Involvement of nitric oxide (NO) signaling pathway in the antidepressant action of the total flavonoids extracted from Xiaobuxin-Tang

Exploring the multifocal role of phytoconstituents as antidepressants

Depression is the most prevalent and devastating neuropsychiatric disorder. There are several conventional antidepressants used for the treatment of depression. But due to their undesired adverse effects, patient compliance is very poor. Thus, developing novel medications for the treatment of depression is a critical strategic priority for meeting therapeutic demands. Current research is looking for alternatives to traditional antidepressants to reduce undesired side effects and increase efficacy. Phytoconstituents provide a wide research range in antidepressant treatments. In the present article, we have conducted a comprehensive assessment of neurological evidence, which supports the usefulness of phytoconstituents in the treatment of the depressive disorder. Secondary plant metabolites including alkaloids, polyphenols, glycosides, saponins, and terpenoids were found to exhibit antidepressant action. Most of the phytoconstituents were found to mediate their antidepressant effect through the upregulation of brain-derived neurotrophic factor (BDNF), serotonin, noradrenaline, and dopamine. Some were also found to exert antidepressant effects by inhibiting the monoamine oxidase (MAO) activity and hypothalamic-pituitary-adrenal (HPA) axis overactivity.

Emerging Role of Flavonoids as the Treatment of Depression

Depression is one of the most frequently observed psychological disorders, affecting thoughts, feelings, behavior and a sense of well-being in person. As per the WHO, it is projected to be the primitive cause of various other diseases by 2030. Clinically, depression is treated by various types of synthetic medicines that have several limitations such as side-effects, slow-onset action, poor remission and response rates due to complicated pathophysiology involved with depression. Further, clinically, patients cannot be given the treatment unless it affects adversely the job or family. In addition, synthetic drugs are usually single targeted drugs. Unlike synthetic medicaments, there are many plants that have flavonoids and producing action on multiple molecular targets and exhibit anti-depressant action by affecting multiple neuronal transmissions or pathways such as noradrenergic, serotonergic, GABAnergic and dopaminergic; inhibition of monoamine oxidase and tropomyosin receptor kinase B; simultaneous increase in nerve growth and brain-derived neurotrophic factors. Such herbal drugs with flavonoids are likely to be useful in patients with sub-clinical depression. This review is an attempt to analyze pre-clinical studies, structural activity relationship and characteristics of reported isolated flavonoids, which may be considered for clinical trials for the development of therapeutically useful antidepressant.

The effects of methylated flavonoids on depression-like activity and pro-inflammatory cytokine thresholds in mice induced by repeated finasteride administration

The aim of the study was to investigate the influence of naringenin (NGN) and its methylated derivatives (50 or 100 mg kg−1) on finasteride-caused depression-like performance in mice to identify the effects on behavior and biomarkers of inflammation in the management of depression. Depression-like behavior was induced by repeated dose of finasteride (100 mg kg−1, subcutaneously) in mice. The effects of the naringenin (50 or 100 mg kg−1) or its methylated derivatives (Ngn-M; 50 or 100 mg kg−1 or Ngn-DM; 50 or 100 mg kg−1) and duloxetine (DXT, 10 mg kg−1) were evaluated for the immobility time in tail suspension and forced swimming tests following finasteride pre-treatment. The levels of brain pro-inflammatory cytokines such as IL-1β and TNF-α were also measured by Enzyme-Linked Immunosorbent Assay to further evaluate the impact of naringenin and its methylated derivatives on inflammation. Pre-treatment with finasteride substantially increased both the immobility time spent in tail suspension and forced swimming tests and brain levels of IL-1β and TNF–α in mice. Doluxetine (DLX) was given at a dose of 10 mg kg−1, and Naringenin or its methylated derivatives were given at doses of 50 and 100 mg kg−1 orally. It reduced immobility time in both tests, restored the preference to sucrose solution, and normalized cytokine levels (p < 0.01) in mice. Similar effects were observed with DTX (10 mg kg−1) as positive control. The increased brain levels of malondialdehyde (MDA) or nitrite were considerably (p < 0.05) decreased while substantially (p < 0.05) increased glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) levels after finasteride pre-treatment relative to vehicle-control by naringenin or its methylated derivatives (50 or 100 mg kg−1). These findings demonstrated the potential for methylated flavonoids as safe and effective anti-depressive agents.

Botanicals as modulators of depression and mechanisms involved

Depression is the most disastrous mood disorder affecting the health of individuals. Conventional treatments with chemical compounds for depression have limitations, while herbal medicine has unique therapeutic effects. This paper introduces the pharmacological basis and biological mechanisms underlying the botanical antidepressants over the past 5 years. Based upon the specific therapeutic targets or mechanisms, we analyzed the pathological roles of monoamine neurotransmitters, the hypothalamic-pituitary-adrenal axis, inflammation, oxidative stress, synaptic plasticity performed in antidepressant of the botanicals. In addition, gut flora and neurogenesis were also preferentially discussed as treatment approaches. Based on the complex pathogenesis of depression, we suggested that mixed use of botanicals, namely prescription would be more suitable for treatment of depression. In addition, neural circuit affected by botanicals or active components should also attract attention as the botanicals have potential to be developed into fast-acting antidepressants. Finally, gut flora might be a new systemic target for the treatment of depression by botanicals. This review would strength botanical medicine as the antidepressant and also provides an overview of the potential mechanisms involved.

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.

Advances in the Preclinical Study of Some Flavonoids as Potential Antidepressant Agents

Flavonoids are phenolic compounds found commonly in plants that protect them against the negative effects of environmental insults. These secondary metabolites have been widely studied in preclinical research because of their biological effects, particularly as antioxidant agents. Diverse flavonoids have been studied to explore their potential therapeutic effects in the treatment of disorders of the central nervous system, including anxiety and depression. The present review discusses advances in the study of some flavonoids as potential antidepressant agents. We describe their behavioral, physiological, and neurochemical effects and the apparent mechanism of action of their preclinical antidepressant-like effects. Natural flavonoids produce antidepressant-like effects in validated behavioral models of depression. The mechanism of action of these effects includes the activation of serotonergic, dopaminergic, noradrenergic, and γ-aminobutyric acid-ergic neurotransmitter systems and an increase in the production of neural factors, including brain-derived neurotrophic factor and nerve growth factor. Additionally, alterations in the function of tropomyosin receptor kinase B and activity of the enzyme monoamine oxidase A have been reported. In conclusion, preclinical research supports the potential antidepressant effects of some natural flavonoids, which opens new possibilities of evaluating these substances to develop complementary therapeutic alternatives that could ameliorate symptoms of depressive disorders in humans.

Antidepressant-like effects and cognitive enhancement of Schisandra chinensis in chronic unpredictable mild stress mice and its related mechanism

The aim of this study was to evaluate whether Schisandra chinensis extract (SCE) administration influences chronic unpredictable mild stress (CUMS)-induced depression and cognitive impairment, and explores underlying mechanisms. Sucrose preference test (SPT) and forced swimming test (FST) were used for assessing depressive symptoms, and Y-maze, Morris water maze were used for evaluating cognition processes. The results showed that CUMS (4 weeks) was effective in producing both depression and memory deficits in mice. Additionally, CUMS exposure significantly decreased brain derived neurotrophic factor (BDNF) levels in hippocampus as indicated by ELISA, immunohistochemistry and immunofluorescence assays, accompanied by down-regulated tyrosine kinase receptor B (TrkB)/cAMP-response element binding protein (CREB)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3 kinase (PI3K)/ protein kinase B (AKT)/ glycogen synthase kinase-3β (GSK-3β) signaling pathways. Chronic administration of SCE (600 or 1200 mg/kg, i.g.) significantly prevented all these CUMS-induced behavioral and biochemical alterations. It suggested that SCE could improve the depression-like emotional status and associated cognitive deficits in CUMS mice, which might be mediated by regulation of BDNF levels in hippocampus, as well as up-regulating of TrkB/CREB/ERK and PI3K/AKT/GSK-3β pathways.

Ergosteryl 2-naphthoate, An Ergosterol Derivative, Exhibits Antidepressant Effects Mediated by the Modification of GABAergic and Glutamatergic Systems

Phytosterols are a kind of natural component including sitosterol, campesterol, avenasterol, ergosterol (Er) and others. Their main natural sources are vegetable oils and their processed products, followed by grains, by-products of cereals and nuts, and small amounts of fruits, vegetables and mushrooms. In this study, three new Er monoester derivatives were obtained from the reflux reaction with Er: organic acids (furoic acid, salicylic acid and 2-naphthoic acid), 1-Ethylethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride (EDCI) and 4-dimethylaminopyridine (DMAP) in dichloromethane. Their chemical structures were defined by IR and NMR. The present study was also undertaken to investigate the antidepressant-like effects of Er and its derivatives in male adult mice models of depression, and their probable involvement of GABAergic and glutamatergic systems by the forced swim test (FST). The results indicated that Er and its derivatives display antidepressant effects. Moreover, one derivative of Er, ergosteryl 2-naphthoate (ErN), exhibited stronger antidepressant activity in vivo compared to Er. Acute administration of ErN (5 mg/kg, i.p.) and a combination of ErN (0.5 mg/kg, i.p.), reboxetine (2.5 mg/kg, i.p.), and tianeptine (15 mg/kg, i.p.) reduced the immobility time in the FST. Pretreatment with bicuculline (a competitive γ-aminobutyric acid (GABA) antagonist, 4 mg/kg, i.p.) and N-methyl-d-aspartic acid (NMDA, an agonist at the glutamate site, 75 mg/kg, i.p.) effectively reversed the antidepressant-like effect of ErN (5 mg/kg, i.p.). However, prazosin (a α1-adrenoceptor antagonist, 1 mg/kg, i.p.) and haloperidol (a non-selective D2 receptor antagonist, 0.2 mg/kg, i.p.) did not eliminate the reduced immobility time. Altogether, these results indicated that ErN produced antidepressant-like activity, which might be mediated by GABAergic and glutamatergic systems.

The effect of Schisandra chinensis extracts on depression by noradrenergic, dopaminergic, GABAergic and glutamatergic systems in the forced swim test in mice

Schisandra chinensis (Turcz.) Baill., as a Chinese functional food, has been widely used in neurological disorders including insomnia and Alzheimer's disease.

Effects of the total flavonoid extract of Xiaobuxin-Tang on depression-like behavior induced by lipopolysaccharide and proinflammatory cytokine levels in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaobuxin-Tang (XBXT), a traditional Chinese herbal decoction, has been used for the treatment of depressive disorders from ancient clinic. The aim of the study was to explore the involvement of inflammation or inflammatory markers in the antidepressant-like effects of XBXT-2.

MATERIALS AND METHODS

Depression-like behavior was induced by lipopolysaccharide (LPS, 0.2mg/kg, i.p) in tail suspension test (TST) and forced swimming test (FST) in mice. The effects of the total flavonoids (XBXT-2) extracted from XBXT (25, 50, and 100mg/kg, p.o.) and duloxetine (DLX, 10mg/kg, p.o.) on the immobility time in TST and FST were determined 24h after LPS pretreatment. The locomotor activity was also determined to eliminate the false-positive activity. Additionally, in order to further evaluate the effect of XBXT-2 on inflammation, the levels of brain proinflammatory cytokines including IL-1β and TNF-α were assessed by ELISA.

RESULTS

The pretreatment with LPS significantly increased the immobility time in TST and FST in mice, as well as the brain levels of IL-1β and TNF-α. XBXT-2 (25, 50, and 100mg/kg, p.o.) administration decreased the duration of immobility in TST and FST, and normalized the cytokines levels. The positive control DLX (10mg/kg, p.o.) exerted similar effects. Meanwhile, neither LPS pretreatment nor drugs treatment had any effect on mouse locomotor activity.

CONCLUSIONS

These results suggest that inflammation and inflammatory cytokines may be involved in the antidepressant-like effects of XBXT-2.