title: PLCgamma signaling underlies BDNF potentiation of Purkinje cell responses to GABA.
abstract: Brain-derived neurotrophic factor (BDNF) regulates neuronal survival, neurite outgrowth, and excitatory synaptic transmission. We reported recently that acute BDNF exposure decreased gamma-aminobutyric acid (GABA) responses in cultured mouse cerebellar granule cells through tyrosine receptor kinase B (TrkB) receptor-mediated signaling. In the present study, we extend this work to investigate BDNF-induced modulation of GABA responses and GABA(A) receptor-mediated synaptic events in cerebellar slices. Thin (200 microm) parasagittal slices of cerebellum were prepared from postnatal Day 7 and 14 mice. Purkinje cells and granule cells, both of which express TrkB-like immunoreactivity, were identified for whole-cell recording. BDNF promptly enhanced GABA responses in Purkinje cells but, consistent with our previous finding in culture, attenuated those recorded in granule cells. In Purkinje cells, BDNF exposure shifted rightward the cumulative peak amplitude distribution for miniature inhibitory postsynaptic currents (mIPSCs) without changing the mIPSC frequency. BDNF-induced potentiation of Purkinje cell responses to GABA was blocked by TrkB-Fc (receptor body that sequesters BDNF), K252a (inhibitor of TrkB receptor autophosphorylation), U73122 (inhibitor of phospholipase-Cgamma [PLCgamma]), KN62 (specific inhibitor of calcium/calmodulin-dependent kinase), KT5720 (specific cyclic AMP-dependent kinase inhibitor), and by intracellular dialysis of Rp-cyclic AMP or BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N, N',N'-tetraacetic acid). Overall, our results indicate that BDNF acutely potentiates GABA(A) receptor function in cerebellar Purkinje cells via the TrkB receptor-PLCgamma signal transduction cascade. In addition, we propose that cyclic AMP-mediated intracellular signaling mechanisms may facilitate manifestation of the BDNF-induced modulatory outcome.
authors.affiliation: Center for Aging and Developmental Biology, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Cheng
authors.forename: Hermes H
authors.initials: HH
authors.lastname: Yeh
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002531:Cerebellum / Q000166:cytology*; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects / Q000528:radiation effects; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D009433:Neural Inhibition / Q000187:drug effects; D018408:Patch-Clamp Techniques / Q000379:methods; D011689:Purkinje Cells / Q000187:drug effects*; D020813:Receptor, trkB / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D010738:Type C Phospholipases / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D004533:Egtazic Acid; D005680:gamma-Aminobutyric Acid; D020813:Receptor, trkB; D010738:Type C Phospholipases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid