title: Isoproterenol increases CREB phosphorylation and olfactory nerve-evoked potentials in normal and 5-HT-depleted olfactory bulbs in rat pups only at doses that produce odor preference learning.
abstract: Norepinephrine (NE) and serotonin (5-HT) are important modulators of early odor preference learning. NE can act as an unconditioned stimulus (UCS), whereas 5-HT facilitates noradrenergic actions. In this study, we examined the phosphorylation of an important transcription factor, cAMP response element binding protein (CREB), which has been implicated in long-term-memory formation (McLean et al. 1999) during NE-induced odor preference learning in normal and olfactory bulb 5-HT-depleted rat pups. We also examined NE modulation of olfactory nerve-evoked field potentials (ON-EFPs) in anesthetized normal and bulbar 5-HT depleted pups. Systemic injection of 2 mg/kg isoproterenol (beta-adrenoceptor agonist) induced odor preference learning, enhanced pCREB expression in the olfactory bulbs at 10 min after odor pairing, and increased ON-EFPs in normal rat pups but not in bulbar 5-HT-depleted rat pups. A dose of 6 mg/kg isoproterenol, which was ineffective in modulating these measures in normal rat pups, induced odor preference learning, enhanced phosphorylated CREB (pCREB) expression, and increased ON-EFPs in bulbar 5-HT-depleted pups. These outcomes suggest that NE and 5-HT promote specific biochemical and electrophysiological changes that may critically underlie odor preference learning.
authors: Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3V6, Canada.
authors: Q
authors: Q
authors: Yuan
authors: C W
authors: CW
authors: Harley
authors: J C
authors: JC
authors: Bruce
authors: A
authors: A
authors: Darby-King
authors: J H
authors: JH
authors: McLean
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D005071:Evoked Potentials / Q000187:drug effects* / Q000502:physiology; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology*; D007858:Learning / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology*; D009832:Olfactory Nerve / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D012701:Serotonin; D007545:Isoproterenol