Researcher Department of Sports Medicine and Science in Graduate School, Konkuk University Seoul, Republic of Korea
Hippocampal neurogenesis plays an important role in learning and memory. Healthy hippocampal environment is also necessary for improvement of its cognitive function. Therefore, enhancing of both hippocampal neurogenesis and environment is required to prevent or ameliorate neurodegenerative statements.
Exercise is powerful enhancer of both, and it is considered that the exercise effects are resulted from alterations in brain (central mechanism), also in soma, i.e., skeletal muscle, (somatic mechanism). Yet the exact mechanism is unclear.
Lactate, known as just byproduct of glycolysis and primary factor of fatigue when exercise, is highlighting as a promising signaling molecule that mediates the exercise effects on hippocampus. In this perspective, exercise training with intake of lactate can be remarkable strategy for strengthening the exercise effects on hippocampus.
Therefore, the purpose of the current study is to investigate whether combination of exercise and lactate intake can additively enhance exercise-induced hippocampal neurogenesis and neurotrophic factors.
The study was conducted for 5 weeks using 4 groups of mice: CON (vehicle group), LAC (oral administration of 3g/kg lactate 5days/week), EXE (mid-intensity exercise 5days/week), and EXE+LAC (lactate administration immediately after every exercise). At the last week of experiment, cognitive function was evaluated by Y-maze spontaneous alternation test. After the experiment ended, hippocampal neurogenesis (Ki67, neural stem cell proliferation marker; DCX, marker of differentiation to immature neurons) and neurotrophic factors (PGC1α, FNDC5, VEGFA, and BDNF) were evaluated respectively by immunohistochemistry (IHC) and by Western blot (WB) on hippocampus.
From the IHC results, exercise training significantly increased the number of Ki67 and DCX positive cells (p = 0.001 and p = 0.004 respectively) which were also increased in LAC than CON (p = 0.064 and p = 0.03 respectively). There was no difference in Ki67 and DCX positive cells between EXE and EXE+LAC. From the WB results, however, FNDC5 of EXE+LAC was significantly higher than that of EXE (p = 0.005). BDNF and PGC1α of EXE+LAC was higher than that of EXE respectively by 20% and 9% (but not significant). There was no difference in VEGFA between EXE and EXE+LAC. From the Y-maze test results, interestingly, while there was no difference in the performance between CON and LAC, the performance of EXE+LAC was significantly enhanced than that of EXE (p = 0.006). In conclusion, combination of exercise training and lactate intake additively promoted the performance of spontaneous alternation test and tended to additively enhance exercise-induced neurotrophic factors, but not hippocampal neurogenesis. Therefore, the study revealed the potential that exercise training with oral intake of lactate can be remarkable strategy for strengthening the exercise effects on hippocampus.
