Institute of biomolecular chemistry (ICB) 1 article published in JoVE Biochemistry Identification of Orexin and Endocannabinoid Receptors in Adult Zebrafish Using Immunoperoxidase and Immunofluorescence Methods Roberta Imperatore1,2, Livia D'Angelo3, Paolo De Girolamo3, Luigia Cristino2, Marina Paolucci1 1Department of Sciences and Technologies (DST), University of Sannio, 2Endocannabinoid Research Group, Institute of Biomolecular Chemistry, 3Department of Veterinary Medicine and Animal Productions, University of Naples Federico II Presented here are protocols for immunohistochemical characterization and localization of orexin peptide, orexin receptors, and endocannabinoid receptors in the gut and brains of normal and diet-induced obesity (DIO) adult zebrafish models using immunoperixidase and double immunofluorescence methods.