Growth differentiation factor 15 (GDF15) and semaglutide inhibit food intake and body weight through largely distinct, additive mechanisms.

AIMS: To evaluate whether the potent hypophagic and weight-suppressive effects of growth differentiation factor-15 (GDF15) and semaglutide combined would be a more efficacious antiobesity treatment than either treatment alone by examining whether the neural and behavioural mechanisms contributing to their anorectic effects were common or disparate. MATERIALS/METHODS: Three mechanisms were investigated to determine how GDF15 and semaglutide induce anorexia: the potentiation of the intake suppression by gastrointestinal satiation signals; the reduction in motivation to feed; and the induction of visceral malaise. We then compared the effects of short-term, combined GDF15 and semaglutide treatment on weight loss to the individual treatments. Rat pharmaco-behavioural experiments assessed whether GDF15 or semaglutide added to the satiating effects of orally gavaged food and exogenous cholecystokinin (CCK). A progressive ratio operant paradigm was used to examine whether GDF15 or semaglutide reduced feeding motivation. Pica behaviour (ie, kaolin intake) and conditioned affective food aversion testing were used to evaluate visceral malaise. Additionally, fibre photometry studies were conducted in agouti-related protein (AgRP)-Cre mice to examine whether GDF15 or semaglutide, alone or in combination with CCK, modulate calcium signalling in hypothalamic AgRP neurons. RESULTS: Semaglutide reduced food intake by amplifying the feeding-inhibitory effect of CCK or ingested food, inhibited the activity of AgRP neurons when combined with CCK, reduced feeding motivation and induced malaise. GDF15 induced visceral malaise but, strikingly, did not affect feeding motivation, the satiating effect of ingested food or CCK signal processing. Combined GDF15 and semaglutide treatment produced greater food intake and body weight suppression than did either treatment alone, without enhancing malaise. CONCLUSIONS: GDF15 and semaglutide reduce food intake and body weight through largely distinct processes that produce greater weight loss and feeding suppression when combined.

Comparison of the neuromuscular blocking effects of cisatracurium during isoflurane or propofol anesthesia in dogs.

OBJECTIVE: To compare the neuromuscular blocking effects of cisatracurium during isoflurane versus propofol anesthesia in dogs. STUDY DESIGN: Prospective, randomized study. ANIMALS: A total of 20 healthy, client-owned dogs (16 females, four males) weighing 12.5-22 kg and aged 1-8 years. METHODS: Dogs undergoing elective surgery were randomized in equal numbers to an isoflurane (ISO) or propofol (PPF) group. Other drugs used during anesthesia were equal between groups. Single-twitch (ST) stimulation was used to monitor neuromuscular response. After recording the baseline ST (T0), cumulative doses of cisatracurium (0.05 mg kg-1) were administered intravenously until ST/T0 ≤5%. Effective doses 50 (ED50) and 95 (ED95) of cisatracurium in each group were calculated from group dose-response curves. Recovery of ST (TR) was defined as spontaneous recovery of ST to 80-120% of T0 remaining stable for 2 minutes. The ST after each dose of cisatracurium, duration 25% (time after the last dose until 25% recovery of TR), recovery index (time to recovery from 25% to 75% of TR) and duration to TR (time after the last dose until recovery of TR) were recorded. RESULTS: Incremental doses of cisatracurium, median (range), were 2 (1-3) in ISO and 4 (2-5) in PPF to achieve ≥95% depression of ST/T0 (p < 0.01). ED50 and ED95 were 20 µg kg-1 and 117 µg kg-1 in ISO and 128 µg kg-1 and 167 µg kg-1 in PPF, respectively. The duration 25%, recovery index and duration to TR, median (range), were longer in ISO [22.6 (10.3-24.3), 5.3 (3.0-7.8) and 36.1 (20.1-49.7) minutes, respectively] than in PPF [10.2 (6.8-16.5), 3.0 (2.0-3.8) and 17.7 (14.2-28.7) minutes, respectively] (p < 0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Cisatracurium-induced neuromuscular blockade was significantly enhanced and prolonged by isoflurane compared with propofol.

A second-generation glucagon-like peptide-1 receptor agonist mitigates vomiting and anorexia while retaining glucoregulatory potency in lean diabetic and emetic mammalian models.

AIM: To develop a conjugate of vitamin B12 bound to the glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (Ex4) that shows reduced penetrance into the central nervous system while maintaining peripheral glucoregulatory function. METHODS: We evaluated whether a vitamin B12 conjugate of Ex4 (B12-Ex4) improves glucose tolerance without inducing anorexia in Goto-Kakizaki (GK) rats, a lean type 2 diabetes model of an understudied but medically compromised population of patients requiring the glucoregulatory effects of GLP-1R agonists without anorexia. We also utilized the musk shrew (Suncus murinus), a mammalian model capable of emesis, to test B12-Ex4 on glycaemic profile, feeding and emesis. RESULTS: In both models, native Ex4 and B12-Ex4 equivalently blunted the rise in blood glucose levels during a glucose tolerance test. In both GK rats and shrews, acute Ex4 administration decreased food intake, leading to weight loss; by contrast, equimolar administration of B12-Ex4 had no effect on feeding and body weight. There was a near absence of emesis in shrews given systemic B12-Ex4, in contrast to reliable emesis produced by Ex4. When administered centrally, both B12-Ex4 and Ex4 induced similar potency of emesis, suggesting that brain penetrance of B12-Ex4 is required for induction of emesis. CONCLUSIONS: These findings highlight the potential therapeutic value of B12-Ex4 as a novel treatment for type 2 diabetes devoid of weight loss and with reduced adverse effects and better tolerance, but similar glucoregulation to current GLP-1R agonists.

Evidence that the multiflorine-derived substituted quinazolidine 55P0251 augments insulin secretion and lowers blood glucose via antagonism at α2 -adrenoceptors in mice.

AIMS: To investigate the mechanism of action of 55P0251, a novel multiflorine-derived substituted quinazolidine that augments insulin release and lowers blood glucose in rodents, but does not act via mechanisms addressed by any antidiabetic agent in clinical use. MATERIALS AND METHODS: Using male mice, we determined the effects of 55P0251 on glucose tolerance, insulin secretion from isolated islets and blood oxygen saturation, including head-to-head comparison of 55P0251 to its inverted enantiomer 55P0250, as well as to other anti-hyperglycaemic multiflorine derivatives discovered in our programme. RESULTS: 55P0251 was clearly superior to its inverted enantiomer in the glucose tolerance test (area under the curve: 11.3 mg/kg 55P0251, 1.19 ± 0.04 min*mol/L vs 55P0250, 1.80 ± 0.04 min*mol/L; P < .0001). For insulin release in vitro, this superiority became visible only under concomitant adrenergic background stimulation (glucose-stimulated insulin release, fmol*islet-1 *30 min-1 : without α2 -adrenoceptor agonist: 500 µmol/L 55P0251, 390 ± 34, vs 55P0250, 459 ± 40, nonsignificant; with α2 -adrenoceptor agonist: 250 µmol/L 55P0251, 138 ± 9, vs 55P0250, 21 ± 6; P < .0001). Since receptor binding assays suggested antagonism at α2A -adrenoceptors as a potential mechanism of action, we measured oxygen saturation in capillary blood from the tail as a surrogate of vasoconstriction, which supported α2 -antagonistic action in vivo (90 mg/kg 55P0251, 83 ± 3%, vs 55P0250, 57 ± 3%; P < .0001). Lack of association between glucose-lowering activities and α2A -adrenoceptor binding affinity arising from comparison of multiflorine derivatives was attributed to differences in their pharmacokinetic properties. CONCLUSIONS: Our findings suggest that 55P0251 and related multiflorine derivatives are to be categorized as α2 -adrenoceptor antagonists with potential to lower blood glucose by blocking α2A -adrenoceptors on pancreatic ß cells.

SCO-792, an enteropeptidase inhibitor, improves disease status of diabetes and obesity in mice.

AIMS: Enteropeptidase is a serine protease localized on the duodenal brush border that catalyzes the conversion of inactive trypsinogen into active trypsin, thereby regulating protein breakdown in the gut. We evaluated the effects of SCO-792, a novel enteropeptidase inhibitor, in mice. MATERIALS AND METHODS: In vivo inhibition of enteropeptidase was evaluated via an oral protein challenge. Pharmacological effects were evaluated in normal mice, in diet-induced obese (DIO) mice and in obese and diabetic ob/ob mice. RESULTS: A single oral administration of SCO-792 inhibited plasma branched-chain amino acids (BCAAs) in an oral protein challenge test in mice, indicating in vivo inhibition of enteropeptidase. Repeated treatment with SCO-792 induced reduction in food intake and decrease in body weight in DIO and ob/ob mice. Plasma FGF21 levels were increased in SCO-792-treated DIO mice, an observation that was probably independent of reduction in food intake. Hyperglycaemia was markedly improved in SCO-792-treated ob/ob mice. A hyperinsulinaemic-euglycaemic clamp study revealed improved muscle insulin sensitivity in SCO-792-treated ob/ob mice. SCO-792 also improved plasma and liver lipid profiles and decreased plasma alanine transaminase, suggesting a potential treatment for liver diseases. Dietary supplementation with essential amino acids attenuated the effect of SCO-792 on reduction in food intake and decrease in body weight in normal mice, suggesting a pivotal role for enteropeptidase in these biological phenomena. CONCLUSIONS: SCO-792 inhibited enteropeptidase in vivo, reduced food intake, decreased body weight, increased insulin sensitivity, improved glucose and lipid control, and ameliorated liver parameters in mouse models with obesity and/or diabetes. SCO-792 may exhibit similar effects in patients.

Liraglutide pharmacotherapy reduces body weight and improves glycaemic control in juvenile obese/hyperglycaemic male and female rats.

AIMS: To examine whether the glucagon-like peptide-1 receptor agonist liraglutide could be used in juvenile male and female rats as an anti-obesity/diabetic pharmaceutical to prevent not only adolescent obesity/hyperglycaemia, but also early-adult onset obesity. MATERIAL AND METHODS: Pregnant dams were fed either standard chow or a high-fat, high-sucrose diet (HFSD) from gestational day 2, throughout pregnancy and lactation. Offspring were weaned onto the respective maternal diet. Juveniles received daily subcutaneous injection of liraglutide (50 µg/kg, from postnatal day [PND]30 to PND40 and 200 µg/kg from PND40 to PND60) or vehicle. Food intake, body weight and glycaemic levels were evaluated across the experimental period. RESULTS: Chronic liraglutide administration in juveniles prevented body weight gain in males and retained a normoglycaemic profile in both male and female rats. CONCLUSION: These preclinical data suggest that maternal and early-life consumption of an HFSD increases caloric intake, body weight gain and hyperglycaemia, a collective set of unwanted metabolic effects that appear to be treatable in juveniles with liraglutide pharmacotherapy intervention.

Empagliflozin reduces myocardial ketone utilization while preserving glucose utilization in diabetic hypertensive heart disease: A hyperpolarized 13 C magnetic resonance spectroscopy study.

AIM: To investigate the effects of the sodium-glucose co-transporter-2 inhibitor empagliflozin on myocardial ketone body utilization in diabetic, obese rats with spontaneously hypertensive heart failure (SHHF), after 6 months of treatment. MATERIALS AND METHODS: Myocardial ketone body utilization was measured in vivo real time using a novel ketone probe (hyperpolarized [3-13 C]acetoacetate) and magnetic resonance spectroscopy (MRS). Myocardial glucose utilization and cardiac function were also determined in vivo using hyperpolarized [1-13 C]pyruvate MRS and magnetic resonance imaging (MRI), respectively. Myocardial fatty acid uptake and liver ketogenesis were assessed via protein expression. RESULTS: At baseline, myocardial ketone and glucose utilization were both higher in SHHF compared with control rats. Six months of empagliflozin treatment in SHHF rats was associated with less obesity, lower blood pressure, reduced blood glucose and insulin levels, and increased fasting blood ß-hydroxybutyrate levels, as expected. Contrary to the hypothesis, myocardial ketone body utilization was lower in empagliflozin-treated SHHF rats, while glucose utilization and cardiac function were unaltered and hepatic congestion was reduced, compared with vehicle-treated SHHF rats. CONCLUSIONS: In diabetic hypertensive heart disease, empagliflozin reduces afterload without altering myocardial function and glucose utilization in the face of falling blood glucose levels, but does not enhance myocardial ketone utilization despite increased circulating levels.

Short- and long-term administration of the non-steroidal mineralocorticoid receptor antagonist finerenone opposes metabolic syndrome-related cardio-renal dysfunction.

AIM: To determine whether non-steroidal mineralocorticoid receptor (MR) antagonists oppose metabolic syndrome-related end-organ, i.e. cardiac, damage. MATERIALS AND METHODS: In Zucker fa/fa rats, a rat model of metabolic syndrome, we assessed the effects of the non-steroidal MR antagonist finerenone (oral 2 mg/kg/day) on left ventricular (LV) function, haemodynamics and remodelling (using echocardiography, magnetic resonance imaging and biochemical methods). RESULTS: Long-term (90 days) finerenone modified neither systolic blood pressure nor heart rate, but reduced LV end-diastolic pressure and LV end-diastolic pressure-volume relationship, without modifying LV end-systolic pressure and LV end-systolic pressure-volume relationship. Simultaneously, long-term finerenone reduced both LV systolic and diastolic diameters, associated with reductions in LV weight and LV collagen density, while proteinuria and renal nGAL expression were reduced. Short-term (7 days) finerenone improved LV haemodynamics and reduced LV systolic diameter, without modifying LV diastolic diameter. Moreover, short-term finerenone increased myocardial tissue perfusion and reduced myocardial reactive oxygen species, while plasma nitrite levels, an indicator of nitric oxide (NO) bio-availability, were increased. CONCLUSIONS: In rats with metabolic syndrome, the non-steroidal MR antagonist finerenone opposed metabolic syndrome-related diastolic cardiac dysfunction and nephropathy. This involved acute effects, such as improved myocardial perfusion, reduced oxidative stress/increased NO bioavailability, as well as long-term effects, such as modifications in the myocardial structure.

What Does It "Mean"? A Review of Interpreting and Calculating Different Types of Means and Standard Deviations.

Typically, investigations are conducted with the goal of generating inferences about a population (humans or animal). Since it is not feasible to evaluate the entire population, the study is conducted using a randomly selected subset of that population. With the goal of using the results generated from that sample to provide inferences about the true population, it is important to consider the properties of the population distribution and how well they are represented by the sample (the subset of values). Consistent with that study objective, it is necessary to identify and use the most appropriate set of summary statistics to describe the study results. Inherent in that choice is the need to identify the specific question being asked and the assumptions associated with the data analysis. The estimate of a "mean" value is an example of a summary statistic that is sometimes reported without adequate consideration as to its implications or the underlying assumptions associated with the data being evaluated. When ignoring these critical considerations, the method of calculating the variance may be inconsistent with the type of mean being reported. Furthermore, there can be confusion about why a single set of values may be represented by summary statistics that differ across published reports. In an effort to remedy some of this confusion, this manuscript describes the basis for selecting among various ways of representing the mean of a sample, their corresponding methods of calculation, and the appropriate methods for estimating their standard deviations.

Dual CCR2/CCR5 antagonist treatment attenuates adipose inflammation, but not microvascular complications in ob/ob mice.

Diabetic peripheral neuropathy (DPN) and diabetic kidney disease (DKD) are common diabetic complications with limited treatment options. Experimental studies show that targeting inflammation using chemokine receptor (CCR) antagonists ameliorates DKD, presumably by reducing macrophage accumulation or activation. As inflammation is implicated in DPN development, we assessed whether CCR2 and CCR5 antagonism could also benefit DPN. Five-week-old ob/ob mice were fed a diet containing MK-0812, a dual CCR2-CCR5 receptor antagonist, for 8 weeks; DPN, DKD and metabolic phenotyping were then performed to determine the effect of CCR inhibition. Although MK-0812 reduced macrophage accumulation in adipose tissue, the treatment had largely no effect on metabolic parameters, nerve function or kidney disease in ob/ob mice. These results conflict with published data that demonstrate a benefit of CCR antagonists for DKD and hyperglycaemia. We conclude that CCR signaling blockade is ineffective in ob/ob mice and suspect that this is explained by the severe hyperglycaemia found in this model. It remains to be determined whether MK-0812 treatment, alone or in combination with improved glycaemic control, is useful in preventing diabetic complications in alternate animal models.

Scriptaid enhances skeletal muscle insulin action and cardiac function in obese mice.

AIM: To determine the effect of Scriptaid, a compound that can replicate aspects of the exercise adaptive response through disruption of the class IIa histone deacetylase (HDAC) corepressor complex, on muscle insulin action in obesity. MATERIALS AND METHODS: Diet-induced obese mice were administered Scriptaid (1 mg/kg) via daily intraperitoneal injection for 4 weeks. Whole-body and skeletal muscle metabolic phenotyping of mice was performed, in addition to echocardiography, to assess cardiac morphology and function. RESULTS: Scriptaid treatment had no effect on body weight or composition, but did increase energy expenditure, supported by increased lipid oxidation, while food intake was also increased. Scriptaid enhanced the expression of oxidative genes and proteins, increased fatty acid oxidation and reduced triglycerides and diacylglycerides in skeletal muscle. Furthermore, ex vivo insulin-stimulated glucose uptake by skeletal muscle was enhanced. Surprisingly, heart weight was reduced in Scriptaid-treated mice and was associated with enhanced expression of genes involved in oxidative metabolism in the heart. Scriptaid also improved indices of both diastolic and systolic cardiac function. CONCLUSION: These data show that pharmacological targeting of the class IIa HDAC corepressor complex with Scriptaid could be used to enhance muscle insulin action and cardiac function in obesity.

L-arginine promotes gut hormone release and reduces food intake in rodents.

AIMS: To investigate the anorectic effect of L-arginine (L-Arg) in rodents. METHODS: We investigated the effects of L-Arg on food intake, and the role of the anorectic gut hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), the G-protein-coupled receptor family C group 6 member A (GPRC6A) and the vagus nerve in mediating these effects in rodents. RESULTS: Oral gavage of L-Arg reduced food intake in rodents, and chronically reduced cumulative food intake in diet-induced obese mice. Lack of the GPRC6A in mice and subdiaphragmatic vagal deafferentation in rats did not influence these anorectic effects. L-Arg stimulated GLP-1 and PYY release in vitro and in vivo. Pharmacological blockade of GLP-1 and PYY receptors did not influence the anorectic effect of L-Arg. L-Arg-mediated PYY release modulated net ion transport across the gut mucosa. Intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administration of L-Arg suppressed food intake in rats. CONCLUSIONS: L-Arg reduced food intake and stimulated gut hormone release in rodents. The anorectic effect of L-Arg is unlikely to be mediated by GLP-1 and PYY, does not require GPRC6A signalling and is not mediated via the vagus. I.c.v. and i.p. administration of L-Arg suppressed food intake in rats, suggesting that L-Arg may act on the brain to influence food intake. Further work is required to determine the mechanisms by which L-Arg suppresses food intake and its utility in the treatment of obesity.

Las grandes directrices de la investigación en homeopatía (parte 1 de 2) / The broad guidelines of research in homeopathy (part 1 of 2)

La Homeopatía se fundó sobre un método que es, al mismo tiempo, experimental y empírico. La Homeopatía es parcialmente experimental debido a que su semiología nació con la experimentación sobre el hombre sano, efectuada según el método hahnemanniano; asimismo, es parcialmente empírica porque se basa en el trabajo de observación de los médicos homeópatas y en la adquisición de la experiencia práctica, la cual ha sido transmitida a alumnos deseosos de utilizar este método terapéutico. La investigación en Homeopatía se ha desarrollado progresivamente, tratando de integrar las aportaciones de estos dos métodos: experimental y empírico. De hecho, los esfuerzos realizados por situar a la Homeopatía dentro de una metodología rigurosa se remontan al inicio mismo de esta disciplina, inscrita desde su origen por Hahnemann dentro de la línea científica y médica original. (AU)

Homeopathy is in part experimental because the semiology was born with the experimentation on the healthy man, which was performed according to Hahnemann´s method; it is also partly empirical because much work is based on the observation of homeopaths and the acquisition of practical experience, which has been transmitted to students eager to use this therapeutic method. Research in Homeopathy has been gradually developed, trying to integrate the contributions of these two methods: experimental and empirical. In fact, efforts have been made to place homeopathy within a rigorous methodology dating back to the beginning of the discipline itself, from its origin registered by Hahnemann within the original scientific and medical field. (AU)

Las grandes directrices de la investigación en homeopatía (parte 1 de 2) / The broad guidelines of research in homeopathy (part 1 of 2)

La Homeopatía se fundó sobre un método que es, al mismo tiempo, experimental y empírico. La Homeopatía es parcialmente experimental debido a que su semiología nació con la experimentación sobre el hombre sano, efectuada según el método hahnemanniano; asimismo, es parcialmente empírica porque se basa en el trabajo de observación de los médicos homeópatas y en la adquisición de la experiencia práctica, la cual ha sido transmitida a alumnos deseosos de utilizar este método terapéutico. La investigación en Homeopatía se ha desarrollado progresivamente, tratando de integrar las aportaciones de estos dos métodos: experimental y empírico. De hecho, los esfuerzos realizados por situar a la Homeopatía dentro de una metodología rigurosa se remontan al inicio mismo de esta disciplina, inscrita desde su origen por Hahnemann dentro de la línea científica y médica original...

Homeopathy is in part experimental because the semiology was born with the experimentation on the healthy man, which was performed according to Hahnemann´s method; it is also partly empirical because much work is based on the observation of homeopaths and the acquisition of practical experience, which has been transmitted to students eager to use this therapeutic method. Research in Homeopathy has been gradually developed, trying to integrate the contributions of these two methods: experimental and empirical. In fact, efforts have been made to place homeopathy within a rigorous methodology dating back to the beginning of the discipline itself, from its origin registered by Hahnemann within the original scientific and medical field...

Open flow microperfusion: pharmacokinetics of human insulin and insulin detemir in the interstitial fluid of subcutaneous adipose tissue.

AIMS: To compare the time profile of insulin detemir and human insulin concentrations in the interstitial fluid (ISF) of subcutaneous adipose tissue during constant i.v. infusion and to investigate the relationship between the pharmacokinetics of both insulin molecules in plasma and the ISF of subcutaneous adipose tissue. METHODS: During a 6-h hyperinsulinaemic-euglycaemic clamp (plasma glucose level 8 mmol/l) human insulin (21 and 42 pmol/min/kg) or insulin detemir (209 and 417 pmol/min/kg) were infused i.v. in eight rats per dose level. Open flow microperfusion (OFM) was used to continuously assess interstitial insulin concentrations in subcutaneous adipose tissue. RESULTS: At the lower infusion rate, insulin detemir appeared significantly later in the ISF than in the plasma (p < 0.05) and also appeared later in the ISF relative to human insulin (p < 0.005). CONCLUSIONS: By using OFM we were able to monitor albumin-bound insulin detemir directly in the ISF of subcutaneous tissue and confirm its delayed transendothelial passage to a peripheral site of action.