ABSTRACT
Caffeine (1, 3, 7-trimethylxanthine), is a well-known purine alkaloid, described by Gennaro as a white, odorless powder with a slightly bitter taste. Physical exercise is a known factor that can promote oxidative stress and may result in cellular damage if not neutralized by antioxidant mechanisms. Oxidative stress is the imbalance between the oxidizing processes and intracellular antioxidants. The aim of this study is to investigate the combined effect of exercise and ingestion of vary doses of caffeine on oxidative stress markers and histology of the lungs of the adult wistar rats. Forty (40) rats weighing between 180-200g were randomly assigned after two (2) weeks acclimatization period into eight (8) groups of five (5) rats each (n=5). Each group were treated as follows: Group 1 (control), Group 2 (20mg/kg caffeine), Group 3 (40mg/kg caffeine), Group 4 (80mg/kg caffeine), Group 5 (20mg/kg caffeine + exercise), Group 6 (40mg/kg caffeine + exercise), Group 7 (80mg/kg caffeine + exercise) and Group 8 (exercise only). Caffeine was administered orally via gavage and the exercise protocol was carried out on a treadmill machine at the speed of 3m/min for 10 minutes at 0% inclination. 2 hrs post caffeine administration and exercise protocol, blood and lungs samples were collected for oxidative stress markers assay and histological processing via cardiac puncture and thoraco-abdominal incision respectively. Images were captured with an MW1- HD2 digital microscope at magnification of ×100 and ×400. Statistical analysis was carried out using the Graph Pad Prism statistical software version 8.1, comparison between groups were done using one-way ANOVA. The results were presented as Mean ±SEM and P-value less than 0.05 (P<0.05) was considered statistically significant. The result showed significant increase in Malondialdehyde (MDA) in the combined 20kg/mg caffeine and exercise group when compared with the control. There were significant decrease in Glutathione Peroxidase (GPx), Reduced Glutathione (GSH), Catalase (CAT) and Superoxide Dismutase (SOD) in the combined 20mg/kg caffeine and exercise group compared with the control. There were no significant difference in MDA, GPx, GSH, CAT and SOD in other groups when compared with the control. The histological finding of the lungs of Group 1 (Control) revealed normal tissue architecture of the lungs such as alveoli, terminal bronchiole, bronchial artery and interstitial spaces. Histological findings of Group 2, 3, and 4 showed activation of the interstitial cells of mononuclear phagocyte system, bronchiolar ulcerations, bronchiolar haemorrhages, alveolar haemorrhages and interstitial haemorrhages. The histological finding of the lungs of Group 7 revealed normal alveoli, bronchial artery and activated bronchiolar alveolar lymphoid aggregate. Exercise was able to attenuate the ulcerations and haemorrhages in the alveolar and bronchioles respectively which could be linked to caffeine. The histological finding of the lungs of group 8 showed normal tissue architecture of the lungs. In conclusion, the findings of this study indicates that caffeine at 20mg/kg, 40mg/kg, combined 20mg/kg and exercise induces oxidative stress which causes activation of the interstitial cells of mononuclear phagocyte system, ulcerations and haemorrhages in the bronchiolar and alveolar cells of the lungs while exercise was able to attenuate the ulcerations and haemorrhages in the bronchiolar and alveolar cells of the lungs.
