The survival of NGF-dependent but not BDNF-dependent cranial sensory neurons is promoted by several different neurotrophins early in their development

Abstract

Recent work has shown that the survival of the nerve growth factor (NGF)-dependent trigeminal ganglion neurons of the mouse embryo is promoted by brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) during the early stages of target field innervation (Buchman and Davies, (1993) Development, 118, 989–1001). The present study was undertaken to ascertain if responsiveness to multiple neurotrophins is a universal feature of the early stages of neuronal development or is restricted to only certain kinds of neurons. To address this issue, we took advantage of the accessibility, from an early developmental stage, of several populations of cranial sensory neurons in the chicken embryo that depend for survival on just one or two known neurotrophins during the phase of naturally occurring cell death. During the mid-embryonic period (E10 to E12) when the number of sensory neurons is declining due to naturally occurring neuronal death, the neurons of the jugular ganglion and the dorsomedial part of the trigeminal ganglion (DMTG) were supported by NGF, the neurons of the ventrolateral part of the trigeminal ganglion (VLTG) were supported by BDNF and the nodose ganglion contained a major subset of neurons supported by BDNF and a minor subset supported by NT-3. Earlier in development (E6), the survival of DMTG and jugular neurons was additionally promoted by BDNF and NT-3. In contrast, E6 VLTG neurons did not exhibit a survival response to either NGF or NT-3, and E6 nodose neurons did not exhibit a survival response to NGF.(ABSTRACT TRUNCATED AT 250 WORDS)