Insulin-like growth factor 1 induced survival of axotomized olfactory neurons in the chick

Insulin-like growth factor 1 (IGF1) receptor is expressed in avian olfactor y neurons and IGF1 in the bulb. To explore the function of IGF1 in olfactor y system in the chick, we infused IGF1 at the lesion site 0 and 12 h after olfactory axotomy. The animals were killed 1-3 days later. TdT mediated dUT P nick end labeling method and bromodeoxyuridine incorporation allowed the evaluation of programmed cell death and mitotic activity respectively in th e olfactory epithelia of IGF1 treated or untreated lesioned animals and con trols. IGF1 treatment suppressed the apoptotic wave, stimulated mitosis whi ch peaked within 24 h (instead of 48 h), to return promptly to normal, and transiently maintained the number of calmodulin related kinase II expressin g neurons at normal levels. It reveals a long lasting effect of IGF1 on the survival of lesioned olfactory neurons and transient effects on maintenanc e of differentiation and mitosis stimulation. (C) 2001 Elsevier Science Ire land Ltd. All rights reserved.