A learned odor evokes an enhanced Fos-like glomerular response in the olfactory bulb of young rats.
Young rats exposed to peppermint odor and reinforcing tactile stimulation from postnatal days (PND) 1-18 increase their preference for that odor relative to controls. This early olfactory memory is accompanied by an 80% increase in the density of glomerular-layer cells displaying Fos-like immunoreactivity in response to the learned odor on PND 19. The difference is observed in midlateral portions of the olfactory bulb that align with foci of 2-deoxyglucose (2-DG) uptake in adjacent sections. Trained and control animals are not different in the Fos-like response of juxtaglomerular cells within ventrolateral 2-DG foci. Ratios of midlateral/ventrolateral response differ significantly between trained and control animals and include differences among cells of three staining intensities. These ratios are correlated with ratios of 2-DG uptake (midlateral/ventrolateral foci), which also differ significantly between trained and control rats. Juxtaglomerular cells associated with 2-DG foci also express Egr-1-like immunoreactivity. However, the midlateral Egr-1 response does not differ between trained and control rats. These results show that early memories can be associated with an increased Fos-like response in a primary sensory area of the CNS. They also suggest that only specific regions within the olfactory bulb are modified following the learning of a given odor in early life.
Johnson
B A
BA
Department of Psychobiology, University of California, Irvine 92717-4550, USA.
Woo
C C
CC
Duong
H
H
Nguyen
V
V
Leon
M
M
D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D005260:Female; D007150:Immunohistochemistry; D007858:Learning; D008297:Male; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar
D016760:Proto-Oncogene Proteins c-fos