UCLA, Brain Research Institute (LA) Voluntary Exercise Induces a BDNF-Mediated Mechanism That Promotes Neuroplasticity Fernando Gomez-Pinilla, Zeh Ting, Roland R. Roy, Raffaella Molteni, and V. Reggie Edgerton UCLA, Brain Research Institute (LA)

Previous Findings BDNF Soleus (Berchtold et al. 2001, 2002; Cotman and Berchtold 2002, 2006; Gomez-Pinilla et al. 2002)

Key Players BDNF: modifies neuronal excitation and synaptic trasmission; important in memory formation and plasticity trkB: 1° transmembrane receptor for BDNF w/ tyr kinase activity Synapsin 1: phosphoprotein important for NT release GAP-43: important for axonal growth and NT release CREB: well-known txn factorregulates gene expression, specifically BDNF

Background Botulinum toxin type A (BTX-A) purpose: determine effects of reducing NM output of single muscle on neurotrophin response to motor activity Botulinum comes from Clostridium Blocks release of Ach from NM jxns, thus preventing muscular contraction Specifically degrades SNAP-25 (SNARE protein)

Botox

Hypothesis Plasticity Exercise induces neuronal plasticity through BDNF and its receptor (trkB) Studying neuromuscular system (hindlimb) Plasticity BDNF

Physical Parametrics Male Sprague-Dawley (rats) 3 months old Individually housed 12/12 hour light/dark Ad libitum food and wa-wa Exercise cage (30x40x20 cm) with wheel Adjustable resistance (1st day, no load…100g thereafter) Carefully euthanized w/ pentobarb-Na+ and intracardial PBS and other goodies

Results

BDNF mRNA levels in spinal cord after 3 and 7 days of VE Figure 1 + correlation

BDNF immunohisto-quimica Figure 2 Sedentary Exercise Lumbar spinal cord

Synapsin 1 (lumbar SC) Figure 3

GAP-43 (lumbar SC) Figure 4 (A,B)

CREB (lumbar SC) Figure 4 (C,D)

Soleus Muscle BDNF mRNA BDNF Protein Synapsin 1 mRNA TrkB mRNA Figure 5 BDNF mRNA BDNF Protein Synapsin 1 mRNA TrkB mRNA

Effect of BTX-A Figure 6 Lumbar SC Side ipsilateral to injection: decreased BDNF mRNA in sedentary and 7 days VE Contralateral side: no change in sedentary, significant increase in 7 days VE Soleus muscle Ipsilateral: BDNF mRNA reduced in both sedentary and 7 days VE Contralateral: no change sedentary, 175% increase with 7 days VE Lumbar SC Lumbar SC Ipsilateral: decrease in sedentary rats, but maintained levels of synapsin 1 mRNA in 7 days VE Contralateral: no change in sedentary synapsin 1 mRNA, significant increase in 7 days VE

Findings BDNF, TrkB, Synapsin 1, GAP-43, and CREB mRNA increased with exercise in lumbar SC (also Synapsin 1 protein) Direct relationship of mRNA levels to distance run (sed < 3d VE < 7d VE) Interestingly, exercise maintained levels of synapsin 1 mRNA on ipsilateral side of BTX-A injection in lumbar SC

Findings (cont’d) In soleus muscle, BDNF mRNA and protein levels increased (higher after 3 days VE than 7 days VE) TrkB and Synapsin 1 mRNA levels increased after 3 days VE and returned to control levels after 7 days VE No change in GAP-43 mRNA seen in VE groups

Findings (cont’d) Effect of BTX-A injection: Decrease in BDNF mRNA in lumbar SC and soleus muscle on ipsilateral side in sedentary and VE Decrease in Synapsin 1 mRNA in lumbar SC on ipsilateral side in sedentary and VE Increase seen on contralateral side of soleus and lumbar SC in VE group (BDNF and Synapsin 1 mRNA) Interestingly, VE maintained levels of synapsin 1 mRNA on ipsilateral side of BTX-A injection in lumbar SC

Acknowledgements Niel Burns sustenance Diet Mt Dew Meeko