Search

P-glycoprotein, which is encoded by the multidrug resistance 1 (MDR1) gene, serves as a barrier to entry and as an active elimination for xenobiotics and cellular metabolites including cortisol, which is implicated in multiple brain functions. Meanwhile, previous studies suggested that genetic factors and cortisol are involved in formation of interpersonal sensitivity, a personality trait predisposing to depression. In the present study, we examined the effects of the C3435T MDR1 polymorphism on interpersonal sensitivity. The subjects were 842 healthy Japanese volunteers. The mean age ±SD of the subjects was 26.7±8.1 (490 males and 352 females). The C3435T polymorphism of MDR1 gene was detected by a PCR method, and interpersonal sensitivity was assessed by the Interpersonal Sensitivity Measure (IPSM). In total subjects, the C allele of the C3435T MDR1 polymorphism was associated with higher scores of the IPSM. In females the C/C genotype group had higher IPSM scores than the C/T genotype group and the T/T genotype group, and the C/T genotype group had higher IPSM scores than the T/T genotype group. In males no significant association was found between the MDR1 genotype and the IPSM scores. The present study suggests that the C3435T polymorphism of the MDR1 gene affects formation of a depression-prone personality trait in Japanese females. [ABSTRACT FROM AUTHOR]

Interpersonal sensitivity is defined as undue and excessive awareness of, and sensitivity to, the behavior and feelings of others and is one of the vulnerable factors to depression. In a twin study, it was suggested that this personality trait was characterized by both genetic and environmental factors. In the present study, we examined the effects of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on interpersonal sensitivity. The subjects were 725 unrelated healthy Japanese volunteers (mean age±SD=27.1±8.5, 405 males and 320 females). Assessment of interpersonal sensitivity was performed by the Japanese version of the Interpersonal Sensitivity Measure (IPSM). Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. The BDNF polymorphism was detected by the PCR-RFLP method. There was no main effect of the BDNF genotype on the IPSM score, while the PBI factors except maternal care had significant main effect on the IPSM score. There was significant interaction effect between the BDNF genotype and maternal care of the PBI on the IPSM score. Post-hoc analysis of simple slopes showed that the negative relationship between the IPSM score and maternal care was strongest and significant in the Met/Met genotype group, intermediate in the Val/Met genotype group, and weakest in the Val/Val genotype group. The present study suggests that the interaction between the BDNF Val66Met polymorphism and parental rearing, especially maternal care, influences interpersonal sensitivity in healthy subjects. [ABSTRACT FROM AUTHOR]

It has been reported 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. The subjects were 209 unrelated physically healthy Japanese who were recruited from medical students at 4th-5th grade. None had psychiatric disorders. 128 subjects were males, and 81 were females. The mean±SD (range) of age was 23.3±1.7 (20-30) years. Personality traits were assessed 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. In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of Neuroticism (β=0.208, p<0.01) and Conscientiousness (β=0.146, p<0.05) of the NEO-PI-R, and lower scores of Harm avoidance (β=0.144, p<0.05) and Reward dependence (β=0.170, p<0.05) of the TCI. 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. [Copyright &y& Elsevier]