Interneuronal transfer of axonally transported proteins: studies with HRP and HRP conjugates of wheat germ agglutinin, cholera toxin and the B subunit of cholera toxin.

Experiments in the visual system and the tongue-hypoglossal nucleus pathway of the rat with HRP and HRP conjugates of wheat germ agglutinin (WGHRP), cholera toxin (CTHRP) and the B subunit of cholera toxin (BHRP) were conducted to study the interneuronal transfer of proteins. Native HRP did not undergo such transfer. Intravitreal injections of WGHRP, CTHRP or BHRP all resulted in interneuronal transfer in the visual system, but there was no evidence for this in the tongue-hypoglossal nucleus pathway. Interneuronal transfer may: (1) require a ligand-cell surface interaction; and (2) occur only after the endocytosis and/or exocytosis of these conjugates at specific sites along the neuronal plasma membrane.