RT Journal Article SR Electronic T1 Delayed Inner Ear Maturation and Neuronal Loss in PostnatalIgf-1-Deficient Mice JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 7630 OP 7641 DO 10.1523/JNEUROSCI.21-19-07630.2001 VO 21 IS 19 A1 Guadalupe Camarero A1 Carlos Avendaño A1 Carmen Fernández-Moreno A1 Angeles Villar A1 Julio Contreras A1 Flora de Pablo A1 José G. Pichel A1 Isabel Varela-Nieto YR 2001 UL http://www.jneurosci.org/content/21/19/7630.abstract AB Insulin-like growth factor-1 (IGF-1) has been shown to play a key role during embryonic and postnatal development of the CNS, but its effect on a sensory organ has not been studied in vivo. Therefore, we examined cochlear growth, differentiation, and maturation in Igf-1 gene knock-out mice at postnatal days 5 (P5), P8, and P20 by using stereological methods and immunohistochemistry. Mutant mice showed reduction in size of the cochlea and cochlear ganglion. An immature tectorial membrane and a significant decrease in the number and size of auditory neurons were also evident at P20. IGF-1-deficient cochlear neurons showed increased caspase-3-mediated apoptosis, along with aberrant expression of the early neural markers nestin and Islet 1/2. Cochlear ganglion and fibers innervating the sensory cells of the organ of Corti presented decreased levels of neurofilament and myelin P0 in P20 mouse mutants. In addition, an abnormal synaptophysin expression in the somata of cochlear ganglion neurons and sensory hair cells suggested the persistence of an immature pattern of synapses distribution in the organ of Corti of these animals. These results demonstrate that lack of IGF-1 in mice severely affects postnatal survival, differentiation, and maturation of the cochlear ganglion cells and causes abnormal innervation of the sensory cells in the organ of Corti.