Distribution of vasoactive intestinal polypeptide-like immunoreactivity in the olfactory bulb of the rainbow trout (Salmo gairdneri).

The distribution of vasoactive intestinal polypeptide-like structures in the olfactory bulb of the rainbow trout was studied using an indirect-immunoperoxidase technique. Olfactory fibres were very strongly labelled, whereas the fibres or cell bodies in the remaining strata of the olfactory bulb showed no immunoreactivity. In addition, the olfactory nerve fibres were not immunoreactive for methionine- and leucine-enkephalins, motilin, neuropeptide Y, substance P, cholecystokinin-8 and tyrosine-hydroxylase.