Differences in the skin peptides of the male and female Australian tree frog Litoria splendida. The discovery of the aquatic male sex pheromone splendipherin, together with phe8 caerulein and a new antibiotic peptide caerin 1.10. (9/463)

The skin secretions of female and male Litoria splendida have been monitored monthly over a three-year period using HPLC and electrospray mass spectrometry. Two minor peptides are present only in the skin secretion of the male. The first of these is the female-attracting aquatic male sex pheromone that we have named splendipherin, a 25 amino acid peptide (GLVSSIGKALGGLLADVVKSKGQPA-OH). This pheromone constitutes about 1% of the total skin peptides during the breeding season (January to March), dropping to about 0.1% during the period June to November. Splendipherin attracts the female in water at a concentration of 10-11-10-9 M, and is species specific. The second peptide is a wide-spectrum antibiotic of the caerin 1 group, a 25 residue peptide (GLLSVLGSVAKHVLPHVVPVIAEKL-NH2) named caerin 1.10. The neuropeptides of L. splendida are also seasonally variable, the change identical for both the female and male. During the period October to March, the sole neuropeptide present in skin secretions is caerulein [pEQDY(SO3)TGWMDF-NH2]; this is active on smooth muscle and is also an analgaesic. During the southern winter (June to September), more than half of the caerulein is hydrolysed to [pEQDYTGWMDF-NH2], a peptide that shows no smooth muscle activity. In place of caerulein, a new peptide, Phe8 caerulein [pEQDY(SO3)TGWFDF-NH2], becomes a major component of the skin secretion. Perhaps this seasonal change is involved in thermoregulation, that is, with the initiation and maintenance of the inactive (hibernation) phase of the animal.  (+info)

Nitric oxide protects the ultrastructure of pancreatic acinar cells in the course of caerulein-induced acute pancreatitis. (10/463)

Nitric oxide (NO) as a unique biological mediator that has been implicated in many physiological and pathophysiological processes may have a significant influence on the course of acute pancreatitis and the recovery process. The aim of the study was to evaluate the effect of a NO synthase inhibitor or a substrate for NO endogenous production on the ultrastructural features of the acinar cells in the course of caerulein-induced acute pancreatitis. Acute pancreatitis was induced in the rats by a supramaximal dose of caerulein. During acute pancreatitis induction, the rats were treated with L-arginine (the substrate for NO synthesis), NG-nitro-L-arginine (L-NNA, NO synthase inhibitor), L-arginine + L-NNA or saline. Light and electron microscopy examinations were performed in all groups after pancreatitis induction and additionally after 7 and 14 days of recovery. The study demonstrated that the NO synthase inhibitor given during pancreatitis induction in rats enhances the damage to the acinar cells, detected ultrastructurally, and increases the cellular inflammatory infiltration. In the later period, the considerable damage to the mitochondria and the changes in secretory compartment were observed, including dilated cisternae of Golgi apparatus, focal degranulation of rough endoplasmic reticulum, and reduced number of zymogen granules and condensing vacuoles. L-arginine reversed to some extent the deleterious effect of L-NNA, although when administered alone it had no apparent effect on the ultrastructure of pancreatic acinar cells compared with untreated animals. The obtained results indicate that the NO synthase inhibitor enhances the ultrastructural degenerative alterations in the pancreatic acinar cells in the course of caerulein-induced acute pancreatitis and confirm the protective role of endogenous nitric oxide in this disease.  (+info)

CEP-1347 inhibits caerulein-induced rat pancreatic JNK activation and ameliorates caerulein pancreatitis. (11/463)

Pancreatic caerulein-induced activation of c-Jun NH(2)-terminal kinase (JNK) has been reported, and JNK has been proposed as a mediator during induction of hyperstimulated pancreatitis. CEP-1347 has recently been described as a specific JNK inhibitor. We tested whether CEP-1347 inhibits caerulein-induced pancreatic JNK activation in isolated acini and in vivo. CEP-1347 dose dependently inhibited acinar caerulein-induced JNK activation with nearly complete inhibition at 2 microM but had no effect on digestive enzyme release. For in vivo studies, rats were pretreated with CEP-1347 before caerulein hyperstimulation. For assessment of JNK activation and histological alterations, animals were killed 30 min or 2 and 4 h after caerulein hyperstimulation, respectively. Pancreatic wet weight, serum enzyme levels, and pancreatic activity of p38 and extracellular signal-regulated kinase (ERK) were also determined. Caerulein hyperstimulation strongly activated JNK, p38, and ERK. CEP-1347 pretreatment dose dependently reduced caerulein-induced pancreatic JNK activation without p38 or ERK inhibition. JNK inhibition also reduced pancreatic edema formation and reduced histological severity of pancreatitis. Thus we show that CEP-1347 inhibits JNK activation in vivo and ameliorates caerulein-induced pancreatitis.  (+info)

Cholecystokinin-induced anxiety in rats: relevance of pre-experimental stress and seasonal variations. (12/463)

OBJECTIVE: To examine the influence of pre-experimental stress on the anxiogenic-like action of caerulein, an agonist of cholecystokinin (CCK) receptors. Differences in the anxiety levels of rats in summer and winter, and the role of CCK in these behavioural alterations, were also examined. DESIGN: Prospective animal study. INTERVENTIONS: Male Wistar rats were injected with the CCK agonist caerulein, or the CCK antagonists L-365,260 or devazepide, after being exposed to pre-experimental stress (handling and isolation). OUTCOME MEASURES: Performance in the plus-maze model of anxiety; serum levels of prolactin, thyrotropin and growth hormone; brain density and affinity of dopamine D2, serotonin 5-HT2 and CCK receptors. RESULTS: Caerulein (5 micrograms/kg, subcutaneous injection) caused the strongest action in animals brought to the experimental room immediately before the experiment and kept in isolation after the administration of caerulein. Caerulein did not cause any reduction of exploratory activity in rats made familiar with the experimental room and kept in the home-cage after the injection of the CCK agonist. The anti-exploratory action of caerulein in stressed rats was reversed by the CCK antagonist L-365,260 (100 micrograms/kg, intraperitoneal injection), demonstrating the involvement of the CCKB receptor subtype. In addition, seasonal fluctuations occur in the exploratory activity of rats; such activity was much lower in July than in November. The rats displaying the reduced exploratory activity had an increased number of CCK receptors in the frontal cortex and hippocampus. Simultaneously, the density of serotonin 5-HT2 receptors in the frontal cortex, but not that of dopamine D2 receptors in the striatum, was elevated. The blood level of growth hormone was also higher in July. CONCLUSIONS: The anti-exploratory action of caerulein appears to be dependent on the pre-experimental stress of rats. Moreover, the seasonal variations of exploratory behaviour of rats are evident in the plus-maze model of anxiety. The reduced exploratory activity in summer appears to be related to the elevated density of CCK and 5-HT2 receptors in the brain.  (+info)

Loss of TGF-beta signaling contributes to autoimmune pancreatitis. (13/463)

Recent observations suggest that immune response is involved in the development of pancreatitis. However, the exact pathogenesis underlying this immune-mediated response is still under debate. TGF-beta has been known to be an important regulating factor in maintaining immune homeostasis. To determine the role of TGF-beta in the initiation or progression of pancreatitis, TGF-beta signaling was inactivated in mouse pancreata by overexpressing a dominant-negative mutant form of TGF-beta type II receptor in the pancreas, under control of the pS2 mouse trefoil peptide promoter. Transgenic mice showed marked increases in MHC class II molecules and matrix metalloproteinase expression in pancreatic acinar cells. These mice also showed increased susceptibility to cerulein-induced pancreatitis. This pancreatitis was characterized by severe pancreatic edema, inflammatory cell infiltration, T- and B-cell hyperactivation, IgG-type autoantibodies against pancreatic acinar cells, and IgM-type autoantibodies against pancreatic ductal epithelial cells. Therefore, TGF-beta signaling seems to be essential either in maintaining the normal immune homeostasis and suppressing autoimmunity or in preserving the integrity of pancreatic acinar cells.  (+info)

Pentoxifylline ameliorates cerulein-induced pancreatitis in rats: role of glutathione and nitric oxide. (14/463)

Reactive oxygen radicals, nitric oxide, and cytokines have been implicated in the initiation of pancreatic tissue damage and impairment of the pancreatic microcirculation in acute pancreatitis. Pentoxifylline is a methylxanthine derivative with rheologic and marked anti-inflammatory properties and inhibits the production of proinflammatory cytokines. We have examined whether pentoxifylline ameliorates interstitial edema, inflammatory infiltrate, and glutathione depletion associated with cerulein-induced pancreatitis. Cotreatment of animals with pentoxifylline significantly reduced cerulein-induced pancreatic inflammation and edema and attenuated the depletion of pancreatic glutathione and the increase in serum lipase activity, nitrate, and tumor necrosis factor-alpha levels. Pentoxifylline also prevented both mitochondrial swelling and damage to mitochondrial cristae caused by cerulein. Our findings provide an experimental basis for using pentoxifylline to attenuate inflammatory responses within the pancreas in acute pancreatitis and as an adjuvant in the treatment of acute pancreatitis.  (+info)

Substance P mediates inflammatory oedema in acute pancreatitis via activation of the neurokinin-1 receptor in rats and mice. (15/463)

Pancreatic oedema occurs early in the development of acute pancreatitis, and the overall extent of fluid loss correlates with disease severity. The tachykinin substance P (SP) is released from sensory nerves, binds to the neurokinin-1 receptor (NK1-R) on endothelial cells and induces plasma extravasation, oedema, and neutrophil infiltration, a process termed neurogenic inflammation. We sought to determine the importance of neurogenic mechanisms in acute pancreatitis. Pancreatic plasma extravasation was measured using the intravascular tracers Evans blue and Monastral blue after administration of specific NK1-R agonists/antagonists in rats and NK1-R(+/+)/(-/-) mice. The effects of NK1-R genetic deletion/antagonism on pancreatic plasma extravasation, amylase, myeloperoxidase (MPO), and histology in cerulein-induced pancreatitis were characterized. In rats, both SP and the NK1-R selective agonist [Sar(9) Met(O(2))(11)]SP stimulated pancreatic plasma extravasation, and this response was blocked by the NK1-R antagonist CP 96,345. Selective agonists of the NK-2 or NK-3 receptors had no effect. In rats, cerulein stimulated pancreatic plasma extravasation and serum amylase. These responses were blocked by the NK1-R antagonist CP 96,345. In wildtype mice, SP induced plasma extravasation while SP had no effect in NK1-R knockout mice. In NK1-R knockout mice, the effects of cerulein on pancreatic plasma extravasation and hyperamylasemia were reduced by 60%, and pancreatic MPO by 75%, as compared to wildtype animals. Neurogenic mechanisms of inflammation are important in the development of inflammatory oedema in acute interstitial pancreatitis.  (+info)

Heat shock protein 70 prevents secretagogue-induced cell injury in the pancreas by preventing intracellular trypsinogen activation. (16/463)

Rodents given a supramaximally stimulating dose of cholecystokinin or its analogue cerulein develop acute pancreatitis with acinar cell injury, pancreatic inflammation, and intrapancreatic digestive enzyme (i.e., trypsinogen) activation. Prior thermal stress is associated with heat shock protein 70 (HSP70) expression and protection against cerulein-induced pancreatitis. However, thermal stress can also induce expression of other HSPs. The current studies were performed using an in vitro system to determine whether HSP70 can actually mediate protection against pancreatitis and, if so, to define the mechanism underlying that protection. We show that in vitro exposure of freshly prepared rat pancreas fragments to a supramaximally stimulating dose of cerulein results in changes similar to those noted in cerulein-induced pancreatitis, i.e., intra-acinar cell trypsinogen activation and acinar cell injury. Short-term culture of the fragments results in HSP70 expression and loss of the pancreatitis-like changes noted after addition of cerulein. The culture-induced enhanced HSP70 expression can be prevented by addition of either the flavonoid antioxidant quercetin or an antisense oligonucleotide to HSP70. Under these latter conditions, addition of a supramaximally stimulating concentration of cerulein results in trypsinogen activation and acinar cell injury. These findings indicate that the protection against cerulein-induced pancreatitis that follows culture-induced (and possibly thermal) stress is mediated by HSP70. They suggest that the HSP acts by preventing trypsinogen activation within acinar cells.  (+info)