Contents lists available at ScienceDirect Hormones and Behavior journal homepage: www.elsevier.com/locate/yhbeh Disturbances of systemic and hippocampal insulin sensitivity in macrophage migration inhibitory factor (MIF) knockout male mice lead to behavioral changes associated with decreased PSA-NCAM levels Ana Djordjevic ⁎ , Biljana Bursać, Nataša Veličković, Ljupka Gligorovska, Djurdjica Ignjatović, Mirko Tomić, Gordana Matić Department of Biochemistry, Institute for Biological Research “Siniša Stanković”, University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia ARTICLE INFO Keywords: Macrophage migration inhibitory factor Hippocampus Insulin sensitivity Plasticity Neurotrophins Polysialylated-neural cell adhesion molecule Novel object recognition Light dark box Elevated plus maze ABSTRACT Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine well known for its role in in- flammation enhancement. However, a growing body of evidence is emerging on its role in energy metabolism in insulin sensitive tissues such as hippocampus, a brain region implicated in cognition, learning and memory. We hypothesized that genetic deletion of MIF may result in the specific behavioral changes, which may be linked tо impairments in brain or systemic insulin sensitivity by possible changes of the hippocampal synaptic plasticity. To assess memory, exploratory behavior and anxiety, three behavioral tests were applied on Mif gene-deficient (MIF -/- ) and “wild type” C57BL/6J mice (WT). The parameters of systemic and hippocampal insulin sensitivity were also determined. The impact of MIF deficiency on hippocampal plasticity was evaluated by analyzing the level of synaptosomal polysialylated-neural cell adhesion molecule (PSA-NCAM) plasticity marker and mRNA levels of different neurotrophic factors. The results showed that MIF -/- mice exhibit emphasized anxiety-like behaviors, as well as impaired re- cognition memory, which may be hippocampus-dependent. This behavioral phenotype was associated with impaired systemic insulin sensitivity and attenuated hippocampal insulin sensitivity, characterized by increased inhibitory Ser 307 phosphorylation of insulin receptor substrate 1 (IRS1). Finally, MIF -/- mice displayed a de- creased hippocampal PSA-NCAM level and unchanged Bdnf, NT-3, NT-4 and Igf-1 mRNA levels. The results suggest that the lack of MIF leads to disturbances of systemic and hippocampal insulin sensitivity, which are possibly responsible for memory deficits and anxiety, most likely through decreased PSA-NCAM- mediated neuroplasticity rather than through neurotrophic factors. 1. Introduction The nervous, endocrine and immune systems are inseparably linked through pleiotropic actions of cytokines, affecting the most of neu- roendocrine and central neurotransmitter processes (Bilbo and Klein, 2012). The behavioral changes, observed as an outcome of the central cytokine action, have been among the extensively investigated intrinsic interactions in the last decade (Bilbo and Schwarz, 2012). Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine, pro- duced by virtually all cell types (Calandra and Roger, 2003; Kudrin and Ray, 2008). It has a pivotal regulatory role in the immune response, with an infamous contribution to the number of inflammatory and autoimmune diseases and carcinogenesis (Lue et al., 2002). Besides its role in inflammation, a growing body of evidence is emerging on the role of MIF in energy metabolism in insulin sensitive tissues such as pancreas, muscle and adipose tissue (Cvetkovic et al., 2005; Morrison and Kleemann, 2015). High expression of MIF was documented throughout the brain, especially in the hippocampus, a brain region involved in cognition, learning and memory (Nishibori et al., 1996; Ogata et al., 1998; Rubin et al., 2014). Some studies showed that ex- perimental animals with genetic deletion of MIF may express depressive and/or anxiety-like behavior (Conboy et al., 2011; Moon et al., 2012). However, some classical tests for measuring behaviors relevant to re- cognition memory and anxiety, such as novel object recognition test and light-dark box, were not assessed so far in MIF knockout mice. The observed behavioral phenotypes induced by the absence of MIF may be related to the alterations in both systemic and hippocampal insulin sensitivity, as previously demonstrated in experimental models of dia- betes and Alzheimer's disease (AD) (Vandal et al., 2014; Winocur et al., 2005). Some clinical studies pointed to decreased hippocampal volume http://dx.doi.org/10.1016/j.yhbeh.2017.09.008 Received 31 March 2017; Received in revised form 11 September 2017; Accepted 12 September 2017 ⁎ Corresponding author at: University of Belgrade, Institute for Biological Research “Siniša Stanković”, Department of Biochemistry, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia. E-mail address: djordjevica@ibiss.bg.ac.rs (A. Djordjevic). Hormones and Behavior 96 (2017) 95–103 0018-506X/ © 2017 Elsevier Inc. All rights reserved. MARK