Seasonal changes in brain serotonin transporter binding in short 5-HTTLPR-allele carriers but not in long-allele homozygotes

Several findings suggest seasonal variations in the serotonin (5-HT) system. We sought evidence for seasonal variation in the serotonin transporter (5-HTT). We found that length of daylight time in minutes correlates negatively with 5-HTT binding in the putamen and the caudate, with a similar tendency in the thalamus, but no such association in the midbrain. In the putamen, an anatomical region with a dense serotonin innervation that is implicated in processing of aversive stimuli, we found a significant gene*daylight effect with a negative correlation between the 5-HTT binding and daylight time in carriers of the short 5-HTTLPR allele, but not in carriers of the long allele. The neurobiological endophenotype identified here directly links activation studies, showing responses on the neural circuit level, with dynamic changes in transporter expression measured in vivo

Serotonin transporter gene ( SLC6A4

Abstract Background The short (s) allele of the 5‐HTTLPR polymorphism in the promoter region of the human serotonin transporter (5‐HTT) gene SLC6A4 has previously been associated with anxiety‐related personality dimensions. However, this relationship has not been confirmed in all studies and may be modified by environmental circumstances and/or psychiatric illness. This study examined whether the temperamental trait sensory processing sensitivity (SPS), characterized by increased responsivity to environmental stimuli, is related to 5‐HTTLPR/rs25531 genotype. Methods 5‐HTTLPR and rs25531 genotypes, level of SPS, self‐reported Revised NEO Personality Inventory (NEO‐PI‐R) and Temperament and Character Inventory (TCI) personality profiles, and symptoms of psychological distress (SCL‐90R Global Severity Index) were determined for 405 healthy volunteers. Results Sensory processing sensitivity was highly correlated with the anxiety‐related dimensions of the NEO‐PI‐R and the TCI models of personality, Neuroticism, and Harm Avoidance, respectively. However, the level of SPS was not associated with the combined 5‐HTTLPR and rs25531 s′/s′ genotype. Neuroticism and Harm Avoidance were also not associated with 5‐HTTLPR/rs25531 s′/s′ genotype. Correcting for symptoms of psychological distress had no effect on the relationships between personality and genotype. Conclusion The level of SPS was not associated with serotonin transporter gene variation. Further, combined 5‐HTTLPR and rs25531 genotype was not associated with other anxiety‐related dimensions