Neuropeptides in the myenteric ganglia and nerve fibres of the forestomach and abomasum of grey, white and black Karakul lambs

Abstract

Previous studies indicated large, thin-walled, milk-filled rumens in lethal grey and white Karakul lambs. There was also a significant decrease in the number and size of the myenteric plexuses and the number of ganglion cells in these lambs. The purpose of this study was to determine whether the myenteric ganglia of the affected lambs are functional, by testing for the presence of vaso-active intestinal peptide, somatostatin, neurotensin, neuropeptide Y, met-enkephalin, calcitonin gene-related peptide and substance P in the myenteric ganglia and nerve fibres in the forestomach and abomasum of grey, white and black Karakul lambs. Four 1-cm² samples were taken from analogous areas of the wall of the rumen, reticulum, omasum and abomasum of five grey, five white and five black newborn Karakul lambs. They were pinned to wax squares, fixed for 18 h in Zamboni's fixative, dehydrated and rehydrated through graded alcohols and stored in phosphate-buffered saline. The outer longitudinal muscle layer of each sample of the rumen, reticulum, omasum and abomasum was separated from the rest of the tissue layers, stained for each of the seven neuropeptides by employment of the immunofluorescence technique, and studied with a Leitz Orthoplan fluorescent microscope. All the material studied tested positive for all the neuropeptides. It is concluded that all the peptides tested for were present in all the lambs and that the myenteric ganglia are therefore functional in the lethal lambs.