Joe R. Kimmel

Coexistence of somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivity in some forebrain neurons

The indirect immunofluorescence technique was used to demonstrate the coexistence of somatostatin together with avian pancreatic polypeptide-like immunoreactivity within certain neurons of the rat forebrain. Numerous neurons containing these peptides were observed in the neocortex, hippocampus, olfactory tubercle, striatum, nucleus accumbens and lateral septum. In studies of serial sections stained alternately for these two peptides, and in restaining experiments, It could be determined that in many neurons in these areas these two peptides coexisted. In other brain areas such as the anterior periventricular hypothalamus, somatostatin cells were never found to contain avian pancreatic polypeptide-like immunoreactivity. Also, within the pancreas these two peptides were never found to coexist in the same cells. The findings represent a further example of the coexistence of more than one neuropeptide within a single neuron.

Avian pancreatic polypeptide (APP) immunoreactive neurons in the spinal cord and spinal trigeminal nucleus

Using indirect immunofluorescence technique, avian pancreatic polypeptide (APP) immunoreactive cell bodies and fibres have been observed in the superficial laminae of the dorsal horn of the spinal cord and of the spinal trigeminal nucleus. Fibres were also seen in the ventral horns, in low numbers at the cervical and thoracic levels and in high numbers at the lower lumbar and upper sacral levels. Neither total cord transection, nor dorsal rhizotomy, nor capsaicin treatment seemed to affect the APP systems described above. The present findings suggest that an APP-like peptide may be involved in processing of sensory information at the level of the first relay station.

Immunohistochemical Studies of the GABA System in the Pancreas

gamma-Amino butyric acid (GABA) is a major inhibitory neurotransmitter in the mammalian brain. In the present study the indirect immunofluorescence technique was employed to localize the GABA-synthesizing enzyme glutamate decarboxylase, and the GABA-metabolizing enzyme GABA-transaminase within the rat pancreas. Both enzymes were found to occur only in the beta-cells of the islets of Langerhans. The other endocrine cell types, the exocrine tissue and the nervous elements in the pancreas did not contain either enzyme. Animals treated with the beta-cell toxins streptozotocin or alloxan showed a loss of immunoreactive cells in the islets. The results provide morphological evidence of the coexistence of GABA and insulin in the beta-cells of the endocrine pancreas.

Spectrum effects of a new polypeptide (third hormone?) isolated from the chicken pancreas.

Abstract A broad evaluation was made of the biological effects of a new polypeptide (APP), 36 amino acid residues, MW 4200, isolated from the chicken pancreas. APP is an effective hepatic glycogenolytic and plasma hypoglycerolemic agent in the absence of plasma glucose perturbation. APP (at much lower doses) is also a powerful gastric secretogogue, inducing within seconds marked increases in proventricular volume, H + , pepsin, and total protein release. Such proventricular response is not mediated through systemic cardiovascular alterations or the vagus nerves, and are quite opposite to those observed with beef or chicken glucagon. It is concluded that the chicken pancreas releases APP to exert a “gastrinlike” secretogogic action on the proventriculus and, at higher concentrations, a metabolic action as well.

Pancreatic polypeptide as screening marker for pancreatic polypeptide apudomas in multiple endocrinopathies

Prospective screening was carried out in 12 members of three families with multiple endocrine adenopathies, type I (MEA,I) and in 14 patients with no multiple endocrine adenopathies with and without other endorcinopathies. Elevated basal and responsive (after a meal) plasma concentrations of a relatively new candidate-hormone, human pancreatic polypeptide (hPP), were associated with pancreatic apudoma tumors in three asymptomatic patients with multiple endocrine adenopathies, type I. Two of these patients had excision of the tumors that resulted in normal plasma hPP concentrations postoperatively. Both tumors contained hPP predominantly by immunocytochemistry; one, a pure pancreatic polypeptide apudoma, was studied extensively demonstrating also by radioimmunoassay a high content of hPP and negligible amounts of insulin, glucagon, somatostatin, vasoactive intestinal polypeptide and gastrin. In this patient plasma concentrations of other polypeptides including insulin, glucagon, somatostatin, vasoactive intestinal polypeptide, gastrin, parathyrin, thyrocalcitonin, prolactin, corticotropin, growth hormone, thyrtropin and amine, serotonin, were within normal limits. The other patient, after excision of an hPP-detected pancreatic mixed hPP-gastrinoma, also became eugastrinemic postoperatively. Normal basal plasma hPP concentrations, but with exaggerated hPP responses to a meal in 11 patients, were associated with various combinations of islet cell hyperplasia, antral G cell hyperplasia with moderate hypergastrinemia and parathyroid hyperplasia. The patients with multiple endocrine adenopathies who have demonstrated this type of increased hPP response to a meal have not been operated on but are at risk for islet hyperplasia. Four of the 12 patients with multiple endocrine adenopathies, type I, with both normal basal and normally responsive hPP concentrations have no evidence as yet of pancreatic involvement.

Isolation and structures of alligator gar (Lepisosteus spatula) insulin and pancreatic polypeptide

Insulin and a 36-residue peptide with homology to pancreatic polypeptide (PP) were isolated from the endocrine pancreas of the alligator gar (Lepisosteus spatula), a ganoid fish, by gel filtration and HPLC. Heterologous radioimmunoassays were used to detect insulin-like and PP-like immunoreactivities during purification of the two peptides. The sequence of the 36-amino acid peptide containing a C-terminal tyrosinamide was identical at 31 of 36 positions to porcine neuropeptide Y (NPY). The amino acid sequence of this peptide is YPPKPENPGEDAPPEELAKYYSALRHYINLITRQRY-NH2. The second peptide, gar insulin, contains 52 amino acid residues and is composed of a 21-residue A chain and a 31-residue B chain. The sequence of the A chain is GIVEQCCHKPCTIYELENYCN. The sequence of the B chain is AANQHLCGSHLVEALYLVCGEKGFFYNPNKV.

Isolation of alligator gar (Lepisosteus spatula) glucagon, oxyntomodulin, and glucagon-like peptide: amino acid sequences of oxyntomodulin and glucagon-like peptide

Oxyntomodulin, glucagon, and a glucagon-like peptide (GLP) have been isolated from the endocrine pancreas of the alligator gar (Lepisosteus spatula), a ganoid fish. The three peptides were isolated by gel filtration and HPLC and were identified by size, composition, and glucagon-like immunoreactivity. The amino acid sequences of the oxyntomodulin and GLP were determined. The oxyntomodulin contains 36 amino acid residues and its sequence is H S Q G T F T N D Y S K Y L D T R R A Q D F V Q W L M S T K R S G G I T. The composition of the glucagon is identical to the N-terminal 29 residues of the gar oxyntomodulin. The single form of GLP found contains 34 amino acid residues in the following sequence: H A D G T Y T S D V S S Y L Q D Q A A K K F V T W L K Q G Q D R R E. These findings suggest that all three peptides are derived from a common precursor.

TRH-like immunoreactivity in endocrine cells and neurons in the gastro-intestinal tract of the rat and guinea pig

SummaryBy use of the indirect immunofluorescence technique, the cellular localization of thyrotropin-releasing hormone (TRH) was studied in the gastrointestinal tract of rats and guinea pigs of different ages. TRH-like immunoreactivity (LI) was observed in many pancreatic islet cells of young rats and guinea pigs but only in single cells of 6-month-old rats. In aged guinea pigs, a reduction in the number of TRH-positive cells was evident; however, numerous strongly fluorescent cells were still present. In the guinea pig, TRH-LI was in addition observed in gastrin cells in the stomach. TRH-positive nerve fibers occurred in the myenteric plexus of the oesophagus, stomach and intestine of the rat, and in the muscle layers of the guinea pig. These results suggest a functional role of TRH both as hormone and neuroactive compound in various portions and sites of the gastro-intestinal tract of the rat and guinea pig

Isolation and characterization of reptilian insulin: partial amino acid sequence of rattlesnake (Crotalus atrox) insulin.

Insulin was isolated from the pancreas of two species of rattlesnake, Crotalus atrox and C. adamanteus. The procedure involved acid-ethanol extraction, gel filtration and DEAE-Sephadex chromatography. The insulin content of the pancreata was high, approximately 20 mg/100 g pancreas. Both insulins were identical in amino acid composition but this composition differed considerably from that of bovine insulin. Insulin from C. atrox assayed at 21.6 IU/mg in the mouse convulsion assay. The amino acid sequence of C. atrox insulin was determined and found to have some uncommon substitutions in the B chain.

Pancreatic polypeptide in islet cell tumors. Morphologic and functional correlations.

Twelve islet cell tumors and one islet cell hyperplasia were studied with immunocytochemical and radioimmunoassay methods. With immunocytochemical staining, all six insulinomas, one mixed insulinoma–glucagonoma, and four gastrinomas were positive for insulin, insulin and glucagon, and gastrin, respectively. Pancreatic polypeptide (PP) was positive in three insulinomas and one mixed insulinoma–glucagonoma. All of the tumors were positive for neuron‐specific enolase (NSE). Radioimmunoassays of tissue extracts further disclosed that all functioning tumors contained more than one pancreatic hormone. PP concentrations of two insulinomas and one mixed insulinoma–glucagonoma were higher than that of normal control pancreases. A study of protein meal‐stimulated PP secretion revealed that three of the insulinoma cases and two gastrinoma cases exhibited higher plasma PP levels than the age‐matched controls. The findings suggest that: (1) both functioning and nonfunctioning islet cell tumors derive from neuroendocrine cells positive for NSE; (2) all functioning islet cell tumors appear to contain PP in the tumor tissue as a minor component; (3) as many as 70% of the patients with islet cell tumors present with abnormally higher plasma PP levels after protein meals; and (4) a study of meal‐stimulated PP secretion may well be used as a marker for the presence of functional islet cell tumors. Cancer 56: 1649‐1657, 1985.