SHORT-TERM RESPONSE OF POSTNATAL RAT VESTIBULAR NEURONS FOLLOWING BRAIN-DERIVED NEUROTROPHIC FACTOR OR NEUROTROPHIN-3 APPLICATION

The effects of the application of brain-derived neurotrophic factor (B DNF) and neurotrophin-3 (NT-3) neurotrophins on the intracellular calc ium level ([Ca2+](i)) were studied in vestibular ganglion neurons (VGN s) from postnatal slay 3 (P3) rats cultured for 50 hr, We first assess ed the expression of trkB and trkC mRNA receptors in cultured VGNs, Im munobloting and immunocytochemistry confirmed the presence of the neur otrophin receptors on neurons, Both neurotrophins induced transient [C a2+](i) elevations in VGNs: BDNF-treated neurons responded in 65% and NT-3-treated neurons in 56%, The responses could be inhibited by anti- BDNF or anti-NT-3 antibodies, The [Ca2+](i) elevation was dependent on extracellular calcium since it was abolished in calcium-free medium b ut also implicates the release of calcium from intracellular stores as tested by prior depletion with thapsigargin, Our results suggest the implication of a shortterm calcium regulation in VGNs, which could ref lect specific fast effects of neurotrophins in the early postnatal rat vestibular system. (C) 1997 Wiley-Liss, Inc.