Phentolamine increases neuronal binding and retrograde transport of dopamine β-hydroxylase antibodies

When ¹²⁵I-labelled antibodies against dopamine β-hydroxylase (DBH) were injected into the anterior eye chamber of guinea-pigs they bound to sympathetic nerve terminals, were internalized into the axons and retrogradely transported to the ipsilateral superior cervical ganglion (SCG). This process was demonstrated to depend on specific binding sites since neutralized antibodies were not taken up and transported. The α-receptor antagonist phentolamine caused a 2.5-fold increase in binding in the iris and a 2.1-fold increase in accumulation of [¹²⁵I]anti-DBH in the SCG. The results demonstrate that retrograde axonal transport of synaptic vesicle components is coupled to their turnover in nerve terminals.