5HTTLPR polymorphism and enlargement of the pulvinar: unlocking the backdoor to the limbic system.
BACKGROUND
The 5HTTLPR genetic variant of the serotonin transporter (SERT), which consists of a long (SERT-l) and short (SERT-s) allele, has emerged as a major factor influencing emotional behavior and brain anatomy. The pulvinar nucleus of the thalamus projects to important limbic nuclei including the amygdala and cingulate cortex, is involved in the processing of stimuli with emotional content, and contains an abundance of SERT.


METHODS
Stereological methods were used to measure pulvinar neuron number in postmortem tissue from major depressive disorder (n = 11), bipolar disorder (n = 11), schizophrenia (n = 12), and control (n = 15) specimens from the Stanley Foundation Neuropathology Consortium. The effect of SERT genotype on pulvinar volume and neuron number was investigated by using analysis of covariance.


RESULTS
Analysis of covariance with diagnosis, SERT genotype, age, hemisphere, postmortem interval, and time-in-formalin covariates identified a 20% increase in pulvinar neuron number and volume in SERT-ss subjects.


CONCLUSIONS
The elevated number of pulvinar neurons in subjects with a SERT-ss genotype may serve to enhance subcortical input of emotionally relevant stimuli to the limbic system, providing a mechanism for the 5HTTLPR genetic variant to affect predisposition to conditions such as major depression.
Young
Keith A
KA
Neuropsychiatry Research Program, Central Texas Veterans Health Care System, Temple, Texas 76504, USA. kayoung@medicine.tamhsc.edu
Holcomb
Leigh A
LA
Bonkale
Willy L
WL
Hicks
Paul B
PB
Yazdani
Umar
U
German
Dwight C
DC
D000483:Alleles; D001714:Bipolar Disorder / Q000235:genetics* / Q000473:pathology; D016022:Case-Control Studies; D002452:Cell Count; D003865:Major Depressive Disorder / Q000235:genetics* / Q000473:pathology; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008032:Limbic System / Q000166:cytology; D008297:Male; D016555:Matched-Pair Analysis; D009474:Neurons / Q000166:cytology / Q000473:pathology; D009929:Organ Size; D020649:Pulvinar / Q000166:cytology*; D012016:Reference Values; D012559:Schizophrenia / Q000235:genetics* / Q000473:pathology; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*
D050486:Serotonin Plasma Membrane Transport Proteins