In vivo imaging with a water immersion objective affects brain temperature, blood flow and oxygenation
- Université Paris Descartes, France
- University of Zurich, Switzerland
Abstract
Previously, we reported the first oxygen partial pressure (Po2) measurements in the brain of awake mice, by performing two-photon phosphorescence lifetime microscopy at micrometer resolution (Lyons et al., 2016). However, this study disregarded that imaging through a cranial window lowers brain temperature, an effect capable of affecting cerebral blood flow, the properties of the oxygen sensors and thus Po2 measurements. Here, we show that in awake mice chronically implanted with a glass window over a craniotomy or a thinned-skull surface, the postsurgical decrease of brain temperature recovers within a few days. However, upon imaging with a water immersion objective at room temperature, brain temperature decreases by ~ 2-3{degree sign}C, causing drops in resting capillary blood flow, capillary Po2, hemoglobin saturation, and tissue Po2. These adverse effects are corrected by heating the immersion objective or avoided by imaging through a dry air objective, thereby revealing the physiological values of brain oxygenation.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Emmanuelle Chaigneau
Funding
Leducq Foundation (Understanding the role of the perivascular space in cerebral small vessel disease)
- Morgane Roche
ERC (Imaging-in-the-Magnet)
- Bruno Weber
The funders had no role in the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in strict accordance with the recommendations by Inserm.All animal care and experimentation were performed in accordance with the INSERM Animal Care and Use Committee guidelines (protocol numbers CEEA34.SC.122.12 and CEEA34.SC.123.12).
Copyright
© 2019, Roche et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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In vivo imaging with a water immersion objective affects brain temperature, blood flow and oxygenation
eLife 8:e47324.
https://doi.org/10.7554/eLife.47324
