Effect of Kaiyu Qingwei Jianji on the morphometry and residual strain distribution of small intestine in experimental diabetic rats

INTRODUCTION Dysfunction of upper gastrointestinal tract (GI) is common among diabetic patients[1]. As many as 75% of patients visiting diabetes clinics report significant GI Symptoms[2,3]. Common complaints include dysphagia, early satiety, reflux, abdominal pain, nausea, vomiting, and diarrhea[2,3]. As with other complications of diabetes, the duration of the disorder and poor glycemic control seem to be associated with more severe GI problems[2,3]. Histologically, many experiments h…     

Biomechanical and morphometric intestinal remodelling during experimental diabetes in rats

Aims/hypothesis Morphometric and passive biomechanical properties were studied in the duodenum, jejunum and ileum in 10 non-diabetic and 40 streptozotocin-induced diabetic rats.Methods The diabetic rats were divided into groups living 4 days, 1, 2, and 4 weeks after diabetes was induced (n=10 for each groups). The mechanical test was done as a ramp distension experiment. The intestinal diameter and length were obtained from digitised images of the intestinal segments at pre-selected pressures and at no-load and zero-stress states. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter and pressure data and from the zero-stress state geometry.Results The blood glucose concentration increased four- to fivefold in the diabetic rats. Streptozotocin-induced diabetes generated pronounced increase in the weight per centimetre length, wall thickness and wall cross-sectional area in all intestinal segments during diabetes (p<0.05). Histological analysis showed that the thickness of the intestinal layers was increased in all segments during diabetes (p<0.05). In the duodenum the opening angle did not change in the first 2 weeks and decreased after 4 weeks (p<0.05). In the jejunum and ileum the opening angle increased after 1 week in the diabetic group. The residual strain showed the same pattern as the opening angle. Furthermore, it was found that the circumferential and longitudinal stiffness of the intestinal wall increased with the duration of diabetes (p<0.05 and p<0.01).Conclusion/interpretation Morphological and biomechanical remodelling of the small intestine occurred during the development of diabetes.Abbreviations GI Gastrointestinal - STZ streptozotocin     

Viscoelastic Behavior of Small Intestine in Streptozotocin-Induced Diabetic Rats

Diabetes is associated with remodeling of the morphology and elastic properties of the small intestine. This study aims to study remodeling of the viscoelastic (time-dependent) properties of the small intestine during experimental diabetes. Stress relaxation tests were performed on the duodenum, jejunum, and ileum in 10 nondiabetic and 28 streptozotocin (STZ) -induced diabetic rats. The rats were made diabetic by a single intraperitoneal injection of 50 mg/kg STZ. The diabetic rats were allocated into groups living four days or one, two, or four weeks after the induction of diabetes (N = 7 in each group). The mechanical test was performed using a machine that rapidly stretched the intestinal tube to 40% more than the resting length. The intestinal diameter and wall area were obtained from digitized images of the intestinal segments at no-load and zero-stress states. The stress (force per area) was computed and a reduced-stress relaxation function was applied. The log decay parameter C and the slow and fast time constants tau1 and tau2 were computed. STZ-induced diabetes was associated with a progressive increase in the wall thickness and wall cross-sectional area (P < 0.05). tau1 and tau2 increased and C decreased. The slope alpha became consistently less negative (P < 0.05), and the stress after 600-sec relaxation gradually increased during diabetes (P < 0.01). In conclusion, the viscoelastic behavior of the intestinal wall changed during the development of diabetes.     

Effective and selective prevention of retinal leukostasis in streptozotocin-induced diabetic rats using gliclazide

AIMS/HYPOTHESIS: Early stage leukocyte entrapment in the retinal microcirculation (retinal leukostasis) is considered to be one of the important pathogenetic events in diabetic retinopathy. Gliclazide, a sulphonylurea, was reported to reduce leukocyte adhesion to endothelial cells in hyperglycaemia in vitro, thus suggesting possible selective efficacy of this sulphonylurea in preventing leukostasis in diabetic patients. This study evaluated the effectiveness and selectivity of gliclazide treatment on retinal leukostasis of diabetic rats in vivo. METHODS: Streptozotocin (STZ) (65 mg/kg)-induced diabetic rats were divided into three groups (n = 8 each): an untreated diabetic group, a gliclazide-treated diabetic group, and a glibenclamide-treated diabetic group. Gliclazide or glibenclamide was administered orally during a 3-week period. Non-diabetic rats were used as a control (n = 8). Retinal leukostasis was quantitatively evaluated in vivo by acridine orange leukocyte fluorography using a scanning laser ophthalmoscope. RESULTS: The number of leukocytes trapped in the area around the optic disc in the untreated diabetic group (36.9 +/- 5.1 cells) increased significantly compared with the non-diabetic control group (21.9 +/- 2.9 cells; p = 0.0007). The number of leukocytes trapped in the gliclazide-treated diabetic group (23.5 +/- 4.0 cells) decreased significantly compared with untreated diabetic group ( p = 0.0008). In contrast, no reduction of retinal leukostasis was found in the glibenclamide-treated diabetic group (37.8 +/- 5.8 cells; p = 0.7923). CONCLUSION/INTERPRETATION: This suggests that gliclazide could directly improve abnormalities in the retinal microcirculation independent of blood glucose control and possibly have selective therapeutic benefits in preventing early, critical events in diabetic retinopathy compared with other sulphonylurea drugs.     

Gliclazide at a lower concentration than therapeutic dose increases the sensitivity of insulin secretion to glucose in perfused rat pancreas

OBJECTIVES: We studied the difference between effects of therapeutic dose and sub-therapeutic dose of gliclazide on the glucose-induced insulin secretion. METHODS: The normal rat pancreas was isolated and perfused with Krebs-Ringer buffer containing 1-14 mmol/l glucose. Influcences of 0.25 and 2.5 microg/ml gliclazide on the glucose concentration-insulin secretion curve was examined. RESULTS: Gliclazide at 0.25 microg/ml significantly potentiated 5-8 mmol/l glucose-induced insulin secretion (2.5 +/- 0.5 vs 1.0 +/- 0.3 mU for 15 min at 6.5 mmol/l glucose, P<0.01), but did not give influence on either 1-3 or 10-14 mmol/l glucose-induced insulin secretion. The glucose concentration, at which half-maximal insulin secretion was observed, was lower with gliclazide (5.9 mmol/l) than in the control (7.5 mmol/l). Gliclazide at 2.5 microg/ml markedly increased the maximally glucose-stimulated insulin secretion from 3.9 +/- 0.5 mU for 15 min in the control to 6.6 +/- 0.7 mU for 15 min (P<0.01). The half-maximal insulin secretion was observed at a lower glucose concentration (5.0 mmol/l) than in the absence of gliclazide. CONCLUSION: Gliclazide in sub-therapeutically low dose has different effects on insulin secretion from in therapeutic dose, namely sharpens the insulin secretion sensitivity to glucose with no influence on the maximal insulin secretion. It is possible that low doses of gliclazide might be of interest in some type 2 diabetics whose main pathophysiology is the blunting of insulin secretion response to hyperglycemia.     

Long-term gliclazide treatment improves the in vitro glucose-induced insulin release in rats with Type 2 (non-insulin-dependent) diabetes induced by neonatal streptozotocin

Summary Neonatal rats treated with streptozotocin on the day of birth (n0-STZ) or on day 5 (n5-STZ) exhibited when fully grown a very mild or frank basal hyperglycaemia respectively and a specific failure of insulin release in response to glucose. To determine whether short (1 day) or long-term (30 days) gliclazide treatment modifies the pancreatic insulin content and the B-cell response to secretagogues, diabetic rats were given oral gliclazide (10 mg/kg per day) and compared to control diabetic and non-diabetic rats. Insulin secretion in the isolated perfused pancreas was studied the day after the last gliclazide administration. In severely hyperglycaemic n5-STZ rats (plasma glucose levels >16 mmol/l) long-term gliclazide treatment did not lower the plasma glucose values, did not affect the pancreatic insulin stores, nor did it significantly modify the insulin release in vitro in response to glucose or arginine. In moderately hyperglycaemic n5-STZ rats (plasma glucose levels <16 mmol/l) the plasma glucose levels declined progressively reaching 8 mmol/l as a mean at the end of the gliclazide therapy. In the n5-STZ rats responsive to gliclazide the pancreatic insulin stores were increased twofold as compared to values in untreated n5-STZ rats, however, this difference did not reached significance and the pancreatic in sulin stores in the responsive gliclazide treated rats remained depleted by 76% compared to normal insulin stores. In the n0-STZ rats (very mild hyperglycaemia) the long-term gliclazide treatment did not significantly modify the plasma glucose levels or the pancreatic insulin stores. After the 30-day gliclazide therapy in both the n5-STZ gliclazide responder group and the n0-STZ group: (1) the in vitro glucose-induced insulin secretion was increased three to fivefold, (2) the response to arginine which was basically increased in the untreated diabetic rats was again amplified two to threefold, (3) the insulin release in response to gliclazide was unchanged. In conclusion, long-term gliclazide therapy augments stimulated insulin secretion in these two rat models of Type 2 (non-insulin-dependent) diabetes and does not induce any refractoriness to acute sulfonylurea stimulation. The improvement of B-cell function observed here was not related to the concomitant variations of hyperglycaemia and/or pancreatic insulin contentThis work was presented in part at the 24th Annual Meeting of the European Association of the Study of Diabetes, Paris, France, 5–8 September 1988     

Intestinal regrowth is amplified after jejunal but not ileal resection during tapeworm infection in the rat

The ileum possesses functions required by a healthy individual that are not fully supplanted by the duodenum or jejunum. Evidence suggests that the ileum may also be necessary to maintain an enteric parasite–host interaction. We hypothesized that the ileum is essential to the survival of the lumen-dwelling, rat tapeworm, H. diminuta. Male rats were divided into three groups: those with ileal or jejunal resections and nonresected controls. Half of each rat group was infected with the tapeworm. After jejunal resection, the weight but not length of intestinal remnant (duodenum + ileum) in infected rats returned to that of control, nonresected intestine 29 days after surgery and tapeworm numbers were fully maintained. In contrast, after ileal removal intestinal length and weight of the remaining duodenum and jejunum in infected rats were significantly decreased and tapeworm survival diminished. Data indicates that intestinal growth following resection is amplified by tapeworm infection when the ileum remains but diminished when the ileum is removed. Furthermore, loss of the ileum results in decreased infection intensity and dry weight of the tapeworm.     

Morphological properties and residual strain along the small intestine in rats

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n =11). METHODS: To approach the no-load state, the intestine was surgically excised, transferred to an organ bath and cut transversely into short ring-shaped segments. Each ring was cut radially for obtaining the zero-stress state. The residual stress can be characterised by an opening angle. The strain difference between the zero-stress state and the no-load state is called residual strain. RESULTS: Large morphometric variations were found along the small intestine. The wall thickness was highest in the proximal duodenum and decreased in distal direction along the axis of the small intestine (P<0.001). The circumferential length of the inner and outer surfaces decreased rapidly along the length of duodenum by 30-50% (P<0.001). The wall area and lumen area showed a similar pattern (P<0.001). In zero-stress state the rings always opened up after making the cut. The experiments resulted in larger inner circumferential length and smaller outer circumferential length when compared to the no-load state. The wall thickness and wall area did not differ between the no-load and zero-stress state. The opening angle and tangent rotation angle increased along the length of the duodenum and had its highest value 30% down the intestine. Further down the intestine it decreased again (P<0.001). The serosal residual strain was tensile with the highest value close to the ligament of Treitz (P<0.001). The mucosal residual strain was compressive in all segments of the small intestine with average values between -0.25 and -0.4 and with the lowest values close to the ligament of Treitz (P<0.001). CONCLUSION: Axial variation in morphometric properties and residual strains were found in the small intestine. Existence of large residual strains indicates that the zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.     

Effect of I-deprenyl and gliclazide on oxidant stress/antioxidant status and dna damage in a diabetic rat model

BACKGROUND: This study investigates the possible effect of monoamine oxidase inhibitor (MAOI), selegyline (l-deprenyl), in combination with oral antidiabetic-gliclazide (OAD), in preventing oxidative stress in streptozotocin-induced diabetes model in male Swiss Albino rats by measuring oxidant stress/ DNA damage and antioxidant levels. METHODS: Diabetic rats were divided into four groups (n = 10) as (1) diabetic untreated (DM), (2) deprenyl treated (DM + D), (3) gliclazide treated (DM + O), and (4) gliclazide and deprenyl treated (DM + O + D). Controls were divided into two groups (n = 8) (1) untreated (C), and (2) deprenyl treated (C + D). Gliclazide 5 mg/kg and/or MAOI 0.25 mg/kg daily were given orally by gavage for 4 weeks. At the end of the 12th week, catalase and superoxide dismutase (SOD) levels in erythrocyte lysates (EL); total antioxidant status (TAS), 8-hydroxy-deoxyguanosine (8-OHdG), malondialdehyde (MDA), and vitamin A and E levels in plasma, MDA, and MAO in liver homogenates were determined. RESULTS: Diabetic rats showed a decrease in EL-SOD, plasma TAS, and vitamin E, and an increase in plasma 8-OHdG, plasma, and liver MDA levels (p < 0.05). Gliclazide and/or deprenyl decreased 8OHdG levels and increased antioxidant levels and survival when compared with untreated diabetic rats (p < 0.05). The lowest 8-OHdG levels were determined in the DM +O + D group. CONCLUSIONS: The combined treatment of deprenyl and gliclazide may contribute to the control of the physiopathological mechanisms underlying both the process of aging and type 2 diabetes by reducing oxidant stress and DNA damage, improving antioxidant status, and increasing survival, and may have implications for further clinical studies.     

Gliclazide improves anti-oxidant status and nitric oxide-mediated vasodilation in Type 2 diabetes.

AIMS: To evaluate the effects of gliclazide on oxidative status and vascular response to systemic administration of L-arginine, the natural precursor of nitric oxide (NO), in Type 2 diabetic patients. METHODS: Thirty Type 2 diabetic patients received glibenclamide (n = 15) or gliclazide (n = 15) in a 12-week, randomized, observer-blinded, parallel study. Plasma lipid peroxides, total radical-trapping anti-oxidant parameter (TRAP), and blood pressure responses to an intravenous bolus of L-arginine were measured pre- and post-treatment. RESULTS: At 12 weeks, gliclazide patients had lower plasma lipid peroxides (13.3 +/- 3.8 micro mol/l vs. 19.2 +/- 4.3 micro mol/l; P = 0.0001) and higher plasma TRAP (1155.6 +/- 143.0 micro mol/l vs. 957.7 +/- 104.3 micro mol/l; P = 0.0001) than the glibenclamide patients. Gliclazide but not glibenclamide significantly reduced systolic and diastolic blood pressure (P = 0.0199 and P = 0.00199, respectively, two-way repeated measures analysis of variance) in response to intravenous L-arginine. CONCLUSIONS: Gliclazide reduces oxidative stress in Type 2 diabetic patients by improving plasma anti-oxidant status. This effect is associated with enhanced NO-mediated vasodilation.     

Tension–Strain Relations and Morphometry of Rat Small Intestine in Experimental Diabetes

Tension–strain relations and morphometric data were studied in isolated segments of the jejunum and distal ileum in untreated diabetic rats, insulin-treated diabetic rats, and nondiabetic control rats. Diabetes was induced by a single intravenous injection of streptozotocin (28 mg/kg body wt). All injected rats developed hyperglycemia. The experiment was terminated after 28 days and the intestinal segments were superfused with saline solution containing papaverine to abolish contractile activity. Stepwise inflation of a balloon in which the cross-sectional area (CSA) was measured provided the luminal pressure-loading stimulus. The circumferential tension–strain relation was derived from steady-state values of internal radius and applied pressure. The intestinal weight, length, and weight per unit length increased significantly in untreated diabetic rats compared to the two other groups (P < 0.05). The body weight decreased in untreated diabetic rats compared to the two other groups (P < 0.05). The pressure–CSA relations differed between jejunum and distal ileum (P < 0.001) but not between the groups (P > 0.2). The tension–strain relations in jejunum and distal ileum were nonlinear and the curves for the two diabetic groups were shifted to the left compared to the curve for controls (P < 0.05), indicating increased wall stiffness. The histomorphometric data showed increased wall thickness in untreated diabetic rats compared to the two other groups both in jejunum and distal ileum (P < 0.02). Mucosal, submucosal, and muscle layer thicknesses did not differ between the three groups. No significant association was found between the histomorphometric and biomechanical parameters.     

Insulin-like growth factor and insulin receptors in intestinal mucosa of neonatal calves

Intestinal development is modified by age and nutrition, mediated in part by insulin-like growth factors (IGF-I, IGF-II) and insulin. We have investigated whether expression of IGF-I, IGF-II and insulin receptors (IGF-IR, IGF-IIR and IR; measured by real-time RT-PCR) and binding capacity (Bmax) of IGF-IR, IGF-IIR and IR in the mucosa of the small and large intestine of neonatal calves are modified by age and different feeding regimes. In experiment 1, pre-term (GrP) and full-term (GrN) calves (after 277 and 290 days of pregnancy respectively) were killed immediately after birth before being fed; a further group of full-term calves were fed for 7 days and killed on day 8 of life (GrC(1-3)). In experiment 2, full-term calves were killed on day 8 after being fed first-colostrum for 7 days (GrCmax), colostrum of the first six milkings for 3 days (GrC(1-3)) or milk-based formula for 3 days (GrF(1-3)). Intestinal sites differed with respect to expression levels of IGF-IR (duodenum>jejunum in GrC(1-3); ileum>colon, duodenum> or = jejunum in GrF(1-3)), IGF-IIR (colon>duodenum and ileum in GrN), and IR (lowest in ileum in GrP and CrN; highest in colon in GrC(1-3) and GrCmax). They also differed with respect to Bmax of IGF-IR (ileum and colon>duodenum and jejunum in GrP; ileum and colon>jejunum in GrN; colon>jejunum in GrC(1-3); lowest in jejunum in GrF(1-3)), IGF-IIR (duodenum and colon>jejunum and ileum in GrP; duodenum>ilem and colon>jejunum in GrN; duodenum, jejunum and colon>ileum in GrCmax, GrC(1-3), and GrF(1-3)) and IR (ileum>duodenum, jejunum and colon in GrCmax, GrC(1-3), and GrF(1-3)). There were significant differences between groups in the expression of IGF-IR (GrF(1-3)> GrCmax and GrC(1-3) in ileum), IGF-IIR (GrN>GrP and GrC(1-3) in colon; GrN>GrC(1-3) in jejunum and total intestine), and IR (GrCmax>GrF(1-3) in colon) and in the Bmax of IGF-IR (GrP>GrN in colon; GrCmax>GrF(1-3) in jejunum), IGF-IIR (GrN>GrP in duodenum, ileum and total intestine; GrN>GrC(1-3) in duodenum, ileum, colon and total intestine) and IR (GrN>GrP in total intestine; GrC(1-3)>GrN in ileum and total intestine). In addition, Bmax values of IGF-IR, IGF-IIR and IR were correlated with villus circumference, villus height/crypt depth and proliferation rate of crypt cells at various intestinal sites. There were marked differences in Bmax of IGF-IR, IGF-IIR and IR dependent on mRNA levels, indicating that differences in Bmax were the consequence of differences in posttranslational control and of receptor turnover rates. In conclusion IGF-IR, IGF-IIR and IR expressions and Bmax in intestinal mucosa were different at different intestinal sites and were variably affected by age, but not significantly affected by differences in nutrition. Receptor densities were selectively associated with intestinal mucosa growth.     

In vitro and in vivo antioxidant properties of gliclazide

Diabetes is a state of increased oxidant stress and there is evidence that oxidation may play a role in the genesis of complications. Gliclazide, a sulfonylurea hypoglycemic drug, has been shown to possess free radical scavenging properties. This study examined the effects of in vitro supplementation with gliclazide and other sulfonylureas as on low-density lipoprotein (LDL) oxidation and the total plasma antioxidant capacity (TPAC). In a separate study, the effects of 10 months of oral gliclazide therapy on oxidative parameters were assessed in 44 type 2 diabetic patients. Gliclazide, but not glibenclamide, glimepiride, glipizide or tolbutamide, inhibited LDL oxidation and enhanced TPAC. With the addition of 1 microM gliclazide, oxidation lag time increased from 53.6+/-2.6 to 113.6+/-5.1 min (p<0.001), and TPAC increased from 1. 09+/-0.11 to 1.23+/-0.11 mM (p<0.01). Administration of either modified release or standard gliclazide to type 2 diabetic patients resulted in a fall in 8-isoprostanes, a marker of lipid oxidation, and an increase in the antioxidant parameters TPAC, SOD and thiols. These studies show that gliclazide possesses antioxidant properties that produce measurable clinical effects at therapeutic doses.     

Morphological properties and residual strain along the stroll intestine in rats

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n = 11 )METHODS: To approach the no-load state, the intestine wassurgically excised, transferred to an organ bath and cuttransversely into short ring-shaped segments. Each ringwas cut radially for obtaining the zero-stress state. Theresidual stress can he characterised by an opening angle.The strain difference between the zero-stress state and theno-load state is called residual strain.RESULTS: Large morphometric variations were found along thesmall intestine. The wall thickness was highest in the proximalduodenum and decreased in distal direction along the axis of the small intestine ( P ＜ 0. 00l ). The circumferential length of the inner and outer surfaces decreased rapidly along the lengthof duodenum by 30-50 % (P＜0.001). The wall area and lumenarea showed a similar pattem( P ＜ 0.001 ). In zen-stress statethe dngs always opened up after making the cut. Theexperiments resulted in larger inner cirumferential length andsmaller outer circtmferential length when compared to the no-load state. The wall thickness and wall area did not differbetween the no-load and zero-stress state. The opening angleand tangent rotation angle increased along the length of theduodenum and had its highest value 30 % down the intestine.Further down the intestine it decreased again (P＜0.001). Theserosal residual strain was tensile with the highest value closeto the ligament of Treitz (P ＜ 0.001 ). The mucosal residualstrain was compressive in all segments of the small intestinewith average values between -0.25 and -0.4 and with the lowestvalues close to the ligament of Treitz ( P＜ 0.001 ).CONCLUSION: Axial variation in morphometric propertiesand residual strains were found in the small intestine.Existence of large residual strains indicates that the zero-stress state must he considered in future biomechanicalstudies in the gastrointestinal tract.     

Vascular action of the hypoglycaemic agent gliclazide in diabetic rabbits

Summary ATP-dependent potassium channel blockers used as hypoglycaemic agents may have effects on vascular disease in diabetes mellitus beyond their effect on blood glucose control. This study was designed to determine the effects of treatment with gliclazide on the isolated abdominal aorta of diabetic rabbits in which endothelium-dependent relaxation is impaired by a mechanism involving oxygen-derived free radicals. After induction of diabetes with alloxan, there was no effect of gliclazide (10 mg · kg⁻¹· day⁻¹ orally) on blood glucose or insulin levels over a 6 week period. Hence, this permitted an examination of the vascular effects of gliclazide in diabetic rabbits exclusive of metabolic effects. Acetylcholine- and nitric oxide-induced relaxation in aortae from rabbits treated with or without gliclazide were measured in the absence or presence of the nitric oxide synthase inhibitor, N^G-nitro-l-arginine (l-NAME). Diabetes was associated with significant impairment of acetylcholine-induced endothelium-dependent relaxation of the abdominal aorta which was not significant in diabetic rabbits treated with gliclazide in vivo. Aortae from diabetic rabbits studied in the presence of l-NAME showed an exaggerated contraction to acetylcholine which was prevented in rabbits treated with gliclazide. Gliclazide treatment did not affect the response to acetylcholine of normal rabbit aorta, and gliclazide when added in vitro had no effect on the response of diabetic rabbit aorta, suggesting that the effect of gliclazide was specific to the abnormality arising with diabetes and was not due to an acute effect of the drug. These data indicate that gliclazide, aside from either a direct antioxidant action or an effect on insulin or glucose levels, may ameliorate diabetic endothelial cell dysfunction. [Diabetolgia (1998) 41: 9–15] Received: 31 January 1997 and in final revised form: 25 August 1997     

Nateglinide or gliclazide in combination with metformin for treatment of patients with type 2 diabetes mellitus inadequately controlled on maximum doses of metformin alone: 1-year trial results

AIM: To compare long-term efficacy and safety of nateglinide plus metformin with those of gliclazide plus metformin in patients with type 2 diabetes not adequately controlled with metformin monotherapy. METHODS: Double-blind, double-dummy, multicentre study extended to a total of 52 weeks. Patients with inadequate glucose control on maximal doses of metformin were randomized to nateglinide (N = 133) or gliclazide (N = 129) add-on treatment. After the initial 6-month study, the majority of patients in the nateglinide group [n = 112 (93.3%)] and in the gliclazide group [n = 101 (92.7%)] entered a 6-month, double-blind, extension study. RESULTS: There was no significant difference between treatment regimens in haemoglobin Alc (HbA1c) change from baseline to 52 weeks (-0.14% for nateglinide vs. -0.27% for gliclazide; p = 0.396). Proportions of patients achieving an endpoint HbA1c of <7% were similar (40 vs. 47.4%) for nateglinide and gliclazide groups. There was no significant between-treatment difference in fasting plasma glucose change from baseline to 52 weeks (nateglinide: -0.2 mmol/l and gliclazide: -0.7 mmol/l; p = 0.096). The decreases in prandial plasma glucose area under the curve(0-4 h) from baseline were -3.26 and -1.86 h x mmol/l in the nateglinide and the gliclazide groups respectively, and the change was statistically significant in the nateglinide group only (p = 0.006). Initial insulin response to a meal was augmented with nateglinide treatment only, without between-treatment difference in 2-h insulin response. The overall rate of hypoglycaemic events was similar with nateglinide and gliclazide combinations with metformin. Nateglinide plus metformin treatment was not associated with weight gain. CONCLUSIONS: No significant difference was seen between nateglinide plus metformin and gliclazide plus metformin in terms of HbA1c. Treatment with nateglinide plus metformin for up to 12 months was not associated with weight gain.     

Age-related changes in substance P and vasoactive intestinal polypeptide immunoreactivity in the rat stomach and small intestine

Immunoreactivity for substance P (SP-LI) and vasoactive intestinal polypeptide (VIP-LI) in the stomach, duodenum, jejunum and ileum of young (3-month-old), adult (12-month-old) and old (28-month-old) male Wistar rats were determined by radioimmunoassay. SP-LI and VIP-LI did not show changes in the stomach or in the small intestine portions investigated in adult in comparison with young rats. In old rats SP-LI levels were unchanged in the stomach and in the duodenum, reduced in the jejunum and increased in the ileum. VIP-LI concentrations were unchanged in the stomach, and remarkably reduced in the duodenum, jejunum and ileum of old rats. Since the two neuropeptides investigated are localized primarily within different intrinsic gastrointestinal neurons, the present findings suggest that the various populations of gastrointestinal neurons are affected in a different manner during aging.