Monoamine storage sites in the rat superior cervical ganglion following synthesis inhibition.

Monoamine storage sites in paraganglionic (PG-) cells of the rat superior cervical ganglion were investigated by electron and fluorescence microscopy following treatment with p-chlorophenylalanine (pCPA), disulfiram or guanethidine respectively. Dense core vesicles in PG-cells are significantly decreased (p less than 0.001) in number following pCPA, and in the majority of these cells following disulfiram and guanethidine. However in a minor portion of PG-cells the latter agents cause an increase in number and in size of dense core vesicles, in parallel with structural alterations. In agreement with these electron microscopic findings fluorescence microscopic and cytophotometric evaluations reveal a general decrease in catecholamine content with few cells showing an increase. The findings provide a morphological basis for the assumption, that monoamine storage sites in PG-cells can be decreased by inhibition of monoamine synthesis, following administration of pCPA, disulfiram and guanethidine. However the two types of responses of PG-cells which occur after disulfiram and guanethidine demonstrate a functional heterogeneity of this cell system in the rat superior cervical ganglion which is discussed.