Characterization of proenkepahlin B-derived opioid peptides in the human hypothalamo-neurohypophyseal axis

Proenkephalin B-derived opioid peptides, such as dyborphin_1–17 dynorphin_1–8, dynorphin B, α-neo-endorphin and ß-neo-endorphin in the human hypothalamo-neurophyseal trct were quantitate and characterized by the combined use of various radioimmunoassays, gel filtration, high performance liquid chromatography and enzymatic cleavage. Chromatographic analysis of immunnoreactive peptide levels determined that, in each case, these were comprised almost exclusively of the autentic peprides both in the neurohypophysial and hypothalamus. Concentrations of autenthic proenkaphalin B-peptides were 100–500-fold lower in the human as compared to the rat neurohyphysis. However, in the paraventricular nucleus (PVN), sipraoptic nucleus (SON) and certain other nuclei of the human hypothalamus concentrations of authentic peptides were found to the in the same range as those in the rat hypothalamus. The ratio of proenkaphalin B-peptides in PVN and SON to those of the neurophypophysis in the rat was ca 1:50. Conversely, in man these ratios were shown to be 80:1 for dynorphin B, 6:1 for α-neo-endorphin and 1:1 for all other peptides evaluated. Examination of postmortem degradation of peptides indicated that these lower levesl in the neurophypophysis are not due to a higher rate of postmortem breaakdown. Since levels of both vasopressin and ß-endorphin were very high, these deficits in proenkephalin B-peptides were selective and do not represent a generalized propertu of the human pituitary. Experiemtns involving enzymatic leavage demonstrated the occurrence of higher molecular weight forms containing the Leu-enkaphalin sequence which were not recognized by the antisera employed. The function significance of our findings as regards the putative role of proenkaphalin B-derived opioid peptides in control of neuroophyseal secretion remains to be determined.     

Immunohistochemical evidence for extrinsic and intrinsic opioid systems in the guinea pig superior cervical ganglion

Summary Immunohistochemical localization of the opioid peptides -neo-endorphin (-neo-END), dynorphin A (DYN) and leu-enkephalin (leu-ENK) in the guinea pig superior cervical ganglion (SCG) was studied following central denervation, peripheral axotomy, and after application of the depleting drug reserpine and of the neurotoxin 6-hydroxydopamine. The paraganglionic cells of the SCG are shown to form an intrinsic opioid — (-neo-END, DYN, leu-ENK) — immunoreactive system being not visibly responsive to the experimental procedures. Leu-ENK-immunoreactive fibres ascend in the preganglionic trunk and supply fibre baskets to defined clusters of postganglionic neurones. Principal ganglion cells of the SCG containing -neo-END-and DYN-immunoreactivity project to extraganglionic targets via the postganglionic nerves. These findings are indicative of a sympathetic -neo-END-ergic and DYN-ergic innervation of effector organs. They also point to a modulatory function of opioids on neuronal activity in a paravertebral ganglion.