Retrograde axonal transport of target tissue-derived macromolecules

Abstract

Neurones depend on contact with their target tissues for survival and subsequent development^1–4. The protein, nerve growth factor (NGF), can be selectively taken up by sympathetic nerve terminals and reaches the neuronal perikaryon by a process of retrograde intra-axonal transport⁵, suggesting that its role in vivo is to act as a target tissue-derived trophic factor⁶. The development of the neurones of the chick ciliary ganglion requires the presence of structures derived from the optic cup⁴. Several studies in vitro have shown that media conditioned by non-neuronal cells contain factors that result in the survival of neurones from ciliary ganglia^7–11. In particular, chick embryo iris, ciliary body and choroid contained large amounts of these factors indicating the presence of a target tissue-derived trophic factor for the cholinergic ciliary ganglion¹². This study demonstrates that neurones of the ciliary ganglion accumulate, by retrograde intra-axonal transport, proteins synthesized and released by optic tissues in culture.