title: Melatonin suppresses nighttime memory formation in zebrafish.
abstract: Memory processes are modulated by the biological clock, although the mechanisms are unknown. Here, we report that in the diurnal zebrafish both learning and memory formation of an operant conditioning paradigm occur better during the day than during the night. Melatonin treatment during the day mimics the nighttime suppression of memory formation. Training in constant light improves nighttime memory formation while reducing endogenous melatonin concentrations. Treatment with melatonin receptor antagonists at night dramatically improves memory. Pinealectomy also significantly improves nighttime memory formation. We adduce that melatonin is both sufficient and necessary for poor memory formation during the night.
authors.affiliation: Department of Biology and Biochemistry, University of Houston, 369 Science and Research II, Houston, TX 77204-5001, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Rawashdeh
authors.forename: Nancy Hernandez
authors.initials: NH
authors.lastname: de Borsetti
authors.forename: Gregg
authors.initials: G
authors.lastname: Roman
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Cahill
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D008297:Male; D008550:Melatonin / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D015027:Zebrafish
chemical_list: D008550:Melatonin