Are mitochondrial energetics in the rat under control of the solar (24 hours) and/or lunar (24.8 hours) day?

This study aims at examining whether brain, liver and myocardial mitochondrial respiration, coenzyme Q, and oxidative phosphorylation follow a circadian and/or a lunar pattern. In different groups of Wistar rats sampled at 6 different circadian stages in relation to the regimen of 12 hours of light alternating with 12 hours of darkness, different parameters of the mitochondrial respiratory chain were determined, namely State 3 (S3), State 4 (S4), the rate of ATP production (OPR), the oxidation-phosphorylation coupling (ADP:O), the respiratory control index (RCI), and the fundamental components of mitochondrial respiratory chain CoQ_9-OX and CoQ_10-OX. To each data series, two different models were fitted by cosinor: one consisted of cosine curves with periods of 24 and 12 hours, representing the circadian variation (“solar day“); the other consisted of cosine curves with periods of 24.8 and 12.4 hours, representing a putative influence from the Moon (“lunar day“). The variance accounted for by each model served to assess the relative influence of the Sun and Moon on mitochondrial function. Results are discussed from a methodological perspective in the light of available evidence of lunar influences on biota, the senior author’s lifetime research focus.