The Impact of Seasonal Fluctuations on Rat Liver Mitochondria Response to Tested Compounds— A Comparison between Autumn and Spring. New Insight into Collecting and Interpretation of Experimental Data Originating from Different Seasons

Abstract

Seasonal variations play an essential role in the metabolism, behavior and activity of the laboratory animals. This study was aimed to examine whether mitochondrial function can be influenced by the seasonal changes and how large is the impact of these fluctuations on experiments with using animal models and further results interpretation. Liver mitochondria were isolated from male Wistar rats and exposed to calcium ions, PAMAM dendrimers G2.5 or their combination: (Ca2+) and dendrimer. The scientific hypothesis assumed that dendrimer G2.5 is able to limit the detrimental effect of Ca2+ ions on mitochondria function, possibly through affecting the following parameters: calcium transport, mitochondrial potential and membrane fluidity. The activity of mitochondria was monitored using fluorescent labels. The changes in calcium transport were detected using Calcium Green 5-N, the mitochondrial membrane potential and membrane fluidity were elucidated using JC-1 and DPH, respectively. The experiments were carried out during the autumn (October/November) or during the spring (May/June). The obtained data emphasize the effect of seasonal differences on liver mitochondria originating from laboratory animals and outline the importance of planning the experiments during the same seasonal period in order to receive objective and reliable results in the future. Finally, it was revealed the neutral effect of G2.5 dendrimer on mitochondria and its inability to protect mitochondria against overload of calcium ions regardless of seasonality. It was also evidenced that liver mitochondria isolated from autumn-derived animals were more sensitive to calcium and/or dendrimer exposure in comparison with mitochondria isolated from animals investigated during the spring.