Axonal transport of synapsin I- and cholinergic synaptic vesicle-like material; further immunohistochemical evidence for transport of axonal cholinergic transmitter vesicles in motor neurons.

The axonal transport of organelles in motor axons in the sympathectomized rat sciatic has been studied using two antisera which recognize specific components of synaptic vesicles. Anti-synapsin I recognizes synapsin I (SYN I) which is affiliated with the external membrane of synaptic vesicles, while rabbit-anti-synaptic vesicle antiserum (RASVA) recognizes integral membrane glycoproteins in cholinergic synaptic vesicles. Immunofluorescence studies, including cytofluorimetric scanning, show that immunoreactive (IR) material recognized by both antisera: rapidly accumulate proximal to a crush; the material has a granular appearance in the microscope; is redistributed in an isolated segment, and that the transport of the material is sensitive to vinblastine. Thus the proximodistal transport has the characteristics of fast axonal transport. Furthermore, recycling organelles, accumulating on the distal side of a crush are recognized by RASVA, but carry only very little SYN I-IR. The results give further support to the hypothesis that motor cholinergic axons transport axonal cholinergic vesicles towards the motor endplates.