Browsing by Subject "fasting"

Current treatments for major depressive disorder have notable limitations including the delay achieving the therapeutic effect. Ketamine has been shown to alleviate the symptoms of depression rapidly and promising findings have also been found when using nitrous oxide. However, the mechanisms behind rapid antidepressant effect are not fully discovered. It seems that rapid-acting treatments alter brain energy metabolism, enhance synaptic plasticity, and repair neuronal dysfunction connected to depression. Particularly, the activation of brain derived neurotrophic factor (BDNF) mediated tropomyosin receptor kinase B (TrkB) signaling has been connected to rapid antidepressant effect. Fasting is also known to induce BDNF production and it is thought to activate BDNF-TrkB signaling. In addition, both of these treatments alter the brain energy metabolism. The objective of this study was to find out how fasting and nitrous oxide alone and in combination affect the rapid antidepressant effect and synaptic plasticity related BDNF-TrkB signaling in mice. Another aim of the research was to determine whether the body temperature changes after these treatments as a marker of metabolic rate. The analyzed brain samples of the mice were collected 15 minutes after cessation of nitrous oxide administration. As a result, it was found that the fasting protocol used in this study did not activate the studied BDNF-TrkB signaling. However, after nitrous oxide administration, the studied signaling and markers related to synaptic plasticity were partly activated. The results from the combination of nitrous oxide and fasting were similar compared to nitrous oxide administration only. It is therefore conceivable, that the effects were caused exclusively by nitrous oxide. Furthermore, a fascinating finding related to energy metabolism was that nitrous oxide reduced the body temperature of the mice significantly 15 minutes after cessation of the gas administration. Overall, these results are promising and consistent with previous research indicating that nitrous oxide administration could be related to induced synaptic plasticity and therefore have antidepressant associated effects. Nitrous oxide could be used to understand the mechanisms behind rapid antidepressant effect and it could be a potential option to treat depression in the future. Based on these results, it seems that energy metabolism could be related to rapid antidepressant effect. It also supports the observations that all different rapid-acting treatments alter the brain energy metabolism.