A combination of immunocytochemistry with transmitter specific autoradiography at the electron microscopic level was used to identify vasoactive intestinal polypeptide (VIP)- or ACTH-containing neurons and serotoninergic nerve terminals in the suprachiasmatic (SCN) and arcuate nuclei (AN). We observed nerve terminals showing selective uptake of [3H]serotonin forming synaptic contact with perikarya or dendrites where the postsynaptic structures exhibited VIP-like immunoreactivity in the SCN and ACTH-like immunoreactivity in the AN. The findings provide ultrastructural evidence that serotoninergic nerve fibers terminate on VIP-neurons in the SCN and on ACTH-neurons in the AN.
- adrenocorticotrophic hormone neurons
- arcuate nucleus
- immunocytochemistry combination
- serotoninergic endings
- suprachiasmatic nucleus
- vasoactive intestinal polypeptide neurons
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