R.C. Cordeiro

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.

Antidepressant-like effect of nitric oxide synthase inhibitors and sildenafil against lipopolysaccharide-induced depressive-like behavior in mice.

Inflammation, oxidative and nitrosative stress underlie depression being assessed in rodents by the systemic administration of lipopolysacharide (LPS). There is an increasing body of evidence of an involvement of nitric oxide (NO) pathway in depression, but this issue was not investigated in LPS-induced model. Thus, herein we evaluated the effects of NO-pathway-modulating drugs, named aminoguanidine, l-NAME, sildenafil and l-arginine, on the behavioral (forced swimming test [FST], sucrose preference [SPT] and prepulse inhibition [PPI] of the startle) and neurochemical (glutathione [GSH], lipid peroxidation, IL-1β) alterations in the prefrontal cortex, hippocampus and striatum as well as in BDNF levels in the hippocampus 24h after LPS (0.5mg/kg, i.p.) administration, a time-point related to depressive-like behavior. Twenty-four hours post LPS there was an increase in immobility time in the FST, decrease in sucrose preference and PPI levels accompanied by a decrease in GSH levels and an increase in lipid peroxidation, IL-1β and hippocampal BDNF levels suggestive of a depressive-like state. The pretreatment with the NOS inhibitors, l-NAME and aminoguanidine as well as sildenafil prevented the behavioral and neurochemical alterations induced by LPS, although sildenafil and l-NAME were not able to prevent the increase in hippocampal BDNF levels induced by LPS. The iNOS inhibitor, aminoguanidine, and imipramine prevented all behavioral and neurochemical alterations induced by LPS. l-arginine did not prevent the alterations in immobility time, sucrose preference and GSH induced by LPS. Taken together our results show that the NO-cGMP pathway is important in the modulation of the depressive-like alterations induced by LPS.

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.

Effects of alpha-lipoic acid in an animal model of mania induced by d-amphetamine

Macêdo DS, Medeiros CD, Cordeiro RC, Sousa FC, Santos JV, Morais TA, Hyphantis TN, McIntyre RS, Quevedo J, Carvalho AF. Effects of alpha‐lipoic acid in an animal model of mania induced by d‐amphetamine. Bipolar Disord 2012: 14: 707–718.

Time course of the effects of lipopolysaccharide on prepulse inhibition and brain nitrite content in mice.

The systemic administration of lipopolysaccharide (LPS) induces time-dependent behavioral alterations, which are related to sickness behavior and depression. The time-course effects of LPS on prepulse inhibition (PPI) remain unknown. Furthermore, the time-dependent effects of LPS on central nitrite content had not been investigated. Therefore, we studied alterations induced by single LPS (0.5mg/kg, i.p.) administration to mice on parameters, such as PPI, depressive- and anxiety-like behaviors, working memory, locomotor activity and motor coordination, 1.5 and 24h post-LPS administration. IL-1β and TNFα in the blood and brain as well as brain nitrite levels were evaluated in the prefrontal cortex (PFC), hippocampus (HC) and striatum (ST). An overall hypolocomotion was observed 1.5h post-LPS, along with depressive-like behaviors and deficits in working memory. Increments in IL-1β content in plasma and PFC, TNFα in plasma and decreases in nitrite levels in the ST and PFC were also verified. Twenty-four hours post-LPS treatment, depressive-like behaviors and working memory deficits persisted, while PPI levels significantly reduced along with increases in IL-1β content in the PFC and a decrease in nitrite levels in the HC, ST and PFC. Our data demonstrate that a delayed increase (i.e., 24h post-LPS) in PPI levels ensue, which may be useful behavioral parameter for LPS-induced depression. A decrease in nitrergic neurotransmission was associated with these behavioral findings.

Effects of lithium on oxidative stress and behavioral alterations induced by lisdexamfetamine dimesylate: relevance as an animal model of mania.

Lisdexamfetamine dimesylate (LDX) is a prodrug that requires conversion to d-amphetamine (d-AMPH) for bioactivity. Treatment with d-AMPH induces hyperlocomotion and is regarded as a putative animal model of bipolar mania. Therefore, we sought to determine the behavioral and oxidative stress alterations induced by sub-chronic LDX administration as well as their reversal and prevention by lithium in rats. A significant increment in locomotor behavior was induced by LDX (10 and 30 mg/kg). To determine Li effects against LDX-induced alterations, in the reversal protocol rats received LDX (10 or 30 mg/kg) or saline for 14 days. Between days 8 and 14 animals received Li (47.5 mg/kg, i.p.) or saline. In the prevention paradigm, rats were pretreated with Li or saline prior to LDX administration. Glutathione (GSH) levels and lipid peroxidation was determined in the prefrontal cortex (PFC), hippocampus (HC) and striatum (ST) of rats. Lithium prevented LDX-induced hyperlocomotion at the doses of 10 and 30 mg/kg, but only reversed LDX-induced hyperlocomotion at dose of 10mg/kg. In addition, both doses of LDX decreased GSH content (in ST and PFC), while Li was able to reverse and prevent these alterations mainly in the PFC. LDX (10 and 30 mg/kg) increased lipid peroxidation which was reversed and prevented by Li. In conclusion, LDX-induced hyperlocomotion along with associated increments in oxidative stress show promise as an alternative animal model of mania.

Neonatal Immune Challenge with Lipopolysaccharide Triggers Long-lasting Sex- and Age-related Behavioral and Immune/Neurotrophic Alterations in Mice: Relevance to Autism Spectrum Disorders

Early-life challenges, particularly infections and stress, are related to neuropsychiatric disorders such as autism and schizophrenia. Here, we conducted a wide range of behavioral tests in periadolescent (postnatal day (PN) 35) and adult (PN70) Swiss mice neonatally challenged with LPS on PN5 and -7, to unveil behavioral alterations triggered by LPS exposure. Immune and neurotrophic (brain-derived neurotrophic factor—BDNF) alterations were determined in the prefrontal cortex (PFC), hippocampus (HC), and hypothalamus (HT). Since the incidence and clinical manifestations of neurodevelopmental disorders present significant sex-related differences, we sought to distinctly evaluate male and female mice. While on PN35, LPS-challenged male mice presented depressive, anxiety-like, repetitive behavior, and working memory deficits; on PN70, only depressive- and anxiety-like behaviors were observed. Conversely, females presented prepulse inhibition (PPI) deficits in both ages studied. Behavioral changes in periadolescence and adulthood were accompanied, in both sexes, by increased levels of interleukin (IL-4) (PFC, HC, and HT) and decreased levels of IL-6 (PFC, HC, and HT). BDNF levels increased in both sexes on PN70. LPS-challenged male mice presented, in both ages evaluated, increased HC myeloperoxidase activity (MPO); while when adult increased levels of interferon gamma (IFNγ), nitrite and decreased parvalbumin were observed. Alterations in innate immunity and parvalbumin were the main LPS-induced remarks between males and females in our study. We concluded that neonatal LPS challenge triggers sex-specific behavioral and neurochemical alterations that resemble autism spectrum disorder, constituting in a relevant model for the mechanistic investigation of sex bias associated with the development of this disorder.

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.

Sex influences in behavior and brain inflammatory and oxidative alterations in mice submitted to lipopolysaccharide-induced inflammatory model of depression

Peripheral inflammation induced by lipopolysaccharide (LPS) causes a behavioral syndrome with translational relevance for depression. This mental disorder is twice more frequent among women. Despite this, the majority of experimental studies investigating the neurobiological effects of inflammatory models of depression have been performed in males. Here, we sought to determine sex influences in behavioral and oxidative changes in brain regions implicated in the pathophysiology of mood disorders (hypothalamus, hippocampus and prefrontal cortex - PFC) in adult mice 24 h post LPS challenge. Myeloperoxidase (MPO) activity and interleukin (IL)-1β levels were measured as parameters of active inflammation, while reduced glutathione (GSH) and lipid peroxidation as parameters of oxidative imbalance. We observed that male mice presented behavioral despair, while females anxiety-like alterations. Both sexes were vulnerable to LPS-induced anhedonia. Both sexes presented increased MPO activity in the PFC, while male only in the hippocampus. IL-1β increased in the PFC and hypothalamus of animals of both sexes, while in the hippocampus a relative increase of this cytokine in males compared to females was detected. GSH levels were decreased in all brain areas investigated in animals of both sexes, while increased lipid peroxidation was observed in the hypothalamus of females and in the hippocampus of males after LPS exposure. Therefore, the present study gives additional evidence of sex influence in LPS-induced behavioral alterations and, for the first time, in the oxidative changes in brain areas relevant for mood regulation.

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.