Oxidative and nitrosative stress in bipolar affective disorder and its familial aggregation.

Introduction: Bipolar disorder (BD) is one of the most encountered disorders in psychiatric clinics. Despite extensive research and advancements in BD treatment, little is known about the disease's primary etiopathogenesis and relationship with different pathophysiological traits. The present study is aimed to evaluate the pathophysiological role of oxidative and nitrosative stress in BD patients and identify their familial aggregation.

Methods: Blood samples from healthy individuals, drug-naive symptomatic BD patients, and their first-degree relatives were obtained, and intracellular reactive oxygen/nitrogen species (ROS/RNS), total nitrites, neuronal nitric oxide synthase (nNOS) mRNA expression, myeloperoxidase (MPO) activity in polymorphonuclear neutrophils (PMNs), and serum cortisol levels were assessed.

Results: ROS, MPO activity, total-nitrite content, nNOS expression in PMNs, and serum cortisol concentration were considerably more in BD patients than in healthy volunteers. All these variables showed a substantial correlation with the YMRS score for disease severity and the presence of one or more manic episodes. Additionally, a positive correlation was noted between the MPO activity and serum cortisol levels of BD patients and their first-degree relatives.

Conclusions: The results of the present study advance our knowledge about the role of oxidative and nitrosative stress in BD pathophysiology and its familial aggregation. Additionally, the study demonstrates a direct correlation between the disease severity and levels of ROS/RNS, MPO, total nitrite, and nNOS transcripts in PMNs. However, future research with larger and more diverse participant populations is required to understand these pathways for use as potential biomarkers for a deeper understanding of BD pathophysiology and to improve therapeutic strategies.