Recent developments in degeneration of the sympathetic neuron.

Degeneration of the sympathetic neuron can be achieved by a variety of procedures. Until 1960 the most common method for producing degeneration of postganglionic sympathetic nerve fibers was either to surgically remove the neuronal cell body, or to cut the extrinsic nerve fibers between the cell body and the effector organ. In recent years a number of chemical agents and immunological methods have become available for producing successful degeneration of sympathetic nerves in experimental animals. The purpose o f this review is to briefly outline various approaches used to produce sympathetic degeneration, and also to discuss possible mechanisms involved in the process of degeneration. Secondary effects of sympathetic degeneration, namely, "degeneration contraction" (a short-lasting sympathomimetic effect produced by leakage of noradrenaline (NA) from degenerating nerves) and "denervation supersensitivity" (a long-lasting effect produced by a loss of the neuronal uptake mechanism for NA, plus increased responsiveness of the effector organ to NA), will not be covered in this review. For discussion of these secondary effects the reader is referred to articles by Trendelenburg (1972) and Thoenen (1972).