Effects of Prolonged Exercise on Angiogenesis in Macaque Monkey Hippocampus
Exercise has been shown to positively affect cognition and reduce the symptoms of Alzheimer's disease and depression, conditions associated with the hippocampus. Yet the mechanisms by which exercise promotes healthy hippocampal function are poorly understood. Exercise is known to upregulate neurogenesis, trophic factor expression, and gliogenesis in the hippocampus. However, it is unknown whether exercise induces angiogenesis in the hippocampus. This study aims to find if prolonged physical exercise increases angiogenesis in the macaque monkey hippocampus, and whether the same effect is seen in aging monkeys. Twenty-four female monkeys (Macaca facicularis) were divided into 3 groups. The first two groups ran on a treadmill for one hour a day at 80% maximum heart rate, 5 days a week, for 20 weeks. The second group had a 12-week sedentary period after this exercise regimen. The third group was an inactive control. Half the monkeys in each group were middle-aged (10-12 yrs) and half were older (15-17 yrs). Immunohistochemistry for CD31 was performed on coronal sections containing the hippocampus, and capillaries were counted using the area fraction fractionator procedure with Stereo Investigator software. Contrary to our hypothesis, our data did not show that exercise increased angiogenesis in the dentate gyrus or in the hippocampus proper. Future studies should examine individual layers of the hippocampus proper, such as the capillary-dense stratum lacunosum moleculare, for small increases in capillary density that may have been overlooked when examining the hippocampus proper as a whole.
School:
Massachusetts Institute of Technology
Department:
Biological Engineering
Research Advisor:
William Greenough
Department of Research Advisor:
Neuroscience
Year of Publication:
2007