Objectives: Agmatine is a cationic amine resulting from the decarboxylation of l-arginine. Agmatine has neuroprotective, anti-inflammatory, anti-stress, and anti-depressant properties. In this study, plasma agmatine, arginine decarboxylase, and agmatinase levels were measured during manic episode and remission period in patients with bipolar disorder. Methods: Thirty healthy volunteers and 30 patients who meet Bipolar Disorder Manic Episode diagnostic criteria were included in the study. Additionally, the changes in the patient group between manic episode and remission period were examined. We evaluated the relationship between levels of l-arginine and arginine decarboxylase in the agmatine synthesis pathway, and level of agmatinase that degrades agmatine. Results: Levels of agmatine and l-arginine were significantly increased than control group during manic episode (p < .01). All parameters were increased during manic episode compared to remission period (p < .05). Agmatinase was significantly decreased both during manic episode (p < .01) and remission period (p < .05) in comparison to the control group. Arginine decarboxylase levels did not show a significant difference between the groups (p > .05). Conclusions: This study indicate that there may be a relationship between bipolar disorder and agmatine and its metabolic pathway. Nonetheless, we believe more comprehensive studies are needed in order to reveal the role of agmatine in etiology of bipolar disorder. Key points Agmantine, agmatinase, l-arginine and arginine decarboxylase levels in BD have not been explored before. Various neuro-chemical mechanisms act to increase agmatine in BD; however, agmatine could have elevated to compensate agmatine deficit prior to the manifestation of the disease as in schizophrenia. Elevated agmatine degradation resulting from excess expression of agmatinase which is suggested to be effective in pathogenesis of mood disorders was compensated by this way. Elevated agmatine may be one of the causes which play a role in mania development. Elevated agmatine levels are also suggested to trigger psychosis and be related with the etiology of manic episode and lead to BD.
Keywords: -arginine; Agmatine; agmatinase; arginine decarboxylase; bipolar disorder.