THE PRESENCE OF CORTICOTROPIN-RELEASING FACTOR-LIKE IMMUNOREACTIVE SYNAPTIC VESICLES IN AXON TERMINALS WITH NICOTINIC ACETYLCHOLINE RECEPTOR-LIKE IMMUNOREACTIVITY IN THE MEDIAN-EMINENCE OF THE RAT

Whether or not corticotropin-releasing factor (CRF) containing synaptic vesicles are located in axon terminals with nicotinic acetylcholine receptor (nAChR) in the median eminence (ME) of the rat was examined by electron microscopic double-labeling immunocytochemistry combining the pre-embedding avidin-biotin-peroxidase complex (ABC) method for nAChR with the post-embedding immunogold staining method for CRF. nAChR-like immunoreactivity (nAChR-LI) was found in the cell membranes of the axon terminals in the ME. CRF-like immunoreactivity (CRF-LI) was found in dense granular vesicles (about 100 nm in diameter) in the axon terminals. Double-labeling method revealed that some of nAChR-LI axon terminals were found to contain CRF-LI dense granular vesicles. The results indicate that nicotine may act on nAChR in axon terminals to release CRF.