Coexistence of cholecystokinin and oxytocin-neurophysin in some magnocellular hypothalamo-hypophyseal neurons

Abstract

The existence of cholecystokinin in the posterior hypophysis and its hypothalamic origin have been unequivocally demonstrated. Immunocytochemical evidence is presented for the coexistence of gastrin-cholecystokinin and oxytocin-neurophysin I immunoreactivities in some magnocellular neurons of the supraoptic and paraventricular nuclei both in rat and bovine hypothalamus.

Proenkephalin, [Met]enkephalin, and oxytocin immunoreactivities are colocalized in bovine hypothalamic magnocellular neurons.

“…Proenkephalinand [Met]enkephalin-immunoreactive fibers and terminals were found in the external median eminence and were concentrated in the periphery of the neurohypophysis. We found a similar distribution for oxytocin in these tissues as has been reported by others (19,25). It has been reported that another opioid peptide, dynorphin, is present in vasopressin-containing magnocellular neurons (9,13).…”

“…The general distribution of proenkephalin IR and [Met]enkephalin IR in the hypothalamo-neurohypophyseal system was superimposable on the distribution of oxytocin. Proenkephalinand [Met]enkephalin-immunostained cell bodies were visualized in the dorsal part of the supraoptic nuclei and in the lateral peripheral part of the paraventricular nuclei, in the same areas as are found oxytocinergic cell bodies (19,25). Proenkephalinand [Met]enkephalin-immunoreactive fibers and terminals were found in the external median eminence and were concentrated in the periphery of the neurohypophysis.…”

“…The magnocellular neurons of the hypothalamo-neurohypophyseal system contain a wide variety of peptide hormones, including vasopressin, oxytocin, cholecystokinin, and corticotropin-releasing factor (19,(24)(25)(26). The hypothalamus is also rich in opiate peptides (8)(9)(10)(11)(12)(13).…”

Depolarizing action of cholecystokinin on rat supraoptic neurones in vitro.

“…Thus CCK may act as an excitatory transmnitter in one or more afferent pathways to these neurosecretory neurones. It is interesting that CCK is also co-localized within oxytocin-containing (Vanderhaeghen, Lostra, Vandesande & Dierickx, 1981) and (to a lesser extent) vasopressin-coritaining magnocellular neurones (Meister, Villar, Ceccatilli & H6kfelt, 1990). Given the evidence that oxytocin is released locally within the magnocellular nuclei (reviewed in Richard, Moos & Freund-Mercier, 1991), it seems appropriate to propose that CCK may also be released locally from axon collaterals, or possibly from soma-dendritic membranes as has been proposed for vasopressin (see Pow & Morris.…”

Distributional patterns of peptide neurons in the paraventricular nucleus of the rat hypothalamus.

“…Coexistence of CCK-like immunoreactive substances and oxytocin and neurophysin I has been found in the same neurons (12). It was also reported that a dynorphin-immunoreactive substance is produced in the same neurons synthesizing vasopressin (13).…”