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Role of leptin in the control of postprandial pancreatic enzyme secretion

100%

Jaworek J., Bonior J., Konturek S. J., Bilski J., Szlachcic A., Pawlik W. W.

Journal of Physiology and Pharmacology

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2003

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tom 54

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nr 4

Leptin released by adipocytes has been implicated in the control of food intake but recent detection of specific leptin receptors in the pancreas suggests that this peptide may also play some role in the modulation of pancreatic function. This study was undertaken to examine the effect of exogenous leptin on pancreatic enzyme secretion in vitro using isolated pancreatic acini, or in vivo in conscious rats with chronic pancreatic fistulae. Leptin plasma level was measured by radioimmunoassay following leptin administration to the animals. Intraperitoneal (i.p.) administration of leptin (0.1, 1, 5, 10, 20 or 50 µg/kg), failed to affect significantly basal secretion of pancreatic protein, but markedly reduced that stimulated by feeding. The strongest inhibition has been observed at dose of 10 µg/kg of leptin. Under basal conditions plasma leptin level averaged about 0.15 ± 0.04 ng/ml and was increased by feeding up to 1.8 ± 0.4 ng/ml. Administration of leptin dose-dependently augmented this plasma leptin level, reaching about 0.65 ± 0.04 ng/ml at dose of 10 µg/kg of leptin. This dose of leptin completely abolished increase of pancreatic protein output produced by ordinary feeding, sham feeding or by diversion of pancreatic juice to the exterior. Leptin (10-10-10-7 M) also dose-dependently attenuated caerulein-induced amylase release from isolated pancreatic acini, whereas basal enzyme secretion was unaffected. We conclude that leptin could take a part in the inhibition of postprandial pancreatic secretion and this effect could be related, at least in part, to the direct action of this peptide on pancreatic acini

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Leptin is able to stimulate pancreatic enzyme secretion via activation of duodeno-pancreatic reflex and CCK release

72%

Nawrot-Porabka K., Jaworek J., Leja-Szpak A., Palonek M., Szklarczyk J., Konturek S. J., Pawlik W. W.

Journal of Physiology and Pharmacology. Supplement

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2004

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tom 55

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nr 2

47-57

Leptin, 16- kDa protein produced and secreted from white adipocytes is known to regulate food intake and energy expenditure. Leptin receptors have been detected in the pancreas and it has been shown that systemic application of this protein diminished postprandial pancreatic secretion. Leptin is also produced in the stomach and released into the gastrointestinal lumen but the implication of luminal leptin in the regulation of pancreatic enzyme secretion has not been elucidated. The aim of our study was to evaluate the effects of intraduodenal (i.d.) leptin administration on pancreatic enzyme secretion and to assess the involvent of afferent nerves and CCK in above effects. The secretory studies were carried out on anaesthetized Wistar rats with acute pancreatic fistulae. Leptin was administered to the animals at doses of 0.1 1.0 or 10.0 µg/kg i.d. Tarazepide (2.5 mg/kg i.d.), a CCK1 receptor antagonist, was given to the rats prior to the application of leptin. Rats with capsaicin deactivated sensory nerves were used in part of the study. Samples of pancreatic juice were taken at 15 min intervals to measure the volume flow and protein and amylase concentrations. CCK plasma level was measured by radioimmunoassay (RIA) following administration of leptin to the rats. Intraduodenal administration of leptin (1.0 or 10.0 µg/kg) to the fasted rats significantly and dose-dependently increased pancreatic protein and amylase outputs. Pancreatic secretory responses to leptin were totally abolished by prior capsaicin deactivation of sensory nerves or by pretreatment of the rats with tarazepide. Under basal conditions plasma CCK level averaged about 15.46 ± 1,4 pg/ml. Exogenous leptin, given i.d. at doses of 0.1 1.0 or 10.0 µg/kg i.d. to the rats with intact or capsaicin-deactivated sensory nerves resulted in dose-dependent rise of plasma CCK level, reaching the highest value at the dose of 10.0 µg/kg i.d. We conclude that leptin given i.d. stimulates pancreatic enzyme secretion and this effect could be related to the stimulation of CCK release and activation of duodeno-pancreatic reflexes.

3

Exposition of newborn rats to bacterial endotoxin impairs pancreatic enzyme secretion at adult age

72%

Jaworek J., Nawrot-Porabka K., Leja-Szpak A., Szklarczyk J., Macko M., Bonior J., Stachura J., Konturek S. J., Pawlik W. W.

Journal of Physiology and Pharmacology

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2007

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tom 58

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nr 2

Lipopolysaccharide (LPS, endotoxin) is the component of the cellular wall of Gram negative bacteria. Endotoxemia (sepsis) could produce multiorgan failure and in the early period of life LPS are responsible for the changes of metabolism and for the reduction of protein synthesis. The influence of neonatal endotoxemia on the pancreas at adults has not been investigated yet. The aim of this study was to assess the pancreatic exocrine function in the adult rats which have been subjected, in the neonatal period of life, to chronic LPS pretreatment. LPS from E. coli or S. typhi at doses of 5, 10 or 15 mg/kg-day was administered intraperitoneally (i.p.) to the suckling rats (30 g) during 5 consecutive days. Three months later these animals (300 g) were equipped with pancreato-biliary fistulae for the in vivo secretory study. Amylase release from isolated pancreatic acini obtained from these rats was also assessed. Pancreatic tissue samples were taken for histological assessment and for the determination of gene expression for CCK1 receptor by RT-PCR. Pancreatic amylase secretions stimulated by caerulein or by diversion of pancreatic-biliary juice to the exterior (DBPJ) was significantly, and dose-dependently reduced in the adult rats which have been subjected in infancy to chronic pretreatment with LPS from E. coli or S. typhi, as compared to the untreated control. In these animals basal secretion was unaffected. In the rats pretreated with LPS in the suckling period of life caerulein-induced amylase release from isolated pancreatic acini was significantly decreased, as compared to the untreated with LPS control. This was accompanied by dose-dependent reduction of mRNA signal for CCK1 receptor on pancreatic acini. Neonatal endotoxemia failed to affect significantly pancreatic morphology as well as plasma amylase level in the adult rats. We conclude that neonatal endotoxemia reduces gene expression for CCK1 receptor and could produce impairment of the exocrine pancreatic function at adult age.

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The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro

72%

Jaworek J., Bilski J., Jachimczak B., Cieszkowski M., Kot M., Bielanski W., Konturek S. J.

Journal of Physiology and Pharmacology

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2000

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tom 51

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nr 2

5

Melatonin as modulator of pancreatic enzyme secretion and pancreatoprotector

58%

Jaworek J., Nawrot-Porabka K., Leja-Szpak A., Bonior J., Szklarczyk J., Kot M., Konturek S. J., Pawlik W. W.

Journal of Physiology and Pharmacology. Supplement

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2007

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tom 58

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nr 6

6

Modulation of pancreatic enzyme secretion by melatonin and its precursor; L-tryptophan. Role of CCK and afferent nerves

58%

Leja-Szpak A., Jaworek J., Nawrot-Porabka K., Palonek M., Mitis-Musiol M., Dembinski A., Konturek S. J., Pawlik W. W.

Journal of Physiology and Pharmacology. Supplement

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2004

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tom 55

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nr 2

33-46

Melatonin, a pineal hormone, is also produced in the gastrointestinal tract. Melatonin receptors have been detected in the stomach, intestine and pancreas. This indole inhibits insulin secretion but its role in the physiological modulation of exocrine pancreatic function is yet unknown. The aim of this study was to evaluate the pancreatic secretory effect of melatonin and its precursor; L-tryptophan given intraduodenally (i.d.) to the conscious rats with intact or capsaicin deactivated sensory nerves. CCK1 receptor antagonist; tarazepide, was used in the part of the study to determine the involvement of CCK in the secretory effects of melatonin. The secretory studies were performed on awaken rats surgically equipped with silicone catheters, one of them was inserted into pancreato-biliary duct, the other one - into duodenum. Melatonin (1, 5 or 25 mg/kg) or L-tryptophan (10, 50 or 250 mg/kg) were administered i.d. Samples of pancreatic juice were collected in 15 minutes aliquots. Tarazepide (2,5 mg/kg i.p.) was given to the rats 15 min prior to the administration of melatonin or L-tryptophan. Neurotoxic dose of capsaicin (100 mg/kg s.c.) was used to deactivate afferent nerves and thus to assess the role of these nerves in the melatonin-induced pancreatic enzyme secretion. Administration of melatonin (1, 5 or 25 mg/kg i.d.) or L-tryptophan (10, 50 or 250 mg/kg i.d.) significantly increased pancreatic amylase outputs. Deactivation of sensory nerves by capsaicin or administration of CCK1 - receptor antagonist; tarazepide, reversed the stimulatory effects of melatonin or L-tryptophan on pancreatic secretory function. Administration of melatonin or its amino-acid precursor to the rats resulted in the significant and dose-dependent rises of melatonin and CCK plasma levels. We conclude that melatonin or its precursor; L-tryptophan stimulates pancreatic enzyme secretion via stimulation of CCK release and activation of duodeno-pancreatic reflexes.

7

Effect of neonatal endotoxemia on the pancreas of adult rats

58%

Jaworek J., Leja-Szpak A., Nawrot-Porabka K., Bonior J., Szklarczyk J., Kot M., Konturek S. J., Tomaszewska R., Pawlik W. W.

Journal of Physiology and Pharmacology. Supplement

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2008

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tom 59

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nr 4

87-102

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Brain-gut axis in the modulation of pancreatic enzyme secretion

58%

Jaworek J., Nawrot-Porabka K., Leja-Szpak A., Konturek S. J.

Journal of Physiology and Pharmacology

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2010

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tom 61

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nr 5

9

Tarazepide - appetite factor in swine

58%

Rzasa A., Gregory P. C., Pierzynowski S. G.

Electronic Journal of Polish Agricultural Universities. Series Veterinary Medicine

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2003

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tom 06

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nr 1

10

Characterization of CCK receptor - mediated effects on intracellular calcium of porcine chief cells

58%

Heim H. K., Elhoft A., Wittstock H., Sewing K. F.

Journal of Physiology and Pharmacology

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1995

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tom 46

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nr 4

Ograniczanie wyników

Role of leptin in the control of postprandial pancreatic enzyme secretion

Leptin is able to stimulate pancreatic enzyme secretion via activation of duodeno-pancreatic reflex and CCK release

Exposition of newborn rats to bacterial endotoxin impairs pancreatic enzyme secretion at adult age

The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro

Melatonin as modulator of pancreatic enzyme secretion and pancreatoprotector

Modulation of pancreatic enzyme secretion by melatonin and its precursor; L-tryptophan. Role of CCK and afferent nerves

Effect of neonatal endotoxemia on the pancreas of adult rats

Brain-gut axis in the modulation of pancreatic enzyme secretion

Tarazepide - appetite factor in swine

Characterization of CCK receptor - mediated effects on intracellular calcium of porcine chief cells