Association of serum nitric oxide levels with depressive symptoms: a study with end-stage renal failure patients

Nitric oxide (NO) is a soluble gas produced by the activity of an enzyme found in neurons. It has been implicated in a great number of normal physiological functions (such as noradrenaline and dopamine release, memory and learning, regulation of the cerebrovascular system, modulation of wakefulness, modulation of nociception, olfaction, food intake and drinking) as well as pathologies (Alzheimer's, Huntington's disease, cerebral ischemia, stroke). Two reports have addressed the involvement of NO in depression.

The objective of the study was to examine the association between NO and specific depressive symptoms. For this purpose, in a sample of 28 end-stage renal failure patients (who have increased NO levels), we tested the hypothesis that the subgroup of patients with these specific depressive symptoms was differentiated from the patients without these symptoms with regard to serum levels of NO metabolites. The depressive symptoms were assessed using the Zung self-rating scale.

Our study revealed an association of NO with the following depressive symptoms: sexual dysfunction, weight loss, psychomotor retardation, indecisiveness and irritability.

The association between NO system and symptoms of depression does not necessarily imply a pathogenetic association between NO and depressive disorder. Further research is needed to verify these findings and study their possible pathogenetic implications.