Co-existence of cholecystokinin- or gastrin-like peptides with other peptides in the hypophysis and the hypothalamus.

The presence of cholecystokinin and gastrin has been reported in the hypothalamohypophyseal system. These peptides present a peculiar distribution in the hypothalamic nuclei, the median eminence, and the neurohypophysis. CCK and gastrin have close relationships with other peptides like oxytocin, CRF, vasopressin, and the enkephalins; these relationships vary in different projecting areas and in different types of hypothalamic neurons. The functional role of G-CCK in neurosecretion seems to be linked to the role of these closely associated peptides and certainly deserves further investigation.

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

The distribution of proenkephalin and [Met]enkephalin immunoreactivities in the bovine hypothalamo-neurohypophyseal system was studied by use of specific antisera. Proenkephalin and [Met]enkephalin immunoreactivities were found in magnocellular neuronal cell bodies in the dorsal part of the supraoptic nuclei and in the peripheral part of the paraventricular nuclei. A densely staining network of nerve terminals was found in the external part of the median eminence and in the posterior hypophysis. This general distribution is identical to that of the neurohypophyseal hormone oxytocin. The precise localization of proenkephalin and [Met]enkephalin immunoreactivities was compared to the distribution of oxytocin and vasopressin in serial 5-micron sections through the magnocellular nuclei. Oxytocin immunoreactivity was nearly always present in cells that were stained with proenkephalin and [Met]enkephalin antisera. The vasopressin-immunoreactive cells were never stained with either the proenkephalin or the [Met]enkephalin antisera.

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

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.

Immunohistochemical localization of cholecystokinin- and gastrin-like peptides in the brain and hypophysis of the rat.

The distribution of gastrin-cholecystokinin-like peptide(s) is reported in brain and hypophysis of the rat. The unlabeled peroxidase-antiperoxidase complex immunohistochemical technique was used. Controls of specificity for various peptides were studied with solid-phase absorption. Colchicine treatment was necessary to obtain positivity in many neuronal cell bodies. In addition to their already known distribution, gastrin-cholecystokinins containing neural cell bodies and fibers were present in olfactory structures, in various preoptic and hypothalamic nuclei (except in mamillary bodies), in mesencephalic nucleus linearis rostralis, and in A-10, A-9, and A-8 regions of Dahlström and Fuxe, which include substantia nigra. From previous investigations and the present distribution study, it can be inferred that, although most of the brain material consists of cholecystokinin, gastrins may also be present in hypothalamo-posthypophyseal magnocellular cells, in nucleus tractus solitarii, and in the dorsal horn of the spinal cord. The distribution of positive cell bodies in the peripheral part of the paraventricular nucleus and in the dorsal part of the supraoptic nuclei in the hypothalamus is similar to that of oxytocin neurons. The localization of positive cell bodies in A-10, A-9, and A-8 regions of Dahlström and Fuxe is similar to that of dopaminergic neurons. The mesencephalic concentration of cell bodies and the wide distribution of fibers in striatal, hypothalamic, septal, and other hemispheric structures together with thick positive fibers in the medial forebrain bundle is consistent with the existence of ascending mesencephalic pathways, including the nigrostriate pathway.