Exercise Primes A Molecular Memory For Brain-Derived Neurotrophic Factor Protein Induction In The Rat Hippocampus N.C. Berchtold, et. Al.

BDNF Enhances synaptic transmission and neuronal excitability with upregulation of gene expression Modulates synaptic change such as LTP in the hippocampus –Deficiencies have shown to exhibit learning deficits Essential survival factor and neuroprotectant

Impaired BDNF Factors in Alzheimer’s Mood and Eating disorders –Such as Depression

BDNF Benefits of Exercise Increased available BDNF for neuronal survival and resistance to brain insults Enhanced neurogenesis and LTP Increased resistance to Depression Lower risks of Alzheimer’s and dementia Allows for a lower threshold for theta- pattern stimulation for LTP

3 Questions of the Study 1.How do hippocampal BDNF protein levels respond to intermittent exercise? 2.Do BDNF protein levels remain elevated or decline rapidly to baseline? 3.How does a second exercise exposure regulate BDNF after levels have decayed to baseline?

Experiments Adult male Sprague-Dawley rats –7 to 8 weeks old –150 to 200 grams Food and water ad libitum 12 hr light/dark cycle

Levels of BDNF Either continuous daily access to running wheel and terminally sampled at 2, 4, 7, 14, 28, or 90 days.

Levels of BDNF Or intermittent access on alternating days of 7, 14, 21, or 28 days.

Stability of elevated BDNF 4 weeks of running, wheel locked and sampled at 0, 1, 3, 7, and 14 days.

Reintroduction of BDNF Determining if BDNF levels are related to absolute number of running days 14 days of priming run – continuous –intermittent 1 or 2 week of rest A second test exercise of 2 days of running

Reintroduction of BDNF 2 weeks of daily running with either 1 week of rest Or 2 weeks of rest

Reintroduction of BDNF 4 weeks of intermittent running –1 week of rest –2 weeks of rest

Results

BDNF daily vs. intermittent Continued to rise even for 90 days 222% 174% 150%

BDNF daily vs. intermittent Similar increase, but slower rate 159% 145% 124%

BDNF has a time component that interacts with the exercise stimulus Intermittent training is ultimately as effective as daily training to elevate BDNF

BDNF elevated BDNF sampled at 0, 1, 3, 7, and 14 after 28 days of exercise BDNF sampled at 0, 3, and 7 days after 28 day period of alternating days of exercise

BDNF elevated Gradually declines, but slight rise at 7 days 151% 128% 133%

BDNF elevated Levels no longer significant after 3 days 160%

BDNF “Memory” Daily runners –Sedentary –2 days of running –14 days of running –14 days of running with 7 days rest –14 days of running with 7 days rest + 2 days running –14 days running with 14 days rest –14 days running with 14 days rest + 2 days running

BDNF “Memory” Test run stimulates higher levels of BDNF

BDNF “Memory” Test run stimulates higher level, but takes longer to reach

Discussion 1.Intermittent exercise as effective as daily exercise to increase BDNF Progressively increase with longer running duration Induction of BDNF has time component that interacts with exercise stimulus

Paul A. Adlard Article Significant increase in running at 4 weeks

Paul A. Adlard Article Shows that BDNF levels closely linked to level of activity as increases over 28 days

Discussion 2.BDNF levels remain elevated for several days Absolute amount of running days is important in regulating rate of decline

Discussion 3.BDNF is rapidly reinduced by brief exercise exposure, creating “molecular memory” May increase the conversion of precursor to BDNF or, May increase pool of available BDNF precursor

Jay’s Question’s Is the length or duration of each daily session have an effect on levels? Does the intensity of exercise during the session have an effect?