Brain-Derived Neurotrophic Factor and Neurotrophin-3 Support the Survival and Neuritogenesis Response of Developing Cochleovestibular Ganglion Neurons

Complex Regulation of Spiral Ganglion Neuron Firing Patterns by Neurotrophin-3

“…Because NT-3 has been shown to promote survival of spiral ganglion neurons in vivo and in vitro (Avila et al, 1993;Mou et al, 1997;Hansen et al, 2001;Fritzsch et al, 2004), one mechanism could be that NT-3 selectively promotes the survival of a subpopulation of spiral ganglion neurons. Our laboratory has shown previously that putative type II spiral ganglion neurons differ in the base from their type I counterparts by demonstrating slow accommodation, longer latencies, and prolonged membrane time constants (Reid et al, 2004), similar to neurons exposed to the appropriate concentrations of NT-3 in the present study.…”

Trophic Support of Cultured Spiral Ganglion Neurons by Depolarization Exceeds and Is Additive with that by Neurotrophins or cAMP and Requires Elevation of [Ca2+]iwithin a Set Range

“…Mice homozygous for NT-3 knockout are born lacking Ͼ85% of the SGNs (Fariñas et al, 1994;Ernfors et al, 1995), whereas mice homozygous for BDNF knockout show only a small loss of SGNs at birth (Conover et al, 1995;Ernfors et al, 1995). Nonetheless, BDNF, like NT-3, supports survival of cultured embryonic and postnatal SGNs (Avila et al, 1993;Lefebvre et al, 1994;Pirvola et al, 1994;Vazquez et al, 1994;Zheng et al, 1995). It is not clear why only NT-3, and not BDNF, is necessary for prenatal trophic support of SGNs; possibly, SGNs lack access to sufficient BDNF at this time.…”

“…SGNs express TrkB and TrkC (Ylikoski et al, 1993;Schecterson and Bothwell, 1994) and are supported by BDNF, NT-4, and NT-3 in vitro (Avila et al, 1993;Vazquez et al, 1994;Zheng et al, 1995). SGNs can receive target-derived neurotrophic support by either BDNF or NT-3 in vivo, because both are expressed in the cochlear nucleus (Lefebvre et al, 1994).…”

Axonal Neuropathy-associated TRPV4 Regulates Neurotrophic Factor-derived Axonal Growth

“…Moreover, mutations of TrKA (a NGF receptor) have been found in hereditary and developmental neuropathies (22). On the other hand, BDNF is known to promote neurite growth and the differentiation of cochleovestibular ganglion neurons (23), and to decrease preganglionic synaptic innervation to sympathetic neurons in BDNF-deficient mice (24). GDNF has been reported to induce neurotrophic activity in developing and mature motor neurons of the brain and spinal cord (25), and to enhance neurite branching and elongation from developing dopamine neurons (26).…”