Russian scientists have found three genes, which affect neurotransmitter dopamine, thus having a link to the feeling of fatigue.
      
      Brain activity is regulated by neurotransmitters, which depend on genes. Researchers studied three genes DAT1, DRD2 and COMT, which influenced dopamine concentration in brain.
      
      140 volunteers – 70 males and 70 females – participated in the experiment – they spent three hours solving logical tasks and tests. Before and after this monotonous work, volunteers were asked whether they felt tired. Then DNA was extracted from venous blood, and nucleotide sequences of mentioned genes were determined.
      
      Females with genes, which provided excess of dopamine in striatum and prefrontal brain cortex, claimed to have felt more exhausted than other people before and after tests. Same results were obtained for health, activity and mood. As for males, they showed less obvious correlation between dopamine, fatigue and other parameters.
      
      Researchers think that dopaminergic system is also affected by sex hormones, especially estrogen. Sex hormones are possibly another fatigue-affecting factor.
      
      Source: Science & Technologies