The effect of mosapride (5HT-4 receptor agonist) on insulin sensitivity and GLUT4 translocation

The role of mosapride and levosulpiride in gut function and glycemic control in diabetic rats

BACKGROUND AND STUDY AIMS

Gastroparesis is a well-known consequence of long-standing diabetes that presents with gastric dysmotility in the absence of gastric outlet obstruction. This study aimed to evaluate the therapeutic effects of mosapride and levosulpiride on improving gastric emptying in type 2 diabetes mellitus (T2DM) while regulating glycemic levels.

MATERIAL AND METHODS

Rats were divided into the normal control, untreated diabetic, metformin-treated (100 mg/kg/day), mosapride-treated (3 mg/kg/day), levosulpiride-treated (5 mg/kg/day), metformin (100 mg/kg/day) + mosapride (3 mg/kg/day)-treated, and metformin (100 mg/kg/day) + levosulpiride (5 mg/kg/day)-treated diabetic groups. T2DM was induced by a streptozotocin-nicotinamide model. Fourweeks from diabetes onset, the treatment was started orally daily for 2 weeks. Serum glucose, insulin, and glucagon-like peptide 1 (GLP-1) levels were measured. Gastric motility study was performed using isolated rat fundus and pylorus strip preparations. Moreover, the intestinal transit rate was measured.

RESULTS

Mosapride and levosulpiride administration showed a significant decrease in serum glucose levels with improvement of gastric motility and intestinal transit rate. Mosapride showed a significant increase in serum insulin and GLP-1 levels. Metformin with mosapride and levosulpiride co-administration showed better glycemic control and gastric emptying than either drug administered alone.

CONCLUSION

Mosapride and levosulpiride showed comparable prokinetic effects. Metformin administration with mosapride and levosulpiride showed better glycemic control and prokinetic effects. Mosapride provided better glycemic control than levosulpiride. Metformin + mosapride combination provided superior glycemic control and prokinetic effects.

Prokinetic Agents

Gastrointestinal (GI) prokinetic agents are drugs that increase GI motility and promote the movement of contents in the GI tract by amplifying and controlling the contraction of GI smooth muscle. Currently used prokinetics increase GI motility by acting as a dopamine D₂ receptor antagonist (e.g., metoclopramide, domperidone, levosulpiride) and 5-HT₄ receptor agonist (e.g., mosapride, prucalopride). Some prokinetics also have a cholinesterase inhibitory property (e.g., itopride), and herb-derived prokinetics (e.g., motilitone) affect multiple receptors. Depending on the type and distribution of receptors on which the prokinetics bind, the effect(s) may be regional or throughout the GI tract. Most prokinetics have been used for functional dyspepsia and gastroparesis because they mainly affect upper GI motility. However, prucalopride, a highly selective 5-HT₄ receptor agonist, is used primarily to treat chronic constipation and pseudo-obstruction. Dopamine D₂ receptor antagonists also inhibit the D₂ receptor in the medulla oblongata chemoreceptor trigger zone; therefore, they can treat nausea and vomiting. However, short term use of dopamine D₂ antagonists at an appropriate dose is recommended because of their potential for central nervous system side effects by penetrating the blood-brain barrier. It is necessary to know the mechanism of action, each clinical trial’s characteristics, and the side effects of prokinetics to obtain the best clinical outcomes. This article aims to summarize the results of clinical studies related to the impact of currently available prokinetic agents in Korea on GI motility.

A Meta-Analysis of the Efficacy of Prokinetic Agents against Glycemic Control

Background

Prokinetic agents are used in diabetic gastroparesis patients to improve gastric emptying and upper gastrointestinal (GI) symptoms. However, the efficacy of prokinetic agents against glycemic control is questionable. Therefore, we conducted a systemic review and meta-analysis to determine the efficacy of prokinetic agents against glycemic control.

Methods

Randomized controlled trials (RCTs) evaluating the effect of prokinetics were identified by searching PubMed, Embase, and the Cochrane Library databases until April 2018. The primary outcome was changes in the mean value of glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), and fasting serum insulin (FINS). The pooled standardized mean differences (SMD) with 95% confidence intervals (CIs) were calculated by evaluating the strength of the association. We used the random effect models to analyze these markers. The effects of each component of the prokinetic agents on glycemic control were separately analyzed.

Results

Five RCTs with 190 patients met the criteria and were included in the meta-analysis. There were statistically significant SMD between prokinetics and placebo-controlled groups with respect to the reduction of HbA1c (-1.141, 95% CI -1.843, -0.438; P < 0.01). No statistically significant differences were noted between the two groups for FBS (-1.270, 95% CI -2.613, -0.074; P = 0.06) and FINS (0.359, 95% CI -1.205~1.923; P = 0.65).

Conclusions

Prokinetics have a positive effect on glycemic control. Further large-scale prospective studies are needed.

High-content analysis of constitutive androstane receptor (CAR) translocation identifies mosapride citrate as a CAR agonist that represses gluconeogenesis

The constitutive androstane receptor (CAR) plays an important role in hepatic drug metabolism and detoxification but has recently been projected as a potential drug target for metabolic disorders due to its repression of lipogenesis and gluconeogenesis. Thus, identification of physiologically-relevant CAR modulators has garnered significant interest. Here, we adapted the previously characterized human CAR (hCAR) nuclear translocation assay in human primary hepatocytes (HPH) to a high-content format and screened an FDA-approved drug library containing 978 compounds. Comparison of hCAR nuclear translocation results with the Tox21 hCAR luciferase reporter assay database in 643 shared compounds revealed significant overlap between these two assays, with approximately half of hCAR agonists also mediating nuclear translocation. Further validation of these compounds in HPH and/or using published data from literature demonstrated that hCAR translocation exhibits a higher correlation with the induction of hCAR target genes, such as CYP2B6, than the luciferase assay. In addition, some CAR antagonists which repress CYP2B6 mRNA expression in HPH, such as sorafenib, rimonabant, and CINPA1, were found to translocate hCAR to the nucleus of HPH. Notably, both the translocation assay and the luciferase assay identified mosapride citrate (MOS), a gastroprokinetic agent that is known to reduce fasting blood glucose levels in humans, as a novel hCAR activator. Further studies with MOS in HPH uncovered that MOS can repress the expression of gluconeogenic genes and decrease glucose output from hepatocytes, providing a previously unidentified liver-specific mechanism by which MOS modulates blood glucose levels.

Gut: A key player in the pathogenesis of type 2 diabetes?

The gut regulates glucose and energy homeostasis; thus, the presence of ingested nutrients into the gut activates sensing mechanisms that affect both glucose homeostasis and regulate food intake. Increasing evidence suggest that gut may also play a key role in the pathogenesis of type 2 diabetes which may be related to both the intestinal microbiological profile and patterns of gut hormones secretion. Intestinal microbiota includes trillions of microorganisms but its composition and function may be adversely affected in type 2 diabetes. The intestinal microbiota may be responsible of the secretion of molecules that may impair insulin secretion/action. At the same time, intestinal milieu regulates the secretion of hormones such as GLP-1, GIP, ghrelin, gastrin, somatostatin, CCK, serotonin, peptide YY, GLP-2, all of which importantly influence metabolism in general and in particular glucose metabolism. Thus, the aim of this paper is to review the current evidence on the role of the gut in the pathogenesis of type 2 diabetes, taking into account both hormonal and microbiological aspects.

Mosapride, a selective serotonin 5-HT4 receptor agonist, and alogliptin, a selective dipeptidyl peptidase-4 inhibitor, exert synergic effects on plasma active GLP-1 levels and glucose tolerance in mice

Pharmacologic stimulation of serotonin 5-HT4 receptors increased plasma active glucagon-like-peptide-1 (GLP-1) levels independent of feeding, and that pharmacologic stimulation of 5-HT4 receptors and pharmacologic inhibition of dipeptidyl peptidase-4 exerted synergic effects on plasma active GLP-1 levels and glucose tolerance in mice.

Mosapride citrate increases postprandial glucagon-like peptide-1, insulin, and gene expression of sweet taste receptors

BACKGROUND AND AIM

Mosapride citrate-a prokinetic agent-improves hemoglobin A1c levels in diabetic patients; however, the underlying mechanism is unclear. We aimed to clarify this mechanism.

METHODS

Preprandial and postprandial (90 min after a meal) blood was obtained from 12 healthy men, and serum insulin and plasma active glucagon-like peptide-1 concentrations were measured. Measurements were also taken after the administration of 5 mg of mosapride citrate three times per day after every meal for 14 days. In addition, C57BL/6 mice were permitted free access to water containing 0.04 % domperidone (D group) or 0.02 % mosapride citrate (M group) for 2 weeks (four mice per group). T1r2 (taste receptor, type 1, member 2), T1r3, and Gnat3 (guanine nucleotide-binding protein, alpha transducing 3) mRNA expression levels of the stomach, duodenum, and proximal and mid-jejunum were evaluated.

RESULTS

In human subjects, postprandial plasma active glucagon-like peptide-1 and serum insulin concentrations after administration of mosapride citrate were significantly higher than those pre-administration (4.8 ± 2.2 pmol/L, 45.6 ± 41.6 μIU/mL, and 3.7 ± 1.2 pmol/L, 34.1 ± 28.4 μIU/mL, respectively). The mouse expression levels of T1r2 and Gnat3 in the proximal jejunum and mid-jejunum in the M group (4.1 ± 1.8-fold, 3.1 ± 1.6-fold, and 4.6 ± 0.8-fold, 3.1 ± 0.9-fold increases, respectively), were significantly higher than those of the control group.

CONCLUSIONS

The administration of mosapride citrate for 2 weeks enhanced postprandial plasma active glucagon-like peptide-1 and serum insulin concentration and increased the expression of sweet taste receptors in the upper intestine.

Effects of resveratrol on the amelioration of insulin resistance in KKAy mice

Resveratrol (Res) has attracted great interest regarding its effects related to metabolic syndrome, especially for lipid metabolic disorder or insulin resistance; however, the underlying mechanisms remain elusive. To explore the effects of Res on insulin sensitivity and the underlying mechanism, insulin-resistant KKA(y) mice were treated with 2 and 4 g/kg diets of Res for 12 weeks. After the treatment, blood glucose, serum insulin, glucose tolerance, and insulin tolerance, as well as other indices such as adiponectin mRNA in epididymal adipose tissues, silent information regulator 1 (Sirt1), AMP-activated protein kinase (AMPK), insulin receptor substrate 1 (IRS1), and phosphorylated protein kinase B (PKB/AKT) proteins in liver and soleus muscles, were investigated. The results indicate that Res intervention reduces blood glucose and serum insulin levels, improves insulin and glucose tolerance, increases serum adiponectin and adiponectin mRNA levels in epididymal adipose tissues, and more importantly, elevates Sirt1, p-AMPK, p-IRS1, and p-AKT levels in liver and soleus muscles. In conclusion, Res could improve insulin sensitivity and ameliorate insulin resistance in KKA(y) mice, which may be associated with the upregulation of Sirt1 protein in liver and soleus muscles and consequent AMPK activation, as well as insulin-signaling related proteins.