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 (β-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.
Footnotes
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↵3 Corresponding author.
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E-MAIL charley{at}play.psych.mun.ca; FAX (709) 737-4000.
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Article and publication are at www.learnmem.org/cgi/doi/10.1101/lm.35900.
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- Received July 19, 2000.
- Accepted October 5, 2000.
- Cold Spring Harbor Laboratory Press