Secretory and biosynthetic responses of gastrin and somatostatin to acute changes in gastric acidity

A Novel Method for Pain Relief in Chronic Pancreatitis: an Old Drug in a New Pack: a Controlled Study

Most of pain-relieving agents in chronic pancreatitis are nonspecific and unpredictable. Omeprazole induces hypergastrinemia due to reduced gastric acidity. Raised serum gastrin, in turn, modulates to reduce secretin level. Secretin is responsible for secretion of almost 80 % bicarbonate-rich pancreatic juice from the ductular epithelium without affecting enzyme output. It is a prospective randomized study in patients with CT-confirmed chronic pancreatitis. The control group got the standard care and 60 mg of omeprazole twice daily was added to the test group. Absence of pain relief at 14 days was considered as failure. Pain relief, weight gain and any toxic effect of omeprazole were reviewed at 12 months. One hundred thirty-seven cases were included, with an age range of 19 to 72 years. (mean 42.67). The majority of them were alcoholic males. At 2 weeks, pain relief was noted in 47/69(68.1 %) and 63/65(96.96 %) in the control and omeprazole group, respectively. At the end of 1 year, the omeprazole group had greater weight gain (95 %) than the control group (69.5 %). All the pseudocysts in the omeprazole group and most in the control group resolved. No side effect of omeprazole was seen. The high-dose omeprazole (HDO) group of patients had significantly better pain relief in chronic pancreatitis than those treated with conventional therapy. A high number of cases gained weight in the HDO group than the controlled group. No patient had clinical, endoscopic, biochemical, or haematological toxicity of HDO. More studies are necessary.

The type 2 CCK/gastrin receptor antagonist YF476 acutely prevents NSAID-induced gastric ulceration while increasing iNOS expression

YF476 differs from the proton pump inhibitor (PPI) esomeprazole in mode of action by antagonizing the type 2 receptor of cholecystokinin/gastrin (CCK-2R). YF476 protection against diclofenac-induced gastric ulcers was compared to esomeprazole and correlated with plasma levels of hormones related to gastric pH (gastrin, ghrelin, and somatostatin), gastric gene expression of these hormones, their receptors, and inducible nitric oxide synthase (iNOS). YF476 or esomeprazole pretreatments were followed by diclofenac. Four hours later, gastric tissue was excised and analyzed for ulcer index. An intragastrically implanted Bravo capsule measured pH for 5 days during YF476 plus pentagastrin treatment. Changes in gene expression were assayed for gastrin, ghrelin, and somatostatin; their receptors; and iNOS. YF476 acutely (within 4 h) protected against diclofenac-induced gastric ulcers equivalent to esomeprazole. Gastric pH recorded during 5 days in the presence of pentagastrin was 1.83 (±0.06). YF476 raised pH to 3.67 (±0.09) and plasma ghrelin, gastrin, and somatostatin increased. YF476 increased gene expression of somatostatin receptor and gastrin, while ghrelin receptor decreased; transcripts coding ghrelin, somatostatin, and CCK-2R remained unchanged. In the presence of diclofenac, esomeprazole increased expression of all these transcripts and that of iNOS, while YF476 yielded only decreased CCK-2R and increased iNOS transcripts. YF476 is a potential new preventative treatment for patients at risk of nonsteroidal antiinflammatory drug (NSAID)-induced ulceration. Gastric gene expressions of ghrelin, gastrin, and somatostatin and their receptors differ between esomeprazole and YF476. Despite these differences and different modes of action to raise gastric pH, both drugs acutely increase iNOS, suggesting iNOS expression parallels pH.

Active immunoneutralization of somatostatin in the sheep: effects on gastrointestinal somatostatin expression, storage and secretion

In the absence of somatostatin antagonists, somatostatin antisera administered acutely or animals chronically immunized against somatostatin have been used to define the functions of somatostatin. However, the circulating immunoglobulins from immunized animals may contain substantial quantities of endogenous hormones. This has not been examined for somatostatin. We have measured the amount of free somatostatin bound to circulating immunoglobulins in somatostatin-immunized animals and the effect of this sequestering of the free peptide on somatostatin secretion and gastric somatostatin synthesis and storage. The average concentration of somatostatin bound to the antisera was 6.9 nmol/l, about 1000-fold higher than normal circulating levels. Compared to control animals, there was a doubling of somatostatin mRNA in the fundus and a 4-fold increase in fundic somatostatin peptide. Similar increases were seen in pancreas, but the antrum was not significantly affected providing further evidence of distinct regulatory mechanisms between the antrum and fundus. We suggest that withdrawal of active somatostatin activates a regulatory loop to increase fundic somatostatin biosynthesis and storage. The data support the concept that somatostatin autoregulates its own expression at both the RNA and peptide level.