Elsevier

Neuroscience

Volume 63, Issue 3, December 1994, Pages 837-850
Neuroscience

Synaptotagmin I is present mainly in autonomic and sensory neurons of the rat peripheral nervous system

https://doi.org/10.1016/0306-4522(94)90528-2Get rights and content
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Abstract

The distribution of synaptotagmin I in the peripheral nervous system of the rat was investigated by immunofluorescence and confocal laser scanning microscopy. After crushing of the sciatic nerve, synaptotagmin I-like immunoreactivity accumulated proximally as well as distally to the crushes in thin and medium-sized axons. Double labelling studies revealed that synaptotagmin I co-localized with tyrosine hydroxylase, a marker of sympathetic adrenergic neurons, and with substance P, a marker for sensory neurons. No synaptotagmin I-like immunoreactivity was found in large axons, while accumulations of the synaptic vesicle proteins synaptophysin and synapsin I were found in all types of axons. Furthermore, no synaptotagmin I-like immunoreactivity was detected in motor endplates. In contrast, the protein was found in muscle spindles of young rats and in perivascular terminals, where it co-localized with synaptophysin and synapsin I. Lumbar sympathectomy resulted in a marked reduction of the amount and intensity of synaptotagmin I-like immunoreactivity in sciatic nerve. High magnification revealed that synaptotagmin I-like immunoreactivity was mainly distributed in a fine granular pattern, but large, brightly fluorescent granules which were not labelled by anti-synaptophysin or anti-synapsin I were occasionally observed.

We conclude that synaptotagmin I is mainly expressed in adrenergic and sensory neurons and is absent from, or below detection levels, in motoneurons.

DRG
dorsal root ganglia
LI
like immunoreactivity
SP
substance P
TH
tyrosine hydroxylase

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