The ultrastructure of adrenergic neurons in sympathetic ganglia of the newborn rabbit after treatment with 6-hydroxydopamine.

Abstract

AbstractThe effects of 6‐hydroxydopamine, an analog of dopamine which produces degeneration of peripheral adrenergic nerve terminals in adult animals, on adrenergic neurons in the sympathetic ganglia of newborn rabbits were studied with the electron microscope. Animals were treated with a 50 mg/kg dose of 6‐hydroxydopamine within six hours after birth and subsequently given daily doses until seven injections had been administered. The results of this study indicate that the adrenergic neurons underwent a “reaction” to 6‐hydroxydopamine which was first manifested by an increase in filaments and smooth membranous structures in the cell bodies. In the axons of these neurons a similar increase in filaments and membranous elements, as well as accumulations of dark‐core vesicles and mitchondria, were evident. Microtubules, although plentiful in normal cells and axons, were not conspicuous in these cells and axons. This initial reaction was later followed by degeneration of the cell bodies and axons and their eventual disappearance, leading to a reduction in cell population and size of the ganglia. It is suggested that the initial effect of 6‐hydroxydopamine on adrenergic neurons (in newborn animals) may be an interference with their axoplasmic transport mechanism which leads to cell degeneration and death. This study also has shown that some of the small “granule‐containing” cells in sympathetic ganglia may be sensitive to 6‐hydroxydopamine, at least in newborn rabbits, as is indicated by their degeneration.