Chapter 4 Hormonal Changes in Humans During Spaceflight

Publisher Summary This chapter focuses upon general endocrine pathophysiology in humans. Animal studies will be referred to only where needed, for a more complete picture of any of the topics discussed. Nevertheless, animal studies are very important to help in aiming human research protocols, to try and verify some hypotheses, and to confirm results obtained in the still too few astronauts available for experiments in flight. This chapter deals only marginally with chronobiology and melatonin, a hormone produced by the pineal gland, which may be considered as an internal clock. An important point is that some endocrine systems seem to undergo changes in space that resemble those observed during senescence, but after spaceflight, recovery always occurs within weeks or months after return. Further space research may help us find new insights in the pathophysiology of aging, and hopefully define novel preventive and therapeutic strategies for extending healthy life on Earth.