Morphine-induced anxiolytic-like effect in morphine-sensitized mice: Involvement of ventral hippocampal nicotinic acetylcholine receptors

► Anxiolytic effect in the elevated plus maze (EPM) was induced by morphine in mice. ► A challenge dose of morphine induced an anxiolytic effect in morphine-sensitized mice. ► Intra-VH injection of nicotine increased sensitized anxiolytic response in the EPM. ► Intra-VH injection of mecamylamine inhibited sensitized anxiolytic response in the EPM.