Evidence suggests that neuroinflammation (inflammation of the nervous tissue) and oxidative stress can be significant contributing factors of Major Depressive Disorder (MDD). Patients suffering from depression can exhibit heightened levels of inflammation-causing cytokines, which are proteins that form part of the immune system. Interleukine-1β (IL-1β) is an example of one of these cytokines, it is caused to mature by the enzyme Caspase-1 in order to form an inflammatory response. Individuals with depression also show an increase in indicators of oxidative stress in the peripheral nervous system (PNS) and the central nervous system (CNS). Oxidative stress occurs when insufficient antioxidants are present to counteract the negative effects of free radicals or reactive oxygen species (ROS). Hydrogen is an effective antioxidant, which can be conveniently used in the form of hydrogen-rich water as both a preventative measure and therapeutically.
Given that conventional medicines used to treat depression are often unsuccessful and result in unpleasant side-effects for many patients, there is a need for an alternative solution. Hydrogen-rich water is not known to cause any side-effects. Therefore this experiment was carried out to investigate the impact of hydrogen-rich water on the depressive-like behaviour of male mice.
The mice were randomly split into four groups:
Hydrogen-rich water & stress
The control group and stress group were given tap water to drink while the hydrogen-rich water group and the hydrogen-rich water & stress group were supplied with hydrogen-rich drinking water. These groups were tested over four weeks using the Chronic Unpredictable Mild Stress model, meaning that those in the stress and hydrogen-rich water & stress groups were subjected to stressful situations at random intervals. Depressive behaviour, Interleukine-1β, Caspase-1 and ROS production were all measured for the four groups.
At the end of experiment, the mice in the stress group had lower body weights than those in all the other groups. The stress group also showed a significantly higher level of depressive-like behaviour. In the hippocampus and cortex (which are regions of the brain) the mice in this group also had a large increase in Interleukine-1β unlike that of any of the other groups; this was also true of the Caspase-1 levels in the hippocampus and prefrontal cortex. Chronic Unpredictable Mild Stress caused all of the mice in the stress group to produce excessive amounts of ROS in the prefrontal cortex and hippocampus. These results indicate that stress can be a contributing factor for depression.
However, those that were under stress but being given hydrogen-rich water did not show a significant increase in depressive behaviour, Interleukine-1β, Caspase-1 or ROS production. This shows that the additional hydrogen acted effectively as an antioxidant, suppressed ROS production and counteracted the effects of stress on the bodies of the mice. In turn, this significantly reduced the expression of depressive-like behaviour.
This study indicates that antioxidants can be beneficial in helping to prevent MDD and therefore hydrogen-rich water could be an effective preventative measure for depression.