title: Enriched expression of serotonin 1B and 2A receptor genes in macaque visual cortex and their bidirectional modulatory effects on neuronal responses.
abstract: To study the molecular mechanism how cortical areas are specialized in adult primates, we searched for area-specific genes in macaque monkeys and found striking enrichment of serotonin (5-hydroxytryptamine, 5-HT) 1B receptor mRNA, and to a lesser extent, of 5-HT2A receptor mRNA, in the primary visual area (V1). In situ hybridization analyses revealed that both mRNA species were highly concentrated in the geniculorecipient layers IVA and IVC, where they were coexpressed in the same neurons. Monocular inactivation by tetrodotoxin injection resulted in a strong and rapid (<3 h) downregulation of these mRNAs, suggesting the retinal activity dependency of their expression. Consistent with the high expression level in V1, clear modulatory effects of 5-HT1B and 5-HT2A receptor agonists on the responses of V1 neurons were observed in in vivo electrophysiological experiments. The modulatory effect of the 5-HT1B agonist was dependent on the firing rate of the recorded neurons: The effect tended to be facilitative for neurons with a high firing rate, and suppressive for those with a low firing rate. The 5-HT2A agonist showed opposite effects. These results suggest that this serotonergic system controls the visual response in V1 for optimization of information processing toward the incoming visual inputs.
authors.affiliation: Division of Brain Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Akiya
authors.initials: A
authors.lastname: Watakabe
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Komatsu
authors.forename: Osamu
authors.initials: O
authors.lastname: Sadakane
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shimegi
authors.forename: Toru
authors.initials: T
authors.lastname: Takahata
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Higo
authors.forename: Shiro
authors.initials: S
authors.lastname: Tochitani
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hashikawa
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Naito
authors.forename: Hironobu
authors.initials: H
authors.lastname: Osaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okamoto
authors.forename: Ayako
authors.initials: A
authors.lastname: Ishikawa
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Hara
authors.forename: Takafumi
authors.initials: T
authors.lastname: Akasaki
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Sato
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Yamamori
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002522:Chlorocebus aethiops; D004594:Electrophysiology; D015870:Gene Expression; D017403:In Situ Hybridization; D008251:Macaca; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010775:Photic Stimulation; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism* / Q000502:physiology; D044402:Receptor, Serotonin, 5-HT2A / Q000378:metabolism* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017366:Serotonin Receptor Agonists / Q000378:metabolism / Q000494:pharmacology; D014793:Visual Cortex / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology
chemical_list: D044302:Receptor, Serotonin, 5-HT1B; D044402:Receptor, Serotonin, 5-HT2A; D017366:Serotonin Receptor Agonists