Serotonergic effects of smoking are independent from the human serotonin transporter gene promoter polymorphism: evidence from auditory cortical stimulus processing.
BACKGROUND
Cigarette smoking has been associated with mood enhancing properties and modulating effects on serotonin activity. The loudness dependence (LD) of the auditory-evoked N1/P2-component has been related to serotonergic neurotransmission, i. e. the allelic variants in the promoter of the 5-hydroxytryptamine-transporter (5-HTT) gene (SCL6A4). Moreover, smoking behavior has been associated to the 5-HTT-genotype. It was hypothesized that cigarette smoking modulates the LD and this effect was expected to interact with the 5-HTT-genotype.


METHODS
5-HTT-genotype and LD were determined in 63 healthy smokers and 114 nonsmokers.


RESULTS
LD was significantly affected by smoking status (p = 0.008) and 5-HTT-genotype (p = 0.045) but not by smoking*genotype-interaction or daily cigarette consumption. Current smokers exhibited a significantly weaker LD compared to nonsmokers. 5-HTT-genotype showed no significant effect on smoking behavior.


CONCLUSIONS
The results indicate a higher serotonergic activity in smokers as compared to nonsmokers independent of 5-HTT-genotype. Since former smokers and never smokers showed similar LDs, the serotonin enhancing effect of smoking seems to be a characteristic state, which may contribute to the maintenance of smoking behavior.
Gallinat
J
J
Clinic for Psychiatry and Psychotherapy, Charité University Medicine, Campus Mitte, Berlin, Germany. juergen.gallinat@charite.de
Kunz
D
D
Lang
U E
UE
Kalus
P
P
Juckel
G
G
Eggers
J
J
Mahlberg
R
R
Staedtgen
M
M
Wernicke
C
C
Rommelspacher
H
H
Smolka
M N
MN
D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004247:DNA / Q000235:genetics; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D005838:Genotype; D006801:Humans; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic / Q000235:genetics; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000502:physiology*; D050486:Serotonin Plasma Membrane Transport Proteins; D012907:Smoking / Q000378:metabolism*
D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin; D004247:DNA