Wheel Running and Wheel Running and Fluoxetine Antidepressant Fluoxetine Antidepressant

Treatment Have Differential Treatment Have Differential Effects in the Hippocampus Effects in the Hippocampus

and the Spinal Cordand the Spinal Cord

C. Engesser-Cesar, A. J. C. Engesser-Cesar, A. J. Anderson, and C. W. CotmanAnderson, and C. W. Cotman

HypothesisHypothesis

Exercise and antidepressants Exercise and antidepressants independently increase hippocampus independently increase hippocampus (BDNF) and neurogenesis.(BDNF) and neurogenesis.

Effects are on BDNF synergistic Effects are on BDNF synergistic

Background InformationBackground Information

Brain-derived neurotrophic factor Brain-derived neurotrophic factor (BDNF) is capable of mediating the (BDNF) is capable of mediating the beneficial effects of exercise on brain beneficial effects of exercise on brain plasticity, supports the health and plasticity, supports the health and functioning of glutamatergic functioning of glutamatergic neurons, promotes differentiation, neurons, promotes differentiation, neurite (process) extension, and the neurite (process) extension, and the survival of a variety of neuronal survival of a variety of neuronal populations (1).populations (1).

Exercise ImprovesExercise Improves

Various neurological conditionsVarious neurological conditions• Age-related neurodegenerationAge-related neurodegeneration• DepressionDepression• Alzheimer’s diseaseAlzheimer’s disease• Traumatic brain injury Traumatic brain injury • Spinal cord injurySpinal cord injury

AnimalsAnimals

C57BL/10 female mice (n=112)C57BL/10 female mice (n=112) 2 months old2 months old Acclimatized for 1 week, 7 days of Acclimatized for 1 week, 7 days of

antibiotic adminantibiotic admin Excluded for difficulty with wheel runningExcluded for difficulty with wheel running Food and water ad libitumFood and water ad libitum 12h light/dark cycle12h light/dark cycle Randomly assigned Randomly assigned

AnimalsAnimals

No Wheel Running Wheel Running

Control Control

5mg/kg fluoxetine 5mg/kg fluoxetine

10mg/kg fluoxetine 10mg/kg fluoxetine

25mg/kg fluoxetine 25mg/kg fluoxetine

• 14 animals/group

Methods and MaterialsMethods and Materials

Methods and MaterialsMethods and Materials

21 days of fluoxetine treatment21 days of fluoxetine treatment• With or without wheel runningWith or without wheel running

Daily i.p. injectionsDaily i.p. injections 6 animals from each group got BrdU 6 animals from each group got BrdU

injections on final 7 daysinjections on final 7 days Killed 24h after last fluoxetine Killed 24h after last fluoxetine

injectioninjection Staggered over 4 days (estrous)Staggered over 4 days (estrous)

FluoxetineFluoxetine

Decreased running distanceDecreased running distance High dose group ran significantly less by High dose group ran significantly less by

the end of the experimentthe end of the experiment Increased weight gainIncreased weight gain

Exercise and FluoxetineExercise and Fluoxetine Together, increase cell proliferation and survival Together, increase cell proliferation and survival

in the hippocampusin the hippocampus

IGF-1: positively linked to hippocampal IGF-1: positively linked to hippocampal neurogenesisneurogenesis• Seen with: Exercise-mediated recovery from traumatic Seen with: Exercise-mediated recovery from traumatic

brain injury brain injury Fluoxetine administration Fluoxetine administration

BDNF: positively linked to hippocampal BDNF: positively linked to hippocampal neurogenesisneurogenesis• is activated more rapidly when used in combination is activated more rapidly when used in combination with exercise and antidepressants (Cotman 2002)with exercise and antidepressants (Cotman 2002)

Spinal CordSpinal Cord

Examined rostral, thoracic, lumbar Examined rostral, thoracic, lumbar Spinal cord IGF-1 protein did not change Spinal cord IGF-1 protein did not change

with wheel running, and decreased with with wheel running, and decreased with fluoxetine (high dose)fluoxetine (high dose)

Cytogenesis also decreased with Cytogenesis also decreased with fluoxetine (dose dependent)fluoxetine (dose dependent)

BDNF did not change in rostral or lumbar BDNF did not change in rostral or lumbar after running or fluoxetine treatmentafter running or fluoxetine treatment

Wheel running and fluoxetine did not Wheel running and fluoxetine did not protect against spinal cord injuryprotect against spinal cord injury

Rostral Cord

Lumbar Cord

Thoracic Cord

Effects of exercise and fluoxetine Effects of exercise and fluoxetine on spinal cordon spinal cord

IGF-1 protein significantly decreased IGF-1 protein significantly decreased with administration of fluoxetinewith administration of fluoxetine

No neurogenesisNo neurogenesis Decreased cytogenesisDecreased cytogenesis

Spinal Cord InjurySpinal Cord Injury

No benefit for pre-injury exercise for No benefit for pre-injury exercise for SCI recoverySCI recovery

Post-injury exercise and/or fluoxetine Post-injury exercise and/or fluoxetine may be protective may be protective (not explored here)(not explored here)• Trophic factors or cytogenesis could be Trophic factors or cytogenesis could be

a recovery mechanisma recovery mechanism Decreased BrdU in spinal cord ??Decreased BrdU in spinal cord ??

ResultsResults

In the hippocampus fluoxetine In the hippocampus fluoxetine increases BDNF, cytogenesis, and increases BDNF, cytogenesis, and neurogenesisneurogenesis• Dose dependentDose dependent

ResultsResults

BDNF was not induced by exerciseBDNF was not induced by exercise• but increased by fluoxetinebut increased by fluoxetine

Hippocampal IGF-1 protein not affected by Hippocampal IGF-1 protein not affected by fluoxetine, exercise, or bothfluoxetine, exercise, or both

Fluoxetine decreased IGF-1 protein in all Fluoxetine decreased IGF-1 protein in all three regions of the spinal cordthree regions of the spinal cord

ResultsResults

Decreased trend of BrdU positive Decreased trend of BrdU positive cells in exercise animalscells in exercise animals

Fluoxetine also decreases BrdUFluoxetine also decreases BrdU

Decrease in cell proliferationDecrease in cell proliferation

BDNF and Serum IGF1BDNF and Serum IGF1

IGF1 hippocampal results

Neurogenesis and CytogenesisNeurogenesis and Cytogenesis

BrdU represents new cells

DCX represents new neurons

a

Control animal, cytogenesis and neurogenesis in the hippocampus

b

Wheel running with 25mg/kg fluoxetine dose animal, cytogenesis and neurogenesis

in the hippocampus

Neurogenesis and cytogenesis results

Increased dentate granule cell layer DCX increases, not BrdU with

fluoxetine Fluoxetine and exercise combined no Fluoxetine and exercise combined no

effect on cytogenesis or neurogenesiseffect on cytogenesis or neurogenesis

Cell numerical density

De Foubert GraphDe Foubert Graph

Four days of Prozac

De Foubert GraphDe Foubert Graph

Seven days of Prozac

De Foubert GraphDe Foubert Graph

Fourteen days of Prozac

De Foubert resultsDe Foubert results

Herein, 21 days of wheel running and Herein, 21 days of wheel running and fluoxetine administration increased fluoxetine administration increased BDNF cells in hippocampusBDNF cells in hippocampus

Dependent on length of treatmentDependent on length of treatment

Discussion

Exercise or fluoxetine did not increase IGF-1 as previously seen

No change in BDNF protein with exercise in female mice

Gender, strain, or amount of exercise could effect BDNF protein

High dose fluoxetine increased hippocampal BDNF protein

Discussion

Wheel running did not effect BDNF in hippocampus

Exercise and fluoxetine may use different mechanisms for BDNF increase

No change in IGF-1 in hippocampus High dose fluoxetine increased

cytogenesis and neurogenesis in hippocampus

Discussion

No increase in BDNF in spinal cord

High dose fluoxetine decreased IGF-1

No increase cytogenesis/neurogenesis in spinal cord with any treatment

No pre-injury exercise helped SCI

Conclusion

Fluoxetine increased BDNF, cytogenesis, and neurogenesis in the hippocampus

Fluoxetine decreased IGF-1 and cytogenesis in the spinal cord

ReferencesReferences

1. Cotman, C. W., and C. Engesser-Cesar. Exercise 1. Cotman, C. W., and C. Engesser-Cesar. Exercise enhances and protects brain function. enhances and protects brain function. Exerc. Sport Sci RevExerc. Sport Sci Rev. . 30:75-79, 2002.30:75-79, 2002.

2. De Foubert, G., S. L. Carney, C. S. Robinson, E. J. 2. De Foubert, G., S. L. Carney, C. S. Robinson, E. J. Destexhe, R. Tomlinson, C. A. Hicks, T. K. Murray, J. P. Destexhe, R. Tomlinson, C. A. Hicks, T. K. Murray, J. P. Gaillard, C. Deville, V. Xhenseval, C. E. Thomas, M. J. Gaillard, C. Deville, V. Xhenseval, C. E. Thomas, M. J. O’Neill, and T. S. C. Zetterstrom. Fluoxetine-induced change O’Neill, and T. S. C. Zetterstrom. Fluoxetine-induced change in rat brain expression of brain-derived neurotrophic factor in rat brain expression of brain-derived neurotrophic factor varies depending on length of treatment. varies depending on length of treatment. J. Neurosci. J. Neurosci. 128:597-604, 2004128:597-604, 2004

3. van Praag, H., G. Kempermann, and F. H. Gage. Running 3. van Praag, H., G. Kempermann, and F. H. Gage. Running increases cell proliferation and neurogenesis in the adult increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. mouse dentate gyrus. Nature NeurosciNature Neurosci. 2:266-270, 1999. 2:266-270, 1999