Differential localization of N-acetylated indolealkylamines in CNS and the Harderian gland using immunohistology

Using two different antisera, one binding only melatonin (M) and the other binding both M and N-acetylserotonin (NAS), brain tissue and the Harderian gland were investigated using fluorescence and peroxidase labeled double antibody immunohistology. M has been identified in the outer nuclear layer of the retina, in the optic nerves, chiasma and the tracts, suprachiasmatic nucleus and the Harderian gland. NAS, but not M, was found in the granule layer of the cerebellum, spinal tract of the trigeminal roots and the pontal and spinal reticular formation. The possible relationship of cerebellar and brain stem NAS to brain excitability as well as localization of M in the visual pathway, suprachiasmatic nucleus and the Harderian gland in the relation to the regulation of light dependent circadian periodicity is discussed.