Overexpression of 12/15-lipoxygenase increases anxiety behavior in female mice Yash B. Joshi, Antonio Di Meco, Domenico Praticò * Department of Pharmacology, Center for Translational Medicine, Temple University, School of Medicine, Philadelphia, PA, USA article info Article history: Received 22 August 2013 Received in revised form 28 October 2013 Accepted 5 November 2013 Available online 11 November 2013 Keywords: 12/15-lipoxygenase Behavior Anxiety CREB abstract The 12/15-lipoxygenase (12/15-LO) is an enzyme widely distributed in the central nervous system, and it has been involved in the neurobiology of Alzheimer’s disease. However, whether this pathway is also involved in neuropsychiatry disorders including anxiety remain to be investigated. In this study we investigated whether genetic over-expression of 12/15-LO (H12/15-LO) modulates some elevated plus maze and Y-maze behaviors. While we observed that H12/15LO mice at the age of 12 months did not differ from wild type in the elevated plus maze paradigm, when they reached the age of 15 months, they manifested an increased anxiety-like behavior compared with controls. By contrast, no differences be- tween the 2 groups at both ages when they were tested for working memory in the Y-maze paradigm. Additionally, we found that the change in anxiety was associated with a reduction in phosphorylation of the transcription factor CREB (cAMP response element-binding protein), and a significant increase in the synaptic protein synaptophysin. Taken together our findings suggest a novel role for 12/15-LO in the pathogenesis of anxiety-like behavior. Ó 2014 Elsevier Inc. All rights reserved. 1. Introduction Although anxiety disorders generally manifest early in life, the ones that evolve in late life represent a significant clinical problem with prevalence rates of 6%e10% in those aged 55 years or older (Schuurmans and van Balkom, 2011). Presently, it is not known whether, if at all, the pathophysiology and progression of anxiety disorders in the elderly group differs from younger age groups. For example, in both aged and young populations, anxiety disorders are associated with major depressive disorders. However, aged persons have additional medical comorbidities and lifetime exposure to various stressors, which could confer an increased biological vulnerability to the development of disorders characterized with clinical anxiety. The aged brain and young brain differ in several biochemical aspects, among which include the oxidation, metabolism, and signaling of bioactive lipids. Emerging work suggests that precise modulation of bioactive lipids in the brain is crucial for proper functioning, and that dysregulation of lipid oxidation could be involved in a number of neurologic and psychiatric diseases. The 12/ 15-lipoxygenase (12/15-LO) is a lipid-peroxidizing enzyme that is widely expressed in the central nervous system. It produces hydroxyperoxyeicosatetraenoic acid metabolites from arachidonic acid substrate and has been linked to aging-associated illnesses such as Alzheimer’s disease (Chu et al., 2012). However, its role in anxiety has not yet been investigated. The goal of this study was to investi- gate whether overexpression of 12/15-lipoxygenase impacted anxiety-like behavior in mice. Here, we report that an anxiety phenotype developed in mice overexpressing the 12/15-LO (H12/15- LO) at the age of 15 months, which was absent at 12 months. 2. Methods 2.1. Animals Female wild type (WT) and H12/15-LO mice (Jackson Labora- tories, Bar Harbor, ME, USA) at the age of 12 and 15 months were used in this experiment (WT, n ¼ 5; H12/15-LO ¼ 5). H12/15-LO animals, which express 3e4-fold greater levels of 12/15-LO than WT counterparts in the brain have been previously described (Reilly et al., 2004). All animal procedures were approved by the Temple Animal Care and Usage Committee and were in accordance with the institutional and National Institute of Health guidelines. After sac- rifice, animals were perfused with ice-cold 0.9% phosphate- buffered saline (PBS) containing ethylenediaminetetraacetic acid (2 mmol/L), pH 7.4. Brains were removed 24 hours after behavioral analyses, gently rinsed in cold 0.9% PBS, and immediately dissected * Corresponding author at: Center for Translational Medicine, 3500 North Broad St. MERB 947, Philadelphia, PA 19104, USA. Tel.: þ1 215 707 9380; fax: þ1 215 707 9890. E-mail address: praticod@temple.edu (D. Praticò). Contents lists available at ScienceDirect Neurobiology of Aging journal homepage: www.elsevier.com/locate/neuaging 0197-4580/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neurobiolaging.2013.11.003 Neurobiology of Aging 35 (2014) 1032e1036