Enkephalin immunoreactive nerve fibres and cell bodies in sympathetic ganglia of the guinea-pig and rat

Abstract

The occurrence and distribution of enkephalin-like immunoreactivity was studied by light microscopy, using an indirect fluorescent-labelled antibody technique, in the superior cervical ganglion, the inferior mesenteric ganglion and the coeliac-superior mesenteric ganglion complex of the guinea-pig and rat. In the guinea-pig a very dense network of enkephalin-positive fibres was observed in the inferior mesenteric ganglion and a less dense one in the coeliac-superior mesenteric ganglion complex. In both ganglia some ‘small intensely fluorescent’ cells were immunoreactive. In the superior cervical ganglion only few fluorescent fibres were seen but several ‘small intensely fluorescent’ cells were enkephalin-positive. In the rat the inferior and coeliac-superior mesenteric ganglia contained medium-dense networks of enkephalin-positive fibres. An irregularly distributed network of fluorescent fibres was observed in the superior cervical ganglion, where also several principal ganglion cells were enkephalinimmunoreactive, particularly after colchicine treatment. These findings indicate the presence of several peripheral neuron systems containing enkephalin or a similar peptide. Several antisera raised to methionine- and leucine-enkephalin as well as to α- and β-endorphin were used. Some of these antisera were compared by incubating sections of the inferior mesenteric ganglion with increasing dilutions of antiserum as well as with antisera treated with increasing concentrations of methionine- and leucine-enkephalin, respectively. On the basis of these findings the problem of differentiating between methionine- and leucine-enkephalin is discussed.