Effects of Near-Infrared Light on Cerebral Bioenergetics Measured with Phosphorus Magnetic Resonance Spectroscopy.

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Effects of Near-Infrared Light on Cerebral Bioenergetics Measured with Phosphorus Magnetic Resonance Spectroscopy.

Photomed Laser Surg. 2017 Feb 09;:

Authors: Mintzopoulos D, Gillis TE, Tedford CE, Kaufman MJ

Abstract
OBJECTIVE: Cerebral photobiomodulation (PBM) improves mood and cognition. Cerebral metabolic enhancement is a mechanism proposed to underlie PBM effects. No PBM studies to date have applied phosphorus magnetic resonance spectroscopy ((31)P MRS), which can be used to assess metabolic intermediates such as phosphocreatine (PCr) and adenosine triphosphate, the latter of which is elevated by PBM. Accordingly, we used 9.4 Tesla (31)P MRS to characterize effects of single and repeat cerebral PBM treatments on metabolism. PBM was delivered to healthy adult beagles in the form of transcranial laser treatment (TLT) at a wavelength of 808 nm, which passes safely through the skull and activates cytochrome C oxidase, a mitochondrial respiratory chain enzyme.
METHODS: Isoflurane-anesthetized subjects (n = 4) underwent a baseline (31)P MRS scan followed by TLT applied sequentially for 2 min each to anterior and posterior cranium midline locations, to irradiate the dorsal cortex. Subjects then underwent (31)P MRS scans for 2 h to assess acute TLT effects. After 2 weeks of repeat TLT (3 times/week), subjects were scanned again with (31)P MRS to characterize effects of repeat TLT.
RESULTS: TLT did not induce acute (31)P MRS changes over the course of 2 h in either scan session. However, after repeat TLT, the baseline PCr/β-nucleoside triphosphate ratio was higher than the scan 1 baseline (p < 0.0001), an effect attributable to increased PCr level (p < 0.0001).
CONCLUSIONS: Our findings are consistent with reports that bioenergetic effects of PBM can take several hours to evolve. Thus, in vivo (31)P MRS may be useful for characterizing bioenergetic effects of PBM in brain and other tissues.

PMID: 28186868 [PubMed - as supplied by publisher]

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