An immunoelectron microscopic study of peptide substances in the rat neurohypophysis

Abstract

The ultrastructural localization of peptide substances, such as vascpressin (VP) substance P (SP), enkephalin (ENK) and somatostatin (SRIF), and the distribution of peptidergic nerves in rat neurohypephysis were studied by immunoelectron microscopy. The results show that VP, SP, ENK and SRIF immunoreactive products are located in large granular vesieles (110–150 nm in diameter), at the periphery of microvosieles and on the outer membrane of mitochondria. The VP-, SP-, ENK -and SRIF-containig nerve fibers are distributed at the pcriphery of capillaries and in the vicinity of pituicytes. VP -and ENK-positive nerve terminals form a xo-a xonie synapses with negative terminals. VP -and ENK-terminals are pre-or postsynaptic elements. Axo-a xonic synapses formed by two SRIF-positive terminals were also found. In addition, ENK -and SP-positive terminals with pituicytes form synaptoid structures respectively. The authors have discovered VP-positive pituicytes for the first time.

Keywords

neurohypophysis / immuno cytochemistry / peptides / rat

References

[1] BargmannW, KnoopA.. Elektronen mikroskopische Beobachtungen an der Neurohypophyse. Z Zellfoisch, 1957, 46: 242-1

[2] StoeckelME, et al. . Immunocytochemical localization of substance P in the neurohypophysis and hypothalamus of the mouse compared with the distribution of other neuropeptides. Cell Tissue Res, 1982, 223: 533-44

[3] Van LeeuwenF.. Enkephalin in the rat neural lobe: Immunocytochemical evidence for its presence within synaptic elements on pituicytes. Prog Brain Res, 1982, 55: 253-64

[4] Van LeeuwenFW, et al. . Enkephalin immunoractivity in synaptoid elements on glial cells in the rat neural lobe. Neuroscience, 1983, 8: 229-41

[5] WeindlA, SofroniewMV, et al. . WuttkeW, et al. . Immunohistochemical localization of hypothalamic peptide hormones in neural target areas. In: Brain and Pituitary Peptides, 1980, Basel, S Karger: 97-109

[6] RabhilM, et al. . Immunocytochemical study of the GABA-ergic innervation of the mouse pituitaiy by use of antobodies against gama aminobutyric acid (GABA). Cell Tissue Res, 1987, 247: 33-40

[7] MartinR, VoigtKH. Enkephalin co-exists with oxytocin and vasopressin in nerve terminals of rat neurohypophysis. Nature, 1981, 289: 502-4

[8] SternbergerLA. Immunocytochemistry, 19792nd ed.New York, John Wiky & Sons, Inc.

[9] TakeiY, et al. . Ultrastructural study of the human neurohypophysis. I. Cellular elements of neural parenchyma, the pituicytes. Cell Tissue Res, 1980, 205: 273-87

[10] 1987; 18:273–41.

[11] LoeschA. The neurosecretory axons in the neurohypophysis of the rat: An electron microscopic study. J Ultrastr Res, 1981, 77: 344-53

[12] WittkowskiW, BrinkmannH. Changes of extent of neurovascular contacts and number of neuro-glial synaptoid contacts in the pituitary posterior lobe of dehydrated rat. Anat Embryol, 1974, 146: 157-65

[13] LightmanSL, et al. . Dopamine and DAla₂-D-Leu₅-enkephalin inhibit the electrically stimulated neurohypophyseal release of vasopressin in vitro: evidence for calcium-dependent opiate action. J Neurosci, 1982, 2: 78-81