Abstracts of the 3rd Biennial Schizophrenia International Research Conference / Schizophrenia Research 136, Supplement 1 (2012) S1–S375 S187 these patients. Therefore, an algorithm for prevention and treatment will be presented based on the literature and clinical experience. Methods: A systematic search in PubMed and other databases towards preventive and treatment options of TD. Results: Prevention is based on communication with the patient (shared care decision making and informed consent), regular systematic screening (see www.psychiatrynet.eu/druginduced/pdf), re-evaluation of the neces- sity, type and dosage of the antipsychotic, awareness of risk factors, and switch to clozapine (if not possible, than another Second Generation An- tipsychotic). The evidence of these steps will be discussed [2,3]. Treatment of TD starts with the evaluation of the necessity of the antipsychotics. If so, then lowering the dosage, adding vitamin E, switching to clozap- ine, and adding an antidyskinetic agent (in particularly botulinum toxin and tetrabenazine, and finally Deep Brain Stimulation), are the main in- terventions [2,3]. Two new interventions are discussed more extensively. Tetrabenazine: Based on the eleven trials (most are small and/or open), one case series and eight case reports, tetrabenazine exhibits some promise as a potentially effective treatment for TD. Most common side effects were drowsiness (13-36.5%), parkinsonism (2.5-28.5%) and depression (1.7-15%) [4]. Deep Brain Stimulation: Eighteen papers included 52 patients suffering from tardive dyskinesia and/or dystonia who were treated with Deep Brain Stimulation. The mean improvement on the Burke Fahn Marsden Rating Scale was 77.5% (95% CI 71.4%-83.3%, p<0.000). Of the 52 patients one patient had a transient episode of persistent laughter and two others had an exacerbation of a depression and psychosis, respectively [5]. Discussion: A new feasible algorithm including promising treatment op- tions for TD such as botulinum toxin, tetrabenazine and Deep Brain Stim- ulation is presented. However, prevention remains the preferred strategy [1–6]. Literature: [1] Soares-Weiser K, Fernandez HH. Tardive dyskinesia Semin Neurol 2007:159–69. [2] van Harten PN, Tenback DE. Tardive dyskinesia: clinical presentation and treat- ment. Int Rev Neurobiol. 2011;98:187-210. [3] Tenback DE, van Harten PN. Epidemiology and risk factors for (tardive) dyskinesia. Int Rev Neurobiol. 2011;98:211-30. [4] Leung G, Breden EL. Tetrabenazine for the treatment of tardive dyskinesia. The Annals of Pharmacotherapy; 2011:525-31. [5] Mentzel CL, Tenback DE, Tijssen MA, Visser-Vandewalle V, van Harten PN. Effi- cacy and safety of deep brain stimulation in patients with a psychiatric illness and tardive dyskinesia and/or dystonia; a systematic review (submitted) [6] Fahn S, Jankovic J (2007). Principles and practice of movement disorders, chapter 20. Poster #7 NEUROCHEMICAL CHANGES IN SCHIZOPHRENIA ARE PRIMED BY THE SYNERGISTIC ACTION OF PRENATAL IMMUNE CHALLENGE AND RESTRAINT STRESS Jessica Deslauriers 1 , Annie Larouche 2 , Philippe Sarret 1 , Sylvain Grignon 1,2 1 University of Sherbrooke, Department of Physiology & Biophysics, Sherbrooke, Quebec, Canada; 2 University of Sherbrooke, Department of Psychiatry, Sherbrooke, Quebec, Canada Background: Prenatal immune challenge (PIC) with polyIC is well estab- lished as a neurodevelopmental model of schizophrenia. It has also been reported that oxidative stress is a phenomenon present in psychiatric dis- orders like schizophrenia. To gain a better understanding of the interaction between these two phenomena in the context of schizophrenia patho- physiology, we have developed a two-hit model (PIC followed by juvenile restraint stress (RS)). We previously reported that both PIC and RS induce a synergistic disruption of prepulse inhibition of acoustic startle (PPI) in juvenile mice. Our goal was thus to assess which neurochemical changes were associated with this PPI disruption. Methods: C57BL/6 gestational mice were injected with polyIC (20 mg/kg) or with saline intraperitoneally at gestational day 12. Mice pups were then submitted, or not, to RS for 2 hours, for three consecutive days, from postnatal days 33 to 35. Pups were euthanized 3 hours after the last period of RS and brains were extracted for neurochemical analyses. For the assessment of oxidative stress, protein carbonylation was evaluated by the 2,4-dinitrophenylhydrazine (DNPH) derivatization method. Dopamine D2 receptor (DRD2) and GAD67 (glutamic acid decarboxylase 67) pro- tein and mRNA levels were determined by western blotting and RT-PCR, respectively. Results: PIC and RS induced an additive increase in carbonyl levels (+111%; p<0.05, compared to saline) in the cortex compared with each treatment alone. Moreover, this double insult increased both DRD2 protein and mRNA levels (+76%; p<0.01 and +211%; p<0.05, respectively, compared to saline) in the cortex. We also observed a synergistic increase in DRD2 mRNA levels with polyIC combined to RS (+112%, compared to saline) in the striatum. Regarding glutamatergic abnormalities, PIC and RS provoked a synergistic decrease in protein GAD67 (glutamic acid decarboxylase 67) levels in the cortex (- 20%; p<0.01, compared to saline) and in GAD67 mRNA expression in the striatum (- 25%; p<0.05, compared to saline). Discussion: These findings support the hypothesis that gestational immune activation and postnatal stress are both involved in the development of oxidative stress and in the changes of the dopaminergic and glutamatergic expression patterns associated to the development of sensorimotor gating deficits in schizophrenia. This two-hit animal model is therefore useful for studying underlying mechanisms of behavioral and neurochemical ab- normalities associated to schizophrenia as well as to evaluate innovative therapies. Poster #8 SUICIDE-RELATED BEHAVIORS INDUCED BY SOCIAL ISOLATION IN A MODEL OF SCHIZOPHRENIA Jessica Deslauriers 1 , Karine Belleville 1 , Karyn Kirby 1 , Nicolas Beaudet 1 , Philippe Sarret 1 , Sylvain Grignon 1,2 1 University of Sherbrooke, Departement of Physiology & Biophysics, Sherbrooke, Quebec, Canada; 2 University of Sherbrooke, Department of Psychiatry, Sherbrooke, Quebec, Canada Background: In the general population, suicide accounts for 30% of deaths among young men (<35 years old). Suicide is also a significant factor for premature death in schizophrenics (5%), but the pathophysiological mechanisms of suicidal behaviors in this subpopulation remain uncertain. To gain a better understanding of suicide risk in a context of schizophrenia, we developed an in vivo model of schizophrenia with a prenatal immune challenge (PIC) using polyIC followed by a post-weaning social isolation (SI). It has been reported that SI induces suicide-related behaviors such as aggressiveness, impulsivity, anxiety and hopelessness. Methods: C57BL/6 gestational mice were injected with polyIC (20 mg/kg) or with saline intraperitoneally at gestational day 12. Pups weres submit- ted, or not, to SI for 4 weeks after the weaning. To validate the model of schizophrenia, prepulse inhibition of acoustic startle (PPI) and exploratory behaviors in an OpenField setup were monitored. Social interaction with the resident-intruder test was also evaluated, more specifically aggressive and impulsive behaviors. Results: We observed a synergistic effect of PIC and SI (-26%; p<0.01, compared to saline) in male on PPI disruption. In the OpenField, PIC and SI synergistically increased immobility (+68%; p<0.05, compared to saline) and reduced exploratory behaviors. In the resident-intruder test, the dou- ble insult negatively affected social interaction (-47%; p<0.05 and -50%; p<0.05 on sequences number and time, respectively, compared to saline). In relation to the suicide-related behaviors, PIC and SI also synergistically increased aggressive behaviors (+686%; p<0.05 and +2293%; p<0.01 on ag- gressiveness sequence number and time, respectively, compared to saline). Impulsivity was shown by a trend in the reduction of the latency before the first attack (-49%; p=0.14, compared to saline). Discussion: These findings support the hypothesis that gestational immune activation and social isolation together contribute to the development of schizophrenia-like (PPI, exploratory behavior and social interaction) and suicide-related behaviors (aggressiveness and impulsivity). This in vivo model helps us to gain a better understanding of suicide risk in the context of schizophrenia. Further work will be necessary to assess (1) other suicide- related behaviors, like anxiety and hopelessness, and (2) the neurochemical changes related to these phenomena.