ABSTRACT
In vitro studies have shown that multidrug resistance protein 1 (MDR1) has an affinity for cortisol; however, in vivo association studies on the relationship between MDR1 gene polymorphisms and blood cortisol levels have produced inconsistent results. Therefore, we examined the effects of the C3435T polymorphism of the MDR1 gene on blood levels of hypothalamus-pituitary-adrenal (HPA) axis hormones such as cortisol and adrenocorticotropic hormone (ACTH) in healthy subjects. The subjects comprised 30 healthy Japanese males. Ten subjects were recruited for each of the C3435T MDR1 genotypes: C/C, C/T, and T/T. Blood samples were taken at 6:00 pm on two occasions with an interval of 2 weeks. Blood levels of cortisol and ACTH were determined by an electrochemiluminescence immunoassay. There were no significant differences in the blood levels of the HPA axis hormones among the MDR1 genotypes. The present study suggests that the C3435T MDR1 polymorphism does not affect blood levels of HPA axis hormones in healthy Japanese males.
Subject(s)
Hypothalamo-Hypophyseal System/metabolism , Pituitary-Adrenal System/metabolism , ATP Binding Cassette Transporter, Subfamily B/genetics , ATP Binding Cassette Transporter, Subfamily B/metabolism , Adrenocorticotropic Hormone/blood , Adult , Alleles , Gene Frequency , Genotype , Healthy Volunteers , Humans , Hydrocortisone/blood , Japan , Male , Polymorphism, Single NucleotideABSTRACT
BACKGROUND: It has been shown that certain personality traits are related to mortality and disease morbidity, but the biological mechanism linking them remains unclear. Telomeres are tandem repeat DNA sequences located at the ends of chromosomes, and shorter telomere length is a predictor of mortality and late-life disease morbidity. Thus, it is possible that personality traits influence telomere length. In the present study, we examined the relationship of leukocyte telomere length with personality traits in healthy subjects. SUBJECTS AND METHODS: The subjects were 209 unrelated healthy Japanese who were recruited from medical students at 4th-5th grade. Assessment of personality traits was performed by the Revised NEO Personality Inventory (NEO-PI-R) and the Temperament and Character Inventory (TCI). Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene. RESULTS: In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of neuroticism (P<0.01) and conscientiousness (P<0.05) of the NEO-PI-R, and lower scores of harm avoidance (P<0.05) and reward dependence (P<0.05) of the TCI. CONCLUSIONS: The present study suggests that leukocyte telomere length is associated with some personality traits, and this association may be implicated in the relationship between personality traits and mortality.
