In-depth characterization of congenital Zika syndrome in immunocompetent mice: Antibody-dependent enhancement and an antiviral peptide therapy.

BACKGROUND: Zika virus (ZIKV) infection during pregnancy may cause major congenital defects, including microcephaly, ocular, articular and muscle abnormalities, which are collectively defined as Congenital Zika Syndrome. Here, we performed an in-depth characterization of the effects of congenital ZIKV infection (CZI) in immunocompetent mice. METHODS: Pregnant dams were inoculated with ZIKV on embryonic day 5.5 in the presence or absence of a sub-neutralizing dose of a pan-flavivirus monoclonal antibody (4G2) to evaluate the potential role of antibody-dependent enhancement phenomenon (ADE) during short and long outcomes of CZI. FINDINGS: ZIKV infection induced maternal immune activation (MIA), which was associated with occurrence of foetal abnormalities and death. Therapeutic administration of AH-D antiviral peptide during the early stages of pregnancy prevented ZIKV replication and death of offspring. In the post-natal period, CZI was associated with a decrease in whole brain volume, ophthalmologic abnormalities, changes in testicular morphology, and disruption in bone microarchitecture. Some alterations were enhanced in the presence of 4G2 antibody. INTERPRETATION: Our results reveal that early maternal ZIKV infection causes several birth defects in immunocompetent mice, which can be potentiated by ADE phenomenon and are associated with MIA. Additionally, antiviral treatment with AH-D peptide may be beneficial during early maternal ZIKV infection. FUND: This work was supported by the Brazilian National Science Council (CNPq, Brazil), Minas Gerais Foundation for Science (FAPEMIG), Funding Authority for Studies and Projects (FINEP), Coordination of Superior Level Staff Improvement (CAPES), National Research Foundation of Singapore and Centre for Precision Biology at Nanyang Technological University.

Opposing roles of CB1 and CB2 cannabinoid receptors in the stimulant and rewarding effects of cocaine.

BACKGROUND AND PURPOSE: The endocannabinoids anandamide and 2-arachidonoylglycerol (2-AG) bind to CB1 and CB2 cannabinoid receptors in the brain and modulate the mesolimbic dopaminergic pathway. This neurocircuitry is engaged by psychostimulant drugs, including cocaine. Although CB1 receptor antagonism and CB2 receptor activation are known to inhibit certain effects of cocaine, they have been investigated separately. Here, we tested the hypothesis that there is a reciprocal interaction between CB1 receptor blockade and CB2 receptor activation in modulating behavioural responses to cocaine. EXPERIMENTAL APPROACH: Male Swiss mice received i.p. injections of cannabinoid-related drugs followed by cocaine, and were then tested for cocaine-induced hyperlocomotion, c-Fos expression in the nucleus accumbens and conditioned place preference. Levels of endocannabinoids after cocaine injections were also analysed. KEY RESULTS: The CB1 receptor antagonist, rimonabant, and the CB2 receptor agonist, JWH133, prevented cocaine-induced hyperlocomotion. The same results were obtained by combining sub-effective doses of both compounds. The CB2 receptor antagonist, AM630, reversed the inhibitory effects of rimonabant in cocaine-induced hyperlocomotion and c-Fos expression in the nucleus accumbens. Selective inhibitors of anandamide and 2-AG hydrolysis (URB597 and JZL184, respectively) failed to modify this response. However, JZL184 prevented cocaine-induced hyperlocomotion when given after a sub-effective dose of rimonabant. Cocaine did not change brain endocannabinoid levels. Finally, CB2 receptor blockade reversed the inhibitory effect of rimonabant in the acquisition of cocaine-induced conditioned place preference. CONCLUSION AND IMPLICATIONS: The present data support the hypothesis that CB1 and CB2 receptors work in concert with opposing functions to modulate certain addiction-related effects of cocaine. LINKED ARTICLES: This article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.

Effects of the monoamine stabilizer (-)-OSU6162 on locomotor and sensorimotor responses predictive of antipsychotic activity.

The monoamine stabilizer (3S)-3-[3-(methenesulfonyl)phenyl]-1-propylpiperidine hidrochloride [(-)-OSU6162] is a promising compound for the treatment of neurological and psychiatric disorders, such as schizophrenia. Here, we tested the hypothesis that (-)-OSU6162 prevents hyperlocomotion and sensorimotor deficits in prepulse inhibition of the startle response (PPI) induced by psychomimetic drugs. Male Swiss mice received injections of (-)-OSU6162 (1, 3, 10, or 30 mg/kg), and their motor responses were investigated in the open field and in the catalepsy tests, which predicts liability to induce sedation and extrapyramidal side effects, respectively. Next, in independent experiments, this compound was evaluated for its efficacy to prevent hyperlocomotion induced by cocaine (10 mg/kg; dopamine transporter inhibitor) or ketamine (60 mg/kg; glutamate NMDA channel blocker) in the open field. Finally, we tested if (-)-OSU6162 prevents PPI disruption induced by MK-801 (0.5 mg/kg; glutamate NMDA channel blocker). (-)-OSU6162 induced neither locomotion impairment nor catalepsy. This compound prevented cocaine-induced hyperlocomotion at the doses of 10 and 30 mg/kg and ketamine-induced hyperlocomotion at the doses of 1 and 3 mg/kg. In the sensorimotor test, (-)-OSU6162 failed to reverse MK-801-induced PPI deficits. The dopamine stabilizer (-)-OSU6162 prevents the hyperactivity induced by dopaminergic and anti-glutamatergic drugs at doses that preserve motor functions, although it failed in the PPI test. Its therapeutic potential for specific symptoms of schizophrenia warrants further investigation in both preclinical and clinical studies.

Effects of early or late prenatal immune activation in mice on behavioral and neuroanatomical abnormalities relevant to schizophrenia in the adulthood.

Maternal immune activation (MIA) during pregnancy in rodents increases the risk of the offspring to develop schizophrenia-related behaviors, suggesting a relationship between the immune system and the brain development. Here we tested the hypothesis that MIA induced by the viral mimetic polyinosinic-polycytidylic acid (poly I:C) in early or late gestation of mice leads to behavioral and neuroanatomical disorders in the adulthood. On gestational days (GDs) 9 or 17 pregnant dams were treated with poly I:C or saline via intravenous route and the offspring behaviors were measured during adulthood. Considering the progressive structural neuroanatomical alterations in the brain of individuals with schizophrenia, we used magnetic resonance imaging (MRI) to perform brain morphometric analysis of the offspring aged one year. MIA on GD9 or GD17 led to increased basal locomotor activity, enhanced motor responses to ketamine, a psychotomimetic drug, and reduced time spent in the center of the arena, suggesting an increased anxiety-like behavior. In addition, MIA on GD17 reduced glucose preference in the offspring. None of the treatments altered the relative volume of the lateral ventricles. However, a decrease in brain volume, especially for posterior structures, was observed for one-year-old animals treated with poly I:C compared with control groups. Thus, activation of the maternal immune system at different GDs lead to neuroanatomical and behavioral alterations possibly related to the positive and negative symptoms of schizophrenia. These results provide insights on neuroimmunonological and neurodevelopmental aspects of certain psychopathologies, such as schizophrenia.