plays an important pattern in adenosine triphosphate (ATP) production. Amelioration of ATP is related to abnormalities in cognitive function and psychiatric diseases. Previous studies have shown that depression is accompanied by the induction of inflammatory and oxidative stress pathways and amelioration of antioxidant status. In a recent study, we investigated the beneficial effects of CoQ₁₀ on behavioral dysfunction and CoQ₁₀ level in the rat brain. Therefore, intracerebroventricular (ICV) infusion of a single dose of streptozotocin (STZ, 0.2 mg/mouse) was used in adult male mice to induce depression. The behavioral data revealed a significant difference between the depression and control groups regarding the forced swim test (FST) and splash test results at 24 h following STZ treatment. Also, the validated and accurate high-performance liquid chromatography (HPLC) technique showed decreased CoQ₁₀ level in the brain samples of the STZ group, compared to the controls. Our findings revealed that behavioral abnormalities due to STZ target mitochondria and affect energy metabolism and hemostasis, resulting in the initiation of oxidative damage in the brain. Besides, 4-week administration of CoQ₁₀ could reverse the depressive like behavior and bioenergetic effects of STZ in the treated groups.

Rationally Designed α-Conotoxin Analogues Maintained Analgesia Activity and Weakened Side Effects

A lack of specificity is restricting the further application of conotoxin from Conus bullatus (BuIA). In this study, an analogue library of BuIA was established and virtual screening was used, which identified high α7 nicotinic acetylcholine receptor (nAChR)-selectivity analogues. The analogues were synthesized and tested for their affinity to functional human α7 nAChR and for the regulation of intracellular calcium ion capacity in neurons. Immunofluorescence, flow cytometry, and patch clamp results showed that the analogues maintained their capacity for calcium regulation. The results of the hot-plate model and paclitaxel-induced peripheral neuropathy model indicated that, when compared with natural BuIA, the analgesia activities of the analogues in different models were maintained. To analyze the adverse effects and toxicity of BuIA and its analogues, the tail suspension test, forced swimming test, and open field test were used. The results showed that the safety and toxicity of the analogues were significantly better than BuIA. The analogues of BuIA with an appropriate and rational mutation showed high selectivity and maintained the regulation of Ca²⁺ capacity in neurons and activities of analgesia, whereas the analogues demonstrated that the adverse effects of natural α-conotoxins could be reduced.

Involvement of opioid system in behavioral despair induced by social isolation stress in mice

Social isolation stress (SIS) as a type of chronic stress could induce depressive- and anxiety-like behaviors. Our study evaluates the role of opioid system on negative behavioral impacts of SIS in male NMRI mice. We investigated effects of morphine, a nonselective opioid receptor (OR) agonist, naltrexone (NLX), an OR antagonist, naltrindole (NLT), a delta opioid receptor (DOR) antagonist, SNC80, a DOR agonist, U-69593, a kappa opioid receptor (KOR) agonist, nor-Binaltorphimine, a selective KOR antagonist and cyprodime hydrochloride a selective mu opioid receptor (MOR) antagonist on depressive- and anxiety-like behaviors. Using RT-PCR we evaluated ORs gene expression in mice brain. Our findings showed that SIS induced anxiety- and depressive-like behavior in the forced swimming test, open field test, splash test and hole-board test. Moreover, administration of SNC-80 significantly mitigated anxiety- and depressive-like behaviors. NLT decreased grooming-activity in the splash test. Excitingly, administration of agents affecting KOR failed to alter the negative effects of SIS. RT-PCR demonstrated that MOR and KOR gene expression decreased in socially isolated mice; however, SIS did not affect DORs expression. Our findings suggest that SIS at least in part, probably via altering endogenous opioids particularly MORs and KORs but not DORs mediated negative impacts on behavior; also, it could be concluded that DORs might be considered as a novel target for studying depression and anxiety.

Serotonin receptors in depression and anxiety: Insights from animal studies

Serotonin regulates many physiological processes including sleep, appetite, and mood. Thus, serotonergic system is an important target in the treatment of psychiatric disorders, such as major depression and anxiety. This natural neurotransmitter interacts with 7 families of its receptors (5-HT1-7), which cause a variety of pharmacological effects. Using genetically modified animals and selective or preferential agonists and antagonist, numerous studies demonstrated the involvement of almost all serotonin receptor subtypes in antidepressant- or anxiolytic-like effects. In this review, based on animal studies, we discuss the possible involvement of serotonin receptor subtypes in depression and anxiety.

Nitric oxide involvement in additive antidepressant-like effect of agmatine and lithium in mice forced swim test

Lithium is still the main agent in the management of mood disorders such as depression. Likewise, agmatine protects the central nervous system (CNS) against depression. The aim of the present study was to examine the possible additive antidepressant-like effect of agmatine and lithium in mice forced swim test (FST) as well as exploration of the probable involvement of nitric oxide (NO) pathway in this response. Results showed that pretreatment with a subeffective dose of agmatine (0.01 mg/kg) augmented the antidepressant-like effect of lithium subeffective dose (3 mg/kg) (P < 0.001). L-NG-nitroarginine methyl ester (L-NAME, nonspecific nitric oxide synthase [NOS] inhibitor) at doses of 10 and 30 mg/kg, and 7-nitroindazole (7-NI, neuronal NOS inhibitor) at doses of 15 and 30 mg/kg potentiated the antidepressant-like effect of the subeffective combination of lithium (3 mg/kg) and agmatine (0.001 mg/kg) (P < 0.001, P < 0.01, respectively). However, various doses of aminoguanidine (25 and 50 mg/kg, inducible NOS inhibitor) failed to alter the immobility time of the same combination (P > 0.05). Moreover, pretreatment with subeffective doses of L-arginine (substrate for NOS, 300 and 750 mg/kg) reversed the augmenting antidepressant-like effect of agmatine (0.01 mg/kg) on lithium (3 mg/kg) (P < 0.001). Our results revealed that agmatine enhances the antidepressant-like effects of lithium and the NO pathway might mediate this phenomenon. In addition, constitutive NOS plays a dramatic role in this response.

Pathologic role of nitrergic neurotransmission in mood disorders

Mood disorders are chronic, recurrent mental diseases that affect millions of individuals worldwide. Although over the past 40 years the biogenic amine models have provided meaningful links with the clinical phenomena of, and the pharmacological treatments currently employed in, mood disorders, there is still a need to examine the contribution of other systems to the neurobiology and treatment of mood disorders. This article reviews the current literature describing the potential role of nitric oxide (NO) signaling in the pathophysiology and thereby the treatment of mood disorders. The hypothesis has arisen from several observations including (i) altered NO levels in patients with mood disorders; (ii) antidepressant effects of NO signaling blockers in both clinical and pre-clinical studies; (iii) interaction between conventional antidepressants/mood stabilizers and NO signaling modulators in several biochemical and behavioral studies; (iv) biochemical and physiological evidence of interaction between monoaminergic (serotonin, noradrenaline, and dopamine) system and NO signaling; (v) interaction between neurotrophic factors and NO signaling in mood regulation and neuroprotection; and finally (vi) a crucial role for NO signaling in the inflammatory processes involved in pathophysiology of mood disorders. These accumulating lines of evidence have provided a new insight into novel approaches for the treatment of mood disorders.

The role of nitric oxide-cGMP pathway in selegiline antidepressant-like effect in the mice forced swim test

BACKGROUND

Considering the pivotal role of nitric oxide (NO) pathway in depressive disorders, the aim of the present study was to investigate the antidepressant-like effect of selegiline in mice forced swimming test (FST), and possible involvement of NO-cyclic guanosine monophosphate (cGMP) pathway in this action.

METHODS

After assessment of locomotor activity in open-field test, mice were forced to swim individually and the immobility time of the last 4 min was evaluated. All drugs were given intraperitoneally (ip).

RESULTS

Selegiline (10 mg/kg) decreased the immobility time in the FST similar to fluoxetine (20 mg/kg). Pretreatment with l-arginine (NO precursor, 750 mg/kg) or sildenafil (a phosphodiesterase 5 inhibitor, 5 mg/kg) significantly reversed the selegiline anti-immobility effect. Sub-effective dose of selegiline (1 mg/kg) showed a synergistic antidepressant effect with NG-nitro-l-arginine methyl ester (L-NAME, inhibitor of NO synthase, 10 mg/kg) or 7-nitroindazole (specific neuronal NO synthase inhibitor, 30 mg/kg), but not with aminoguanidine (specific inducible NO synthase inhibitor, 50 mg/kg). Pretreatment of mice with methylene blue (an inhibitor of NO synthase and soluble guanylyl cyclase, 10 mg/kg) significantly produced a synergistic response with the sub-effective dose of selegiline. Neither of the drugs changed the locomotor activity. Also, hippocampal and prefrontal cortex (PFC) nitrite content was significantly lower in selegiline-injected mice compared to saline-administrated mice. Also, co-injection of 7-nitroindazole with selegiline produced a significant reduction in hippocampal or PFC nitrite contents.

CONCLUSIONS

It is concluded that selegiline possesses antidepressant-like effect in mice FST through inhibition of l-arginine-NO-cyclic guanosine monophosphate pathway.

Involvement of NO/NMDA-R pathway in the behavioral despair induced by amphetamine withdrawal

Abrupt discontinuation of chronic amphetamine consumption leads to withdrawal symptoms including depression, anhedonia, dysphoria, fatigue, and anxiety. These irritating symptoms may result in continuing to take the drug or can lead to suicidal behavior. Past studies have shown the involvement of various biologic systems in depression induced following amphetamine withdrawal (AW). However, there is no evidence about the relation between nitric oxide (NO) with NMDA receptors on depression following AW. In this study, we examined the involvement of the NO/NMDA pathways on depressive-like behaviors after 24 h withdrawal following 5 continuous days of amphetamine administration in male NMRI mice. Behavioral tasks used for depression assessment included the forced swimming test (FST), the Splash test and the open field test (OFT). In order to evaluate the role of NO/NMDA pathways animals treated with MK-801 (NMDA-R antagonist), Aminoguanidine (AG), a selective iNOS inhibitor, Nω-Nitro-l-arginine (L-NNA), a non-selective NOS inhibitor and 7-Nitro indazole (7-NI), a selective nNOS inhibitor. We also measured the level of nitrite in the hippocampus. Our data showed that AW induced the depressive-like effect in the FST and the Splash test. We showed that administration of AG, L-NNA, and MK-801 mitigated AW induced depression, however, 7-NI was failed to decrease depressive-like behaviors. Also, the antidepressant-like effect of co-injection of sub-effective doses of MK-801 with AG suggested that inducible nitric oxide synthase (iNOS) is associated with NMDA-R in AW induced depression. In conclusion, both NO and NMDA-R pathways are involved and related to each other in depression induced following AW.

Schisandrin rescues depressive-like behaviors induced by chronic unpredictable mild stress via GDNF/ERK1/2/ROS and PI3K/AKT/NOX signaling pathways in mice

The current study aimed to prove the antidepressant-like effects and the probable mechanisms of Schisandrin on depression, which induced by chronic unpredictable mild stress (CUMS) in mice. Four weeks of CUMS exposure resulted in depressive-like behavior, as indicated by the significant decrease in sucrose consumption and increase the immobility time in the forced swim test, but without any influence on the locomotor activity. Further, there were significant downregulations of GDNF/ERK1/2/ROS and PI3K/AKT/NOX signaling pathways in the hippocampus and prefrontal cortex in depressed mice. Treatment of mice with Schisandrin (30mg/kg) and Fluoxetine (10mg/kg) significantly ameliorated all the behavioral and biochemical changes induced by CUMS. These results suggest that Schisandrin produces an antidepressant-like effect in CUMS-induced mice, which possibly mediated, at least in part, by rectifying the signaling pathways of GDNF/ERK1/2/ROS and PI3K/AKT/NOX.

Antidepressant-like effects of Marasmius androsaceus metabolic exopolysaccharides on chronic unpredictable mild stress-induced rat model

Marasmius androsaceus (M. androsaceus), a medicinal fungus, has various pharmacological activities including antidepression. The present study investigated the effects of exopolysaccharides obtained during M. androsaceus submerged fermentation in a chronic unpredictable mild stress (CUMS)‑induced depression rat model. Similar to fluoxetine (positive drug), 4‑week administration of M. androsaceus exopolysaccharides (MEPS) at doses of 6, 30 and 150 mg/kg strongly enhanced bodyweight gain and sucrose consumption, and reduced the immobility time in forced swimming test and tail suspension test in CUMS rats. MEPS resulted in significant enhancement on the levels of noradrenalin, dopamine, 5‑hydroxytryptamine (5‑HT), and 5‑hydroxyindoleacetic acid in the serum and hypothalamus of CUMS rats, as detected by ELISA. Western blotting results revealed that MEPS upregulated the protein expression levels of tyrosine hydroxylase in the hypothalamus of CUMS rats. In conclusion, these results confirmed the antidepressant‑like effects of MEPS, and suggested that the monoamine neurotransmitter system is involved in its antidepressive effects in a CUMS rat model. The present study provided evidence for the clinical application of MEPS as an effective agent against depression.

Possible involvement of ATP-sensitive potassium channels in the antidepressant-like effects of gabapentin in mouse forced swimming test

Gabapentin as an anticonvulsant drug also has beneficial effects in treatment of depression. Previously, we showed that acute administration of gabapentin produced an antidepressant-like effect in the mouse forced swimming test (FST) by a mechanism that involves the inhibition of nitric oxide (NO). Considering the involvement of NO in adenosine triphosphate (ATP)-sensitive potassium channels (KATP), in the present study we investigated the involvement of KATP channels in antidepressant-like effect of gabapentin. Gabapentin at different doses (5–10 mg/kg) and fluoxetine (20 mg/kg) were administrated by intraperitoneal route, 60 and 30 min, respectively, before the test. To clarify the probable involvement of KATP channels, mice were pretreated with KATP channel inhibitor or opener. Gabapentin at dose 10 mg/kg significantly decreased the immobility behavior of mice similar to fluoxetine (20 mg/kg). Co-administration of subeffective dose (1 mg/kg) of glibenclamide (inhibitor of KATP channels) with gabapentin (3 mg/kg) showed a synergistic antidepressant-like effect. Also, subeffective dose of cromakalim (opener of KATP channels, 0.1 mg/kg) inhibited the antidepressant-like effect of gabapentin (10 mg/kg). None of the treatments had any impact on the locomotor movement. Our study, for the first time, revealed that antidepressant-like effect of gabapentin in mice is mediated by blocking the KATP channels.

The latest advances in the discovery of nitric oxide hybrid drug compounds

INTRODUCTION

There is a great interest in Nitric oxide (NO) within medicinal chemistry since it's involved in human signaling pathways. Prodrugs or hybrid compounds containing NO-donor scaffolds linked to an active compound are valuable, due to their potential for modulating many pathological conditions due to NO's biological properties when released in addition to the native drug. Compounds that selectively inhibit nitric oxide synthase isoforms (NOS) can also increase therapeutic capacity, particularly in the treatment of chronic diseases. However, search for bioactive compounds to efficiently and selectively modulate NO is still a challenge in drug discovery. Areas covered: In this review, the authors highlight the recent advances in the strategies used to discover NO-hybrid derivatives, especially those related to anti-inflammatory, cardiovascular, anticancer and anti-microorganism activities. They also focus on: nitric oxide synthase inhibitors, NO delivery materials and other related activities. Expert opinion: The process of molecular hybridization can be used to obtain NO-releasing compounds that also interact with different targets. The main problem with this approach is to control NO multiple actions in the right biological system. However, the use of NO-releasing groups with many different scaffolds leads to new molecular structures for bioactive compounds, suggesting synergies.

Effect of sildenafil on the activity of some antidepressant drugs and electroconvulsive shock treatment in the forced swim test in mice

Sildenafil, a potent and selective inhibitor of phosphodiesterase type 5, is used clinically to treat erectile dysfunction and pulmonary arterial hypertension. It is often taken by patients suffering from depression and receiving antidepressant drug treatment. However, its influence on the efficacy of antidepressant treatment was not sufficiently studied. Therefore, the aim of the present study was to investigate the influence of sildenafil on the anti-immobility action of several antidepressant drugs (i.e., sertraline, fluvoxamine, citalopram, maprotiline, trazodone, and agomelatine) as well as on antidepressant-like effect of electroconvulsive stimulations in the forced swim test in mice. The obtained results showed that acute sildenafil treatment enhanced the antidepressant-like activity of all of the studied drugs. The observed effects were not due to the increase in locomotor activity. The interactions between sildenafil and sertraline, maprotiline, and trazodone were pharmacodynamic in nature, as sildenafil did not affect concentrations of these drugs neither in serum nor in brain tissue. Increased concentrations of fluvoxamine, citalopram, and agomelatine in brain tissue evoked by sildenafil co-administration suggest that pharmacokinetic interactions between sildenafil and these drugs are very likely. Sildenafil injected acutely did not alter the antidepressant-like efficacy of electroconvulsive stimulations in mice, as assessed in the forced swim test. Interestingly, repeated (14 days) administration of sildenafil decreased the anti-immobility action of the electroconvulsive stimulations. In conclusion, the present study shows that sildenafil may alter the effectiveness of antidepressant treatment. Further studies are warranted to better characterize the influence of sildenafil on the activity of antidepressant drugs and electroconvulsive therapy.

The role of NMDA receptor and nitric oxide/cyclic guanosine monophosphate pathway in the antidepressant-like effect of dextromethorphan in mice forced swimming test and tail suspension test

Depression is a devastating disorder which has a high impact on the wellbeing of overall society. As such, need for innovative therapeutic agents are always there. Most of the researchers focused on N-methyl-d-aspartate receptor to explore the antidepressant like activity of new therapeutic agents. Dextromethorphan is a cough suppressant agent with potential antidepressant activity reported in mouse force swimming test. Considering N-methyl-d-aspartate as a forefront in exploring antidepressant agents, here we focused to unpin the antidepressant mechanism of dextromethorphan targeting N-methyl-d-aspartate receptor induced nitric oxide-cyclic guanosine monophosphate signaling. Dextromethorphan administered at a dose of 10 and 30mg/kg i.p significantly reduced the immobility time. Interestingly, this effect of drug (30mg/kg) was inhibited when the animals were pretreated either with N-methyl-d-aspartate (75mg/kg), or l-arginine (750mg/kg) as a nitric oxide precursor and/or sildenafil (5mg/kg) as a phosphodiesterase 5 inhibitor. However, the antidepressant effect of Dextromethorphan subeffective dose (3mg/kg) was augmented when the animals were administered with either L-NG-Nitroarginine methyl ester (10mg/kg) non-specific nitric oxide synthase inhibitor, 7-Nitroindazole (30mg/kg) specific neural nitric oxide synthase inhibitor, MK-801 (0.05mg/kg) an N-methyl-d-aspartate receptor antagonist but not aminoguanidine (50mg/kg) which is specific inducible nitric oxide synthase inhibitor as compared to the drugs when administered alone. No remarkable effect on locomotor activity was observed during open field test when the drugs were administered at the above mentioned doses. Therefore, it is evident that the antidepressant like effect of Dextromethorphan is owed due to its inhibitory effect on N-methyl-d-aspartate receptor and NO- Cyclic guanosine monophosphate pathway.

Effect of naloxone on intravenous fentanyl patient-controlled analgesia after laparoscopic cholecystectomy

This study aims to evaluate the effect of naloxone on intravenous fentanyl patient-controlled analgesia after laparoscopic cholecystectomy under total intravenous anesthesia.A total of 90 patients, who underwent intravenous fentanyl patient-controlled analgesia after laparoscopic cholecystectomy under total intravenous anesthesia, were included into this study. All patients were randomly divided into 3 groups (each group, n=30): naloxone group (naloxone+fentanyl), tropisetron group (tropisetron+fentanyl), and fentanyl group (fentanyl). Patients in each group were given a corresponding dose of naloxone. Postoperative analgesia effect and the incidence of side effects such as nausea and vomiting were observed.Small doses of naloxone or tropisetron combined with fentanyl used for intravenous patient-controlled analgesia can significantly reduce the incidence of nausea and vomiting. Six hours after surgery, visual analogue scale (VAS) scores were significantly lower in patients that underwent intravenous patient-controlled analgesia using low-dose naloxone combined with fentanyl compared with patients who received fentanyl alone; however, the postoperative analgesic effect of tropisetron was not observed. Compared with the combination of tropisetron and fentanyl, low-dose naloxone combined with fentanyl can obviously reduce the incidence of nausea and vomiting in patients who underwent intravenous patient-controlled analgesia after laparoscopic cholecystectomy, and enhance the analgesic effect of fentanyl 6 hours after surgery.Low-dose naloxone can reduce the incidence of nausea and vomiting in patients who underwent laparoscopic cholecystectomy under total intravenous anesthesia, and exhibits a certain synergic analgesic effect.

Structural Features and Potent Antidepressant Effects of Total Sterols and β-sitosterol Extracted from Sargassum horneri

The purified total sterols and β-sitosterol extracted from Sargassum horneri were evaluated for their antidepressant-like activity using the forced swim test (FST) and tail suspension test (TST) in mice. Total sterols and β-sitosterol significantly reduced the immobility time in the FST and TST. Total sterols were administered orally for 7 days at doses of 50, 100, and 200 mg/kg, and β-sitosterol was administered intraperitoneally at doses of 10, 20, and 30 mg/kg. β-sitosterol had no effect on locomotor activity in the open field test. In addition, total sterols and β-sitosterol significantly increased NE, 5-HT, and the metabolite 5-HIAA in the mouse brain, suggesting that the antidepressant-like activity may be mediated through these neurotransmitters.

Pharmacological evidence for the involvement of the NMDA receptor and nitric oxide pathway in the antidepressant-like effect of lamotrigine in the mouse forced swimming test

Lamotrigine is an anticonvulsant agent that shows clinical antidepressant properties. The aim of the present study was to investigate the involvement of N-methyl-d-aspartate (NMDA) receptors and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) synthesis in possible antidepressant-like effect of lamotrigine in forced swimming test (FST) in mice. Intraperitoneal administration of lamotrigine (10mg/kg) decreased the immobility time in the FST (P<0.01) without any effect on locomotor activity in the open-field test (OFT), while higher dose of lamotrigine (30mg/kg) reduced the immobility time in the FST (P<0.001) as well as the number of crossings in the OFT. Pretreatment of animals with NMDA (75mg/kg), l-arginine (750mg/kg, a substrate for nitric oxide synthase [NOS]) or sildenafil (5mg/kg, a phosphodiesterase [PDE] 5 inhibitor) reversed the antidepressant-like effect of lamotrigine (10mg/kg) in the FST. Injection of l-nitroarginine methyl ester (l-NAME, 10mg/kg, a non-specific NOS inhibitor), 7-nitroindazole (30mg/kg, a neuronal NOS inhibitor), methylene blue (20mg/kg, an inhibitor of both NOS and soluble guanylate cyclase [sGC]), or MK-801 (0.05mg/kg), ketamine (1mg/kg), and magnesium sulfate (10mg/kg) as NMDA receptor antagonists in combination with a sub-effective dose of lamotrigine (5mg/kg) diminished the immobility time of animals in the FST compared with either drug alone. None of the drugs produced significant effects on the locomotor activity in the OFT. Based on our findings, it is suggested that the antidepressant-like effect of lamotrigine might mediated through inhibition of either NMDA receptors or NO-cGMP synthesis.

Antidepressant effect of pramipexole in mice forced swimming test: A cross talk between dopamine receptor and NMDA/nitric oxide/cGMP pathway

Pramipexole is a dopamine D2 receptor agonist indicated for treating Parkinson disorder. This study was aimed to investigate the effect of pramipexole in forced swimming test (FST) in mice and the possible involvement of activation of D2 receptors and inhibition of N-methyl-d-aspartate (NMDA) receptors and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) on this effect. Intraperitoneal administration of pramipexole (1-3mg/kg) reduced the immobility time in the FST similar to fluoxetine (20mg/kg, i.p.). This effect of pramipexole (1mg/kg, i.p.) was ceased when mice were pretreated with haloperidol (0.15mg/kg, i.p,) and sulpiride (5mg/kg, i.p) as D2 receptor antagonists, NMDA (75mg/kg,i.p.), l-arginine (750mg/kg, i.p., a substrate for nitric oxide synthase) or sildenafil (5mg/kg, i.p., a phosphodiesterase 5 inhibitor). The administration of MK-801 (0.05mg/kg, i.p., a NMDA receptor antagonist) l-NG-Nitro arginine methyl ester (l-NAME, 10mg/kg, i.p., a non-specific nitric oxide synthase (NOS) inhibitor), 7-nitroindazole (30mg/kg, i.p., a neuronal NOS inhibitor) and methylene blue (10mg/kg, i.p.), an inhibitor of both NOS and soluble guanylyl cyclase (sGC) in combination with the sub-effective dose of pramipexole (0.3mg/kg, i.p.) reduced the immobility. Altogether, our data suggest that the antidepressant-like effect of pramipexole is dependent on the activation of D2 receptor and inhibition of either NMDA receptors and/or NO-cGMP synthesis. These results contribute to the understanding of the mechanisms underlying the antidepressant-like effect of pramipexole and reinforce the role of D2 receptors, NMDA receptors and l-arginine-NO-GMP pathway in the antidepressant mechanism of this agent.