Bovine pituitary intraglandular colloid fraction F5 localized in the rat endocrine pancreas

Bovine pituitary intraglandular colloid thought to be a waste product, is the holocrine secretion of intermediate lobe cells. It is housed in the intraglandular lumen (residual lumen) and is extruded into the venous circulation of the cavernous sinuses via clefts in the capsule of the gland aligned with the intraglandular lumen. Intraglandular colloid, fraction F5 (mol.wt 34,000), radiolabeled with (125I)Na and injected (0.15 ml) into the right internal jugular vein of male Wistar rats, accumulated in the endocrine pancreas. Autoradiographs showed that the material had specifically localized in the capillary network of the endocrine pancreas. Since the intermediate lobe is poorly vascularized, intraglandular colloid is considered to be the transport medium for intermediate lobe materials.     

Preliminary observations on the co-existence of regulatory peptides in cells of the baboon endocrine pancreas

Summary Immunocytochemical procedures at ultrastructural and light microscopy level revealed, in the Chacma baboon endocrine pancreas, cells which were immunoreactive for glucagon and pancreatic polypeptide (PP). Some D cells were observed to contain secretory granules with both the appearance and immunoreactivity of A cell secretory granules.     

Occurrence,distribution and nature of neuropeptide Y in the rat pancreas

Summary Significant quantities of a newly discovered peptide, neuropeptide Y, were found in the rat pancreas, where they were localized to nerves in the exocrine parenchyma and around arterial and ductal structures. Although unaffected by surgical parasympathectomy, the periarterial and periductal nerves were abolished by chemical sympathectomy, suggesting that NPY is partially costored with sympathetic transmitters in nerve fibers.     

Supramarginal cells in the rat pituitary cleft revealed by scanning electron microscopy

Summary An unusual cell type consisting of free elements widely scattered over the marginal epithelium of the rat pituitary cleft is revealed by SEM. Most of these supramarginal cells characteristically have irregularly shaped cell bodies from which thin branched processes extend. Supramarginal cells bear resemblances to Kolmer (epiplexus) cells and to supraependymal cells of the brain ventricles. Their ultrastructural features make it probable that supramarginal cells are phagocytes, and can be regarded as scavengers of the cleft. Considering the close topographical association between the hypophysial cleft and the floor or the 3rd ventricle, supramarginal cells may be members of the motile macrophagic Kolmer cells populating the ventricular surfaces of the brain.Work supported by grants from MPI-60%-193/84     

Pancreastatin (33–49) enhances the priming effect of glucose in the rat pancreas

Short-term exposure to glusoe increases insulin secretion during subsequent stimulation. We investigated the effect of the new regulatory peptide pancreastatin on this priming effect of glucose in the perfused rat pancreas. Pancreastatin (33–49) at a concentration of 10^–8 M inhibited insulin release when stimulated by glucose at a concentration of 16.7 mM. However, after a second pulse of 16.7 mM glucose, pancreastatin potentiated the priming effect of glucose on insulin secretion. The modulation of insulin secretion by pancreastatin results in a potentiation of the priming effect of glucose in the rat pancreas, suggesting a role for pancreastatin in the adaptation of the B cell to glucose-stimulated insulin secretion.     

Studies on the modulation of the desensitization of the pituitary gland by luteinizing hormone-releasing hormone in the ovariectomized rat

Summary In ovariectomized rats the desensitization of the LH cells in vivo, which develops during constant rate infusion of LHRH, 1) does not depend on a concomitant depletion of the pituitary LH stores, 2) proceeds normally when the hypothalamo-pituitary connection has been severed and 3) is a process in which LH itself is not involved.