Abnormal sympathoadrenal activity, but normal energy expenditure in hypopituitarism

Randomized controlled trial of Tesomet for weight loss in hypothalamic obesity

CONTEXT

Hypothalamic injury often leads to rapid, intractable weight gain causing hypothalamic obesity, which is associated with increased risk of cardiovascular and metabolic morbidity and mortality. There are no approved or effective pharmacological treatments for hypothalamic obesity, and conventional lifestyle management remains ineffective.

OBJECTIVE

To investigate the safety and efficacy of Tesomet (0.5 mg tesofensine/50 mg metoprolol) in adults with hypothalamic obesity.

METHODS

Twenty-one adults with hypothalamic obesity (16 females) were randomized to Tesomet (0.5 mg/50 mg) or placebo for 24 weeks. Patients also received diet/lifestyle counselling. The primary endpoint was safety; secondary endpoints included measures of body weight, appetite scores, quality of life, and metabolic profile.

RESULTS

Eighteen patients completed 24 weeks. Consent withdrawal, eligibility, and serious adverse events (SAE) unrelated to treatment resulted in dropouts. One patient experienced a Tesomet-related SAE of exacerbated pre-existing anxiety leading to treatment discontinuation. Tesomet-related adverse events were otherwise mostly mild and included sleep disturbances (Tesomet 50%, placebo 13%), dry mouth (Tesomet 43%, placebo 0%), and headache (Tesomet 36%, placebo 0%). No significant differences in heart rate or blood pressure were observed between groups. Compared to placebo, Tesomet resulted in additional mean (95% CI) weight change of -6.3% ((-11.3; -1.3); P = 0.017), increased the number of patients achieving ≥5% weight loss (Tesomet 8/13, placebo 1/8; P = 0.046), and tended to augment the reduction in waist circumference by 5.7 cm ((-0.1; 11.5); P = 0.054).

CONCLUSION

Tesomet was welltolerated, did not affect heart rate or blood pressure, and resulted in significant reductions in body weight compared to placebo in adults with hypothalamic obesity.

Mediation of the Acute Stress Response by the Skeleton

We hypothesized that bone evolved, in part, to enhance the ability of bony vertebrates to escape danger in the wild. In support of this notion, we show here that a bone-derived signal is necessary to develop an acute stress response (ASR). Indeed, exposure to various types of stressors in mice, rats (rodents), and humans leads to a rapid and selective surge of circulating bioactive osteocalcin because stressors favor the uptake by osteoblasts of glutamate, which prevents inactivation of osteocalcin prior to its secretion. Osteocalcin permits manifestations of the ASR to unfold by signaling in post-synaptic parasympathetic neurons to inhibit their activity, thereby leaving the sympathetic tone unopposed. Like wild-type animals, adrenalectomized rodents and adrenal-insufficient patients can develop an ASR, and genetic studies suggest that this is due to their high circulating osteocalcin levels. We propose that osteocalcin defines a bony-vertebrate-specific endocrine mediation of the ASR.

Thermic effect of a meal and appetite in adults: an individual participant data meta-analysis of meal-test trials

Background

Thermic effect of a meal (TEF) has previously been suggested to influence appetite.

Objective

The aim of this study was to assess whether there is an association between appetite and TEF. Second, to examine whether protein intake is associated with TEF or appetite.

Design

Individual participant data (IPD) meta-analysis on studies were performed at the Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark. Five randomized meal-test studies, with 111 participants, were included. The included studies measured energy expenditure (EE) in respiration chambers and pre- and postprandial appetite sensations using Visual Analog Scales (VAS). The primary meta-analysis was based on a generic-inverse variance random-effects model, pooling individual study Spearman's correlation coefficients, resulting in a combined r-value with 95% confidence interval (95% CI). The I² value quantifies the proportion (%) of the variation in point estimates due to among-study differences.

Results

The IPD meta-analysis found no association between satiety and TEF expressed as the incremental area under the curve (TEF_iAUC) (r=0.06 [95% CI −0.16 to 0.28], P=0.58; I²=15.8%). Similarly, Composite Appetite Score (CAS) was not associated with TEF_iAUC (r=0.08 [95% CI −0.12 to 0.28], P=0.45; I²=0%). Posthoc analyses showed no association between satiety or CAS and TEF expressed as a percentage of energy intake (EI) (P>0.49) or TEF expressed as a percentage of baseline EE (P>0.17). When adjusting for covariates, TEF_iAUC was associated with protein intake (P=0.0085).

Conclusions

This IPD meta-analysis found no evidence supporting an association between satiety or CAS and TEF at protein intakes ∼15 E% (range 11–30 E%).

The use of sibutramine in the management of obesity and related disorders: an update

Aims:

To review the major trials that evaluated the efficacy and safety of the use of sibutramine for weight loss and the impact of this agent on obesity-related disorders.

Methods and results:

The most important articles on sibutramine up to January 2009 were located by a PubMed and Medline search. Sibutramine reduces food intake and body weight more than placebo and has positive effects on the lipid profile (mainly triglycerides and high density lipoprotein cholesterol), glycemic control and inflammatory markers in studies for up to one year. Preliminary studies showed that sibutramine may also improve other obesity-associated disorders such as polycystic ovary syndrome, left ventricular hypertrophy, binge eating disorder and adolescent obesity. The high discontinuation rates and some safety issues mainly due to the increase in blood pressure and pulse rate have to be considered. Additionally, it has not yet been established that treatment with sibutramine will reduce cardiovascular events and total mortality.

Conclusions:

Sibutramine, in conjunction with lifestyle measures, is a useful drug for reducing body weight and improving associated cardiometabolic risk factors and obesity-related disorders. Studies of longer duration are required to determine the precise indications of the drug, to evaluate safety issues and to assess its efficacy on cardiovascular mortality.

Short-term fasting-induced autonomic activation and changes in catecholamine levels are not mediated by changes in leptin levels in healthy humans

OBJECTIVE

In animal models, the adipocyte-secreted hormone leptin increases energy expenditure by increasing sympathetic outflow but its role in humans remains to be elucidated. We evaluated whether inducing hypoleptinaemia (with and without administration of leptin at replacement doses) for 3 days would influence catecholamine levels and sympathetic and parasympathetic activity in healthy humans.

METHODS

We studied six normal-weight subjects in the General Clinical Research Center (GCRC) under three conditions: baseline fed state (control study) and two 72-h fasting studies (to decrease leptin levels), with administration of either placebo or replacement-dose recombinant methionyl human leptin (r-metHuLeptin) in a randomized, double-blind fashion. In each condition, 24-h urinary catecholamine levels, heart rate and heart rate variability (HRV), a standard tool for assessing cardiac autonomic modulation, were measured.

RESULTS

Study parameters remained stable during the control condition and the baseline assessment of all three studies. In response to 72-h fasting, which decreased serum leptin levels by 80%, 24-h urinary norepinephrine and dopamine levels and heart rate increased while cardiac vagal modulation decreased (all P < 0.05). Replacement-dose r-metHuLeptin to keep leptin levels within the physiological range during fasting did not alter fasting-associated changes in heart rate, catecholamine levels or cardiac vagal tone.

CONCLUSIONS

The findings of this controlled, interventional study indicate that changes in heart rate, catecholamine levels and cardiac vagal modulation associated with 72-h fasting are independent of regulation by leptin. Thus, changes in leptin levels within the physiological range do not seem to play a role in regulating autonomic function during short-term starvation in healthy humans.

Combined dietary and pharmacological weight management in obese hypopituitary patients

OBJECTIVE

The high prevalence of obesity and cardiovascular risk factors in hypopituitarism affirms the need for effective weight loss intervention. In this study, we investigated the combined effect of sibutramine, diet, and exercise in obese hypopituitary patients (HPs).

RESEARCH METHODS AND PROCEDURES

In an open-label prospective intervention trial, 14 obese well-substituted nondiabetic HPs and 14 matched simple obese controls were allocated to 11-month treatment with sibutramine (10 to 15 mg), diet (600 kcal/d deficit), and exercise. Anthropometric indices and body composition (obtained from DXA scan) were assessed monthly for the first 5 months and thereafter every second month for the next 6 months.

RESULTS

Mean (+/-SD) weight loss at 11 months was 11.3 +/- 4.8 kg in patients vs. 10.7 +/- 4.7 kg in controls. The HPs exhibited the same improvements in body composition, waist circumference, blood lipids, and fasting glucose as the simple obese. In a multivariate model, baseline weight, duration of growth hormone replacement therapy, and duration of pituitary disease explained 79% (p = 0.001) of the variation in weight loss at 4 months in the HPs. Only baseline weight and waist circumference could predict weight loss at 11 months.

DISCUSSION

HPs are not resistant to weight loss therapy. Almost all will achieve at least 5% weight loss, and 60% can lose >10% weight within 11 months. However, the long-term effect on risk factors associated with type 2 diabetes and cardiovascular disease as well as on mortality needs to be established.