PEPTIDE-IMMUNOREACTIVE NEURONS AND NERVE-FIBERS IN LUMBOSACRAL SYMPATHETIC-GANGLIA - SELECTIVE ELIMINATION OF A PATHWAY-SPECIFIC EXPRESSIONOF IMMUNOREACTIVITIES FOLLOWING SCIATIC-NERVE RESECTION IN KITTENS

The distributions of peptide-immunoreactive nerve fibres and cell bodi es in lumbosacral paravertebral sympathetic ganglia of young cats were analysed with antibodies to calcitonin gene-related peptide, enkephal in, neurotensin, somatostatin, substance P, galanin, neuropeptide Y an d vasoactive intestinal polypeptide. Fairly dense networks of nerve fi bres showing enkephalin-, neurotensin-, somatostatin- or substance P-l ike immunoreactivity were observed in the ganglia. Double-staining exp eriments revealed that enkephalin- and somatostatin-immunoreactive ner ve fibres preferentially surrounded calcitonin gene-related peptide- a nd/or vasoactive intestinal polypeptide-immunoreactive cell bodies. Ne urotensin- and substance P-immunoreactive nerve fibres were mainly ass ociated with neurons showing neuropeptide Y and/or galanin-like immuno reactivity. Occasional nerves containing calcitonin gene-related pepti de-, galanin-, neuropeptide Y- or vasocative intestinal polypeptide-li ke immunoreactivity were observed. These fibres did not seem to have a ny direct regional distribution within the ganglia. In kittens survivi ng for three months after early postnatal sciatic nerve resection, no calcitonin gene-related peptide-immunoreactive cell bodies could be de tected in ganglia ipsilateral to the operation. In contrast, vasoactiv e intestinal polypeptide-like immunoreactivity, which partly co-exists with calcitonin gene-related peptide, was observed to the same extent as in control ganglia. Furthermore, almost all of the somatostatin-im munoreactive varicose nerve fibres had disappeared, whereas a fairly d ense network of calcitonin gene-related peptide-immunoreactive nerve f ibres could be observed. This change was paralleled by an increased co ntent of nerve fibres that were immunoreactive to antibodies against t he growth-associated protein GAP-43 (also known as B-50). The present findings suggest that experimental perturbations where postganglionic neurons are separated from their target areas by axotomy, not only ind uce differential changes in neurotransmitter expression in the princip al ganglion cells, but also in preganglionic sympathetic neurons proje cting to the ganglia. One possible explanation for the occurrence of a n axotomy-induced network of calcitonin gene-related peptide-immunorea ctive nerve fibres, is that extrinsic sensory nerve fibres grow into t he ganglia after the sciatic nerve lesion. Thus, these findings seem t o suggest one additional possibility with regard to the question of a possible interaction between sympathetic and sensory neurons after per ipheral nerve injury.