1. Contributions of BDNF to the Maturation of Cortical Inhibitory Circuits
Ali Hamodi

2. Introduction BDNF: Brain-Derived Neurotrophic Factor
A member of the neurotrophin family
Plays important roles ranging from cell survival to cell death
Important in modulating synaptic morphology and activity (McAllister et al, 1997)
Little is known about how BDNF contributes to activity-dependent remodeling of inhibitory synapses
-Excitatory cells vs. inhibitory cells
-While neurotrophin’s modulation of synaptic morphology and activity has been extensively studied in dissociated cells and slice cultures, little is known about how BDNF contributes to the activity-dependent remodeling of inhibitory synapses in vivo.
-Roles of BDNF:
cell survival
apoptosis
gene expression
synaptic plasticity,
neurotransmitter release in the CNS,
and cellular outgrowth

3. Hypothesis
Local BDNF mediates long-lasting intracellular calcium mobilization in neonatal GABAergic interneurons
Goal
What are the cellular and pharmacological properties of BDNF-induced long-lasting intracellular calcium?

4. Methods Brain-slice cutting Brain-slice Incubation
Immunohistochemistry
C-fos/DAB staining
Immunoflourescent labeling
Data analysis
Counting cell density using Axiovision software
Computer-aided cell reconstruction using Neurolucida software

5. What are the cellular and pharmacological properties of BDNF-induced long-lasting intracellular calcium?
Pharmacological agents used
K252a: Receptor tyrosine kinase inhibitor
SKF96365: TRPC inhibitor
MRS1845: Capacitative Ca+2 inhibitor
LOE908: Broad-spectrum cation channel blocker
2-APB: IP3 antagonist
U73122: Phospholipase C inhibitor
Thapsigargin: SERCA ATPase inhibitor
KB-R7943: TPRC and Na+/Ca2+ exchanger
Suramin: Broad-spectrum antagonist of P2 receptors (ATP receptors) and agonist of Ryanodine receptors
PPDA: NMDAR antagonist

6. Results *

7. Results

8. Results P=

9. Results Antagonist Effective TrkB inhibitor Yes TRPC inhibitor
Capacitative Ca2+ inhibitor
No 
Broad-spectrum cation channel blocker
 No
IP3 antagonist
PLC inhibitor
SERCA ATPase inhibitor
TRPC and Na+/Ca2+ exchanger
Broad-spectrum antagonist of P2 receptors and agonist of Ryanodine receptors
NMDAR antagonist

10. BDNF & GABAergic interneurons
GAD67-GFP
C-fos
DAPI
Merged

11. Summary
What are the cellular and pharmacological properties of BDNF-induced long-lasting increase in intracellular calcium?
BDNF plays a role in activity-dependent remodeling of GABAergic cells through c-fos expression
BDNF-induced signaling cascade initiated by BDNF/TrkB interaction
Ca2+ influx mainly mediated by release from intracellular stores
IP3
SERCA pumps
Secondary effect of Ca2+ influx through TRPC channels

12. Health Relevance
BDNF’s role in neuronal development and maturation of cognitive function (Hong et al, 2005)
Deficits
Epilepsy
Rhett Syndrome
Schizophrenia
Autism spectrum disorders
-BDNF knockout mice had major cortical cytoarchitechtural deficit and die at birth;
-BDNF overexpression mice exhibited precautious maturation of cortical inhibitory circuits and disturbed visual critical period formation.
-Schizophrenic patients have decreased BDNF &TrkB
-Autism: decreased BDNF

13. QUESTIONS??