Zebrafish models relevant to studying central opioid and endocannabinoid systems

Marijuana and Opioid Use during Pregnancy: Using Zebrafish to Gain Understanding of Congenital Anomalies Caused by Drug Exposure during Development

“…Zebrafish is an outstanding model system to study vertebrate development. It is increasingly becoming a popular model to study the effects of exposure to different compounds during development because of its various advantages compared to the avian or mammalian systems [ 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. It is easy to expose externally fertilized embryos to different drugs and to monitor their effects on development in transparent embryos.…”

“…Unlike invertebrates, the eCB system is highly conserved between zebrafish and mammals, including humans. The zebrafish contain orthologs of all human cannabinoid signaling genes except N-acylethanolamine acid amidase gene [ 40 , 58 , 59 ]. Another difference is that zebrafish have two homologs for each of the four human genes FAAH2, PTGS2, TRPA1, and PPARA.…”

“…Another difference is that zebrafish have two homologs for each of the four human genes FAAH2, PTGS2, TRPA1, and PPARA. Zebrafish Cnr1 and Cnr2 share 75% and 46% identity with their human counterparts [ 40 , 58 ].…”

“…An extensive body of research on the expression and the functions of zebrafish eCB genes are summarized in recent reviews [ 40 , 45 , 58 , 59 ]. During development, the expression of zebrafish cannabinoid receptor 1 ( cnr1 ) was first detected in the pre-optic area as early as 1 day post fertilization (dpf).…”

“…The NOP system is considered to be a part of the opioid system, although it produces antiopioid actions depending on the region in which it is expressed in the brain. These receptors are activated by endogenous ligands ß-endorphin (MORP ligand), dynorphin (KORP ligand), enkephalin and deltorphin (DORP ligand), nociceptin/orphanin FQ (N/OFQ) (NOP ligand) that result in physiological effects including analgesia, dysphoria, water diuresis, and antipruritic effects [ 40 , 45 ]. These ligands are derived from precursor compounds that are produced by the genes POMC, PENK, PDYN, and PNOC.…”