Chronic Treatment With Electroconvulsive Shock May Modulate the Immune Function of Macrophages Adam Roman, PhD, Dominika Nawrat, MSc, and Irena Nalepa, PhD Objective: To determine the effect of single and chronic electro- convulsive shock (ECS) administration on the immunoregulatory functions of macrophages. Methods: Male Wistar rats received single or chronic treatment with ECS (150 mA, 50 Hz, 0.5 seconds) delivered through ear clips, once a day for 10 consecutive days, or sham ECS administered likewise. The rats were killed 24 hours after the last treatment, and peritoneal macrophages were cultured in vitro for 3 or 36 hours for a subsequent determination of their metabolic activity. The ability of macrophages to reduce Alamar Blue, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl- 2H-tetrazolium bromide (MTT), and nitrotetrazolium blue chloride and pinocytosis, adherence, and vitality, as well as synthesis of nitric oxide and arginase activity, was assessed. Results: We found statistically significant changes in the biological properties of macrophages which occurred after 36 hours of incubation, especially in cultures stimulated with lipopolysaccharide; in contrast, no differences were observed between groups assessed after 3 hours of incubation. Rats receiving chronic 10-fold ECS showed a substantial increase in the metabolic activity of macro- phages, reflected as their ability to reduce Alamar Blue and MTT and to increase arginase activity, accompanied with a marked but statistically insignificant decrease in nitric oxide synthesis compared with respective controls. Conclusions: Our results suggest that chronic treatment with ECS may induce long-lasting changes in the activity of peritoneal macrophages. Attenuation of their proinflammatory properties indicates that ECS can change the primarily immunoregulatory functions of macrophages. Key Words: electroconvulsive treatment, macrophages, nitric oxide, arginase, MTT, Alamar Blue, redox status of the cells (J ECT 2008;24:260Y267) D epressive disorders are associated with the abnormal functions of the immune system and immunosuppression, as well as with the pathological activation of some immunor- eactivity indices. 1,2 Regarding macrophages, an increased number of monocytes/macrophages and their enhanced activity have been reported. On the ground of these and a wide range of other observations, a macrophage theory of depression has been proposed, 3,4 and a lipopolysaccharide (LPS)-induced animal model of depression has been devel- oped. 5,6 According to the above theory, an excessive activity of monocytes and macrophages, as well as an elevated level of their products, that is, proinflammatory cytokines, is respon- sible for the development of depressive states. The proin- flammatory cytokines are able to reach the central nervous system and to alter monoamine neurotransmission, 7 inducing depressive-like symptoms both in humans and in animal models. 8,9 Macrophages are an important part of the immune system. They play a role of effectors in innate immunity and are antigen-presenting cells which induce a specific immune response. 10 Their involvement in the regulation of adaptive immunity is also of primary importance. On the basis of some functional criteria, they can be divided into 2 subsets named M1 and M2 by analogy with the respective subpopula- tions of T-helper (T H ) lymphocytes: T H 1 and T H 2. 11Y14 The M1 macrophages support the proinflammatory immune response of the T H 1 type and show high production of nitric oxide (NO) upon stimulation with a LPS. The M2 subset reinforces the humoral-promoting T H 2 type of immune response and shows low NO production and high activity of arginase. M1/T H 1 and M2/T H 2 cells promote their own development and differentiation, as well as the respective immune response. 12,14 The functional status of macrophages is not static, and it seems to be progressively influenced by changes in their microenvironment. 15,16 Normalization of the immunological dysfunction observed in depression seems to be an important part of successful treatment in the light of the macrophage theory of depression. 3,4 Electroconvulsive therapy (ECT) is regarded as the most efficacious method of treatment of refractory depression. 17 However, little is known about the effect of ECT on the immune system. Hestad et al 18 reported ECT- induced normalization of the increased plasma level of tumor necrosis factor in depressed patients parallel to clinical improvement. It has also been shown that electroconvulsive shock (ECS), in an animal model of ECT, reduces experi- mentally induced inflammatory states in rats. 19 We previously reported that repeated administration of ECS to rats reduced the ability of their macrophages to produce NO when assessed 24 hours after the last treatment. 20 Presently, we investigated the effects of single and repeated administration of ECS on the chosen parameters of the activity of peritoneal macrophages. ORIGINAL STUDY 260 J ECT & Volume 24, Number 4, December 2008 From the Department of Brain Biochemistry, Institute of Pharmacology, Polish Academy of Sciences, Krako ´w, Poland. Received for publication November 9, 2007; accepted January 3, 2008. The study was supported by a statutory fund from the Institute of Pharmacology, Polish Academy of Sciences, Krako ´w, Poland. Reprints: Adam Roman, PhD, Institute of Pharmacology, Polish Academy of Sciences, 12 Sm<tna St, 31-343 Krako ´w, Poland (e-mail: roman@if-pan. krakow.pl). Copyright * 2008 by Lippincott Williams & Wilkins Copyright @ 2008 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.