Endocrine Abstracts

Increasing evidence indicates chronic stress plays an important role in a variety of health problems such as the development of autoimmune disease, and the results from mice studies suggest that the central endocannabinoid (eCB) system regulates endocrine and neuronal responses to stress. However, it is unclear how the eCB system responds to chronic stress in healthy humans. A 520-day isolation-and-confinement study simulating an interplanetary spaceflight mission to Mars provided an extraordinary chance to study the effects of chronic stress imposed by prolonged isolation. Six healthy males participated in this mission and stayed in the simulated spacecraft for 520 days. The current study aimed to investigate the effects of chronic stress on circulating concentrations of eCBs in these healthy subjects. Blood samples for eCBs measurements were obtained before and at regular intervals during the isolation period. Salivary samples were taken for cortisol assay. 24 h urine samples were collected for catecholamines measurements. Blood concentrations of the eCBs, N-arachidonylethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), were determined. Compared with the baseline level, stress hormone cortisol levels and urine norepinephrine secretions were significantly increased during the isolation period, indicating a stressed condition. Interestingly, stress decreased blood concentrations of 2-AG, but not AEA. Furthermore, 2-AG concentrations were negatively correlated with salivary cortisol levels. These results indicate that chronic stress decreases circulating 2-AG in healthy human subjects, suggesting dysregulation of 2-AG signalling is specifically implicated in humans under chronic stress.

Disclosure: This study was supported by grants from the German Ministry of Technology and Economics (BMWi as handled by DLR) (grant numbers 50WB0919 and 50WB1317).