CYSTEINE STRING PROTEIN IMMUNOREACTIVITY IN THE NERVOUS-SYSTEM AND ADRENAL-GLAND OF RAT

Cysteine string proteins (csps) are a recently discovered class of cys teine-rich proteins. They have been shown to associate preferentially with synaptic vesicle fractions of Torpedo electric organ or rat brain where they have been implicated in events associated with transmitter secretion. However, to date there has been no information concerning the distribution of csps in rat tissues, We investigated the localizat ion of csps in the rat retina and CNS using immunohistochemistry with affinity purified anti-csp antibodies. Specific csp immunoreactivity h aving a punctate appearance is present throughout the neuraxis. Csp im munoreactivity is particularly abundant in synapse-rich regions includ ing those of the retina, main olfactory bulb, hippocampal formation, a nd cerebellum. White matter tracts are devoid of csp immunoreactivity, Neuromuscular junctions show strong csp immunoreactivity. This locali zation of csp immunoreactivity is compatible with a role for csps in p resynaptic events at a wide variety of synapses, Immunohistochemical a nalysis of a non-neuronal, secretory tissue, the adrenal gland, reveal s prominent csp immunoreactivity in the chromaffin cells of the adrena l medulla. However, csp immunoreactivity is not detected in adrenal co rtical regions. These findings are confirmed and extended by immunoblo t and Northern analyses which identify a 35 kDa and a 5 kb product, re spectively, in extracts of adrenal. The presence of csps in the adrena l medulla suggests that these proteins may also participate in secreti on-related events in certain non-neuronal cells.