Protective properties of marine alkyl glycerol ethers in chronic stress.

A lymphocyte surrounded by red blood cells.

Sultanov RM, Poleshchuk TS, Ermolenko EV, and Kasyanov SP. (2023) Protective properties of marine alkyl glycerol ethers in chronic stress. Marine Drugs

Social and environmental factors can cause long-term and constant psycho-emotional stress in people. Stress and the adaptation to stress has been an important area of research since it is widely established that long-term stress can cause systemic issues in the body, including the breakdown of adaptation mechanisms and allow for the development of diseases. These diseases can target the cardiovascular system, nervous system, the gastrointestinal tract, and can cause anemias and other disorders. More and more people are affected by stress, especially chronic stress, therefore possible treatments to reduce stress and its effects are necessary. Plasmalogens are a type of lipid that contain a vinyl-ether bond at the sn-1 position which gives these lipids unique properties. They are highly abundant throughout the body and have roles in cell membranes, neuronal development and health, immune response, and act as antioxidants. Previous work has demonstrated their role as a therapeutic for cardiometabolic and neurodegenerative diseases. Following a preliminary study on alkylglycerol ethers (AGs), a plasmalogen precursor, in acute immobilization where the AGs showed an improvement, Sultanov et al wanted to determine if AGs extracted from Berryteuthis magister could be an effective treatment for chronic stress.

To complete this study, 32 Wistar rats were treated with a control treatment of water or 200 mg/kg AGs in water by oral gavage for 6 weeks. To model stress in the rats, chronic immobilization was performed by placing the rat into a plexiglass cage for two hours daily for 15 days after the 6 weeks of AGs or control treatment began. The animals were separated into four groups: a control group receiving water, a group receiving AGs treatment, a group that received water and were subjected to stress, and a final group that received AGs treatment and were subjected to stress. To determine if body weight was altered by chronic stress first body weight gain was assessed after the treatment stage and before stress was initiated. At this point, no significant difference in body weight gain was seen between the treatments, however after 15 days of stress, a significant difference was seen where chronic stress caused a reduction in body weight gain, and this was most profound after only one week of stress.

The blood lipid levels within the rats were determined at the end of the experiment. They found that the group treated with AGs and were stressed had reduced triglyceride levels. In addition, there were significant differences between the control rats and the stressed rats and the group that was treated with AGs and stressed. No differences were seen between the control treated and AGs treated animals that were not stressed, or between the animals after treatment and before the stress occurred. Fatty acid and plasmalogens levels were also assessed. Significant differences in fatty acids were not found, but there were significant differences in plasmalogens between the treatment levels. The amount of plasmalogen was shown through the ratio of 18:0 DMA to stearic acid and by the ratio of 16:0 DMA to palmitic acid. In animals treated with AGs, the concentration of 16:0 DMA (dimethyl acetal) was increased compared to the control treated animals.  

Since the immune response can also be affected by chronic stress, blood tests were also performed to determine levels of lymphocytes, a type of white blood cells in the vertebrate immune system. Here they found significant differences between the groups with lymphocyte levels being decreased in the group that experienced stress and the control treatment compared to the group with the control treatment and no stress. Also, it was shown that lymphocyte levels were increased in the AGs treated and stressed group compared to the stressed group that received control treatment. This indicated that stress reduces lymphocytes, but the AGs treatment can recover and surpass the control levels even in the presence of stress.

Sultanov et al were interested in whether a plasmalogen precursor treatment of alkylglycerol ethers could provide protection against the effects of chronic stress using a rat model. They found that chronic stress decreased body weight in the first week of stress induction but since this was not maintained to the same degree to the end of the study, the authors suggest that the animals underwent a resistance stage. Interestingly, lymphocyte levels did appear to be affected by stress, with a reduction seen in the group that received stress induction. However, this was attenuated in the animals that were treated with AGs prior to the stressor. Prolonged suppression of the immune system in a state of chronic stress is harmful to the body, so this improvement by AGs is encouraging. Further work using different plasmalogen precursors, plasmalogens themselves, different levels, and testing different stressors could provide more answers for the mechanisms involved in the role of plasmalogens in stress and the immune response.