title: Pharmacobehavioural evidence for nitric oxide and noradrenaline interactions with ryanodine receptors during memory formation in the young chick.
abstract: Impairment of nitric oxide (NO) production, ryanodine receptor (RyR) calcium channel function and adrenoceptor activation have been found to prevent the formation of the long-term memory stage in young chicks trained on a single-trial discrimination avoidance task. The current study investigated whether these three activities were linked, and if so, the sequence of activation. Young chicks were trained using either a strongly or weakly reinforced variant of the single-trial discrimination avoidance task, yielding either a persistent or labile memory trace, respectively. Following strongly reinforced training, retention loss induced by a RyR inhibitor was prevented by a NO donor or noradrenaline (NA). A RyR agonist also prevented retention loss induced by either NO synthase or β1+2-adrenoceptor inhibition. These findings were interpreted to reflect the capacity of NO, RyR-dependent calcium release and NA to modulate memory by preventing retention loss. A second set of studies used weakly reinforced training. Although the administration of a RyR agonist promoted long-term memory formation, this facilitation was compromised in the presence of a β1+2-adrenoceptor antagonist, but not a NO synthase inhibitor. Similarly, the inhibition of RyRs interfered with the facilitation of retention induced by a NO donor, but not NA. These differential findings with weakly reinforced training suggest that NO facilitates memory formation through mechanisms involving RyR-dependent calcium release. The findings also indicate that RyRs may promote memory formation through noradrenergic activation of β2-adrenoceptors. This study demonstrates an intricate role for RyRs underlying memory formation.
authors.affiliation: School of Psychology and Psychiatry, Monash University, Clayton, 3800 Victoria, Australia. Kathryn.Baker@monash.edu
authors.forename: Kathryn D
authors.initials: KD
authors.lastname: Baker
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Edwards
authors.forename: Nikki S
authors.initials: NS
authors.lastname: Rickard
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D002645:Chickens; D003620:Dantrolene / Q000378:metabolism / Q000494:pharmacology; D008568:Memory / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism / Q000494:pharmacology; D009569:Nitric Oxide / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000378:metabolism / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D011433:Propranolol / Q000378:metabolism / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*
chemical_list: D020030:Nitric Oxide Donors; D019837:Ryanodine Receptor Calcium Release Channel; D009569:Nitric Oxide; D011433:Propranolol; D003620:Dantrolene; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine