Chrysin reverses the depressive-like behavior induced by hypothyroidism in female mice by regulating hippocampal serotonin and dopamine

Design, synthesis, molecular docking, molecular dynamic simulation, and MMGBSA analysis of 7-O-substituted 5-hydroxy flavone derivatives

A series of chrysin derivatives were designed, synthesized, and evaluated for their antibacterial activity against four different bacterial strains. We have synthesized new propyl-substituted and butyl-substituted chrysin-piperazine derivatives, which show marvellous inhibition against E. coli and S. aureus. The free hydroxyl group at the C-5 position of chrysin improved therapeutic efficacy in vivo and was a beneficial formulation for chemotherapy. All synthesized compounds were confirmed by various spectroscopic techniques such as IR, NMR, HPLC, and mass spectrometry. The compounds exhibited moderate to good inhibition, and their structure-activity relationship (SAR) has also been illustrated. Among the synthesised compounds, compounds 4 and 10 were the most active against S. pyogenes and E. coli, with 12.5 g/mL MICs; additionally, compound 12 exhibits significant activity on both the S. aureus and E. coli stains. Based on the promising activity profile and docking score of compound 12, it was selected for 100 ns MD simulation and post-dynamic binding free energy analysis within the active sites of S. aureus TyrRS (PDB ID: 1JIJ) and E. coli DNA GyrB (PDB ID: 6YD9) to investigate the stability of molecular contacts and to establish how the newly synthesized inhibitors fit together in the most stable conformations.Communicated by Ramaswamy H. Sarma.

Is the acquired hypothyroidism a risk factor for developing psychiatric disorders?

Hypothyroidism is a prevalent thyroid condition in which the thyroid gland fails to secrete an adequate amount of thyroid hormone into the bloodstream. This condition may develop due to genetic or acquired factors. The most frequent cause of acquired hypothyroidism is chronic autoimmune thyroiditis, also known as Hashimoto's disease. Acquired hypothyroidism is diagnosed when patients present with overt hypothyroidism (also known as clinical hypothyroidism), as they exhibit increased TSH and decreased T3 and T4 serum levels. This article examines the prevalence of psychiatric disorders among patients diagnosed with acquired hypothyroidism with or without Levothyroxine treatment. We discuss the available evidence indicating that acquired hypothyroidism may be a risk factor for psychiatric disorders, and the effectiveness of thyroid treatment in relieving psychiatric symptoms. Additionally, we provide critical details on thyroid hormone cutoff values reported in the literature, their potential clinical importance, and their correlation with psychiatric symptoms. Finally, we examined the various mechanisms by which acquired hypothyroidism can lead to depression. The high rate of comorbidity between hypothyroidism and psychiatric disorders deserves special attention, indicating the importance of consistent monitoring and timely identification of psychiatric symptoms to prevent disease exacerbation and facilitate therapeutic management. On the other hand, several mechanisms underlie the strong association between depression and acquired hypothyroidism. Deeper research into these mechanisms will allow knowledge of the pathophysiology of depression in patients with acquired hypothyroidism and will provide clues to design more precise therapeutic strategies for these patients.

Targeting autophagy to counteract neuroinflammation: A novel antidepressant strategy

Depression is a common disease that affects physical and mental health and imposes a considerable burden on afflicted individuals and their families worldwide. Depression is associated with a high rate of disability and suicide. It causes a severe decline in productivity and quality of life. Unfortunately, the pathophysiological mechanisms underlying depression have not been fully elucidated, and the risk of its treatment is still presented. Studies have shown that the expression of autophagic markers in the brain and peripheral inflammatory mediators are dysregulated in depression. Autophagy-related genes regulate the level of autophagy and change the inflammatory response in depression. Depression is related to several aspects of immunity. The regulation of the immune system and inflammation by autophagy may lead to the development or deterioration of mental disorders. This review highlights the role of autophagy and neuroinflammation in the pathophysiology of depression, sumaries the autophagy-targeting small moleculars, and discusses a novel therapeutic strategy based on anti-inflammatory mechanisms that target autophagy to treat the disease.

Polyphenols as novel interventions for depression: exploring the efficacy, mechanisms of action, and implications for future research

Numerous animal and human studies have assessed the relationship between polyphenols and outcomes related to depression. However, no comprehensive synthesis of the main findings has been conducted. The aim of this manuscript was to systematically review the available evidence from animal and human studies on the association and the effects of dietary polyphenols on depression and provide recommendations for future research. We based our review on 163 preclinical animal, 16 observational and 44 intervention articles assessing the relationship between polyphenols and outcomes related to depression. Most animal studies demonstrated that exposure to polyphenols alleviated behaviours reported to be associated with depression. However, human studies are less clear, with some studies reporting and inverse relationship between the intake of some polyphenols, and polyphenol rich foods and depression risk and symptoms, while others reporting no association or effect. Hence, while there has been extensive research conducted in animals and there is some supporting evidence in humans, further human studies are required, particularly in younger and clinical populations.

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.

Inflammatory Immune Process and Depression-like Behavior in Hypothyroid Rats: A [18F] DPA-714 Micro Positron Emission Tomography Study

Hypothyroidism is closely related to mental disorders, mainly depression, through an as-yet-unknown mechanism. The cerebral inflammatory immune process has been implied to play a pivotal role in the onset of affective symptoms in several conditions. In order to gain insight into the mechanism underlying the depressive behaviors in hypothyroid rats, brain microglial activation was evaluated using micro positron emission tomography imaging with a translocator protein (TSPO) radioligand. Hypothyroidism was induced in adult male Wistar rats by administration of 0.05% propylthiouracil in drinking water for five weeks. Open field, forced swimming and tail suspension tests were employed to evaluate the depressive behavior in hypothyroid rats, and the relationship between the behavioral changes and brain microglial activation was evaluated using [18F] DPA-714 micro positron emission tomography imaging. The open field test revealed significantly reduced first-minute activity and rearing behavior in the hypothyroid group, as well as significantly increased immobility in the forced swimming test and the tail suspension test. Hypothyroidism induced significantly increased microglial activation in the hippocampus. The radioligand uptake in the hippocampus correlated negatively with first-minute activity in the open field test (p < 0.05), and the radioligand uptake in the hippocampus correlated positively with changes in the immobility time in the forced swimming test and the tail suspension test (p < 0.05). Immunohistochemistry also confirmed the activation of microglia and inflammatory bodies in hypothyroid rats. The results indicate that hypothyroidism can induce depressive behavior in adult Wistar rats, microglial activation in the hippocampus plays an important role in the depressive behavior in hypothyroid rats and the inflammatory immune mechanism may underlie the behavioral abnormalities in thyroid dysfunction. Furthermore, the findings in the present study suggest there might be a common mechanism underlying depressive behavior in adult-onset hypothyroidism and depression.

Attenuation of Hypothyroidism-Induced Cognitive Impairment by Modulating Serotonin Mediation

Thyroid hormones play an important role in the modeling of neural networks in the brain. Besides its metabolic effects, thyroid dysfunction, and hypothyroidism in particular, is frequently associated with cognitive decline and depressive-like behavior. The current study aimed to examine the changes in behavior, cognition, and memory in rats with propylthiouracil-induced overt hypothyroidism. The behavior and cognition were assessed using the open field test, T-maze, and novel object recognition test. We found significant differences in the behavioral patterns of the hypothyroid animals showing a reduction in locomotor activity, frequency of rearing, and impaired memory function compared to the euthyroid controls. As serotonin is an essential biomarker regulating cognition and mood, we tried to modulate the serotonin mediation in hypothyroid animals through tryptophan administration. Treatment with 5-hydroxy-tryptophan (5-OH-TRP) intraperitoneally for 10 days or directly into the hippocampus as a single injection led to attenuation of the hypothyroidism-induced cognitive and memory decline. A staggering amount of research is suggesting that the common denominators in the pathophysiology of depression and the behavior changes in hypothyroidism are the hippocampal complex and the distorted serotonin metabolism. In our study, it was observed a significant alleviation of cognitive impairment and an improvement of memory performance in hypothyroid rats after 5-OH-TRP administration. Current results are promising and may serve as groundwork for further investigation of functional and structural changes in the hippocampus during a hypothyroid state, and in particular, the effects of serotonin mediation in hypothyroid-associated depressive-like behavior.

Untargeted Metabolomics Analysis of the Orchid Species Oncidium sotoanum Reveals the Presence of Rare Bioactive C-Diglycosylated Chrysin Derivatives

Plants are valuable sources of secondary metabolites with pharmaceutical properties, but only a small proportion of plant life has been actively exploited for medicinal purposes to date. Underexplored plant species are therefore likely to contain novel bioactive compounds. In this study, we investigated the content of secondary metabolites in the flowers, leaves and pseudobulbs of the orchid Oncidium sotoanum using an untargeted metabolomics approach. We observed the strong accumulation of C-diglycosylated chrysin derivatives, which are rarely found in nature. Further characterization revealed evidence of antioxidant activity (FRAP and DPPH assays) and potential activity against neurodegenerative disorders (MAO-B inhibition assay) depending on the specific molecular structure of the metabolites. Natural product bioprospecting in underexplored plant species based on untargeted metabolomics can therefore help to identify novel chemical structures with diverse pharmaceutical properties.

Participation of the Serotonergic System and Brain-Derived Neurotrophic Factor in the Antidepressant-like Effect of Flavonoids

Depressive disorders are among the most disabling diseases experienced around the world, and their incidence has significantly increased over the last few decades due to multiple environmental, social, and biological factors. The search for new pharmacological alternatives to treat depression is a global priority. In preclinical research, molecules obtained from plants, such as flavonoids, have shown promising antidepressant-like properties through several mechanisms of action that have not been fully elucidated, including crossing of the blood brain barrier (BBB). This review will focus on discussing the main findings related to the participation of the serotonergic system and brain-derived neurotrophic factor (BDNF) on the antidepressant-like effect of some flavonoids reported by behavioral, neurochemical, and molecular studies. In this sense, evidence shows that depressive individuals have low levels of serotonin and BDNF, while flavonoids can reverse it. Finally, the elucidation of the mechanism used by flavonoids to modulate serotonin and BDNF will contribute to our understanding of the neurobiological bases underlying the antidepressant-like effects produced by these natural compounds.

Experimental hypothyroidism induces cardiac arrhythmias and ranolazine reverts and prevents the phenotype

AIMS

Hypothyroidism is associated with an increased risk of cardiovascular disease and enhanced susceptibility to arrhythmias. In our investigation, we evaluated the potential involvement of late sodium current (I_Na,late) in cardiac arrhythmias in an experimental murine model of hypothyroidism.

MAIN METHODS

Male Swiss mice were treated with methimazole (0.1 % w/vol, during 21 days) to induce experimental hypothyroidism before ECG, action potential (AP) and intracellular Ca²⁺ dynamics were evaluated. Susceptibility to arrhythmia was measured in vitro and in vivo.

KEY FINDINGS

The results revealed that hypothyroid animals presented ECG alterations (e.g. increased QTc) with the presence of spontaneous sustained ventricular tachycardia. These changes were associated with depolarized resting membrane potential in isolated cardiomyocytes and increased AP duration and dispersion at 90 % of the repolarization. Aberrant AP waveforms were related to increased Ca²⁺ sparks and out-of-pace Ca²⁺ waves. These changes were observed in a scenario of enhanced I_Na,late. Interestingly, ranolazine, a clinically used blocker of I_Na,late, restored the ECG alterations, reduced Ca²⁺ sparks and aberrant waves, decreased the in vitro events and the severity of arrhythmias observed in isolated cardiomyocytes from hypothyroid animals. Using the in vivo dobutamine + caffeine protocol, animals with hypothyroidism developed catecholaminergic bidirectional ventricular tachycardia, but pre-treatment with ranolazine prevented this.

SIGNIFICANCE

We concluded that animals with hypothyroidism have increased susceptibility to developing arrhythmias and ranolazine, a clinically used blocker of I_Na,late, is able to correct the arrhythmic phenotype.

Pathophysiology of Depression: Stingless Bee Honey Promising as an Antidepressant

Depression is a debilitating psychiatric disorder impacting an individual’s quality of life. It is the most prevalent mental illness across all age categories, incurring huge socio-economic impacts. Most depression treatments currently focus on the elevation of neurotransmitters according to the monoamine hypothesis. Conventional treatments include tricyclic antidepressants (TCAs), norepinephrine–dopamine reuptake inhibitors (NDRIs), monoamine oxidase inhibitors (MAOIs), and serotonin reuptake inhibitors (SSRIs). Despite numerous pharmacological strategies utilising conventional drugs, the discovery of alternative medicines from natural products is a must for safer and beneficial brain supplement. About 30% of patients have been reported to show resistance to drug treatments coupled with functional impairment, poor quality of life, and suicidal ideation with a high relapse rate. Hence, there is an urgency for novel discoveries of safer and highly effective depression treatments. Stingless bee honey (SBH) has been proven to contain a high level of antioxidants compared to other types of honey. This is a comprehensive review of the potential use of SBH as a new candidate for antidepressants from the perspective of the monoamine, inflammatory and neurotrophin hypotheses.

Chrysin-Loaded Chitosan Nanoparticle-Mediated Neuroprotection in Aβ1-42-Induced Neurodegenerative Conditions in Zebrafish

Amyloid β plaques and neurofibrillary tangles are the characteristic features of Alzheimer's disease (AD). Plaques of amyloid β play a pivotal role in affecting cognitive functions and memory. Alzheimer's disease is a progressive neurodegenerative disease and is one of the leading causes of dementia worldwide. Several treatment strategies focusing on the amyloid cascade have been implemented to treat AD. The blood-brain barrier (BBB) poses the main obstructive barrier by refraining drugs from penetrating the brain. Nanotechnology is a promising research field for brain drug delivery using nanosized particles. Zebrafish is emerging as a model of interest to elaborate on brain targeting and nanotechnology-based therapeutics for neurodegenerative diseases. In the current study, we have synthesized and characterized chrysin-loaded chitosan nanoparticles (Chr-Chi NPs) and evaluated them for neuroprotection against amyloid-β-induced toxicity. We find that treatment with Chr-Chi NPs helps to retain memory, cognition, and synaptic connections, which are otherwise compromised due to Aβ_1-42 toxicity. The NPs further help in reducing aggregates of amyloid β, thus decreasing neuronal death and generation of reactive oxygen species (ROS). Taken together, our study brings to light a novel strategy for treating AD by a combined action on the neurons and amyloid aggregates mediated by chrysin and chitosan, respectively. Chr-Chi NPs, therefore, have the potential to provide a beneficial combinatorial treatment strategy for AD.

Pharmacological, Neurochemical, and Behavioral Mechanisms Underlying the Anxiolytic- and Antidepressant-like Effects of Flavonoid Chrysin

Chrysin (5,7-dihydroxyflavone) is a flavonoid isolated from plants, such as Passiflora coerulea, Passiflora incarnata, and Matricaria chamomilla. This natural molecule exerts diverse pharmacological effects, which includes antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and anti-apoptotic effects. Additionally, in brain structures, such as the hippocampus, prefrontal cortex, raphe nucleus, and striatum, involved in the physiopathology of anxiety and depression disorders, several neuropharmacological activities, including the activation of neurotransmitter systems (GABAergic, serotonergic, dopaminergic, and noradrenergic), neurotrophic factors, such as brain-derived neurotrophic factor and the nerve growth factor, and some signaling pathways are affected. The results showed that the anxiolytic and antidepressant-like effects of chrysin occurs through its interaction with specific neurotransmitter systems, principally the GABAergic and the serotonergic, and activation of other neurotrophic factors. However, it is not possible to discard the antioxidant and anti-inflammatory activities of chrysin while producing its anxiolytic- and antidepressant-like effects. Although these results have been obtained principally from pre-clinical research, they consistently demonstrate the potential therapeutic use of flavonoid chrysin as an anxiolytic and antidepressant agent. Therefore, this flavonoid could be considered as a promising novel therapy for anxiety and depression disorders.

Chrysin restores memory deficit in hypothyroidism mice: Behavioral, neurochemical and computational approaches involving the neurotrophinergic system

Hypothyroidism is a condition that affects multiple systems, including the central nervous system, causing, for example, cognitive deficits closely related to Alzheimer's disease. The flavonoid chrysin is a natural compound associated with neuronal improvement in several experimental models. Here, we evaluated the effect of chrysin on cognitive impairment in hypothyroid female mice by exploring neuroplasticity. Hypothyroidism was induced by continuous exposure to 0.1% methimazole (MTZ) in drinking water for 31 days. On the 32nd day, the animals showed low plasma levels of thyroid hormones (hypothyroid mice) than the control group (euthyroid mice). Subsequently, mice were intragastrically administered with vehicle or chrysin (20 mg/kg) once a day for 28 consecutive days. At the end of the treatments, behavioral tests were performed: open-field test (OFT) and morris water maze (MWM). Then, the levels of neurotrophins (BDNF and NGF) in the hippocampus and prefrontal cortex were measured and tested the affinity of chrysin with neurotrophinergic receptors through molecular docking. Hypothyroid mice showed memory deficit in the MWM and reduced neurotrophins levels in the hippocampus and prefrontal cortex, meanwhile, the chrysin treatment was able to reversed the deficit of spatial memory function and increased the levels of BDNF in hipocamppus and NGF in both structures. Additionally, molecular docking analysis showed that chrysin potentially binds to the active site of the TrkA, TrkB, and p75NTR receptors. Together, these findings suggest that chrysin reversed behavioral and neurochemical alterations associated with memory deficit induced by hypothyroidism, possibly by modulating synaptic plasticity in the neurotrophinergic system.

Neuroprotective Potential of Chrysin: Mechanistic Insights and Therapeutic Potential for Neurological Disorders

Chrysin, a herbal bioactive molecule, exerts a plethora of pharmacological effects, including anti-oxidant, anti-inflammatory, neuroprotective, and anti-cancer. A growing body of evidence has highlighted the emerging role of chrysin in a variety of neurological disorders, including Alzheimer's and Parkinson's disease, epilepsy, multiple sclerosis, ischemic stroke, traumatic brain injury, and brain tumors. Based on the results of recent pre-clinical studies and evidence from studies in humans, this review is focused on the molecular mechanisms underlying the neuroprotective effects of chrysin in different neurological diseases. In addition, the potential challenges, and opportunities of chrysin's inclusion in the neurotherapeutics repertoire are critically discussed.

Neuroprotective Efficacy of Apple Cider Vinegar on Zinc-High Fat Diet-Induced Mono Amine Oxidase Alteration in Murine Model of AD

OBJECTIVE

Monoamine Oxidase (MAO), which catalyzes the oxidative deamination of amines present in the brain and peripheral tissues, is involved in the metabolism of monoamines and is vital for cognition. This study was designed to examine the protective effect of Apple Cider Vinegar (ACV) on MAO and amine neurotransmitters such as dopamine (DA), serotonin (5-HT), non-adrenaline (NA) levels.

METHOD

In this experiment, out of five groups, three groups of animals were pretreated with one of the test drugs each i.e., Chrysin (10 mg/kg), ACV (0.7% v/v) and Rivastigmine (2.5 mg/kg) along with Zn with high fat diet (HFD) for 3 months and the rest two groups were that of control and disease induced. After the treatment period, mice were examined for MAO-A & B, DA, 5-HT and NA level estimation.

RESULTS

The results showed that Zn with HFD had induced a significant increase (p < 0.01, p < 0.001) in MAO-A & B levels and a significant decrease (p < 0.001) in the levels of 5-HT, DA, and NA. Pretreatment of test drugs with Zn with HFD caused a restoration activity and a significant decrease (p < 0.01, p < 0.05) in MAO-A & B levels and a significant increase (p < 0.05, p < 0.01, p < 0.001) in the level of DA, 5HT and NA as compared to the Zn treated group. Amongst all three test drugs mentioned above, the ACV-treated group showed the most improvement during pretreatment.

CONCLUSIONS

The findings suggest that ACV, might prove to be a beneficial nutraceutical & provide a protective effect against Alzheimer's disease (AD)-like neurological diseases.

An updated review on the versatile role of chrysin in neurological diseases: Chemistry, pharmacology, and drug delivery approaches

Neurological diseases are responsible for a large number of morbidities and mortalities in the world. Flavonoids are phytochemicals that possess various health-promoting impacts. Chrysin, a natural flavonoid isolated from diverse fruits, vegetables, and even mushrooms, has several pharmacological activities comprising antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. The current study was designed to review the relationship between chrysin administration and neurological complications by discussing the feasible mechanism and signaling pathways. Herein, we mentioned the sources, pharmacological properties, chemistry, and drug delivery systems associated with chrysin pharmacotherapy. The role of chrysin was discussed in depression, anxiety, neuroinflammation, Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, cerebral ischemia, spinal cord injury, neuropathy, Multiple Sclerosis, and Guillain-Barré Syndrome. The findings indicate that chrysin has protective effects against neurological conditions by modulating oxidative stress, inflammation, and apoptosis in animal models. However, more studies should be done to clear the neuroprotective effects of chrysin.

Serotonin 2A receptor function and depression-like behavior in rats model of hypothyroidism

Hypothyroidism causes somatic, psychosocial and affective psychosis, including depression-like behaviors. In this study, (hypothyroidism group; HP group) adult male Sprague Dawley (SD) rats were induced to hypothyroidism after 5 weeks of exposure to 0.05% propylthiouracil (PTU) in potable water, control animals (CON group) were given the same amount of water. The following behavioral experiments were conducted, respectively: open-field test (OFT), forced swimming test (FST), tail suspension test (TST). TT[Formula: see text] and TT[Formula: see text] levels were measured after the behavior tests and the expression levels of 5-HT[Formula: see text] receptor and 5-HT[Formula: see text] receptor proteins were analyzed in the hippocampus and prefrontal cortex. The level of TT[Formula: see text] and TT[Formula: see text] in the HP group rats was much lower than that in the CON group. The hypothyroid rats also showed weight loss, much longer immobility time in tail suspension test and forced swimming test. Besides, 5 weeks of PTU administration was associated with significantly decreased expression levels of 5-HT[Formula: see text] receptor and 5-HT[Formula: see text] receptor proteins compared with control group, which were significantly negatively correlated with immobility time in FST and TST. In conclusion, our results suggest that hypothyroidism induces depressive behaviors through the influence of the serotonin system, and the decreased expression of the 5-HT[Formula: see text] receptor is an important cause of the depressive behaviors in hypothyroidism.

Chrysin Stimulates Subcutaneous Fat Thermogenesis in Mice by Regulating PDGFRα and MicroRNA Expressions

The activation of adipose tissue browning and thermogenesis provides a new strategy to counter obesity and associated metabolic diseases. Here, a natural flavonoid chrysin is used as the supplement of a high-fat diet (HFD). Dietary chrysin alleviates adiposity and insulin resistance in HFD-fed mice. Meanwhile, dietary chrysin elevates systemic energy expenditure and enhances the uncoupling protein-1 (UCP1) level in subcutaneous adipose tissue (SAT), which is accompanied by the increased thermogenic program, beige preadipocyte number, and angiogenesis in SAT. Dietary chrysin also induces the expression of SAT platelet-derived growth factor receptor α (PDGFRα), which commits adipose progenitor cells to differentiate into beige or white adipocytes in response to various environmental signals. Double immunofluorescent staining for UCP1 and PDGFRα reveals that chrysin elevates the number of UCP1⁺PDGFRα⁺ beige progenitors in SAT. Further, chrysin treatment reverses the effects of the specific PDGFRα inhibitor imatinib on browning differentiation of stromal vascular fraction cells from SAT. Finally, chrysin-induced adipocyte browning is correlated with the expressions of microRNAs as PDGFRα inhibitors or thermogenesis suppressors. In conclusion, dietary chrysin promotes subcutaneous adipocyte browning and systematic energy expenditure by regulating PDGFRα and microRNA expressions in HFD-fed mice.

Antidepressant-Like Properties of Fish Oil on Postpartum Depression-Like Rats Model: Involvement of Serotonergic System

Pathophysiology of postpartum depression (PPD) has been associated with many factors, such as neuroendocrine, neuroinflammation and neurotransmitter changes. Fish oil (FO) improves PPD both in humans and animals. However, little is known with regards to its pharmacology on a PPD-like rat model. Hence, the current study aimed at investigating the effects of FO on a PPD-like rat model. Female rats were induced with PPD-like symptoms and then randomly divided into six groups (n = 6) for two experimental protocols. Protocol 1 consisted of PPD-like rats (2 mL distilled water), PPD-like + FO (9 g/kg/d) and PPD-like + Fluoxetine (FLX) (15 mg/kg/d) groups of rats, whereas Protocol 2 consisted of PPD-like rats (2 mL distilled water) + PCPA (p-chlorophenylalanine) 150 mg/kg, PPD-like + FO (9 g/kg/d) + PCPA 150 mg/kg and PPD-like + FLX (15 mg/d) + PCPA 150 mg/kg groups of rats, respectively. All treatments were administered orally for 10 days postpartum, except PCPA, which was given intraperitoneally. Prior to euthanasia, the antidepressant-like effect of the FO was evaluated using the forced swimming test (FST) and open field test (OFT) on day 10 postpartum. Biochemical analysis of serotonin, serotonin metabolite and serotonin turnover from their prefrontal cortex and hippocampus were also measured. The results showed that FO decreased immobility time and increased swimming time significantly, but not climbing time in FST. Further, it also decreased serotonin metabolite and turnover significantly in the hippocampus of the PPD-like rats. In contrast, administration with PCPA reversed all the outcomes. The antidepressant-like effects of FO were found to be similar with that of FLX. Thus, it can be concluded that FO exerts its antidepressant-like effects in PPD-like rats through modulation of serotonergic system.

Chrysin, but not flavone backbone, decreases anxiety-like behavior in animal screens

Chrysin (5,7-dihydroxyflavone), a nutraceutical flavonoid present in diverse plants, has a backbone structure shared with the flavone backbone, with additional hydroxyl groups that confers its antioxidant properties and effects at the GABA_A receptor complex. However, whether these effects are due to the hydroxyl groups is unknown. Here we report the effects of chrysin or the flavone backbone (1 mg/kg) in rats subjected to the elevated plus-maze and the locomotor activity test, as well as in the zebrafish evaluated in light/dark model. Chrysin, but not flavone, increased entries and time in the open arms of the elevated plus-maze, as well as time on white compartment of the light/dark model in zebrafish. These effects were comparable to diazepam, and were devoid of motor effects in both tests, as well as in the locomotor activity test. On the other hand, flavone decreased risk assessment in the light/dark test but increased rearing in the locomotor activity test in rats, suggesting effects threat information gathering; important species differences suggest new avenues of research. It is suggested that the specific effects of chrysin in relation to flavone include more of a mechanism of action in which in addition to its action at the GABA_A/benzodiazepine receptor complex also could be involved its free radical scavenging abilities, which require specific research. Preprint: https://doi.org/10.1101/575514; Data and scripts:https://github.com/lanec-unifesspa/chrysin.

5-HT1A receptor-mediated attenuation of heat hyperalgesia and mechanical allodynia by chrysin in mice with experimental mononeuropathy

BACKGROUND

Persistent neuropathic pain poses a health problem, for which effective therapy or antidote is in dire need. This work aimed to investigate the pain-relieving effect of chrysin, a natural flavonoid with monoamine oxidase inhibitory activity, in an experimental model of neuropathic pain and elucidate mechanism(s).

METHODS

Chronic constriction injury (CCI) was produced by loose ligation of sciatic nerve in mice. The pain-related behaviors were examined using von Frey test and Hargreaves test. The serotonin-related mechanisms were investigated by serotonin depletion with p-chlorophenylalanine (PCPA) and antagonist tests in vivo and in vitro.

RESULTS

Repeated treatment of CCI mice with chrysin (orally, two times per day for 2 weeks) ameliorated heat hyperalgesia and mechanical allodynia in a dose-dependent fashion (3-30 mg/kg). The chrysin-triggered pain relief seems serotonergically dependent, since its antihyperalgesic and antiallodynic actions were abolished by chemical depletion of serotonin by PCPA, whereas potentiated by 5-hydroxytryptophan (a precursor of 5-HT). Consistently, chrysin-treated neuropathic mice showed enhanced levels of spinal monoamines especially 5-HT, with depressed monoamine oxidase activity. Moreover, chrysin-evoked pain relief was preferentially counteracted by 5-HT_1A receptor antagonist WAY-100635 delivered systematically or spinally. In vitro, chrysin (0.1-10 nM) increased the maximum effect (Emax, shown as stimulation of [³⁵S] GTPγS binding) of 8-OH-DPAT, a 5-HT_1A agonist. Beneficially, chrysin was able to correct comorbid behavioral symptoms of depression and anxiety evoked by neuropathic pain, without causing hypertensive crisis (known as 'cheese reaction').

CONCLUSION

These findings confirm the antihyperalgesic and antiallodynic efficacies of chrysin, with spinal 5-HT_1A receptors being critically engaged.

Modulation of glutamate levels and Na+,K+-ATPase activity contributes to the chrysin memory recovery in hypothyroidism mice

Abnormalities in the thyroid hormones, like in hypothyroidism, are closely related to dementia and Alzheimer's disease demonstrating the main symptom of these disorders: memory deficit. In this study we evaluated the effect of chrysin on deficit spatial and aversive memories and the contribution of glutamatergic, cholinergic pathways and Na⁺, K⁺-ATPase activity on hippocampus and prefrontal cortex in hypothyroid adult female mice C57BL/6. Hypothyroidism was induced by the continuous exposure to 0.1% methimazole (MTZ) in drinking water for 31 days. The exposure to MTZ was associated to low plasma levels of thyroid hormones (TH) compared to the control group on the 32nd. Subsequently, euthyroid and MTZ-induced hypothyroid mice received (intragastrically) either vehicle or chrysin (20 mg/kg) once a day for 28 consecutive days. After treatments mice performed the following behavioral assessments: open-field test (OFT), morris water maze (MWM) and passive avoidance test. Additionally, plasma TH levels were measured again, as well as glutamate levels, Na⁺,K⁺-ATPase and acetylcholinesterase (AChE) activities were analyzed in the hippocampus and prefrontal cortex of mice. Mice with hypothyroidism showed a deficit of spatial and aversive memory and chrysin treatment reversed these deficits. It also reduced the levels of glutamate and decreased Na⁺,K⁺-ATPase activity in both cerebral structures in the hypothyroid mice compared with the euthyroid ones, with the exception of glutamate in the hippocampus, which was a partial reversal. AChE activity was not altered by treatments. Together, our results demonstrate that chrysin normalized hippocampal glutamate levels and Na⁺,K⁺-ATPase activity, which could be involved in the reversal of memory deficit.

Cardiovascular Responses to 5-hydroxytryptamine in Methimazole-induced Hypothyroid Pithed Rats

BACKGROUND

Patients suffering from hypothyroidism tend to develop diastolic hypertension. 5-Hydroxytryptamine (5-HT) is an amine that contributes to the maintenance of the blood pressure through central and peripheral 5-HT receptors. Curiously, the hypothyroidism alters the density of the 5-HT receptors in rodent brains.

AIM OF THE STUDY

Analyze the effect of the methimazole-induced hypothyroidism on the peripheral cardiovascular responses elicited by 5-HT.

METHODS

The vasopressor and tachycardic responses to 5-HT (3-300 μg/kg), and the vasodepressor responses to 5-HT, 5-carboxamidotryptamine (5-CT, 0.001-0.1 μg/kg), isoprenaline (0.03-1 μg/kg) and acetylcholine (ACh, 0.03-3 μg/kg), during an infusion of methoxamine, were determined in pithed hypothyroid rats.

RESULTS

The tachycardic and vasopressor responses to 5-HT and the vasodepressor responses to 5-CT and ACh remained unaffected, the vasodepressor response to 5-HT reduced, and the vasodepressor response to isoprenaline enhanced and reduced at the lowest and highest dose, respectively.

CONCLUSION

These results suggest that hypothyroidism impairs the vasodepressor response to 5-HT, which could contribute to hypothyroidism-induced hypertension.

Exposure to deltamethrin in adolescent mice induced thyroid dysfunction and behavioral disorders

Deltamethrin (DM) has become one of the most widely used insecticides in the world due to its low toxicity, high efficiency and low persistence in soil. However, it is still unknown whether DM exposure has any effects on the Hypothalamic-Pituitary-Thyroid (HPT) axis in adolescent mice. In this study, the open field test and circadian activity test showed that DM exposure increased activity. There was no significant difference between the groups in the light/dark box test and nest building test. Forced swimming test showed that after 6 and 12 mg kg^-1 DM exposure 28 days, the immobility time was increased and the swimming time was reduced. After 6 mg kg^-1 DM treatment, the thyroid stimulating hormone (TSH) content increased, and thyrotropin releasing hormone (TRH), triiodothyronine (T3) and thyroxine (T4) decreased. After exposure to 6 and 12 mg kg^-1 DM, mRNA levels of HPT axis-related genes were destroyed. The histological examination showed that, the DM groups mice thyroid tissues appeared expanded thyroid follicles, scanty colloid and hyperplastic thyroid cells. Western blot results showed that the expression level of tyrosine hydroxylase (TH) protein decreased and the content of dopamine transporter (DAT) protein increased in DM treated mice striatum. Collectively, our results indicated that DM exposure could induce thyroid dysfunction and behavioral disorders in adolescent mice.

Antidotal or protective effects of honey and one of its major polyphenols, chrysin, against natural and chemical toxicities

OBJECTIVE

Honey and its polyphenolic compounds are of main natural antioxidants that have been used in traditional medicine. The aim of this review was to identify the protective effects of honey and chrysin (a polyphenol available in honey) against the chemical and natural toxic agents.

METHOD

The scientific databases such as MEDLINE, PubMed, Scopus, Web of Science and Google Scholar were searched to identify studies on the antidotal effects of honey and chrysin against toxic agents.

RESULTS

This study found that honey had protective activity against toxic agents-induced organ damages by modulating oxidative stress, inflammation, and apoptosis pathways. However, clinical trial studies are needed to confirm the efficacy of honey and chrysin as antidote agents in human intoxication.

CONCLUSION

Honey and chrysin may be effective against toxic agents. (www.actabiomedica.it).

Chrysin ameliorates ANTU-induced pulmonary edema and pulmonary arterial hypertension via modulation of VEGF and eNOs

Alpha-naphthylthiourea (ANTU), a rodenticide induces lung toxicity. Chrysin a flavonoid possesses antioxidant, anti-inflammatory, and antihypertensive potential. The aim of this study was to evaluate the efficacy of chrysin against ANTU-induced pulmonary edema (PE) and pulmonary arterial hypertension (PAH) in laboratory rats. Sprague-Dawley rats were used to induce PE (ANTU, 10 mg/kg, ip) and PAH (ANTU, 5 mg/kg, ip, 4 weeks). Animals were treated with chrysin (10, 20, and 40 mg/kg) and various biochemical, molecular, and histological parameters were evaluated. Acute administration of ANTU induces PE revealed by significant (P < 0.05) increase in relative lung weight, pleural effusion volume, lung edema, bronchoalveolar lavage fluid cell counts, total protein, 5-hydroxytryptamine (5-HT), lactate dehydrogenase (LDH), and γ-glutamyl transferase (GGT), whereas pretreatment with chrysin (20 and 40 mg/kg, ip) significantly (P < 0.05) attenuated these ANTU-induced biochemical and histological alterations. Repeated administration of ANTU caused induction of PAH evaluated by significant (P < 0.05) alterations in electrocardiographic, hemodynamic changes, and left ventricular function, whereas chrysin (20 and 40 mg/kg, p.o.) treatment significantly (P < 0.05) attenuated these alterations. ANTU-induced hematological and serum biochemical (aspartate transaminase, alanine transaminase, LDH, and creatinine kinase MB) alterations were significantly (P < 0.05) inhibited by chrysin. It also significantly (P < 0.05) decreased elevated levels of oxido-nitrosative stress in the right ventricle (RV) and lung. Chrysin significantly (P < 0.05) attenuated downregulated endothelial nitric oxide synthase and upregulated vascular endothelial growth factor messenger RNA and protein expressions both in the RV and pulmonary artery. Chrysin inhibited ANTU-induced PE and PAH via modulation of inflammatory responses (5-HT, LDH, and GGT), oxido-nitrosative stress, and VEGF and eNOs levels.