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Selective facilitation of the serotonin 1B receptor causes disorganization of thalamic afferents and barrels in somatosensory cortex of rat
Author(s) -
YoungDavies Cara L.,
BennettClarke Carol A.,
Lane Richard D.,
Rhoades Robert W.
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/1096-9861(20000911)425:1<130::aid-cne11>3.0.co;2-b
Subject(s) - somatosensory system , biology , agonist , serotonin , medicine , endocrinology , receptor , cortex (anatomy) , 5 ht receptor , neuroscience , biochemistry
Alteration of serotonin (5‐HT) levels influences developing thalamocortical afferents (TCAs) in primary somatosensory cortex (SI) of rats and mice. The 5‐HT 1B receptor, present on TCAs during the first postnatal week, may be involved in these effects. The present study asked whether administration of 5‐nonyloxytriptamine (NNT), a selective 5‐HT 1B receptor agonist, affects TCA organization in rat SI. Littermates were injected five times daily (5×/day), with either 0.1 mg/kg NNT or vehicle from birth to postnatal day 6 (P‐6). Animals were killed on P‐6, and their brains were processed for high‐performance liquid chromatography (HPLC), cytochrome oxidase (CO) histochemistry, cresyl violet, or demonstration of TCAs by placement of 1,1′‐dioctadecyl‐3,3,3′′,3′‐tetra‐methylindocarbocyanine perchlorate (Di‐I) on thalamocortical radiations. At P‐6, NNT treatment decreased 5‐HT levels slightly compared with controls, although this difference was not statistically significant. In NNT‐treated rats, the Di‐I‐labeled vibrissae‐related pattern showed a range of effects, from fusion of patches related to mystacial vibrissae in treated animals to a less distinct vibrissae‐related pattern in SI barrelfield compared with controls. Staining for CO and Nissl stain in layer IV of SI showed a similar range of abnormalities. These results indicate that the agonist action of NNT at the 5‐HT 1B receptor causes TCA disorganization in rat barrel field cortex in the absence of elevated 5‐HT. J. Comp. Neurol. 425:130–138, 2000. © 2000 Wiley‐Liss, Inc.