Benzo[a]pyrene (B[a]P) induces anxiolytic like behavioral response. B[a]P induces neuropeptide Y (NPY) over expression in brain regions. NPY over expression confers anxiolytic like behavioral response following B[a]P administration. B[a]P induced NPY over expression leads to orexigenic effect. B[a]P induced NPY overexpression in brain causes increase in intracellular Ca2 + level.