Retinal blood vessel diameter changes with 60-day head-down bedrest are unaffected by antioxidant nutritional cocktail

Tijs Louwies; Patrick De Boever; Robin Hasso; Malcom F Tremblay; Da Xu; Andrew P Blaber; Nandu Goswami

doi:10.1038/s41526-024-00443-y

Retinal blood vessel diameter changes with 60-day head-down bedrest are unaffected by antioxidant nutritional cocktail

NPJ Microgravity. 2024 Nov 15;10(1):105. doi: 10.1038/s41526-024-00443-y.

Authors

Tijs Louwies¹, Patrick De Boever^{2

3}, Robin Hasso⁴, Malcom F Tremblay⁵, Da Xu⁵, Andrew P Blaber⁶, Nandu Goswami^{7

8

9}

Affiliations

¹ Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
² Center of Environmental Sciences, Hasselt University, Diepenbeek, Belgium.
³ Antwerp University Hospital, Edegem, Belgium.
⁴ Gravitational Physiology and Medicine Research Unit, Division of Physiology and Pathophysiology, Otto Loewi Research Center of Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria.
⁵ Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada.
⁶ Aerospace Physiology Laboratory, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada. [email protected].
⁷ Gravitational Physiology and Medicine Research Unit, Division of Physiology and Pathophysiology, Otto Loewi Research Center of Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria. [email protected].
⁸ Department of Health Sciences, Alma Mater Europaea, Maribor, Slovenia. [email protected].
⁹ Center for Space and Aviation Health, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates. [email protected].

PMID: 39548129
DOI: 10.1038/s41526-024-00443-y

Abstract

Long-term human spaceflight can lead to cardiovascular deconditioning, but little is known about how weightlessness affects microcirculation. In this study, we examined how the retinal microvessels and cerebrovascular regulation of 19 healthy male participants responded to long-term head-down bedrest (HDBR), an earth-based analog for weightlessness. In addition, we examined whether an anti-inflammatory/antioxidant cocktail could prevent the vascular changes caused by HDBR. In all study participants, we found a decrease in retinal arteriolar diameter by HDBR day 8 and an increase in retinal venular diameter by HDBR day 16. Concurrently, blood pressure at the level of the middle cerebral artery and the cerebrovascular resistance index were higher during HDBR, while cerebral blood flow velocity was lower. None of these changes were reversed in participants receiving the anti-inflammatory/antioxidant cocktail, indicating that this cocktail was insufficient to restore the microvascular and cerebral blood flow changes induced by HDBR.