Molecular neuropsychopharmacology S21 insights into the roles of parvalbumin expressing neurons in the brain. Reference(s) [1] Klugmann, M., Symes, C.W., Leichtlein, C.B., Klaussner, B.K., Dunning, J., Fong, D., Young, D., During, M.J., 2005, AAV-mediated hippocampal expression of short and long Homer 1 proteins differentially affect cognition and seizure activity in adult rats. Mol Cell Neurosci 28: 347–360. [2] Cetin, A., Komai, S., Eliava, M., Seeburg, P.H., Osten, P., 2006, Stereotaxic gene delivery in the rodent brain. Nat Protoc 1: 3166–3173. [3] Fuchs, E.C., Zivkovic, A.R., Cunningham, M.O., Middleton, S., Lebeau, F.E., Bannerman, D.M., Ro- zov, A., Whittington, M.A., Traub, R.D., Rawlins, J.N., Monyer H 2007 Recruitment of parvalbumin-positive interneurons determines hippocampal function and associated behaviour. Neuron 53: 591–604. P.1.23 The effect of neonatal handling or drug treatment on behaviour and gene expression in prenatally stressed rats Y. Nachum-Biala 1 ° , Y. Bogoch 1 , M. Weinstock 1 . 1 The Hebrew University of Jerusalem, Pharmacology, Jersualem, Israel Previously we have shown that prenatally stressed (PS) rats exhibit increased anxiety in the elevated plus maze (EPM) that can be prevented by neonatal handling (H) [1]. Furthermore, we have been shown that prenatal stress causes a reduction in specific hippocampal genes expression in prepubertal female rats which is also prevented by H [2]. The most prominent of these were presynaptic nerve terminal-related genes that are active in synaptic vesicle transport, and neurotransmitter release. The aim of the present study was to compare the effect of H with that of a novel brain selective monoamine oxidase inhibitor (ladostigil) on behavioural alterations in PS rats. In addition, we investigated the molecular processes in the hippocampus laying in the basis of the behavioural abnormalities seen in PS rats and in the effect of H. Pregnant rats were stressed daily during the last week of gestation. Offspring were either handled daily for 3 minutes from day 1−10 of age, were given ladostigil (17mg/kg/day) from weaning until adulthood or were left undisturbed. At the age of 60 days half of the offspring were tested in the EPM to assess anxiety or in the forced swimming test (FST) to measure depressive-like behaviour. The remaining rats were sacrificed and the hippocampus was removed for gene analysis that was done using microarray technology. Both H and ladostigil treatments decreased anxiety in the EPM and depressive-like behaviour in the FST of PS rats in the same manner. Like in prepubertal females, prenatal stress caused a significant down-regulation of genes related to exocytosis, trafficking of synaptic vesicles and neurotransmitter release (P < 0.05) in adults of both sexes, with many more genes changed in female compared with males and with young females (25% compared with 10% and 3% from total genes, respectively). Of the genes that were down-regulated in PS rats, 36% were restored to normal levels by H in adult females. These genes play a role in synaptic transmission, vesicle transport and neurotransmitter release. Only 4% of the genes that were down regulated in PS male rats were restored to normal by H. However, H up regulates other genes related to the same biological processes. This study demonstrates that H has the same anxiolytic and antidepressant effect in PS rats as treatment with ladostigil. Moreover, Exposure to prenatal stress has long lasting effect on gene expression and behaviour. H affects differently gene expression in males and females. While in females, handling restores to normal genes that were down regulated by prenatal stress, those related to synaptic vesicle transport and neurotransmitter release. In males, H up regulates other genes related to the same biological processes. The effect of H on gene expression could explain its effect on behaviour. Reference(s) [1] Wakshlak, A., Weinstock, M., 1990, Neonatal handling reverses behavioral abnormalities induced in rats by prenatal stress. Physiol Behav 48: 289–292. [2] Bogoch, Y., Nachum-Biala, Y., Linial, M., Wein- stock, M., 2007, Anxiety induced by prenatal stress is associated with suppression of hippocampal genes involved in synaptic function. J Neurochem 101: 1018–1030. P.1.24 Prenatal stress interferes with glutamatergic response to acute swim stress at adulthood M. Pasini 1 ° , F. Fumagalli 1 , F. Drago 2 , G. Racagni 1 , M.A. Riva 1 . 1 University of Milan, Pharmacological Sciences, Milan, Italy; 2 University of Catania, Experimental and Clinical Pharmacology School of Medicine, Catania, Italy Evidence exists that adverse early life events profoundly and persistently affect brain functions and may represent a risk factor for psychopathology later in life. Prenatal