Early locus coeruleus lesions increase the density of beta-adrenergic receptors in the main olfactory bulb of rats.
Norepinephrine is supplied to both deep and superficial layers of the olfactory bulb through dense projections from the locus coeruleus. Beta-adrenergic receptors are located in nearly all bulb laminae, with high-density foci of beta-1 and beta-2-adrenoceptors present in the glomerular layer. Early olfactory experiences that increase norepinephrine levels in the bulb also decrease the density of beta-1- and beta-2-adrenoceptors, as well as the number of high-density glomerular foci of beta-2-receptors. Changes in bulb norepinephrine levels, therefore, may affect the density of beta-adrenoceptors in the bulb. In the current study, we test this hypothesis by performing unilateral lesions of the locus coeruleus with 6-hydroxydopamine on postnatal day 4, and examining the density of beta-1- and beta-2-adrenergic receptors in the main olfactory bulb of the rat using 125I-labeled iodopindolol receptor autoradiography on postnatal day 19. Locus coeruleus destruction resulted in a statistically significant increase in the density of adrenergic receptors in the ipsilateral bulb compared to the contralateral bulb. Both beta-1- and beta-2-adrenoceptor subtypes increased in density with this manipulation, although the number of glomerular layer high-density beta-2 foci was not significantly different between the two bulbs. These results are consistent with the hypothesis that changes in olfactory bulb norepinephrine can regulate the density of beta-adrenergic receptors in the bulb.
Woo
C C
CC
Department of Psychobiology, University of California, Irvine 92717, USA.
Wilson
D A
DA
Sullivan
R M
RM
Leon
M
M
D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers; D004299:Dopamine beta-Hydroxylase / Q000032:analysis; D005786:Gene Expression Regulation; D008125:Locus Coeruleus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D009498:Neurotoxins / Q000633:toxicity; D009638:Norepinephrine / Q000378:metabolism / Q000502:physiology*; D009830:Olfactory Bulb / Q000378:metabolism*; D016627:Oxidopamine / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D018342:Receptors, Adrenergic, beta-1 / Q000096:biosynthesis* / Q000235:genetics; D018343:Receptors, Adrenergic, beta-2 / Q000096:biosynthesis* / Q000235:genetics
D015415:Biomarkers; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D016627:Oxidopamine; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine