5-HT1A receptor expression during memory formation.
BACKGROUND
It has been reported that 5-HT(1A) receptors modulate learning and memory and diverse pharmacological and genetic evidence supports this notion. Nevertheless, there are few works about expression of these receptors during memory formation.


OBJECTIVE
We aimed to determine 5-HT(1A) receptor expression in brain areas of untrained, passive, and autoshaping trained groups of rats.


METHODS
Ex vivo receptor autoradiography using the ligand agonist [(3)H]8-hydroxy-2-[di-n-propylamino]tetralin] (8-OH-DPAT) was used.


RESULTS
The trained group relative to untrained animals showed increases of 5-HT(1A) receptor expression in 14 brain areas, decrements in 7, and no changes in 12. Thus, in contrast to untrained rats, 5-HT(1A) receptor expression of autoshaping trained rats was augmented in the tubercule olfactory, septal nucleus, nucleus accumbens, caudate putamen, globus pallidus, striate, and parietal (1 and 2), temporal cortex (1 and 3), granular retrosplenial cortex (1), amygdala, and median and dorsal raphe nuclei. In contrast, in the latter group, receptors were decreased in the CA1 area, hypothalamus dorsal, frontal cortex (1 and 3), occipital cortex, cingulate cortex (1 and 2), and cuneiform nucleus. There were significant differences between passive vs trained groups, but not regarding untrained rats, in the lateral olfactory tract, dentate gyrus, CA3 area, ventromedial hypothalamic, lateral hypothalamus, preoptic medial, frontal cortex (2), granular retrosplenial cortex (2), entorhinal cortex (1 and 2), piriform cortex, and substantia nigra.


CONCLUSIONS
These data suggest that upregulated, downregulated, and "silence" of 5-HT(1A) receptors in brain areas form part of neural circuits engaged in memory formation by demonstrating a high degree of specificity and memory mapping.
Luna-Munguía
H
H
Departo. Farmacobiología, CINVESTAV-IPN, Tenorios 235, Granjas Coapa, México City.
Manuel-Apolinar
L
L
Rocha
L
L
Meneses
A
A
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000378:metabolism; D000818:Animals; D001345:Autoradiography / Q000379:methods; D001667:Binding, Competitive / Q000187:drug effects; D003216:Conditioning, Operant; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010879:Piperazines / Q000008:administration & dosage; D011725:Pyridines / Q000008:administration & dosage; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D012153:Retention, Psychology / Q000502:physiology*; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists / Q000008:administration & dosage; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism; D013687:Telencephalon / Q000187:drug effects / Q000378:metabolism; D014316:Tritium
D010879:Piperazines; D011725:Pyridines; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D014316:Tritium; D044282:Receptor, Serotonin, 5-HT1A; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin