Depression, Cardiovascular Disease and Amino Acids

• Author / Creator

  Hess, Scott L

• Major depression (MD) is one of the most prominent medical conditions worldwide in terms of societal cost and morbidity. MD has been associated with increased risk for cardiovascular disease (CVD) and conversely CVD has been associated with increased MD symptoms. Previous studies have shown that serum levels of nitric oxide (NO) were reduced in MD patients and in patients with CVD. We measured serum levels of arginine, the precursor amino acid of NO and found that they were reduced in MD subjects compared to healthy controls (HCs). Similarly, levels of citrulline, an amino acid formed during the formation of NO from arginine, were reduced. These results suggest that reduced levels of arginine may be contributing to the reduced NO observed in MD subjects. Dysfunction of the arteries has been identified as a precursor of CVD risk and has been proposed to be related to decreased NO. We hypothesized that endothelium function would be impaired in MD patients compared to HCs. Endothelial function was examined but no differences were observed between the two groups. It may be the case that despite risk of CVD being increased in MD patients, impaired endothelial dysfunction may not be observable. A variety of other amino acids proposed to be important in neurotransmission and the etiology of MD were measured in a population of unmedicated MD subjects and HCs matched for age, sex, dietary intake and lipid profiles; smokers and obese subjects were not included (similar conditions applied in the two studies mentioned above). Cysteine and histidine levels were elevated in the MD group. When male MD subjects were compared to their corresponding controls, the decreases in levels of arginine and citrulline were present, as was the increase in levels of cysteine, but levels of taurine, aspartate, glutamine and tryptophan were also significantly lower in MD subjects. In contrast, when female MD subjects were compared with their corresponding HCs, the differences were not significant. These results emphasize the importance of studying both male and female subjects and their corresponding controls when conducting such biomarker studies.

• Subjects / Keywords

  • Cardiovascular diseases
  • Major Depression

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3FT8DR6X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.