Apigenin reverses depression-like behavior induced by chronic corticosterone treatment in mice

The Therapeutic Potential of Apigenin

Several plant bioactive compounds have exhibited functional activities that suggest they could play a remarkable role in preventing a wide range of chronic diseases. The largest group of naturally-occurring polyphenols are the flavonoids, including apigenin. The present work is an updated overview of apigenin, focusing on its health-promoting effects/therapeutic functions and, in particular, results of in vivo research. In addition to an introduction to its chemistry, nutraceutical features have also been described. The main key findings from in vivo research, including animal models and human studies, are summarized. The beneficial indications are reported and discussed in detail, including effects in diabetes, amnesia and Alzheimer's disease, depression and insomnia, cancer, etc. Finally, data on flavonoids from the main public databases are gathered to highlight the apigenin's key role in dietary assessment and in the evaluation of a formulated diet, to determine exposure and to investigate its health effects in vivo.

Cortisol and Major Depressive Disorder-Translating Findings From Humans to Animal Models and Back

Major depressive disorder (MDD) is a global problem for which current pharmacotherapies are not completely effective. Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has long been associated with MDD; however, the value of assessing cortisol as a biological benchmark of the pathophysiology or treatment of MDD is still debated. In this review, we critically evaluate the relationship between HPA axis dysfunction and cortisol level in relation to MDD subtype, stress, gender and treatment regime, as well as in rodent models. We find that an elevated cortisol response to stress is associated with acute and severe, but not mild or atypical, forms of MDD. Furthermore, the increased incidence of MDD in females is associated with greater cortisol response variability rather than higher baseline levels of cortisol. Despite almost all current MDD treatments influencing cortisol levels, we could find no convincing relationship between cortisol level and therapeutic response in either a clinical or preclinical setting. Thus, we argue that the absolute level of cortisol is unreliable for predicting the efficacy of antidepressant treatment. We propose that future preclinical models should reliably produce exaggerated HPA axis responses to acute or chronic stress a priori, which may, or may not, alter baseline cortisol levels, while also modelling the core symptoms of MDD that can be targeted for reversal. Combining genetic and environmental risk factors in such a model, together with the interrogation of the resultant molecular, cellular, and behavioral changes, promises a new mechanistic understanding of MDD and focused therapeutic strategies.

Antioxidant and antidepressant-like effects of Eugenia catharinensis D. Legrand in an animal model of depression induced by corticosterone

This work investigated the antioxidant and antidepressant-like effects of ethyl acetate extract from Eugenia catharinensis in mice treated with corticosterone (20 mg/Kg). The animals received saline or corticosterone (21 days) and, in the last 7 days, they were treated with the extract (50, 125, 200 or 250 mg/Kg) or vehicle. After 24 h, the mice were submitted to the open field and forced swimming tests, after which the hippocampus and cerebral cortex were removed. Our results showed that the extract decreased the immobility time of mice in the forced swimming test and that the extract was able to reverse the effect caused by corticosterone. Corticosterone pre-treatment generated oxidative stress, altering antioxidant enzymes in the nervous tissue. The extract increased the catalase and superoxide dismutase activities and reversed the effects of corticosterone. In the hippocampus, the extract increased superoxide dismutase activity and reversed the increase in catalase activity elicited by corticosterone. We propose that the effects elicited by the Eugenia catharinensis are dependent on the presence of phenolic compounds (gallic acid, protocatechuic acid, syringic acid, 4-hydroxy methylbenzoic acid, chlorogenic acid, salicylic acid, caffeic acid, vanillic acid, p-coumaric acid, isoquercetin, rutin, ferulic acid, aromadendrin, galangin and apigenin) in this extract, as demonstrated by HPLC-ESI-MS/MS.

Standardized Citrus unshiu peel extract ameliorates dexamethasone-induced neurotoxicity and depressive-like behaviors in mice

Dried Citrus unshiu peel, also known as Chinpi, have been commonly used as a traditional medicine to improve for allergy, inflammation and hepatopathy. Many previously studies have reported that citrus flavonoids show neuroprotective activities. However, the antidepressant-related effects of C. unshiu peels have not been well characterized. Here, the antidepressant-like effects of standardized C. unshiu peel extract (SCP) were evaluated in in vivo and in vitro depression models induced by dexamethasone (DEX), a synthetic glucocorticoid. Male ICR mice (9-week-old) were injected the DEX (40 mg/kg) and were orally given SCP daily (30, 100, and 300 mg/kg) for 14 consecutive days. The depressive-like behaviors were determined by use of open filed test (OFT), sucrose preference test (SPT), tail suspension test (TST), and forced swim test (FST). We show that treatment with SCP significantly alleviated DEX-induced depressive-like behaviors and reduced neurotoxicity in a concentration dependent manner in SH-SY5Y cells. Additionally, repeated DEX injection markedly decreased brain derived neurotrophic factor (BDNF) level, tropomyosin receptor kinase B (TrkB), and cyclic AMP-response element-binding protein (CREB), while SCP treatment improved these levels in the cerebral cortex and hippocampus regions. Our findings suggest that SCP exhibits significant antidepressant-like effects in the DEX-induced depressive animal model, and this activity may be mediated by preventing corticosterone-induced neurotoxicity.

Cholecalciferol counteracts depressive-like behavior and oxidative stress induced by repeated corticosterone treatment in mice

Depression is one of the most frequent neuropsychiatric diseases in the western world and its physiological causes are not yet fully understood. Since the available antidepressants failed to provide a complete illness remission, the diversification of the therapy in the management of depression could be a useful contribution. The present study aimed to investigate the cholecalciferol capability to revert depressive-like behavior induced by chronic corticosterone (CORT) treatment in mice and its implication on the oxidative stress modulation. Sixty minutes after having orally received different doses of cholecalciferol, adult male mice were evaluated in the forced swimming and tail suspension tests, whereas in the seven-day treatment they were only tested in tail suspension. Additionally, for 21 days, the animals received CORT (20 mg/kg, p.o.) and cholecalciferol or fluoxetine, once a day for the last 7-days of the CORT treatment. Moreover, the markers of oxidative stress, lipid peroxidation, protein carbonyl and nitrite levels were assessed in the plasma and brain's mice after the splash and tail suspension tests. It was observed that corticosterone treatment resulted in depressive-like behavior with established oxidative stress in mice, while cholecalciferol ameliorated both, behavioral (immobility time and grooming latency) and biochemical (protein carbonyl and nitrite levels) changes induced by CORT model, suggesting that cholecalciferol has antidepressant-like effect with the involvement of the oxidative stress modulation.

Antidepressant effects of magnolol in a mouse model of depression induced by chronic corticosterone injection

Evidence showed that the stress hormone corticosterone (CORT) injection resulted in dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis implicated in major depressive disorder. Magnolol, main constituent identified in the barks of Magnolia officinalis, exerted antidepressant effects in a rat model of depression induced by chronic unpredictable mild stress in previous studies. However, its antidepressant-like effects and mechanisms have never been studied in depression model induced by CORT administration in rodents. This study aimed to investigate the antidepressant-like effects and possible mechanisms of magnolol in CORT-treated mice by utilizing a combination of behavioral and biochemical analysis. The depressive model was developed by subcutaneous injection of CORT for 21 days at a dose of 20 mg/kg. CORT administration formed depressive-like behaviors in mice, as indicated by increased immobility time in the forced swim test (FST) and tail suspension test (TST), as well as decreased sucrose intake in sucrose preference test (SPT). Moreover, we also found that CORT levels in serum were significantly increased, along with the decrease of brain-derived neurotrophic factor (BDNF) mRNA, BDNF protein, 5-hydroxytryptamine (5-HT) and norepinephrine (NE) levels in the hippocampus. Treatment with magnolol alleviated depressive-like behaviors, reduced the levels of CORT, and improved the levels of BDNF protein, 5-HT, and NE compared with those in CORT-treated mice. These findings indicated that magnolol possessed antidepressant effects in mice exposed to CORT, which might be partially related to modulate HPA axis, up-regulate BDNF expression and increase neurotransmitters levels in the hippocampus.

Agathisflavone, a flavonoid derived from Poincianella pyramidalis (Tul.), enhances neuronal population and protects against glutamate excitotoxicity

Flavonoids are bioactive compounds that are known to be neuroprotective against glutamate-mediated excitotoxicity, one of the major causes of neurodegeneration. The mechanisms underlying these effects are unresolved, but recent evidence indicates flavonoids may modulate estrogen signaling, which can delay the onset and ameliorate the severity of neurodegenerative disorders. Furthermore, the roles played by glial cells in the neuroprotective effects of flavonoids are poorly understood. The aim of this study was to investigate the effects of the flavonoid agathisflavone (FAB) in primary neuron-glial co-cultures from postnatal rat cerebral cortex. Compared to controls, treatment with FAB significantly increased the number of neuronal progenitors and mature neurons, without increasing astrocytes or microglia. These pro-neuronal effects of FAB were suppressed by antagonists of estrogen receptors (ERα and ERβ). In addition, treatment with FAB significantly reduced cell death induced by glutamate and this was associated with reduced expression levels of pro-inflammatory (M1) microglial cytokines, including TNFα, IL1β and IL6, which are associated with neurotoxicity, and increased expression of IL10 and Arginase 1, which are associated with anti-inflammatory (M2) neuroprotective microglia. We also observed that FAB increased neuroprotective trophic factors, such as BDNF, NGF, NT4 and GDNF. The neuroprotective effects of FAB were also associated with increased expression of glutamate regulatory proteins in astrocytes, namely glutamine synthetase (GS) and Excitatory Amino Acid Transporter 1 (EAAT1). These findings indicate that FAB acting via estrogen signaling stimulates production of neurons in vitro and enhances the neuroprotective properties of microglia and astrocytes to significantly ameliorate glutamate-mediated neurotoxicity.

Antidepressant and pro-neurogenic effects of agmatine in a mouse model of stress induced by chronic exposure to corticosterone

Agmatine is an endogenous neuromodulator that has been shown to have beneficial effects in the central nervous system, including antidepressant-like effects in animals. In this study, we investigated the ability of agmatine (0.1mg/kg, p.o.) and the conventional antidepressant fluoxetine (10mg/kg, p.o.) to reverse the behavioral effects and morphological alterations in the hippocampus of mice exposed to chronic corticosterone (20mg/kg, p.o.) treatment for a period of 21days as a model of stress and depressive-like behaviors. Chronic corticosterone treatment increased the immobility time in the tail suspension test (TST), but did not cause anhedonic-like and anxiety-related behaviors, as assessed with the splash test and the open field test (OFT), respectively. Of note, the depressive-like behaviors induced by corticosterone were accompanied by a decrease in hippocampal cell proliferation, although no changes in hippocampal neuronal differentiation were observed. Our findings provide evidence that, similarly to fluoxetine, agmatine was able to reverse the corticosterone-induced depressive-like behaviors in the TST as well as the deficits in hippocampal cell proliferation. Additionally, fluoxetine but not agmatine, increased hippocampal differentiation. Agmatine, similar to fluoxetine, was capable of increasing both dendritic arborization and length in the entire dentate hippocampus, an effect more evident in the ventral portion of the hippocampus, as assessed with the modified Sholl analysis. Altogether, our results suggest that the increase in hippocampal proliferation induced by agmatine may contribute, at least in part, to the antidepressant-like response of this compound in this mouse model of stress induced by chronic exposure to corticosterone.

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.

Ferulic acid reverses depression-like behavior and oxidative stress induced by chronic corticosterone treatment in mice

Corticosterone (CORT) treatment has been evidenced to develop a depression-like state in animals, that mimic hypothalamic-pituitary-adrenal (HPA)-axis dysregulation implicated in the development of depression. The present study aimed to examine the ferulic acid (FA), a natural phenolic compound, antidepressant and antioxidant activities on the CORT chronic model. Mice orally treated with 20mg/kg of CORT for 21days were connsidered control group, while mice treated with FA (1mg/kg) or fluoxetine (10mg/kg) for the last week of CORT treatment, as drug groups. Three weeks of CORT treatment resulted in depressive-like behavior, as indicated by the increase on the immobility time in the tail suspension test, grooming in the splash test and an increase in the oxidative stress markers in the brain. It was observed that FA ameliorated the behavioral and oxidative stress alterations induced by CORT, which may plausibly suggest a mode of action for the FA antidepressant effect. The involvement of FA repairing the stress caused by HPA-axis dysfunction evidenced that this phenolic acid could be further investigated as a novel potential agent to improve the management of depression.

Mangiferin prevents corticosterone-induced behavioural deficits via alleviation of oxido-nitrosative stress and down-regulation of indoleamine 2,3-dioxygenase (IDO) activity

BACKGROUND

In recent years, a substantial amount of experimental studies have demonstrated that exogenous administration of corticosterone causes anxiety and depressive-like behaviour in rodents which involves hypothalamic-pituitary-adrenal axis dysregulation. Our present study aimed to explore the neuroprotective potential of mangiferin against corticosterone-induced anxiety and depressive-like behaviour.

METHODS

Corticosterone (40 mg/kg; subcutaneously) was administered once daily in swiss albino mice for 21 days. Mice were treated simultaneously with mangiferin (40 mg/kg; p.o.), 30 min prior to the corticosterone injection.

RESULTS

Chronic administration of corticosterone caused anxiety and depressive-like behaviour in mice which was significantly alleviated by mangiferin treatment. Biochemical analysis revealed that mangiferin treatment significantly attenuated corticosterone-induced oxido-nitrosative stress and neuroinflammation in the hippocampus region. Furthermore, concomitant treatment with mangiferin significantly enhanced the hippocampal brain-derived neurotrophic factor (BDNF) level and decreased the serum corticosterone level in the corticosterone-treated animals. Western blotting analysis revealed that corticosterone administration significantly up-regulated the indoleamine 2,3-dioxygenase (IDO) protein expression level in the hippocampus which was significantly reduced by mangiferin treatment.

CONCLUSION

Taken together, our results suggest that mangiferin exerts anti-anxiety and antidepressant effect in corticosterone-treated rats, which is probably mediated through up-regulation of BDNF level along with inhibition of oxido-nitrosative stress, neuroinflammation and IDO up-regulation in the hippocampus region.

Differential Behavioral and Neurobiological Effects of Chronic Corticosterone Treatment in Adolescent and Adult Rats

Adolescence is a critical period with ongoing maturational processes in stress-sensitive systems. While adolescent individuals show heightened stress-induced hormonal responses compared to adults, it is unclear whether and how the behavioral and neurobiological consequences of chronic stress would differ between the two age groups. Here we address this issue by examining the effects of chronic exposure to the stress hormone, corticosterone (CORT), in both adolescent and adult animals. Male Sprague-Dawley (SD) rats were injected intraperitoneally with CORT (40 mg/kg) or vehicle for 21 days during adolescence (post-natal day (PND) 29–49) or adulthood (PND 71–91) and then subjected to behavioral testing or sacrifice for western blot analyses. Despite of similar physical and neuroendocrine effects in both age groups, chronic CORT treatment produced a series of behavioral and neurobiological effects with striking age differences. While CORT-treated adult animals exhibited decreased sucrose preference, increased anxiety levels and cognitive impairment, CORT-treated adolescent animals demonstrated increased sucrose preference, decreased anxiety levels, and increased sensorimotor gating functions. These differential behavioral alterations were accompanied by opposite changes in the two age groups in the expression levels of brain-derived neurotrophic factor (BDNF), the phosphorylation of the obligatory subunit of the NMDA receptor, GluN1, and PSD-95 in rat hippocampus. These results suggest that prolonged glucocorticoid exposure during adolescence produces different behavioral and neurobiological effects from those in adulthood, which may be due to the complex interaction between glucocorticoids and the ongoing neurodevelopmental processes during this period.

Changes in C57BL6 Mouse Hippocampal Transcriptome Induced by Hypergravity Mimic Acute Corticosterone-Induced Stress

Centrifugation is a widely used procedure to study the impact of altered gravity on Earth, as observed during spaceflights, allowing us to understand how a long-term physical constraint can condition the mammalian physiology. It is known that mice, placed in classical cages and maintained during 21 days in a centrifuge at 3G gravity level, undergo physiological adaptations due to hypergravity, and/or stress. Indeed, an increase of corticosterone levels has been previously measured in the plasma of 3G-exposed mice. Corticosterone is known to modify neuronal activity during memory processes. Although learning and memory performances cannot be assessed during the centrifugation, literature largely described a large panel of proteins (channels, second messengers, transcription factors, structural proteins) which expressions are modified during memory processing. Thus, we used the Illumina technology to compare the whole hippocampal transcriptome of three groups of C57Bl6/J mice, in order to gain insights into the effects of hypergravity on cerebral functions. Namely, a group of 21 days 3G-centrifuged mice was compared to (1) a group subjected to an acute corticosterone injection, (2) a group receiving a transdermal chronic administration of corticosterone during 21 days, and (3) aged mice because aging could be characterized by a decrease of hippocampus functions and memory impairment. Our results suggest that hypergravity stress induced by corticosterone administration and aging modulate the expression of genes in the hippocampus. However, the modulations of the transcriptome observed in these conditions are not identical. Hypergravity affects per-se the hippocampus transcriptome and probably modifies its activity. Hypergravity induced changes in hippocampal transcriptome were more similar to acute injection than chronic diffusion of corticosterone or aging.