Involvement of kynurenine pathway in depressive-like behaviour induced by nandrolone decanoate in mice

Nandrolone decanoate (ND) belongs to the class II of anabolic-androgenic steroids (AAS), which is composed of 19-nor-testosterone-derivatives. AAS represent a group of synthetic testosterone that is used in clinical treatment. However, these drugs are widely abused among individuals as a means of promoting muscle growth or enhancing athletic performance. AAS in general and ND in particular have been associated with several behavioral disturbances, such as anxiety, aggressiveness and depression. A factor that contributes to the development of depression is the brain activation of indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme of kynurenine pathway (KP). In the present study, we examined the involvement of KP in depressive phenotype induced by a ND treatment (10 mg/kg/day/s.c., for 28 days) that mimics human abuse system (e.g. supraphysiological doses) in C57B/6J mice. Our results showed that ND caused depressive like-behavior in the tail suspension test and anhedonic-like state measured in the sucrose preference test. ND administration decreased the levels of brain-derived neurotrophic factor and neurotrophin-3 and reduced Na⁺,K⁺-ATPase activity in the hippocampus, striatum and prefrontal cortex. We also found that ND elicited KP activation, as reflected by the increase of IDO activity and kynurenine levels in these brain regions. Moreover, ND decreased serotonin levels and increased 5-hydroxyindoleacetic acid levels in the brain. Treatment with IDO inhibitor 1-methyl-dl-trypthophan (1 mg/kg/i.p.) reversed the behavioral and neurochemical alterations induced by ND. These results indicate for the first time that KP plays a key role in depressive-like behavior and neurotoxicity induced by supraphysiologicaldoses of ND in mice.

Blackberry juice anthocyanidins limit cisplatin-induced renal pathophysiology in mice

Some studies have showed that intake of blackberry juice (BBJ) can prevent urinary tract infections. However, there is a lack of studies that evaluate the mechanisms by which BBJ has protective effect. Thus, the aim of current study was to evaluate the effects of BBJ supplementation on cisplatin-induced renal pathophysiology in mice. Mice were supplemented with BBJ (10 mL/kg) for seven days. One hour after the last supplementation with BBJ, mice received cisplatin (10 mg/kg, i.p.). Seventy-two hours after cisplatin administration, blood was collected and biochemical analysis were performed (urea and creatinine), kidney was dissected and utilized in histological and oxidative evaluations. Cisplatin caused severe injury in renal tissue, in markers of renal damage (urea and creatinine) generated increased of plasmatic levels. Besides that, the cisplatin induced decreased of enzymes activities in renal tissue (superoxide dismutase, glutathione S-transferase and catalase). In contrast, BBJ supplementation protected against histopathological alterations through decreased in urea and creatinine levels and modulation of catalase enzyme activity. Thus, BBJ supplementation protected the renal system of mice from deleterious effects. We suggest that high concentrations of Cyanidin 3-O-glucoside and Cyanidin 3-O-rutinoside are responsible for antioxidant role of BBJ supplementation in renal pathophysiology induced by cisplatin exposure. Also, these results reinforcing the importance of including BBJ in the human diet aimed at preventing renal diseases.

Aging exacerbates cognitive and anxiety alterations induced by an intracerebroventricular injection of amyloid-β1-42 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 Aβ_1-42-neurotoxicity and AD pathogenesis. We have reported for the first time that brain IDO activation is related to Aβ_1-42 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 Aβ_1-42 (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 Aβ_1-42 administration. Aged mice also responded to Aβ_1-42 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 Aβ_1-42 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 Aβ_1-42-induced memory loss, anxiety symptoms and KYN pathway dysregulation.

Activation of Brain Indoleamine-2,3-dioxygenase Contributes to Depressive-Like Behavior Induced by an Intracerebroventricular Injection of Streptozotocin in Mice

There is a lack of information concerning the molecular events underlying the depressive-like effect of an intracerebroventricular injection of streptozotocin (ICV-STZ) in mice. The elevated activity of the tryptophan-degrading enzyme indoleamine-2,3-dioxygenase (IDO) has been proposed to mediate depression in inflammatory disorders. In the present study, we reported that ICV-STZ activates IDO in the hippocampus of mice and culminates in depressive-like behaviors, as measured by the increased duration of immobility in the tail suspension test and decreased sucrose intake in the sucrose preference test. The blockade of IDO activation by the IDO inhibitor 1-methyltryptophan (1-MT) prevents the development of depressive-like behaviors and attenuates STZ-induced up-regulation of proinflammatory cytokines in the hippocampus. 1-MT abrogates kynurenine production and normalizes brain-derived neurotrophic factor (BDNF) and the kynurenine/tryptophan ratio, but does not protect the biomarkers of the serotonin (5-HT) system in the hippocampus of STZ-injected mice. These results implicate IDO as a critical molecular mediator of STZ-induced depressive-like behavior, likely through activation of the kynurenine pathway and subsequent reduction of BDNF levels. Impairment of the 5-HT system may reflect the inflammatory response induced by STZ and also contributes to observed depression symptoms. The present study not only provides evidence that IDO plays a critical role in mediating inflammation-induced depression but also supports the notion that neuroinflammation and the kynurenine pathway are important targets for novel therapeutic drugs for depression. In addition, this study provides new insights on the neurobiological mechanisms underlying ICV-STZ and indicates that this model could be employed in preclinical research of depression.

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.

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.

Antinociceptive and anti-hyperalgesic effects of bis(4-methylbenzoyl) diselenide in mice: evidence for the mechanism of action

CONTEXT

The organoselenium compounds have been described to demonstrate several biological activities, including pain management.

OBJECTIVE

This study investigated the antinociceptive, hyperalgesic, and toxic effects of oral administration of bis(4-methylbenzoyl) diselenide (BMD) in mice.

MATERIALS AND METHODS

The antinociceptive and anti-hyperalgesic effects of BMD (1, 5, 10, 25, and 50 mg/kg, p.o.) were evaluated using models of nociception: formalin, capsaicin, bradykinin (BK), cinnamaldehyde, phorbol myristate acetate (PMA), 8-bromo-cAM, and glutamate-induced nociception; and mechanical hyperalgesia induced by carrageenan (Cg) or complete Freund's adjuvant (CFA). The acute toxicity was evaluated by biochemical markers for hepatic and renal damages.

RESULTS

BMD significantly inhibited the licking time of the injected paw in the early and late phases of a formalin test with ED50 values of 14.2 and 10.8 mg/kg, respectively. This compound reduced nociception produced by capsaicin (ED50 of 32.5 mg/kg), BK (ED50 of 24.6 mg/kg), glutamate (ED50 of 28.7 mg/kg), cinnamaldehyde (ED50 of 18.9 mg/kg), PMA (ED50 of 9.6 mg/kg), and 8-bromo-cAMP (ED50 of 24.8 mg/kg). In the glutamate test, the pretreatment with nitric oxide (NO) precursor, L-arginine, reversed antinociception caused by BMD or N(ω)-nitro-L-arginine (L-NOARG), but the effect of BMD was not abolished by naloxone. Mechanical hyperalgesia induced by Cg and CFA was attenuated by BMD, 70 ± 4% and 65 ± 4%, respectively. Furthermore, a single oral dose of BMD did not change plasma aspartate (AST) and alanine aminotransferase (ALT) activities or urea and creatinine levels.

CONCLUSION

BMD demonstrated as a promising compound because of the antinociceptive and anti-hyperalgesic properties in mice.

Evidence for the Involvement of Potassium Channel Inhibition in the Antidepressant-Like Effects of Hesperidin in the Tail Suspension Test in Mice

The administration of hesperidin elicits an antidepressant-like effect in mice by a mechanism dependent on an interaction with the L-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway, whose stimulation is associated with the activation of potassium (K(+)) channels. Thus, this study investigated the involvement of different types of K(+) channels in the antidepressant-like effect of hesperidin in the mice tail suspension test (TST). The intracerebroventricular administration of tetraethylammonium (TEA, a nonspecific blocker of K(+) channels), glibenclamide (an ATP-sensitive K(+) channel blocker), charybdotoxin (a large- and intermediate-conductance calcium-activated K(+) channel blocker) or apamin (a small-conductance calcium-activated K(+) channel blocker) combined with a subeffective dose of hesperidin (0.01 mg/kg, intraperitoneally [i.p.]) was able to produce a synergistic antidepressant-like effect in the mice TST. Moreover, the antidepressant-like effect elicited by an effective dose of hesperidin (0.3 mg/kg, i.p.) in TST was abolished by the treatment of mice with pharmacological compounds K(+) channel openers (cromakalim and minoxidil). Results showed that the antidepressant-like effect of hesperidin in TST may involve, at least in part, the modulation of neuronal excitability through inhibition of K(+) channels and may act through a mechanism dependent on the inhibition of L-arginine-NO pathway.

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.