Journal of Neuroscience, Vol 9, 339-346, Copyright © 1989 by Society for Neuroscience
Inositol 1,4,5-trisphosphate receptor binding: autoradiographic localization in rat brain
PF Worley, JM Baraban and SH Snyder
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Inositol 1,4,5-trisphosphate is a second messenger generated by stimulation
of the phosphoinositide cycle, thought to release calcium from
intracellular stores. We have mapped the distribution of 3H- inositol
1,4,5-trisphosphate receptor binding sites in rat brain by autoradiographic
techniques. The cerebellum contains the highest level of inositol
1,4,5-trisphosphate binding sites in brain, which appear to be selectively
localized to Purkinje cells. Moderate levels of binding sites are present
in the hippocampus, cerebral cortex, caudate, and substantia nigra. Lesion
studies indicate that binding in the hippocampus is restricted to intrinsic
neuronal elements and in the nigra is found on terminals of the
striatonigral projection. Overall, the autoradiographic distribution of
inositol 1,4,5-trisphosphate receptors resembles the distribution of
phorbol ester binding sites associated with protein kinase C. However, the
inositol 1,4,5- trisphosphate receptor has a more restricted distribution
since it is not detectable in the spinal cord or olfactory bulb, regions
with substantial levels of protein kinase C.