Neuropeptide Y expression confers benzo[a]pyrene induced anxiolytic like behavioral response during early adolescence period of male Wistar rats Saroj Kumar Das, Manorama Patri ⁎ Neurobiology Laboratory, Department of Zoology, School of Life Sciences, Ravenshaw University, Odisha, India abstract article info Article history: Received 24 May 2016 Received in revised form 4 July 2016 Accepted 4 July 2016 Available online xxxx Environmental neurotoxicant like benzo[a]pyrene (B[a]P) is known to induce neurobehavioral changes. Our pre- vious reports address the adverse effect of B[a]P on the neurobehavioral responses and neuromorphology of sen- sitive brain regions in adolescent rats. Present study was conducted on male Wistar rat neonates at postnatal day 5 (PND5) to ascertain B[a]P induced anxiolytic like behavioral response could be an outcome of neuropeptide Y (NPY) overexpression in brain. Single intracisternal administration of B[a]P was carried out at PND5 to elucidate the role of NPY on neurobehavioral responses at PND30. The behavioral studies showed anxiolytic like effect of B[a]P in both light and dark box and elevated plus maze tests. Antioxidant assay involving glutathione peroxidase activity was significantly decreased where as lipid peroxidation was significantly augmented in both hippocam- pus and hypothalamus of B[a]P treated group as compared to naive and control. The neurotransmitter estimation by HPLC-ECD showed significant increase in 5-HT level in both hippocampus and hypothalamus of B[a]P treated group. Significant elevation in NPY expression was observed in both hippocampus and hypothalamus of B[a]P group. Intracellular Ca 2+ estimation using Fura-2AM by fluorometry showed that B[a]P induced increase in Ca 2+ influx was associated with augmented NPY expression in brain. As NPY has orexigenic effect, our result re- vealed that there was a significant increase in body weight at PND30 following B[a]P administration to rat neo- nates at PND5. These findings suggested that NPY overexpression in brain regions might be associated with anxiolytic like behavioral response and orexigenic effect in rats following single intracisternal B[a]P administra- tion. Future research directing towards understanding the signaling cascades of B[a]P induced biochemical and neuromorphological alteration might address the independent pathway which induce neurodegeneration de- spite NPY overexpression in brain regions of adolescent rats. © 2016 Published by Elsevier Ltd. Keywords: Benzo[a]pyrene Anxiety Neuropeptide Y Calcium Oxidative stress Serotonin 1. Introduction Polycyclic aromatic hydrocarbons (PAHs) like benzo[a]pyrene (B[a]P) are known for their neurotoxic potential to induce alteration in behavior, biochemical and neuromorphology of sensitive brain re- gions (Bouayed et al., 2012; Chen et al., 2012; Mohanty et al., 2016; Patri et al., 2013; Zhang et al., 2016). B[a]P induced anxiolytic like be- havioral response has been well documented, but the possible causes behind this behavioral response are still elusive. B[a]P induced oxidative stress leading to altered hippocampal cytomorphometry advocates its neurodegenerative potential (Patel et al., 2016a). Thus the plausible role of B[a]P in mediating neurodegeneration of sensitive brain regions can't be ignored (Das et al., 2016a; Patel et al., 2016b). As neonates are mostly exposed to these neurotoxicants through in- direct routes such as breast milk and inhaled air over a protracted period of time, it might exhibit its confounding effects on various organs of the body including the brain. Most of the prescribed routes of B[a]P exposure are environmentally relevant, but a direct route of exposure to study its specific effect on neonatal brain development causing neu- robehavioral changes during early adolescence period is required. Intracisternal mode of administration specifically gives a short and di- rect route to study the effects of B[a]P on neurobehavioral, biochemical, molecular and neuromorphological changes (Patri et al., 2013; Patel et al., 2016a). As the blood-brain barrier acts like a check point for meta- bolic transportation of compounds into the brain tissues, in most of the previously prescribed route of exposure, it is difficult to measure ap- proximately the amount of B[a]P injected peripherally that might reach the brain after crossing liver metabolism. The present approach pro- vides a unique opportunity to study the effects of B[a]P directly on bio- chemical status of brain during early stage of postnatal life and to study behavioral, biochemical and molecular alteration thereof. With the ever increasing rate of industrialization and growth of human civilization, exposure to persistent anthropogenic genotoxicants like B[a]P during early stage of postnatal life might affect the mood status leading to Neuropeptides xxx (2016) xxx–xxx ⁎ Corresponding author at: Neurobiology Laboratory, Department of Zoology, School of Life Sciences, Ravenshaw University, Cuttack-753003, Odisha, India. E-mail address: mpatri@ravenshawuniversity.ac.in (M. Patri). YNPEP-01732; No of Pages 8 http://dx.doi.org/10.1016/j.npep.2016.07.001 0143-4179/© 2016 Published by Elsevier Ltd. Contents lists available at ScienceDirect Neuropeptides journal homepage: www.elsevier.com/locate/npep Please cite this article as: Das, S.K., Patri, M., Neuropeptide Y expression confers benzo[a]pyrene induced anxiolytic like behavioral response during early adolescence period of ma..., Neuropeptides (2016), http://dx.doi.org/10.1016/j.npep.2016.07.001