Are opioid peptides co-localized with vasopressin or oxytocin in the neural lobe of the rat?

The content of vasopressin, oxytocin, neurophysin, leucine-enkephalin, methionine-enkephalin, dynorphin-(1-13), and alpha-neoendorphin in the rat neurohypophysis was measured after different periods of dehydration and after depolarisation of isolated neural lobes and of neurosecretory nerve endings. The rates at which the amount of neurohypophysial hormone and opioid peptides decreased, and the changes in the ratios between the amount of vasopressin or oxytocin and opioid peptide in the neurohypophysis after dehydration and in the incubation medium after depolarization in vitro cast some doubt on, and can be explained by mechanisms other than co-localisation of the different peptides.