Fig. 3-4 Fig. 3-4: Pregnant SJL/J mice received injections of vehicle or murine IL-2 (0.4  g, IP; once/day for 5-days) during the second trimester. Adult male offspring showed significant increases in the frequency of stereotypic motor behavior after challenge with a single injection of GBR (5 mg/kg, IP), a dopamine uptake inhibitor with stimulant-like properties. Maternal Exposure to Interleukin-2 Induces Long-Lasting Increases in Behavioral and Neuronal Responses to Novelty and Psychostimulant Challenge in Offspring and Neuronal Responses to Novelty and Psychostimulant Challenge in Offspring Steven S. Zalcman, Alba Rossi-George, Jessica Hu, Mark D. Bobbin, Janet Worobiej, Nicholas M. Ponzio UMD-NJ Medical School, Departments of Psychiatry and Pathology, 183 South Orange Ave. Newark New Jersey Fig. 5: Fig. 5: : Pregnant SJL/J mice received injections of vehicle or murine IL-2 (0.4  g, IP; once/day for 5-days) during the second trimester. Adult male offspring received a single injection of GBR (5 mg/kg, IP). Offspring of IL-2-treated dams showed significant increases in Fos-like immunoreactivity in the septal area 2-hr after challenge with a single injection of GBR Introduction Maternal immune activation is thought to increase vulnerability to psychiatric disorders involving repetitive and stereotypic behavior (notably schizophrenia and autism). Interleukin (IL)-2 is a TH1-derived cytokine that potently modulates dopamine activity and neuronal excitability in mesolimbic and mesostriatal structures (Lapchak, 1992; Alonso et al., 1993; Zalcman et al., 1994; Anisman et al., 1996; Pettito et al., 1997; Song et al., 1999; Ye et al., 2001). IL-2 also acts as a potent neuromodulator. For example, IL-2 influences the survival of hippocampal, septal, striatal, cerebellar, and cortical neurons, and promotes neurite extension, and growth and survival of septohippocampal neurons. We showed that interleukin IL-2 potentiates novelty- and psychostimulant-induced locomotion (Zalcman et al., 1998; Zalcman, 2001). As well, mice receiving repeated injections of IL-2 (once a day for 5 days) display marked increases in stereotypic motor behavior (Zalcman, 2002). In light of these effects of IL-2, it might not be surprising that it is implicated in neurodevelopmental disorders that involve the expression of repetitive and motor stereotypies (notably, schizophrenia, autism). We thus hypothesized that maternal exposure to IL-2 induces long-term behavior-activating effects in offspring, and potentiates behavioral and neuronal responses to psychostimulant challenge. Materials and Methods SJL/J mice were housed 3-4 females per male in breeding cages. Pregnant females received an in injection of PBS or murine IL-2 (PeproTech Inc., Rocky Hill, NJ; 0.4 mg/mouse) once a day for 5 days during the second trimester. Offspring were weaned at PND 21, housed in standard polypropylene cages, maintained on a 12 hour light / 12 hour dark cycle, and permitted ad lib access to food and water. Adult offspring were tested for behavioral responses to novelty stress (i.e, exposure to a novel environment) and psychostimulant challenge (i.e., an injection of 5 mg/kg GBR 12909; Tocris-Cookson). Test sessions were taped with a VHS camera and scored at a later date by an experienced rater. The frequency of stereotypic behavior was determined every 30-min in 1-min epochs after GBR challenge by an experienced rater who was blind to the treatment groups. Frequency was defined as the duration of time during each observation period that the mouse was engaged in motor stereotypies.A modification of a scale developed by Creese and Iverson (1972) and Capper-Loup et al. (2002) was used where: 0=undetectable, 1=very weak, 2=weak, 3=weak to moderate, 4= moderate, 5=moderate to strong, 6=strong, 7=intense, 8=very intense, and 9= extreme. Summary and Conclusions Adult male offspring of IL-2-treated dams displayed marked increases in novelty-induced rearing and grooming behavior compared with PBS controls. Adult male offspring of IL-2-treated dams displayed marked increases in levels of stereotypic behavior following a single injection of GBR 12909, a DA uptake inhibitor with stimulant-like properties. GBR-stimulated c-fos expression was increased in the septum as a function of maternal IL-2 treatment. This is the first evidence that prenatal IL-2 exposure: (1) produces very long-lasting behavior-activating effects in offspring, (2) potentiates the expression of dopamine-dependent stereotypy, and (3) augments stimulant-induced neuronal activation in limbic structures. We suggest that increased maternal IL-2 levels during pregnancy could induce in offspring a long-lasting increased vulnerability to neurobehavioral abnormalities associated with dimensions of schizophrenia and autism. Since behavioral effects were most pronounced in male offspring, we suggest that this study has implications on the development of a model of autism. Supported by NIH/NIMH, National Alliance for Autism Research, NJ Governor’s Council on Autism. Effects of Maternal IL-2 Exposure on Novelty-Induced Behavior in Offspring Effects of Maternal IL-2 Exposure on Stereotypic Behavior following Psychostimulant Challenge Fig. 5 Fig. 1-2: Fig. 1-2: Pregnant SJL/J mice received injections of vehicle or murine IL-2 (0.4  g, IP; once/day for 5-days) during the second trimester. Adult offspring of IL-2-treated dams displayed marked increases in rearing (Fig. 1) within 10-min of exposure to a novel environment. In male offspring, the number of grooming episodes was also significantly increased (Fig. 2). Fig. 3 Fig. 4 Fig. 1 Fig. 2 Effects of Maternal IL-2 Exposure on Fos-like Immunoreactivity in GBR Treated Offspring