Dietary hydrogenated vegetable fat exacerbates the activation of kynurenine pathway caused by peripheral lipopolysaccharide immune challenge in aged mice.

Sickness behavior is a normal immune response of body to fight infection, accompanied by endocrine and behavioral alterations. Lipopolysaccharide (LPS) causes sickness behavior in rodents through the increase of proinflammatory cytokines, generating peripheral inflammation and thus overactivation of kynurenine pathway (KP). In the present study we investigated the effects of dietary hydrogenated vegetable fat (HVF) in sickness behavior induced by LPS in aged mice. Male C57BJ/6 aged mice received a supplementation with HVF for six months. After HVF supplementation mice were treated with LPS (0.15 mg/kg; i. p. injection). Twenty-four hours post LPS injection mice were submitted to behavioral tests and then, the hippocampus, striatum and prefrontal cortex were removed for neurochemical determinations. Our results showed that dietary HVF did not exacerbate the behavioral alterations induced by LPS. Although HVF did not modulate the proinflammatory cytokines analyzed, it caused a potentiation in the increase of brain tumor necrosis factor-alpha levels induced by LPS. Moreover, dietary HVF aggravated LPS-induced KP activation in the brain of mice, mainly by further increase of neurotoxic metabolite quinolinic acid and further decrease of kynurenic acid/kynurenine ratio, a marker of neuroprotective branch of KP. Overall, our study demonstrated that dietary HVF did not worsen the sickness behavioral induced by LPS administration. However, HVF aggravated the activation of KP and exacerbated the shift of KP metabolism towards the neurotoxic branch.

Fish oil ameliorates sickness behavior induced by lipopolysaccharide in aged mice through the modulation of kynurenine pathway.

Sickness behavior is an expression of a central motivational state triggered by activation of the immune system, being considered a strategy of the organism to fight infection. Sickness behavior is induced by peripheral administration of lipopolysaccharide (LPS). LPS can increase the levels of proinflammatory cytokines, which induce the activation of the kynurenine pathway (KP) and behavioral alterations. Previous studies have shown that omega-3 (n-3) polyunsaturated fatty acid (PUFA) has anti-inflammatory properties. Because of this, the purpose of the present study was to evaluate the protective effect of fish oil (FO) supplementation against LPS-induced sickness behavior in aged mice with respect to anhedonia, locomotor activity and body weight. Moreover, we evaluated the ability of FO treatment on the regulation of neuroinflammation (levels of interleukin-1ß, interleukin-6, tumor factor necrosis-α and interferon-γ), KP biomarkers (levels of tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine and quinolinic acid and activities of indoleamine-2,3-dioxygenase, kynurenine monooxygenase and kynurenine aminotransferase) and serotonergic system (levels of serotonin and 5-hydroxyindoleactic acid) in the hippocampus, striatum and prefrontal cortex of LPS-treated mice. We found that FO prevented the LPS-mediated body weight loss, anhedonic behavior, reduction of locomotor activity, up-regulation of the proinflammatory cytokines and serotoninergic alterations. We also found that FO was effective in modulating the KP biomarkers, inhibiting or attenuating KP dysregulation induced by LPS. Together, our results indicated that FO may have beneficial effects on LPS induced sickness-behavior in aged mice either by modulating central inflammation, KP and serotonergic signaling (indirectly effect) or by fatty acids incorporation into neuronal membranes (direct effect).

Aging exacerbates cognitive and anxiety alterations induced by an intracerebroventricular injection of amyloid-ß1-42 peptide in mice.

An increasing body of evidence indicates that the activation of indoleamine-2,3-dyoxigenase (IDO), a first and rate-limiting enzyme in the kynurenine (KYN) pathway, is involved in Aß1-42-neurotoxicity and AD pathogenesis. We have reported for the first time that brain IDO activation is related to Aß1-42 exposure in young mice. Because aging is characterized by a brain dyshomeostasis and because it remains the most dominant risk factor for AD, the purpose of this study was to determine whether aging is associated with a higher sensitivity to behavioural and neurochemical alterations elicited by an intracerebroventricular (i.c.v.) injection of Aß1-42 (400 pmol/mice), and whether KYN pathway is involved in these effects. We confirmed that aged mice displayed higher cognitive deficit in the object recognition test and higher anxiety-like behaviour in the elevated plus-maze and open field tests after the Aß1-42 administration. Aged mice also responded to Aß1-42 with a higher deficiency of brain-derived neurotrophic factor, glutathione levels and total radical-trapping antioxidant capacity, a higher IDO activity, and a higher KYN and KYN/tryptophan ratio in the prefrontal cortex and hippocampus. These effects of Aß1-42 were associated with a higher proinflammatory status, as measured by higher levels of interleukin-6, lower levels of interleukin-10 and higher expression of glial fibrillary acidic protein (GFAP) and allograft inflammatory factor 1 (Iba1) in the brain of aged mice. These results represent primary evidence suggesting that age-associated inflammatory signature and down-regulation of neuroprotectants in the brain render aged mice more vulnerable to Aß1-42-induced memory loss, anxiety symptoms and KYN pathway dysregulation.

Swimming exercise prevents behavioural disturbances induced by an intracerebroventricular injection of amyloid-ß1-42 peptide through modulation of cytokine/NF-kappaB pathway and indoleamine-2,3-dioxygenase in mouse brain.

Emerging evidence indicates that the activation of indoleamine-2,3-dioxygenase (IDO), a first and rate-limiting enzyme in the kynurenine (KYN) pathway, is involved in amyloid-beta (Aß1-42)-neurotoxicity and Alzheimer's disease (AD) pathogenesis. Physical exercise has been considered an effective intervention in AD, attenuating or limiting their progression. Nevertheless, the neurobiological mechanisms underlying the neuroprotective effects of exercise have not yet been fully elucidated. In present study, we investigated the protective effect of an 8-week swimming training (ST) exercise on cognitive and non-cognitive functions and its role in modulating biomarkers of KYN pathway, before an intracerebroventricular (i.c.v.) injection of Aß1-42 (400pmol/animal; 3µl/site) peptide in mice. Our results demonstrated that ST was effective in preventing the following behavioural disturbances caused by Aß1-42 injection: memory impairment in the object recognition test and depressive/anxiety-like behaviour in the tail suspension test and elevated plus-maze test, respectively. ST abrogated the neuroinflammatory response and neurotrophic deficiency in the prefrontal cortex and hippocampus induced by Aß1-42. Also, Aß1-42 increased IDO activity, KYN and tryptophan (TRP) levels and KYN:TRP ratio in the prefrontal cortex and hippocampus - alterations that were blocked by ST. It can be concluded that ST prevented behavioural and neurobiological deficits induced by Aß1-42, and suggest that these neuroprotective effects are likely to involve the inhibition of inflammation/IDO activation and up-regulation of neurotrophic factors in brain of mice. Thus, it is possible that physical exercise can be used as a non-pharmacological approach to alleviates both cognitive and non-cognitive symptoms of AD.

Chrysin promotes attenuation of depressive-like behavior and hippocampal dysfunction resulting from olfactory bulbectomy in mice.

Chrysin is a natural flavonoid which is found in bee propolis, honey and various plants, and antidepressant-like effect of chrysin in chronically stressed mice was previously demonstrated by our group. In this work, we investigated the action of chrysin treatment (5 or 20 mg/kg) for 14 days in the depressant-like behavior and in the hippocampal dysfunction induced by olfactory bulbectomy (OB), an animal model of agitated depression. Results demonstrated that OB occasioned a depressant-like behavior in the splash test, open field test and forced swimming test. Chrysin administration, similarly to fluoxetine (positive control), promoted the attenuation of these behavioral modifications. OB also caused the elevation of tumor necrosis factor-α, interferon-γ, interleukin-1ß, interleukin-6, kynurenine (KYN) levels and indoleamine-2,3-dioxygenase activity, as well as occasioned the decrease of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) levels and increase KYN/tryptophan and 5-hydroxyindoleacetic acid/5-HT ratio in the hippocampus. Chrysin therapy prevented against all these alterations in the hippocampus. In addition, chrysin treatment (20 mg/kg) resulted in the up-regulation of BDNF levels in the control animals, reinforcing our hypothesis that up-regulation of BDNF synthesis play a key role in the antidepressant action of chrysin. In conclusion, this study showed that chrysin, similarly to fluoxetine, is capable of promoting the attenuation of depressant-like behavior and hippocampal dysfunction resulting from OB in mice. These results reinforced the potential of chrysin for the treatment or supplementary treatment of depression, as well as showed that chrysin is also effective with 14 days of therapy in a model of agitated depression.

Neurochemical factors associated with the antidepressant-like effect of flavonoid chrysin in chronically stressed mice.

Chrysin is a flavonoid which is found in bee propolis, honey and various plants. Antidepressant-like effect of chrysin in chronically stressed mice was previously demonstrated by our group. Conversely, neurochemical factors associated with this effect require further investigations. Thus, we investigated the possible involvement of pro-inflammatory cytokines, kynurenine pathway (KP), 5-hydroxytryptamine (5-HT) metabolism and caspases activities in the effect of chrysin in mice exposed to unpredictable chronic stress (UCS). UCS applied for 28 days induced a depressive-like behavior, characterized by decrease in the time of grooming in the splash test and by increase in the immobility time in the tail suspension test. Oral treatment with chrysin (5 or 20mg/kg, 28 days), similarly to fluoxetine (10mg/kg, positive control), culminated in the prevention of these alterations. UCS elevated plasma levels of corticotropin-releasing hormone and adrenocorticotropic hormone, as well the tumor necrosis factor-α, interleukin-1ß, interleukin-6 and kynurenine levels in the prefrontal cortex (PFC) and hippocampus (HP). UCS induced the decrease in the 5-HT levels in the HP and the increase in the indoleamine-2,3-dioxygenase, caspase 3 and 9 activities in the PFC and HP. Treatment with chrysin, similarly to fluoxetine, promoted the attenuation of these alterations occasioned by UCS. These results corroborated with the antidepressant potential of chrysin in the treatment of psychiatric diseases. Furthermore, this work indicated the association of pro-inflammatory cytokines synthesis, KP, 5-HT metabolism and caspases activities with the action exercised by chrysin in mice exposed to UCS.

Flavonoid Chrysin prevents age-related cognitive decline via attenuation of oxidative stress and modulation of BDNF levels in aged mouse brain.

In this study, the effect of Chrysin (5,7-dihydroxyflavone), an important member of the flavonoid family, on memory impairment, oxidative stress and BDNF reduction generated by aging in mice were investigated. Young and aged mice were treated daily per 60days with Chrysin (1 and 10mg/kg; per oral, p.o.) or veichle (10ml/kg; p.o.). Mice were trained and tested in Morris Water Maze task. After the behavioural test, the levels of reactive species (RS), the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the activity of Na(+), K(+)-ATPase and the levels of brain-derived neurotrophic factor (BDNF) were determined in the prefrontal cortex (PFC) and hippocampus (HC) of mice. Results demonstrated that the age-related memory decline was partially protected by Chrysin at a dose of 1mg/kg, and normalized at the dose of 10mg/kg (p<0.001). Treatment with Chrysin significantly attenuated the increase of RS levels and the inhibition of SOD, CAT and GPx activities of aged mice. Inhibition of Na(+), K(+)-ATPase activity in PFC and HP of aged mice was also attenuated by Chrysin treatment. Moreover, Chrysin marked mitigated the decrease of BDNF levels in the PFC and HC of aged mice. These results demonstrated that flavonoid Chrysin, an antioxidant compound, was able to prevent age-associated memory probably by their free radical scavenger action and modulation of BDNF production. Thus, this study indicates that Chrysin may represent a new pharmacological approach to alleviate the age-related declines during normal age, acting as an anti-aging agent.

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.

Lycopene treatment prevents hematological, reproductive and histopathological damage induced by acute zearalenone administration in male Swiss mice.

Zearalenone (ZEA) is a mycotoxin commonly found as a contaminant in cereals. ZEA toxicity targets mainly the reproductive system, and oxidative stress plays an etiological role in its toxic effects. Therefore, the present study aimed to investigate the effect of lycopene, a potent carotenoid antioxidant, on markers of oxidative stress in liver, kidney and testes, and on reproductive, hematological and histopathological parameters after ZEA administration. Adult Swiss albino male mice received lycopene (20mg/kg, p.o.) for ten days before a single oral administration of ZEA (40mg/kg, p.o.), and 48h thereafter tissues (liver, kidney, testes and blood) were collected for biochemical, hematological and histological analyses. Lycopene prevented ZEA-induced changes in hematological parameters (increased number of leukocytes, segmented neutrophils, sticks, eosinophils and monocytes and decreased number of red blood cells (RBC), number of lymphocytes and platelets). Moreover, lycopene prevented the reduction in the number and motility of spermatozoa and the testicular tissue damage induced by ZEA. In addition, lycopene prevented the decrease in glutathione-S-transferase activity in kidney and testes and increased glutathione-S-transferase activity per se in the liver, kidneys and testes as well as superoxide dismutase activity in the liver. In summary, lycopene was able to prevent ZEA-induced acute toxic effects in male mice, suggesting that this antioxidant carotenoid may represent a promising prophylactic strategy against ZEA toxicity.

Hepatoprotective effect of bis(4-methylbenzoyl) diselenide against CCl(4)-induced oxidative damage in mice.

From a pharmacological point of view, organoseleniums are compounds with important and interesting antioxidant and biological activities. The aim of this study was to evaluate the hepatoprotective effect of bis(4-methylbenzoyl) diselenide (BMD) against carbon tetrachloride (CCl4 )-induced oxidative damage in mice. The animals received BMD (25 mg/kg p.o., for 3 days), and after 1 day, CCl4 (1 mg/kg body weight) was administered by intraperitoneal route. One day after the CCl4 exposure, the animals were euthanized for biochemical and histological analysis. Treatment with BMD (25 mg/kg p.o.) protected against aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and lactate dehydrogenase activity increases induced by CCl4 plasma exposure. Treatment with BMD (25 mg/kg) protected against increases in thiobarbituric reactive species and decreasing non-protein thiols and ascorbic acid levels in liver of mice. Catalase and superoxide dismutase activity inhibition in the liver caused by CCl4 were protected by treatment with BMD (25 mg/kg). Glutathione S-transferase activity was inhibited by CCl4 and remained unaltered even after treatment with BMD. Sections of liver from CCl4 -exposed mice presented an intense infiltration of inflammatory cells and loss of the cellular architecture. BMD (25 mg/kg) attenuated CCl4 -induced hepatic histological alterations. The results demonstrated the hepatoprotective effects of BMD in the mouse liver, possibly by modulating the antioxidant status.

Possible role for glutathione-S-transferase in the oligozoospermia elicited by acute zearalenone administration in Swiss albino mice.

Zearalenone (ZEA) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium, commonly found in the soil in temperate and warm countries and is a frequent contaminant of cereal crops worldwide. Accordingly, it has been implicated in several mycotoxicosis in farm animals and in humans, but the underlying mechanisms remain largely unknown. Therefore, the current study was aimed to investigate the effect of an acute dose of ZEA (40 mg/kg, p.o.) on reproductive and hematological parameters, as well as on markers of oxidative stress in liver, kidney and testes in mice. Adult Swiss albino male mice were exposed to a single oral administration of ZEA, and 48 h thereafter behavioral and biochemical tests were performed. No differences in locomotor or exploratory activity were observed in the open-field test. On the other hand, ZEA increased the number of leukocytes, segmented neutrophils, sticks, eosinophils, monocytes and decreased platelets and lymphocytes number. Moreover, ZEA drastically reduced the number and motility of live spermatozoa. Additionally, while levels of thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH) and ascorbic acid in liver, kidney and testes were not altered by ZEA administration, superoxide dismutase activity increased in all tissues evaluated, catalase activity increased in the kidney, and glutathione-S-transferase activity decreased in kidney and testes. In summary, we showed that ZEA have acute toxic effects mainly in reproductive system of adult male Swiss albino mice and its effect probably is related to a reduced activity of GST and increased in SOD activity in testes.