Distribution of serotonin transporter labeled fibers in amygdaloid subregions: implications for mood disorders.
BACKGROUND
The serotonin transporter 5-HTT mediates responses to serotonin reuptake inhibitors (SSRIs), a mainstay treatment in mood disorders. The amygdala, a key emotional processing center, has functional abnormalities in mood disorders, which resolve following successful SSRI treatment. To better understand the effects of SSRIs in mood disorders, we examined the distribution of 5-HTT labeled fibers relative to specific nuclear groups in the amygdala.


METHODS
Immunocytochemical techniques were used to chart 5-HTT labeled fibers in the amygdala in coronal sections through the brain of six adult Macaques. Nissl staining was used to define nuclear groups in the amygdala.


RESULTS
The serotonin transporter 5-HTT is distributed heterogeneously in the primate amygdala, with the lateral subdivision of the central nucleus, intercalated cell islands, amygdalohippocampal area, and the paralaminar nucleus showing the heaviest concentrations.


CONCLUSIONS
5HTT-labeled fibers are very densely concentrated in output regions of the amygdala. High concentrations of 5-HTT-positive fibers in the central nucleus indicate that tight regulation of serotonin is critical in modulating fear responses mediated by this nucleus. High concentrations of 5-HTT-labeled fibers in the intercalated islands and parvicellular basal nucleus/paralaminar nucleus, which contain immature -appearing neurons, suggest a potential trophic role for serotonin in these subregions.
O'Rourke
Howard
H
Department of Psychiatry, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
Fudge
Julie L
JL
D000679:Amygdala / Q000033:anatomy & histology / Q000378:metabolism*; D000818:Animals; D001931:Brain Mapping; D005260:Female; D007150:Immunohistochemistry; D008251:Macaca; D008297:Male; D019964:Mood Disorders / Q000378:metabolism; D009412:Nerve Fibers / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D014018:Tissue Distribution
D050486:Serotonin Plasma Membrane Transport Proteins