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At least 19 recordsLinked to original sources
PubMed1991

Hormonal control of avian pancreas by gastrin-releasing peptide from the proventriculus.

Endocrine cells in the acid-secreting part of the avian stomach, the proventriculus, contain two forms of gastrin-releasing peptide (GRP) of 27 and 6 residues, respectively. We have examined the actions of exogenous GRP-27 and GRP-6 and endogenously released GRP in the control of pancreatic secretion in urethan-anesthetized turkeys. Chicken GRP-27 and the structurally related amphibian peptide bombesin were potent stimulants of fluid and protein output from the pancreas (at 6-100 pmol/kg, iv). GRP-6 had no significant effect at doses up to 1,000 times higher. A bombesin antagonist, (CH3)2-CHCO-[D-Ala24]GRP-20--26-NHCH3, inhibited the action of exogenous chicken GRP-27 but did not inhibit intravenous cholecystokinin octapeptide (CCK-8). Distension of the proventriculus with a solution of peptone produced an increase in the flow of pancreatic juice and an increase in protein output, which was not reduced by atropine. The bombesin antagonist produced a reversible inhibition of this response. A CCK-gastrin antagonist, BOC-beta-Ala-Trp-Leu-Asp-O(CH2)2- phenyl(4F), which inhibited the action of exogenous CCK, had no effect on the pancreatic response to exogenous GRP-27 or to distension of the proventriculus with peptone. We suggest that protein-rich solutions in the proventriculus release GRP, which in turn acts directly on the pancreas to stimulate enzyme secretion.

Amino Acid Sequence↗
PubMed1986

Ultrastructural differentiation of glandular stomach (proventriculus) in chick embryo.

Cytochemical characterization of mucosubstances of chick glanular stomach (proventriculus) changes from 15 days of development to postnatal and adult stages was studied. To corroborate these data cytochemical, ultrastructural and ultracytochemical study of chick embryo proventriculus from 7 to 20 days of development was performed. At the 7th day several layers of undifferentiated cells formed an epithelium which covered the walls of the glandular stomach. Mocosubstances were not found. Between the 9th and 5th day a single layer of cylindrical cells was encountered forming invaginations which originated deep glands. Three types of cells were separated from the above mentioned layer, dark, clear and undifferentiated. The dark cells had organelles which are involved in protein synthesis and the clear ones were rich in mitochondria. Argentaffine cells appeared at 15th day instead mucosubstances formed a thin coat on the epithelium at 9th day which increased at the end of development in the apical cytoplasm and gland cells. These observations demonstrate that proventriculus of chick embryo has ultrastructurally differentiated cells involved with enzymatic and hydrochloric acid secretion after the 9th day. These progressive events are correlated with the digestion process of yolk during embryogenesis. At the end of development the proventriculus has completely organized the glandular layer.

Animals↗
PubMed1992

Development and birthdates of vasoactive intestinal peptide immunoreactive neurons in the chick proventriculus.

To gain insight into the mechanisms regulating expression of transmitter phenotypes in the enteric nervous system, we have studied the development and birthdate of vasoactive intestinal peptide immunoreactive (VIP-IR) myenteric neurons in the chicken proventriculus (secretory portion of the avian stomach) by a combination of immunocytochemistry and radioautography. The appearance and numbers of VIP-IR neurons in whole mounts of the myenteric plexus from chick embryos and chickens were examined. We found that VIP-IR neurons first appeared at embryonic day (E) 5.5-6.5 in the distal part of the proventriculus. At E7.5, VIP-IR neurons were found singly, in pairs, or in small groups, which together with unlabeled cells formed primitive myenteric ganglia. VIP-IR fibers were found within the developing fiber tracts which connected the ganglia. The number of VIP-IR neurons was found to be maximum in the E15.5 embryo and to decline to 68% of maximum in the 4 week old chicken. Birthdate studies were performed by application of either single pulses or cumulative doses of [3H]-thymidine to embryos between E3 and E14. Whole mounts of the myenteric plexus from the proventriculus of these embryos were immunostained for VIP at E10 or E17. The whole mounts were subsequently sectioned and processed for radioautography. We found that VIP-IR myenteric neurons were born between E3 and E10 with a peak at E7. Most cells underwent terminal division between E5 and E9. These data will be useful in determining the time and conditions when cells make decisions about transmitter phenotypes.

Aging↗
PubMed1977

[Development and function of endocrine cells in the proventriculus of the chicken (author's transl)].

An argyrophil endocrine cell type with typical intraepithelial development is seen initially on the 8th day of incubation in the epithelium of the main lumen of the chicken-proventriculus. During the embryonic period, rapid development of these cells can be observed with a quantitative maximum on the 13th day of incubation. At this time increased digestive efficiency is necessary for the chicken embryo with the start of gastric secretion combined with the first swallowing of albumen. There is a subsequent decrease in the number of endocrine cells in the main lumen epithelium, their function in hatched or adult specimens is largely taken over by cells which appear in the epithelium of the glands of the proventriculus on the 16th and later days of incubation. On the 2nd day after hatching the adult distribution pattern of endocrine cells in the proventriculus is attained.

Age Factors↗
PubMedDate not supplied

[The proventriculus of the Xenopsylla cheopis flea studied by scanning electron microscopy].

The proventriculus of the flea X. cheopis was studied by means of scanning electron microscopy. The external surface of the proventriculus is a rigid structure with an alveolate surface ("wasp nest") formed by muscular cords. The internal surface of the proventriculus is represented by numerous acanthae which fall close together. They have a shape of bent dens with longitudinal sharply angular edges and concave spaces between them. Some edges are crenate.

Animals↗
PubMed1991

Immunocytochemical and ultrastructural characterization of endocrine cells in chicken proventriculus.

The endocrine cells of the chicken proventriculus were investigated immunocytochemically, using the peroxidase-antiperoxidase technique on paraffin and semithin sections for light microscopy, and immunogold staining in osmium-fixed material for electron microscopy. The fixation procedure also allowed a detailed ultrastructural investigation. Twenty-three antisera were tested and 7 immunoreactive cell-types were identified: D-cells containing somatostatin-like peptide; EG-cells immunoreactive to anti-glucagon, anti-GLP1 and anti-neurotensin; NT-cells labelled only with anti-neurotensin; BN-cells containing bombesin-like material; ENK-cells showing met-enkephalin immunoreactivity; EC-cells reactive to anti-serotonin; and APP-cells positive to anti-avian pancreatic polypeptide. In addition, enterochromaffin-like (ECL) cells, were also detected by electron microscopy. The presence of ENK-cells and the ultrastructure of these and NT-cells are described for the first time in chicken proventriculus, and glucagon. GLP1 and neurotensin are shown to be colocalized in the EG-cells.

Animals↗
PubMed1979

The avian proventriculus is an abundant source of endocrine cells with bombesin-like immunoreactivity.

Radioimmunoassays using specific bombesin antisera revealed high concentrations of immunoreactivity in the turkey proventriculus, and negligible amounts of activity elsewhere in the gut. In immunohistochemical studies the same antisera revealed abundant endocrine-like cells in proventriculus mucosa, and isolated cells in small intestinal mucosa. In contrast to the rat, immunoreactivity was not demonstrated in nerves.

Animals↗
PubMed1990

Arginine vasotocin and mesotocin in the anterior hypothalamus, neurohypophysis, proventriculus and plasma of White Leghorn cockerels, during dehydration.

1. The effect of 96 hrs of water deprivation on plasma electrolytes, osmolarity, arginine vasotocin (AVT), mesotocin (MT), and on AVT and MT content in the neurohypophysis, anterior hypothalamic area (AHA) and proventriculus, was studied at 24 hrs intervals, in adult White Leghorn cockerels. 2. Plasma AVT increased three fold during the first 24 hrs but there was no further change during the next 48 hrs. In the last 24 hrs, plasma AVT decreased in about 25%. Plasma MT did not change during the entire period of dehydration. 3. Plasma sodium and osmolarity gradually increased during that time. 4. Neurohypophysial AVT content was depleted by 95% during the period of dehydration while MT content did not change. 5. In the AHA there was no change in AVT levels during dehydration while the levels of MT increased while in the proventriculus there was no change in either AVT or MT levels. 6. For the data collected during the entire experimental period, no correlation was found between plasma osmolarity and plasma AVT, but there was a highly significant negative correlation between plasma osmolarity and neurohypophysial AVT content. 7. It may be suggested that the depletion in AVT content in the neurohypophysis during progressive water deprivation resulted in an insufficient level of AVT in circulation to enable the cockerels to counter the dehydration. This may explain the death of those cockerels which were dehydrated for a further 24 hr period.

Animals↗
PubMed1988

Gizzerosine raises the intracellular cyclic adenosine-3',5'-monophosphate level in isolated chicken proventriculus.

Gizzerosine, which was originally found in fish meal, is a compound that causes gizzard erosion and ulceration in chicks. The action of gizzerosine on the isolated cells of chicken proventriculus was studied in the present investigations. Gizzerosine increased intracellular cyclic adenosine-3',5'-monophosphate (cAMP) levels, reaching a plateau within 30 min. Similar maxima of cAMP level were observed in the presence of histamine or gizzerosine. However, the potency of gizzerosine was approximately 1,000-fold higher than that of histamine. The action of gizzerosine was depressed by cimetidine, a histamine H2-receptor antagonist, but not by pyrilamine, a histamine H1-receptor antagonist, indicating that gizzerosine is a very strong histamine H2-receptor agonist. The mucosal cells isolated from the proventriculus by the present procedure had both histamine H1 and H2-receptors. Gizzerosine showed a higher affinity to the cell surface histamine receptor than histamine. These results partly explain the potent activity of gizzerosine in inducing gastric acid secretion and causing gizzard erosion and ulceration in chickens.

Animals↗
PubMedDate not supplied

Cryptosporidium sp. infection in the proventriculus of an Australian diamond firetail finch (Staganoplura bella: Passeriformes, Estrildidae).

An Australian diamond firetail finch died following the acute onset and development of severe diarrhea. The bird was purchased from a wholesaler and was housed in a pet store aviary with 12 other birds. Necropsy, histologic evaluation, and electron microscopic evaluation revealed organisms in the proventriculus (surface, ductal, and glandular epithelium) compatible in site of development, size, and morphology with Cryptosporidium spp. Lesions in the proventriculus were focal cuboidal metaplasia of glandular epithelial cells and deposition of amyloid in the perivascular interstitial tissues at the base of the glands. Amyloid also was present in the duodenum, liver, spleen, pancreas, and kidney. Inability to recover other organisms suggested that Cryptosporidium was the primary cause of diarrhea and death. The affected bird likely suffered dehydration as a result of acute gastrointestinal disturbance, concomitant with renal amyloidosis and urate nephrosis.

Animals↗
PubMed1975

Demonstration of acid phosphatase activity in the proventriculus of common weaver bird, Ploceus philippinus and whitebreasted kingfisher, Halcyon smyrnensis.

Acid phosphatase activity was histochemically localized in the proventriculus of two birds namely Ploceus philippinus and Halcyon smyrnensis. It was found that acid phosphatase-rich lysosomal activity appears to be relatively better developed in the proventriculus of piscivorous form, H. smyrnensis than that of granivorous form. P. philippinus. Simultaneously, a possible correlationship between the variable lysosomal activity and specific food diets of the birds has been discussed.

Acid Phosphatase↗
PubMed1976

Electrical activity of the proventriculus of the polychaete worm Syllis spongiphila.

The straited myoepithelial cells of the proventriculus of Syllis spongiphila are composed of only one or two sarcomeres that may reach 40 mum in length. Experiments were performed to study some of their electrophysiological properties and their synaptic control. The mean resting potentials recorded in two different bathing media were 59-1 +/- 5-5 mV (S.D., n=91) and 62-5 +/- 6-3 mV (S.D., n=98). At rest the membrane potential is determined largely by permeability of the membrane to K+ ions, but the membrane is also permeable to other ions. On a semilogarithmic plot of membrane potential v. [K]o the mean slope of the data points from 9 to 90 mM-[K]o was 48 +/- 3 mV for a 10-fold change in [K]o. The anterior end of the animal was stimulated with a suction electrode to elicit activity of nerve fibres that innervate the proventriculus. Single indirect stimuli usually evoked hyperpolarizing or biphasic responses, and occasionally depolarizing responses, from the myoepithelial cells. The depolarizing synaptic potentials exhibited a faster time course than the hyperpolarizing ones. The rise time to peak ranged from 20 to 35 ms for simple depolarizations (n=32) and 25-75 ms for simple hyperpolarizations (n=103). Time to decay to half amplitude ranged from 20 to 55 ms for depolarizations (n=29) and 62-135 ms for hyperpolarizations (n=87). Low frequency (is less than or equal to 4 Hz) trains of indirectly applied stimuli elicited mainly hyperpolarizing responses; higher frequency (5-40 Hz) trains elicited complex responses composed of hyperpolarizations and depolarizations. Hyperpolarizations were selectively and reversibly abolished in chloride-free solutions. The reversal potential of the hyperpolarizing synaptic potential was -104 +/- 3 mV (S.D., n=8, 2 preparations). In calcium-free solution both hyperpolarizations and depolarizations were almost completely abolished. 4 mM-Mn2+ added to the bath almost completely abolished the depolarization but not the hyperpolarization. It was not clear whether Mn2+ acted at the presynaptic membrane, the postsynaptic membrane or both. The myoepithelial cells are electrically coupled. The mean space constant of five preparations was 0-52 mm (range 0-40-0-66 mm).

Action Potentials↗
PubMed1980

Histochemical localization of carbonic anhydrase in fowl proventriculus.

The carbonic anhydrase activity in fowl proventriculus was studied by the histochemical method of Hanssom. The activity was observed in the mucose membrane cells and in proventricular gland cells. These results, about which there is disagreement in the literature, are discussed in the text.

Animals↗
PubMed1980

Purificaton and characterization of a pepsinogen and its pepsin from proventriculus of the Japanese quail.

A crude extract of the proventriculus of the Japanese quail gave at least five bands of peptic activity at pH 2.2 on polyacrylamide gel electrophoresis. The main component, constituting about 40% of the total acid protease activity, was purified to homogeneity by hydroxyapatite and DEAE-Sepharose column chromatographies. At below pH 4.0, the pepsinogen was converted to a pepsin, which had the same electrophoretic mobility as one of the five bands of peptic activity present in the crude extract. The molecular weights of the pepsinogen and the pepsin were 40 000 and 36 000, respectively. Quail pepsin was stable in alkali up to pH 8.5. The optimal pH of the pepsin on hemoglobin was pH 3.0. The pepsin had about half the milk-clotting activity of purified porcine pepsin, but the pepsinogen itself had no activity. The hydrolytic activity of quail pepsin on N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine was about 1% of that of porcine pepsin. Among the various protease inhibitors tested, only pepstatin inhibited the proteolytic activity of the pepsin. The amino acid composition of quail pepsinogen was found to be rather similar to that of chick pepsinogen C, and these two pepsinogens possessed common antigenicity.

Animals↗
PubMed1990

Isolation, sequence and biosynthetic significance of a novel fragment of gastrin-releasing peptide from chicken proventriculus.

The isolation of bombesin-related peptides in chicken proventriculus was monitored by radioimmunoassay using a C-terminal specific bombesin antibody. Two peptides were identified, one corresponded to the 27-residue, chicken gastrin-releasing peptide (GRP-27) previously identified; the other corresponded to its C-terminal hexapeptide. Chicken GRP-27 stimulated pancreatic and gastric acid secretion in anaesthetized turkeys, but the hexapeptide was inactive. No evidence could be found to suggest that the hexapeptide was an artifact of degradation generated during extraction or isolation. It is proposed that the hexapeptide is produced either by chymotryptic-like cleavage of GRP-27 or by trypsin-like cleavage followed by two cycles of dipeptidylaminopeptidase cleavage. This type of biosynthetic processing may be more common than formerly supposed.

Amino Acid Sequence↗
PubMed1985

The isolation and characterization of pepsinogens from the proventriculus of the ostrich Struthio camelus.

Three pepsinogens were isolated and purified from the proventriculus of the ostrich Struthio camelus, by a combination of chromatography steps on DEAE-cellulose, Sephadex G-100 and Hydroxylapatite. The purified pepsinogens manifested peptic activity towards haemoglobin as substrate after activation, but resembled chicken pepsinogens in that they appeared to lose their potential peptic activities during storage. All three pepsinogens contained glycine as N-terminal amino acid, but differed in their overall amino acid compositions. The pH and temperature optima of the activated pepsinogens were determined, as well as their molecular weights.

Amino Acids↗
PubMed1995

Ostrich pepsinogens I and II: purification, activation and chemical and immunochemical characterization of the enzymes from the proventriculus.

Pepsins are a series of gastric proteases secreted as inactive precursors (pepsinogens) which are active at acidic pH. The aim of this study was to purify ostrich pepsin(ogen)s and to compare their biochemical and immunological characteristics with those of pepsin(ogen)s of mammalian and avian origin. Ostrich pepsinogens were purified by ammonium sulphate fractionation, Toyopearl Super Q-650S chromatography and rechromatography, and hydroxylapatite chromatography of a pH 8.0 mucosal extract. Pepsins were obtained through acidification, and purified by chromatography on SP-Sephadex C-50. Amino acid compositions, N-terminal sequences, Ouchterlony double-diffusion as well as Western blot analysis were performed. Two pepsinogens were isolated and purified from the proventriculus of the ostrich, pepsinogens I and II. Both pepsinogens and pepsins were purified to homogeneity as shown by PAGE and SDS-PAGE, with SDS-PAGE revealing M(r) values of 40,400 and 41,900 for pepsinogens I and II, respectively. SDS-PAGE revealed M(r) values of 36,000 and 36,300 for ostrich pepsins I and II, respectively. Ostrich pepsinogens I and II were found to have identical N-terminal sequences, with Asp as N-terminal amino acid. Amino acid compositions were obtained for both pepsinogens, with ostrich pepsinogen I being slightly smaller in size with a total of 356 residues compared to 371 for ostrich pepsinogen II. Pepsinogen II showed a pI of 4.29. Ostrich pepsinogens I and II were found to be immunologically separate entities, and no cross-reactivity was observed between anti-(ostrich pepsinogen I/II) sera and porcine pepsin/pepsinogen. The study indicates that only two pepsinogens are present in the ostrich. They differ in terms of electrophoretic mobility, molecular mass and immunological reactivity, but have been found to have identical N-terminal sequences. It is concluded that both pepsinogens belong to the pepsinogen A class of aspartyl proteases (EC 3.4.23.1).

Amino Acid Sequence↗