Corticotropin-releasing-factor-like immunoreactivity (CRF-LI) was measured in a number of subcellular fractions from rat brain using a highly sensitive and specific radioimmunoassay. CRF-LI was highly enriched in the crude synaptosomal/mitochondrial fraction (P2) relative to the homogenate, P1, S1, and S2 fractions. Separation of the P2 fraction into synaptosomal, myelin, and mitochondria-enriched subfractions on a rapid one-step sucrose gradient revealed that CRF-LI was present at higher concentrations in the synaptosomal fraction than in the mitochondrial and myelin fractions. The distribution of CRF-LI paralleled that of synapsin, a synaptic vesicle marker phosphoprotein, but not that of pyruvate dehydrogenase, a mitochondrial phosphoprotein. These results are consistent with a nerve terminal localization of CRF and a potential role for this peptide as a central nervous system neurotransmitter.
- central nervous system
- corticotropin-releasing factor
- pyruvate dehydrogenase
- subcellular distribution
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