Ketamine treatment protects against oxidative damage and the immunological response induced by electroconvulsive therapy.

BACKGROUND: Electroconvulsive therapy (ECT) is often recommended for major depressive disorder (MDD) for those who do not respond to the first and second antidepressant trials. A combination of two therapies could improve antidepressant efficacy. Thus, this study aimed to investigate the synergistic effects of ECT combined to antidepressants with a different mechanism of action. METHODS: Rats were treated once a day, for five days with ketamine (5 mg/kg), fluoxetine (1 mg/kg), and bupropion (4 mg/kg) alone or in combination with ECT (1 mA; 100 V). After, oxidative damage and antioxidant capacity were assessed in the prefrontal cortex (PFC) and hippocampus, and pro-inflammatory cytokines levels were evaluated in the serum. RESULTS: ECT alone increased lipid peroxidation in the PFC and hippocampus. In the PFC of rats treated with ECT in combination with fluoxetine and bupropion, and in the hippocampus of rats treated with ECT combined with ketamine and bupropion there was a reduction in the lipid peroxidation. The nitrite/nitrate was increased by ECT alone but reverted by combination with ketamine in the hippocampus. Superoxide dismutase (SOD) was increased by ECT and maintained by fluoxetine and bupropion in the PFC. ECT alone increased interleukin-1ß (IL-1ß) and the administration of ketamine was able to revert this increase showing a neuroprotective effect of this drug when in combination with ECT. CONCLUSION: The treatment with ECT leads to an increase in oxidative damage and alters the immunological system. The combination with ketamine was able to protect against oxidative damage and the immunological response induced by ECT.

Effects of microbiota transplantation and the role of the vagus nerve in gut-brain axis in animals subjected to chronic mild stress.

INTRODUCTION: Currently, there is a growing emphasis on the study of intestinal signaling as an influencer in the pathophysiology of neuropsychiatric diseases, and the gut-brain axis is recognized as a communication route through endocrine, immune, and neural pathways (vagus nerve). Studies have shown that diets that modify the microbiota can reduce stress-related behavior and hypothalamic-pituitary-adrenal axis activation. Investigators have used fecal microbiota transplantation (FMT) approaches to demonstrate that stress-related microbiota composition plays a causal role in behavioral changes. AIM: We hypothesized that FMT may present immunomodulatory, biochemical, endocrine, cognitive, and behavioral benefits in stress situations and that these changes can be mediated via the vagus nerve. METHODS: Animals were subjected to a chronic mild stress (CMS) protocol. In one experiment, animals were divided into five groups: control, control + FMT, control + FMT + CMS, CMS + saline, and CMS + FMT. The animals received FMT, and behavioral tests were performed; cytokine and carbonyl levels were measured. In a second experiment, animals were submitted to vagotomy and divided into two groups: CMS + FMT and CMS + vagotomy + FMT. RESULTS: Animals submitted to the CMS protocol or that received FMT from stressed animals showed behavioral changes and changes in neuroactive substances (increased IL-6 and TNF-α levels and carbonyl proteins). The FMT of healthy donors improved the analyzed parameters. In addition, vagotomy influenced beneficial FMT results, confirmed by behavioral testing and protein carbonyl in the hippocampus. CONCLUSION: Manipulation of the microbiota reversed the behavioral and biochemical changes induced by the CMS protocol, and the vagus nerve influenced the gut-brain axis response.

Strategies for Treatment-Resistant Depression: Lessons Learned from Animal Models.

Around 300 million individuals are affected by major depressive disorder (MDD) in the world. Despite this high number of affected individuals, more than 50% of patients do not respond to antidepressants approved to treat MDD. Patients with MDD that do not respond to 2 or more first-line antidepressant treatments are considered to have treatment-resistant depression (TRD). Animal models of depression are important tools to better understand the pathophysiology of MDD as well as to help in the development of novel and fast antidepressants for TRD patients. This review will emphasize some discovery strategies for TRD from studies on animal models, including, antagonists of N-methyl-D-aspartate (NMDA) receptor (ketamine and memantine), electroconvulsive therapy (ECT), lithium, minocycline, quetiapine, and deep brain stimulation. Animal models of depression are not sufficient to represent all the traits of TRD, but they greatly aid in understanding the mechanism by which therapies that work for TRD exert antidepressant effects. Interestingly, these innovative therapies have mechanisms of action different from those of classic antidepressants. These effects are mainly related to the regulation of neurotransmitter activity, including general glutamate and increased connectivity, synaptic capacity, and neuroplasticity.