["Altered nitric oxide (NO) signaling has been associated with the pathophysiology of Bipolar Disorder (BD), directly affecting neurotransmitter release and synaptic plasticity cascades. Lithium has shown to regulate NO levels in preclinical models. However, no study has addressed peripheral NO levels in unmedicated BD. Also, lithium's effects on NO levels have not been studied in humans.", 'Plasma NO was evaluated in subjects with BD I and II during a depressive episode (n\xa0=\xa026). Subjects had a score of ≥18 in the 21-item Hamilton Depression Rating Scale and were followed-up during a 6-week trial with lithium. Plasma NO levels were also compared to matched healthy controls (n\xa0=\xa028). NO was determined by chemiluminescence method.', 'Lithium treatment significantly increased plasma NO levels after 6 weeks of treatment in comparison to baseline levels in bipolar depression (p\xa0=\xa00.016). Baseline NO levels during depressive episodes showed no difference when matching up to healthy controls (p\xa0=\xa00.66).'] Does lithium increase nitric oxide levels in subjects with bipolar disorder during depressive episodes?