Hesperidin protects against behavioral alterations and loss of dopaminergic neurons in 6-OHDA-lesioned mice: the role of mitochondrial dysfunction and apoptosis.

Hesperidin is a flavonoid glycoside that is frequently found in citrus fruits. Our group have demonstrated that hesperidin has neuroprotective effect in 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD), mainly by antioxidant mechanisms. Although the pathophysiology of PD remains uncertain, a large body of evidence has demonstrated that mitochondrial dysfunction and apoptosis play a critical role in dopaminergic nigrostriatal degeneration. However, the ability of hesperidin in modulating these mechanisms has not yet been investigated. In the present study, we examined the potential of a 28-day hesperidin treatment (50 mg/kg/day, p.o.) in preventing behavioral alterations induced by 6-OHDA injection via regulating mitochondrial dysfunction, apoptosis and dopaminergic neurons in the substantia nigra pars compacta (SNpc) in C57BL/6 mice. Our results demonstrated that hesperidin treatment improved motor, olfactory and spatial memory impairments elicited by 6-OHDA injection. Moreover, hesperidin treatment attenuated the loss of dopaminergic neurons (TH+ cells) in the SNpc and the depletion of dopamine (DA) and its metabolities 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum of 6-OHDA-lesioned mice. Hesperidin also protected against the inhibition of mitochondrial respiratory chain complex-I, -IV and V, the decrease of Na + -K + -ATPase activity and the increase of caspase-3 and -9 activity in the striatum. Taken together, our findings indicate that hesperidin mitigates the degeneration of dopaminergic neurons in the SNpc by preventing mitochondrial dysfunction and modulating apoptotic pathways in the striatum of 6-OHDA-treated mice, thus improving behavioral alterations. These results provide new insights on neuroprotective mechanisms of hesperidin in a relevant preclinical model of PD.

Hesperidin Ameliorates Anxiety-Depressive-Like Behavior in 6-OHDA Model of Parkinson's Disease by Regulating Striatal Cytokine and Neurotrophic Factors Levels and Dopaminergic Innervation Loss in the Striatum of Mice.

The mechanisms underlying the neuroprotective effects of hesperidin in a murine model of PD are not fully elucidated. The current study was carried out to investigate the ability of hesperidin in modulating proinflammatory cytokines, neurotrophic factors, and neuronal recovery in 6-hydroxydopamine (6-OHDA)-induced nigral dopaminergic neuronal loss. Adult male C57BL/6 mice were randomly assigned into four groups: (I) sham/vehicle, (II) sham/hesperidin, (III) 6-OHDA/vehicle, and (IV) 6-OHDA/hesperidin. Mice received a unilateral intrastriatal injection of 6-OHDA and treated with hesperidin (50 mg/kg; per oral) for 28 days. After hesperidin treatment, mice were submitted to behavioral tests and had the striatum removed for neurochemical assays. Our results demonstrated that oral treatment with hesperidin ameliorated the anxiety-related and depressive-like behaviors in 6-OHDA-lesioned mice (p < 0.05). It also attenuated the striatal levels of proinflammatory cytokines tumor necrosis factor-α, interferon-gamma, interleukin-1ß, interleukin-2, and interleukin-6 and increased the levels of neurotrophic factors, including neurotrophin-3, brain-derived neurotrophic factor, and nerve growth factor in the striatum of 6-OHDA mice (p < 0.05). Hesperidin treatment was also capable to increase striatal levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid and protects against the impairment of dopaminergic neurons in the substantia nigra pars compacta (SNpc) (p < 0.05). In conclusion, this study indicated that hesperidin exerts anxiolytic-like and antidepressant-like effect against 6-OHDA-induced neurotoxicity through the modulation of cytokine production, neurotrophic factors levels, and dopaminergic innervation in the striatum.

Protective role of chrysin on 6-hydroxydopamine-induced neurodegeneration a mouse model of Parkinson's disease: Involvement of neuroinflammation and neurotrophins.

Chrysin is a natural flavonoid which is found in bee propolis, honey and various plants, and neuroprotective effect of chrysin in mice was previously demonstrated by our group. Neuroinflammation, neurotrophic factors and neuronal recovery factors associated with the neuroprotective effect of this flavonoid require further investigations. Thus, now we investigated the possible involvement of inflammatory cytokines, neurotrophic factors and neuronal recovery in the effect of chrysin in 6-hydroxidopamine (6-OHDA), a well-established model of Parkinson's disease, in striatum of mice. The 6-OHDA microinjection induced behavioral alterations on the rotarod test and apomorphine-induced circling behavior in mice. 6-OHDA administration elevated levels of tumour necrosis factor-α, interferon-gamma, interleukin-1ß, interleukin-2, interleukin-6 and nuclear factor-kappa B and decreased the interleukin-10 levels, total reactive antioxidant potential and total antioxidant reactivity in striatum, as well as, modified the calcium-binding protein B (S100B), brain-derived neurotrophic factor, nerve growth factor and glial cell line-derived neurotrophic factor levels. The intrastriatal injection of 6-OHDA also induced an decrease of dopamine, 3,4-dihydroxyphenylacetic acid, homovanylic acid levels and tyrosine hydroxylase content. Oral treatment with chrysin (10 mg/kg, 28 days), culminated with the prevention of these alterations occasioned by 6-OHDA. These results corroborated with the neuroprotective effect of chrysin in the treatment of Parkinson's disease and, indicated the mechanism involved throught the inflammatory cytokines, neurotrophic factors and recovery of dopaminergic neurons in striatum.

Hesperidin reverses cognitive and depressive disturbances induced by olfactory bulbectomy in mice by modulating hippocampal neurotrophins and cytokine levels and acetylcholinesterase activity.

Depression is a serious mental disorder that is becoming more common. To better treat patients suffering from this illness, elucidation of the underlying psychopathological and neurobiological mechanisms of depression is needed. Based on the evidence, we sought to investigate the effects of hesperidin in a model of depression induced by olfactory bulbectomy (OB). C57BL/6 mice were treated with hesperidin (50mg/kg) and imipramine (10mg/kg, positive control) after OB induction. The brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), interleukin 1ß (IL-1ß) and interleukin 6 (IL-6) levels and acetylcholinesterase activity were analyzed in the hippocampus of the mice. The behavioral parameters were also verified in the model of depression induced by OB. This study demonstrated that OB increased the pro-inflammatory cytokines levels and acetylcholinesterase activity in the hippocampus, exploratory activity in the open field test and immobility in the forced swimming test in mice. In addition, OB decreased the BDNF and NGF levels in the hippocampus, grooming time in the splash test and memory consolidation in the Morris water maze task. Treatment with hesperidin, similar to imipramine, was effective in preventing these behavioral and neurochemical alterations. We suggest that the main targets of hesperidin are pro-inflammatory cytokine modulation, helping to maintain brain plasticity and acetylcholinesterase activity regulation, which are closely linked with antidepressant-like action, as shown by behavior tests. This study demonstrated that there is a pharmacological effect of hesperidin in alterations induced by OB in mice, indicating that hesperidin could be useful as a treatment for depression.

Indoleamine-2,3-dioxygenase mediates neurobehavioral alterations induced by an intracerebroventricular injection of amyloid-ß1-42 peptide in mice.

Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by a progressive cognitive decline along with various neuropsychiatric symptoms, including depression and anxiety. Increasing evidence has been proposed the activation of the tryptophan-degrading indoleamine-2,3-dyoxigenase (IDO), the rate-limiting enzyme of kynurerine pathway (KP), as a pathogenic factor of amyloid-beta (Aß)-related inflammation in AD. In the current study, the effects of an intracerebroventricular (i.c.v.) injection of Aß1-42 peptide (400pmol/mice; 3µl/site) on the regulation of KP biomarkers (IDO activity, tryptophan and kynurerine levels) and the impact of Aß1-42 on neurotrophic factors levels were investigated as potential mechanisms linking neuroinflammation to cognitive/emotional disturbances in mice. Our results demonstrated that Aß1-42 induced memory impairment in the object recognition test. Aß1-42 also induced emotional alterations, such as depressive and anxiety-like behaviors, as evaluated in the tail suspension and elevated-plus maze tests, respectively. We observed an increase in levels of proinflammatory cytokines in the Aß1-42-treated mice, which led to an increase in IDO activity in the prefrontal cortex (PFC) and the hippocampus (HC). The IDO activation subsequently increased kynurerine production and the kynurenine/tryptophan ratio and decreased the levels of neurotrophic factors in the PFC and HC, which contributed to Aß-associated behavioral disturbances. The inhibition of IDO activation by IDO inhibitor 1-methyltryptophan (1-MT), prevented the development of behavioral and neurochemical alterations. These data demonstrate that brain IDO activation plays a key role in mediating the memory and emotional disturbances in an experimental model based on Aß-induced neuroinflammation.

Neuropeptide Y administration reverses tricyclic antidepressant treatment-resistant depression induced by ACTH in mice.

Depression is one of the most common mental disorders and a primary cause of disability. To better treat patients suffering this illness, elucidation of the underlying psychopathological and neurobiological mechanisms is urgently needed. Based on the above-mentioned evidence, we sought to investigate the effects of neuropeptide Y (NPY) treatment in tricyclic antidepressant treatment-resistant depression induced by adrenocorticotropic hormone (ACTH) administration. Mice were treated with NPY (5.84, 11.7 or 23.4mmol/µl) intracerebroventricularly (i.c.v.) for one or five days. The levels of serum corticosterone, tryptophan (TRP), kynurenine (KYN), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and indoleamine 2,3-dioxygenase (IDO) activity in the hippocampus were analyzed. The behavioral parameters (depressive-like and locomotor activity) were also verified. This study demonstrated that ACTH administration increased serum corticosterone levels, KYN, 5-HIAA levels, IDO activity (hippocampus), immobility in the forced swimming test (FST) and the latency to feed in the novelty suppressed feeding test (NSFT). In addition, ACTH administration decreased the BDNF and NGF levels in the hippocampus of mice. NPY treatment was effective in preventing these hormonal, neurochemical and behavioral alterations. It is suggested that the main target of NPY is the modulation of corticosterone and neuronal plasticity protein levels, which may be closely linked with pharmacological action in a model of tricyclic antidepressant treatment-resistant depression. Thus, this study demonstrated a protective effect of NPY on the alterations induced by ACTH administration in mice, indicating that it could be useful as a therapy for the treatment of tricyclic antidepressant treatment-resistant depression.

Protective effect of hesperidin in a model of Parkinson's disease induced by 6-hydroxydopamine in aged mice.

OBJECTIVE: Parkinson's disease (PD) may be caused by the interaction of a number of factors, including genetics, toxins, oxidative stress, mitochondrial abnormalities, and aging. Studies have shown that consumption of an antioxidant-rich diet may reduce the incidence of neurodegenerative diseases. The aim of this study was to evaluate the role of the flavonoid hesperidin in an animal model of PD induced by 6-hidroxidopamine (6-OHDA). METHODS: Aged mice were treated with hesperidin (50 mg/kg) during 28 d after an intracerebroventricular injection of 6-OHDA. The enzymatic activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, the levels of glutathione, reactive oxygen species, total reactive antioxidant potential, dopamine and its levels of metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid, was analyzed in the striatum. The behavioral parameters (depressive-like, memory, and locomotor) were measured. RESULTS: This study demonstrated that hesperidin (50 mg/kg) treatment was effective in preventing memory impairment in the Morris water maze test, as well as, depressive-like behavior in the tail suspension test. Hesperidin attenuated the 6-OHDA-induced reduction in glutathione peroxidase and catalase activity, total reactive antioxidant potential and the dopamine and its metabolite levels in the striatum of aged mice. 6-OHDA increased reactive oxygen species levels and glutathione reductase activity in the striatum, and these alterations were mitigated by chronic administration of hesperidin. CONCLUSION: This study demonstrated a protective effect of hesperidin on the neurotoxicity induced by 6-OHDA in aged mice, indicating that it could be useful as a therapy for the treatment of PD.

Hesperidin exerts antidepressant-like effects in acute and chronic treatments in mice: possible role of l-arginine-NO-cGMP pathway and BDNF levels.

Hesperidin (4'-methoxy-7-O-rutinosyl-3',5-dihydroxyflavanone), a naturally occurring flavanone glycoside, was previously shown to produce an antidepressant-like effect with modultation of the serotonergic 5-HT1A and kappa-opioid receptors. In this study, the signaling mechanisms underlying their antidepressant-like effects were further evaluated by investigating in acute and chronic treatments. Results showed that chronic treatment of hesperidin or hesperitin (0.1, 0.3 and 1mg/kg, intraperitoneal, i.p.) have an antidepressant-like effect in the mouse tail suspension test (TST) without modified the locomotor activity in the open field test. Pretreatment with l-arginine (a nitric oxide (NO) precursor), sildenafil (a phosphodiesterase 5 inhibitor) or S-nitroso-N-acetyl-penicillamine (a NO donor) significantly reversed the reduction in immobility time elicited by acute treatment with hesperidin (0.3mg/kg) in the TST. Hesperidin (0.01mg/kg, a sub-effective dose in acute treatment) produced an additive antidepressant-like effect with N(G)-nitro-l-arginine (an inhibitor of nitric oxide synthase (NOS)) or 7-nitroindazole (a neuronal NOS inhibitor) in the TST. Pretreatment of animals with methylene blue (an inhibitor of NOS/soluble guanylate cyclase (sGC)) or ODQ (a specific inhibitor sGS) caused an additive effect with hesperidin in the TST. Hesperidin in the acute (1mg/kg) and chronic (0.1, 0.3 and 1mg/kg) treatments caused a significant decrease in nitrate/nitrite (NOX) levels in the hippocampus of mice. Chronic treatment with hesperidin (0.3 and 1mg/kg) also resulted in an increase in hippocampal brain-derived neurotrophic factor (BDNF) levels. These results demonstrated that the antidepressant-like effect of hesperidin is likely mediated by inhibition of l-arginine-NO-cGMP pathway and by increased of the BDNF levels in hippocampus.