Long-term effects of lipase inhibition by orlistat on gastric emptying and orocecal transit time of a solid meal

Intestinal Lipase Characterization in Common Snook (Centropomus undecimalis) Juveniles

The common snook (Centropomus undecimalis) is a euryhaline fish with high commercial demand in the Mexican southeast, Caribbean, and South America. However, some aspects of its digestive physiology are still unknown, particularly in relation to lipid hydrolysis. Therefore, the characterization of the digestive lipase of this species was carried out. Our results show that the digestive lipase’s optimal temperature is 35 °C, being stable between 25 and 35 °C, and shows maximum activity at pH 9, with stability between pH 5 and 8. Different degrees of inhibition were presented by Orlistat (61.4%), Ebelactone A (90.36%), Ebelactone B (75.9%), SDS 1% (80.7%), SDS 0.1% (73.5%), and SDS at 0.01% (34.9%). Orlistat and Ebelactone A and B completely inhibited the lipase band in the zymogram, but not SDS addition. Lipase showed a molecular weight of 43.8 kDa. The high lipase activities in the digestive tract indicate the importance of lipids in the diet of C. undecimalis.

Lipase Inhibitors for Obesity: A Review

With the rapid increase in the population of obese individuals, obesity has become a global problem. Many kinds of chronic metabolic diseases easily caused by obesity have received increasing attention from researchers. People are also striving to find various safe and effective treatment methods as well as anti-obesity medicines. Pancreatic lipase (PL) inhibitors have received substantial attention from researchers in recent years, and PL inhibitors from natural products have attracted much attention due to their structural diversity, low toxicity and wide range of sources. They have been used in the intestinal tract, blood, and the central nervous system with no side effects, and these advantages could lead to a new generation of diet pills or health care products with great development potential. This article is mainly aimed at discussing the research of obesity drug treatment with PL inhibitors and offers a brief review of related properties and the use of PL inhibitors in the field of weight loss.

Benefit-risk assessment of orlistat in the treatment of obesity

Orlistat, an inhibitor of intestinal lipase, has been available for the treatment of obesity for nearly two decades. In conjunction with a hypocaloric diet, orlistat treatment results in a placebo-subtracted reduction in body weight of around 3 kg at 1 year, and increases the likelihood of achieving clinically significant (≥5%) weight loss by around 20%. Orlistat-induced weight loss also confers modest improvements in systolic and diastolic blood pressure, low-density lipoprotein (LDL) cholesterol, glycemic parameters, and progression to diabetes in people with impaired glucose tolerance. Overall, it has a good safety profile, and serious adverse events (including reports of severe kidney and liver injury) are rare. However, a high rate of gastrointestinal side effects limits adherence to treatment.

Long-term inhibition of intestinal lipase by orlistat improves release of gut hormones increasing satiety in obese women

BACKGROUND

Reduced postprandial secretion of peptide YY (PYY), glucagon-like peptide-1 (GLP-1), cholecystokinin, and increased hunger was reported after a single dose of orlistat, an inhibitor of intestinal lipase. As yet, the influence of long-term therapy with orlistat on PYYand GLP-1 release has not been studied. Our study was aimed at assessing the influence of 8-week therapy with orlistat as a component of a weight loss program on pre-prandial circulating PYY and GLP-1 levels.

METHODS

Forty obese women, without concomitant diseases, were randomly allocated to groups receiving orlistat or placebo during an 8-week weight management program. Body mass, body composition and plasma levels of PYY, GLP-1 and insulin (for QUICKI calculation) were determined prior to and at the end of therapy.

RESULTS

Women treated with orlistat obtained significantly greater body and fat mass loss than those receiving placebo (9.0 ± 3.1 vs. 5.9 ± 3.2% and 21.9 ± 10.9 vs. 7.4 ± 15.6%, respectively). Only in those treated with orlistat a slight, but significant increase of the QUICKI was found (8.0 ± 16.5 vs. -0.1 ± 12.7 %, respectively). Weight loss was followed by a significant increase of plasma levels of PYY and GLP-1 in group treated with orlistat, and was about 2-times greater than receiving placebo. The increase was independent of body mass changes.

CONCLUSION

The long-term inhibition of intestinal lipase by orlistat increases the pre-prandial levels of GLP-1 and PYY, independent of body mass changes. Therefore, it seems that long-term treatment with orlistat may exert hunger suppressing and insulin sensitizing incretin effect beyond weight reduction.

A semi-mechanistic gastric emptying pharmacokinetic model for (13)C-octanoic acid: an evaluation using simulation

The aim of this paper is to assess the performance of a new mechanistic model for analysing (13)C-octanoic acid breath test data using simulation studies. The (13)C-octanoic acid breath test is widely used for indirect assessment of the rate of gastric emptying and it is yet to achieve universal acceptance due to inconsistencies when the results are compared with simultaneous and direct measurements using scintigraphy. The new semi-mechanistic model has five separate compartments; stomach, intestine, central and peripheral body and breath compartments. Stomach and breath profiles were simulated for 50 individuals under four conditions: variability on all parameters; no variability on the rate constant of gastric emptying and the rate constant of absorption; variability on the rate constant of gastric emptying and the rate constant of absorption only; and no variability on all parameters. A mono-exponential model was fitted to the stomach profile and the new semi-mechanistic model and three other widely used methods were fitted to the breath profiles. The gastric emptying half times from stomach profiles correlate better (R(2)=1,1,1,1 for the four conditions) with the half emptying times from the semi-mechanistic model compared with half emptying times from the modified exponential model (R(2)=0.72,0.53,0.88,1), Ghoos method (R(2)=0.72,0.54,0.88,1) and Wagner-Nelson method (R(2)=0.79,0.68,0.89,1) for the four simulation studies. The semi-mechanistic model is very effective for the assessment of GE using the (13)C-octanoic acid breath test and could be applied in the development of drugs that influence GE.

SIRT1 inhibits the mouse intestinal motility and epithelial proliferation

Sirtuin 1 (SIRT1), a NAD(+)-dependent histone deacetylase, is involved in a wide array of cellular processes including glucose homeostasis, energy metabolism, proliferation and apoptosis, and immune response. However, it is unknown whether SIRT1 plays any physiological role in the regulation of intestinal homeostasis and motility. Thus the aim was to define SIRT1 expression and function in the gastrointestinal (GI) tract under physiological conditions. Forty 12-14-wk-old SIRT1 knockout (KO) and wild-type (WT) mice were fasted 21 h and/or refed 3 h. Fasted mice were injected intraperitoneally with bromodeoxyuridine (120 mg/kg body wt) 2 h before euthanasia. SIRT1 protein was localized to gastric and intestinal epithelial nuclei and was responsive to the nutritional status. SIRT1 was required for intestinal epithelial homeostasis. The SIRT1 KO mice showed enhanced crypt proliferation and suppressed villous apoptosis, resulting in increased intestinal villous height. In the SIRT1 KO intestine, the abundance of Forkhead box protein O1 and p53 protein decreased, whereas the subcellular localization of β-catenin protein accumulated mainly in the crypts. The SIRT1 KO mice showed accelerated gastric emptying rate with increased abundance of ghrelin mRNA and protein in the stomach. Moreover, the SIRT1 KO mouse intestine showed enhanced ex vivo spontaneous contraction. We concluded that, SIRT1 plays a critical role in the control of intestinal homeostasis (by promoting apoptosis and inhibiting proliferation) and gastrointestinal motility (by reducing gastric emptying and intestinal contractile activity), implicating a novel role for SIRT1.

On a refinement of the ¹³C-mixed TAG breath test

The present study was aimed to improve and simplify the 13C-mixed TAG (13C-MTG) breath test while keeping it acceptable for the patient. Healthy volunteers (ten women and eight men) were examined on four occasions, receiving in a random order 300 mg 13C-MTG: (1) contained in two wafers; (2) administered with a 50 g wheat roll; as well as given with either (3) 10 or (4) 30 g butter, spread onto a 50 g wheat roll, as the test meal, respectively. Samples of expiratory air were taken for 6 h postprandially for the mass spectroscopic measurement of 13CO2 enrichment. After intake of the sole 13C-MTG, the cumulative 13C recovery in breath air (AUC) appeared to be unsatisfactory, as after 6 h it did not exceed 10 %. Application of the substrate with the 50 g wheat roll did not bring about any improvement in this parameter. The addition of the unlabelled fat to the test meal dramatically increased the cumulative 13C recovery. However, we found higher values for the momentary 13C recovery and AUC with 10 g butter compared with 30 g. It can be concluded that: (1) addition of unlabelled fat is indispensable to obtain a proper course of the breath 13C elimination during the conduct of the 13C-MTG breath test and (2) it is possible to apply a considerably smaller amount of the unlabelled fat than has previously been recommended for this test.