Direct adrenergic inputs to sacral autonomic neurons: using a double-immunostaining method at the light and electron microscopic levels.

Relationships between adrenergic fibers and cholinergic neurons were examined in the rat sacral intermediolateral nucleus using a double-immunostaining method at light and electron microscopic levels. Adrenergic fibers were immunohistochemically stained brown by peroxidase reaction, and cholinergic neurons in the same sections were stained bluish green by beta-galactosidase reaction. In the light microscope, many cholinergic neurons were seen in the intermediolateral nucleus and some of them were surrounded by adrenergic fibers. In the electron microscope, adrenergic fibers made synapses with the cholinergic neurons in the intermediolateral nucleus. These results suggest that adrenergic fibers directly influence the activity of the sacral parasympathetic preganglionic neurons.