Aline Santos Monte

Effects of doxycycline on depressive-like behavior in mice after lipopolysaccharide (LPS) administration.

Current evidences support inflammation, oxidative and nitrogen stress, as well as brain-derived neurotrophic factor (BDNF) signaling mechanisms as important in depression pathophysiology. Tetracycline antibiotics have anti-inflammatory and antioxidant properties. Preliminary evidence indicates that minocycline has antidepressant properties. Doxycycline (DOXY) has favorable pharmacokinetic and safety profiles when compared to other tetracycline congeners. The antidepressant activity of DOXY has not been adequately investigated. This study evaluated the effects of DOXY (25 and 50 mg/kg, i.p.) on LPS-induced (0.5 mg/kg, i.p.) depressive-like behavior. Doxycycline was administered 30 min before LPS (pre-LPS) or 1.5 and 23.5 h following LPS (post-LPS) administration in mice. LPS-treated animals presented an increase in immobility time in the forced swimming test (FST) when compared to controls 24 h after endotoxin administration. Similarly to imipramine (IMI-10 mg/kg, i.p.), DOXY at both doses prevented and reversed LPS-induced alterations in the FST. IL-1β content was increased 24 h after LPS administration in striatum, hippocampus and prefrontal cortex. IMI and DOXY prevented and reversed LPS-induced increase in IL-1β. IMI and DOXY also prevented and reversed LPS-induced alterations in nitrite content and oxidative stress parameters (lipid peroxidation and reduced glutathione levels). Both DOXY and IMI prevented LPS-induced decrease in hippocampal BDNF levels. Taken together, our results demonstrate that DOXY is comparable to IMI in effectively ameliorate LPS-induced depressive-like behavior, providing a rationale for testing DOXYs antidepressant efficacy in humans.

Evidences for a progressive microglial activation and increase in iNOS expression in rats submitted to a neurodevelopmental model of schizophrenia: Reversal by clozapine

Schizophrenia was proposed as a progressive neurodevelopmental disorder. In this regard herein we attempted to determine progressive inflammatory and oxidative alterations induced by a neonatal immune challenge and its possible reversal by clozapine administration. For this end, Wistar rats at postnatal day (PN) 5-7 were administered the viral mimetic polyriboinosinic-polyribocytidilic acid (polyI:C) or saline. A distinct group of animals additionally received the antipsychotic drug clozapine (25mg/kg) from PN60 to 74. At PN35 (periadolescence), 60 (adult) and 74 (adulthood) the animals were submitted to behavioral determinations of prepulse inhibition of the startle (PPI) and Y maze task for working memory evaluation. At PN35 and 74 the animals were sacrificed and the hippocampus (HC), prefrontal cortex (PFC) and striatum (ST) immunostained for Iba-1, a microglial marker, and inducible nitric oxide synthase (iNOS). At PN74 oxidative stress parameters, such as, reduced glutathione levels (GSH) and lipid peroxidation were determined. The results showed a progressive increase of microglial activation and iNOS immunostaining from PN35 to PN74 mainly in the CA2 and CA3 regions of the HC and in the ST. At PN74 neonatal challenge also induced an oxidative imbalance. These inflammatory alterations were accompanied by deficits in PPI and working memory only in adult life that were reversed by clozapine. Clozapine administration reversed microglial activation and iNOS increase, but not the alterations of oxidative stress parameters. Taken together these results give further evidences for a neuroprogressive etiology and course of schizophrenia and that clozapine may partly alleviate this process.

Prevention and reversal of ketamine-induced schizophrenia related behavior by minocycline in mice: Possible involvement of antioxidant and nitrergic pathways.

It has been hypothesized that oxidative imbalance and alterations in nitrergic signaling play a role in the neurobiology of schizophrenia. Preliminary evidence suggests that adjunctive minocycline treatment is efficacious for cognitive and negative symptoms of schizophrenia. This study investigated the effects of minocycline in the prevention and reversal of ketamine-induced schizophrenia-like behaviors in mice. In the reversal protocol, animals received ketamine (20 mg/kg per day intraperitoneally or saline for 14 days, and minocycline (25 or 50 mg/kg daily), risperidone or vehicle treatment from days 8 to 14. In the prevention protocol, mice were pretreated with minocycline, risperidone or vehicle prior to ketamine. Behaviors related to positive (locomotor activity and prepulse inhibition of startle), negative (social interaction) and cognitive (Y maze) symptoms of schizophrenia were also assessed. Glutathione (GSH), thiobarbituric acid-reactive substances (TBARS) and nitrite levels were measured in the prefrontal cortex, hippocampus and striatum. Minocycline and risperidone prevented and reversed ketamine-induced alterations in behavioral paradigms, oxidative markers (i.e. ketamine-induced decrease and increase in GSH levels and TBARS content, respectively) as well as nitrite levels in the striatum. These data provide a rationale for evaluating minocycline as a novel psychotropic agent and suggest that its mechanism of action includes antioxidant and nitrergic systems.

Gender and estrous cycle influences on behavioral and neurochemical alterations in adult rats neonatally administered ketamine

Neonatal N‐methyl‐D‐aspartate (NMDA) receptor blockade in rodents triggers schizophrenia (SCZ)‐like alterations during adult life. SCZ is influenced by gender in age of onset, premorbid functioning, and course. Estrogen, the hormone potentially driving the gender differences in SCZ, is known to present neuroprotective effects such as regulate oxidative pathways and the expression of brain‐derived neurotrophic factor (BDNF). Thus, the aim of this study was to verify if differences in gender and/or estrous cycle phase during adulthood would influence the development of behavioral and neurochemical alterations in animals neonatally administered ketamine. The results showed that ketamine‐treated male (KT‐male) and female‐in‐diestrus (KTF‐diestrus, the low estrogen phase) presented significant deficits in prepulse inhibition of the startle reflex and spatial working memory, two behavioral SCZ endophenotypes. On the contrary, female ketamine‐treated rats during proestrus (KTF‐proestrus, the high estradiol phase) had no behavioral alterations. This correlated with an oxidative imbalance in the hippocampus (HC) of both male and KTF‐diestrus female rats, that is, decreased levels of GSH and increased levels of lipid peroxidation and nitrite. Similarly, BDNF was decreased in the KTF‐diestrus rats while no alterations were observed in KTF‐proestrus and male animals. The changes in the HC were in contrast to those in the prefrontal cortex in which only increased levels of nitrite in all groups studied were observed. Thus, there is a gender difference in the adult rat HC in response to ketamine neonatal administration, which is based on the estrous cycle. This is discussed in relation to neuropsychiatric conditions and in particular SCZ.

Central effects of lipoic acid associated with paroxetine in mice.

Antidepressants, including selective serotonin reuptake inhibitors, are commonly prescribed for the treatment of affective disorders such as anxiety and depression. The purpose of this study was to investigate the central effects of acute administration of paroxetine (PXT) combined with lipoic acid (LA) on various behavioral models in mice. Paroxetine (10 and 20 mg/kg), LA (100 mg/kg), or vehicle was administered, intraperitoneally, 30 minutes before the tests. The results showed that PXT (10 mg/kg) alone and in combination with LA increased locomotor activity. In the anxiety models studied, an anxiolytic effect was observed after the administration of LA and PXT. In the tail suspension test, PXT at both doses and in combination with LA caused a significant decrease in immobility time. These results indicate possible anxiolytic and antidepressant effects of LA associated with PXT. These data suggest that coadministration of LA and PXT may improve anxiolytic and antidepressant responses, and being more effective than each drug alone. However, further studies are necessary to investigate the mechanism by which antioxidants exert antidepressant or anxiolytic action.

Two-hit model of schizophrenia induced by neonatal immune activation and peripubertal stress in rats: Study of sex differences and brain oxidative alterations

HighlightsWe developed a new two‐hit model of schizophrenia with neonatal poly(I:C) challenge.Sex differences were observed in the behavior of rats exposed to our two‐hit model.Male two‐hit rats presented worse schizophrenia‐like negative symptoms.Female two‐hit rats presented worse schizophrenia‐like positive symptoms.Distinct brain oxidative changes occurred in male and female two‐hit animals. Abstract Schizophrenia is considered to be a developmental disorder with distinctive sex differences. Aiming to simulate the vulnerability of the third trimester of human pregnancy to the developmental course of schizophrenia, an animal model was developed, using neonatal poly(I:C) as a first‐hit, and peripubertal stress as a second‐hit, i.e. a two‐hit model. Since, to date, there have been no references to sex differences in the two‐hit model, our study sought to determine sex influences on the development of behavior and brain oxidative change in adult rats submitted to neonatal exposure to poly(I:C) on postnatal days 5–7 as well as peripubertal unpredictable stress (PUS). Our results showed that adult two‐hit rats present sex‐specific behavioral alterations, with females showing more pronounced deficits in prepulse inhibition of the startle reflex and hyperlocomotion, while males showing more deficits in social interaction. Male and female animals exhibited similar working memory deficits. The levels of the endogenous antioxidant, reduced glutathione, were decreased in the prefrontal cortex (PFC) of both male and female animals exposed to both poly(I:C) and poly(I:C) + PUS. Only females presented decrements in GSH levels in the striatum. Nitrite levels were increased in the PFC of male and in the striatum of female poly(I:C) + PUS rats. Increased lipid peroxidation was observed in the PFC of females and in the striatum of males and females exposed to poly(I:C) and poly(I:C) + PUS. Thus, the present study presents evidence for sex differences in behavior and oxidative brain change induced by a two‐hit model of schizophrenia.

Preclinical Evidences for an Antimanic Effect of Carvedilol

Oxidative imbalance, alterations in brain-derived neurotrophic factor (BDNF), and mitochondrial dysfunction are implicated in bipolar disorder (BD) pathophysiology and comorbidities, for example, cardiovascular conditions. Carvedilol (CVD), a nonselective beta-blocker widely used for the treatment of hypertension, presents antioxidant and mitochondrial stabilizing properties. Thus, we hypothesized that CVD would prevent and/or reverse mania-like behavioral and neurochemical alterations induced by lisdexamfetamine dimesylate (LDX). To do this, male Wistar rats were submitted to two different protocols, namely, prevention and reversal. In the prevention treatment the rats received daily oral administration (mg/kg) of CVD (2.5, 5 or 7.5), saline, valproate (VAL200), or the combination of CVD5 + VAL100 for 7 days. From the 8th to 14th day LDX was added. In the reversal protocol LDX was administered for 7 days with the drugs being added from the 8th to 14th day of treatment. Two hours after the last administration the behavioral (open field and social interaction) and neurochemical (reduced glutathione, lipid peroxidation, and BDNF) determinations were performed. The results showed that CVD prevented and reversed the behavioral and neurochemical alterations induced by LDX. The administration of CVD5 + VAL100 potentiated the effect of VAL200 alone. Taken together these results demonstrate a possible antimanic effect of CVD in this preclinical model.

P.1.h.039 Time-course of changes in lipid peroxidation after acute exposure to GBR 12909 in brain areas of mice

behaviour between Nos1-knockout and wild-type animals. In wildtype mice, MS stimulated the locomotor activity in OF (p< 0.05), but increased the anxiety of these animals, as it reduced the time spent exploring the open arm of EPM (p = 0.06). MS had stronger effects on the behaviour of the Nos1-knockout mice. Interestingly, many of the behaviours brought about by the lack of Nos1 − hyperactivity in the Nos1-knockout mice: their behaviour in OF, EPM, and LD was indistinguishable from the wild-type animals. However, MS did not change the impairment of contextual fear learning induced by Nos1-deficiency, and additionally decreased freezing to tone (p< 0.05). Conclusions: These findings reveal an interplay between adverse early life experiences and NO signalling impacting on affective behaviour, suggesting higher stress-sensitivity in animals lacking the neuronal nitric oxide synthase.