John Ngai at Berkeley’s Helen Wills Neuroscience Institute recently reported in Neuron a role for insulin-like growth factor (Igf) in the neural development of olfaction – IGF was previously established mainly as a hormone that stimulated cell proliferation.

By studying Igf1 and Igf2 mutant mice, Ngai and colleagues in China and Columbia found the disruption of IGF signaling pathways during neural development disrupted the mirror symmetry of the olfactory bulb’s sensory innervation map. Furthermore, axons targeted for the lateral olfactory bulb were misrouted to ectopic sites, suggesting a role for Igf in axon guidance. Igf was also shown, through primary neuronal cultures, to be a chemoattractant for axon growth cones; this is a new role for Igf in development and is currently being investigated further.

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