Neuron-specific enolase in the pituitary gland.

Neuron-specific enolase (NSE) is present in many types of peptide-secreting neuroendocrine cells and in tumours derived from them, but little work has been done on the pituitary gland. Serial sections of normal rat (n = 9) and human (n = 7) pituitary gland, spontaneous rat pituitary tumours (n = 14) and human pituitary tumours, both hormonally active (n = 7) and inactive (n = 10), were immunostained for NSE and the 6 major anterior pituitary hormones. The neural lobe stained strongly and the intermediate lobe variably for NSE. In the anterior lobe, NSE immunoreactivity was present with variable intensity in the majority of hormone-producing cells of all six types. Cells with strong hormone immunoreactivity were usually only moderately stained for NSE. All the human and rat pituitary adenomas examined were positively stained for NSE, though to varying degrees. The pituitary gland is thus no exception to the rule that NSE is found in peptide-secreting neuroendocrine cells and their tumours.

Immunostaining of neuron-specific enolase as a diagnostic tool for Merkel cell tumors.

Conventional histologic examination of Merkel cell tumors may result in misdiagnosis because of the close similarities these tumors bear to either malignant lymphomas or certain undifferentiated carcinomas. The authors have previously reported that neuron-specific enolase (NSE), a specific marker for neuroendocrine cells, is present in normal Merkel cells and can be used as a marker to identify this cell type. In this study, 11 Merkel cell tumors, identified employing electron microscopy, were studied using immunostaining of NSE by the peroxidase-antiperoxidase method. Varying intensities of NSE immunoreactivity were found in the cytoplasm of all the neoplastic cells in the different cases. The uniformly stained cytoplasm formed a small rim surrounding the large, unstained nucleus. Immunostaining of NSE thus provides a simple and reliable method for the differential diagnosis of Merkel cell tumors from other primary skin tumors which, with the exception of some malignant melanomas, have been shown not to contain NSE immunoreactivity.

Neuron specific enolase: a common marker for the endocrine cells and innervation of the gut and pancreas.

Neuron specific enolase, the most acidic isoenzyme of the glycolytic enzyme enolase, was first believed to be present exclusively in central neurons. More recently, it has been found in peripheral autonomic nerves and in a number of endocrine cells. An immunocytochemical study was carried out concerning the distribution of neuron specific enolase in the gastrointestinal tract and pancreas of humans and rats. In addition, immunocytochemistry and histochemistry were used to obtain a characterization of the different types of cells and nerves in which neuron specific enolase can be detected. Neuron specific enolase was found in all currently identifiable endocrine cell types and nerves of the gut and pancreas. Neuron specific enolase is therefore a common marker for both endocrine cells and enteric nerves, thus providing a simple means for their simultaneous demonstration and examination of their morphologic characteristics and integration.

Gastro-intestinal and neurohormonal peptides in the alimentary tract and cerebral complex of Ciona intestinalis (Ascidiaceae).

Polypeptide-hormone producing cells were localized in the alimentary tract and cerebral ganglion of Ciona intestinalis using cytochemical, immunocytochemical and electron-microscopical methods. Antisera to the following peptides of vertebrate type were employed: bombesin, human prolactin (hPRL), bovine pancreatic polypeptide (PP), porcine secretin, motilin, vasoactive intestinal polypeptide (VIP), beta-endorphin, leu-enkephalin, met-enkephalin, neurotensin, 5-hydroxytryptamin (5-HT), cholecystokinin (CCK), human growth (GH), ACTH, corticotropin-like intermediate lobe peptide (CLIP) and gastric inhibitory peptide (GIP). Immunoreactive cells were found both in the alimentary tract epithelium and in the cerebral ganglion for bombesin, PP, substance P, somatostatin, secretin and neurotensin. Additionally, in the cerebral ganglion only, there were cells immunoreactive for beta-endorphin, VIP, motilin and human prolactin. 5-HT positive cells, however, were restricted to the alimentary tract. No immunoreactivity was obtained either in the cerebral ganglion or in the alimentary tract with antibodies to leu-enkephalin, met-enkephalin, CCK, growth hormone, ACTH, CLIP and GIP. Prolactin-immunoreactive and pancreatic polypeptide-immunoreactive cells were argyrophilic with the Grimelius' stain and were found in neighbouring positions in the cerebral ganglion. At the ultrastructural level five differently granulated cell types were distinguished in the cerebral ganglion. Granules were present in the perikarya as well as in axons. The possible functions of the peptides as neurohormones, neuroregulators and neuromodulators are discussed.

Neuron-specific enolase in the Merkel cells of mammalian skin. The use of specific antibody as a simple and reliable histologic marker.

Merkel cells are specialized skin receptor cells, characterized by their particular location in the epidermis and close association with nerve terminals. Although they can be distinguished ultrastructurally by their small, electron-dense secretory granules, there is no specific and reliable method for identifying them by light microscopy. Using antibodies to neuron-specific enolase (NSE), the authors have shown sparsely distributed groups of specifically immunostained cells and associated nerve terminals in the nose skin of cats and rats. These cells were easily distinguished from other epithelial cell types, including melanocytes and Langerhans cells and had all the morphologic features of Merkel cells and their so-called neurite complexes, including the characteristic cytoplasmic secretory granules (60 nm in diameter). NSE immunostaining is a simple and reliable method for the specific light-microscopic staining of Merkel cells and provides further evidence for NSE as a marker for the diffuse neuroendocrine system.

Neuron-specific enolase is produced by neuroendocrine tumours.

Neuron-specific enolase (NSE) is a neuronal form of the glycolytic enzyme enolase, which was first found in extracts of brain tissue, and was later shown to be present in APUD (amine precursor uptake and decarboxylation) cells and neurons of the diffuse neuroendocrine system but not in other peripheral cells. 90 neuroendocrine neoplasias (APUDomas) (including islet-cell tumours, phaeochromocytomas, medullary thyroid carcinomas, oat-cell tumours, and APUDomas of the gut, pancreas, and lung) reacted strongly with antisera to NSE. In addition, large amounts of the enzyme were found by radioimmunoassay in the tumours (mean 1626 +/- 479 SEM ng of NSE/mg protein), whereas control non-endocrine neoplasias contained less than 15 ng NSE/mg protein. Thus NSE, a specific enzyme produced in the neural and endocrine systems, was found to be produced in considerable quantities by all types of APUDomas but not in any non-endocrine tumours. NSE seems to be a useful and easily detected marker which may be used to distinguish endocrine from nonendocrine neoplasias. Clinical detection of endocrine tumours is difficult and such tumours are often missed. Use of NSE as a marker may avoid this.

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in anuran intestine.

Immunocytochemical and radioimmunological techniques with region specific antisera have been used to identify a vasoactive intestinal polypeptide-like material in the anuran intestine. Seven species of Anura were investigated: Bombina bombina, Alytes obstetricans, Rana temporaria, Rana esculenta, Hyla arborea, Hyla crepitans and Bufo bufo. In five of the species (A. obstetricans, R. temporaria, H. arborea, H. crepitans and B. bufo) vasoactive intestinal polypeptide-like immunoreactive mucosal endocrine cells and nerve fibres in all layers of the gut wall, were detected by both immunofluorescence and peroxidase-antiperoxidase methods. In the other two species, R. esculenta and B. bombina, no mucosal endocrine cells were detected although the vasoactive intestinal polypeptide-immunoreactive nerve fibres were plentiful. Radioimmunoassay showed the presence of significant amounts of vasoactive intestinal polypeptide-immunoreactivity in intestinal extracts from all species. The highest quantities were present in those anurans with both immunostained cells and nerves. Gel permeation chromatography showed that most of the vasoactive intestinal polypeptide-like peptide eluted in a position identical to that of natural mammalian (porcine) vasoactive intestinal polypeptide. The results indicate that a vasoactive intestinal polypeptide-like peptide is well represented in the Anura and that it is immunologically very similar to the mammalian peptide.

Pancreatic-polypeptide-producing apudoma of the liver.

A large hepatic excised from a 62-year-old man resembled a carcinoid tumor. No endocrine syndrome was present and an alternative primary source of tumor was found, despite an intensive search. The tumor cells were classified according to the type of electron-dense granules present: ACTH, gastrin (G), bombesin (P), and pancreatic polypeptide (PP) type granules were identified. Immunofluorescent staining with antibodies to several polypeptide hormones detected PP-containing tumor cells only. This rare tumor is therefore a PP-apudoma; possibly of intrahepatic bile duct origin.