Alterations of plasma immunoreactive glucagon-like peptide-1 behavior in non-insulin-dependent diabetics.

The basal level of plasma immunoreactive glucagon-like peptide-1 (IR GLP-1) was significantly elevated in non-insulin-dependent diabetics (NIDD), and this elevation of IR GLP-1 was mainly due to an increase in the large component of IR GLP-1, corresponding to the pancreatic form. During the oral glucose-tolerance test (OGTT), the total plasma IR GLP-1 decreased in normal subjects but increased significantly in diabetic patients. Chromatographic analysis showed that IR GLP-1 consisted of several different molecular forms.

Suppression of synthesis and release of glucagon by glucagon-like peptide-1 (7-36 amide) without affect on mRNA level in isolated rat islets.

Glucagon-like peptide-1 (GLP-1) has been reported to inhibit glucagon release. To investigate the mechanism involved, we examined the effects of GLP-1 on the preproglucagon mRNA level and the content and release of glucagon in the isolated rat islets. Arginine significantly increased the content and release of glucagon after incubation for 1 h or 18 h.

Radioimmunoassay of glycated serum protein using monoclonal antibody to glucitollysine and coomassie-brilliant-blue-coated polystyrene beads.

A radioimmunoassay for glycated serum protein (GSP) was developed using monoclonal antibody to glucitollysine and polystyrene beads coated with Coomassie-Brilliant-Blue (CBB) as adsorbent for serum protein. The monoclonal antibody was raised by immunizing BALB/c mice with reduced glycated LDL and fusing their spleen cells with mouse myeloma cells. CBB-coated polystyrene beads were introduced to absorb a constant amount of serum protein.

Identification of glucagon-like peptide-1(7-36) amide in rat brain.

Acid-urea extract of rat brain was examined by glucagon-like peptide-1 (GLP-1) specific radioimmunoassay. A single peak was observed which co-eluted with GLP-1(7-36)amide on gel filtration and anion exchange chromatography. In contrast, GLP-1(1-37) was not detected under our experimental conditions.

Effect of glucagon-like peptide-1 on insulin secretion.

The insulinotropic actions of two forms of glucagon-like peptide 1 (GLP-1) containing 31 and 37 amino acid residues on perfused rat pancreas were compared with that of gastric inhibitory polypeptide (GIP), hitherto the most potent intestinal insulinotropic polypeptide known. The smaller form, C-terminally amidated GLP-1-(7-36), strongly enhanced insulin secretion stimulated by 11.1 mM D-glucose at a concentration as low as 0.

Comparison of half-disappearance times, distribution volumes and metabolic clearance rates of exogenous glucagon-like peptide 1 and glucagon in rats.

The pharmacokinetics of glucagon-like peptide-1 (GLP-1) in vivo after bolus and continuous i.v. administrations of the peptide were compared with those of glucagon in rats.

Specific radioimmunoassay of glucitol-lysine--application to lens proteins in streptozotocin-diabetic rats.

A radioimmunoassay using antibody against glucitol-lysine was developed to quantitate glycated proteins in the lens of diabetic rats. The amount of glycated protein was expressed as molar equivalents of reduced glycated hippuryl lysine (GlcRED-Hip-Lysine). Significant differences (p less than 0.

Effect of the enteroinsular axis on both the A- and B-cell response to arginine after oral glucose in man.

Studies were made on the effect of the enteroinsular axis on amino acid-induced insulin and glucagon secretion during hyperglycaemia in man. The responses of plasma immunoreactive insulin, C-peptide, and immunoreactive glucagon to arginine infusion were investigated in nine healthy subjects after induction of hyperglycaemia by an oral glucose load and by intravenous glucose infusion to produce similar glucose concentrations in the arterialised blood. The plasma immunoreactive insulin and C-peptide levels increased to higher levels after an oral glucose load than after an intravenous infusion of glucose.

Identification and localization of glucagon-like peptide-1 and its receptor in rat brain.

The existence and distribution of glucagon-like peptide-1 (GLP-1) and its receptor in rat brain in relation to that of glucagon were examined. The concentration of GLP-1 immunoreactivity (GLP-1-IR), measured by a specific and sensitive RIA established in this study with anti GLP-1 serum (LMT-01), was found to be highest in the thalamus-hypothalamus, followed by the medulla oblongata. The distribution of glucagon-like immunoreactivity was similar to that of GLP-1-IR.

A large molecular form of glucagon-like peptide-1 (GLP-1) immunoreactivity is co-released with glucagon from pancreas by arginine in normal subjects.

Plasma immunoreactivities of glucagon-like peptide-1 (GLP-1IR) in normal subjects were measured with a specific radioimmunoassay during the arginine tolerance test. Plasma GLP-1IR after arginine infusion showed a 3-fold increase in parallel to plasma glucagon immunoreactivity and plasma glucagon-like immunoreactivity, measured with a glucagon C-terminal specific antiserum (OAL 123) and an N-terminal and/or central region specific glucagon antiserum (OAL 196), respectively. This finding suggested that the increased immunoreactivities of GLP-1 as well as that of glucagon were of pancreatic origin.

Release of glucagon-like peptide 1 immunoreactivity from the perfused rat pancreas.

A reliable radioimmunoassay for glucagon-like peptide 1 (GLP-1) was developed with a detection limit of 12 pmol/l, which enabled us to detect the subtle change in concentrations of this peptide in the perfusate from the perfused rat pancreas. With this RIA, GLP-1 immunoreactivity (GLP-1 IR) was found to be secreted synchronously with glucagon immunoreactivity upon arginine stimulation from the perfused rat pancreas. Gel chromatographic analysis showed the presence of GLP-1 IR in the pancreatic extract which is eluted at the same position as synthetic GLP-1 (1-37).