Anthony Sclafani: Consummate scientist.

In this article we review the scientific contributions of Anthony Sclafani, with specific emphasis on his early work on the neural substrate of the ventromedial hypothalamic (VMH) hyperphagia-obesity syndrome, and on the development of diet-induced obesity (DIO). Over a period of 20 years Sclafani systematically investigated the neuroanatomical basis of the VMH hyperphagia-obesity syndrome, and ultimately identified a longitudinal oxytocin-containing neural tract contributing to its expression. This tract has since been implicated in mediating the effects of at least two gastrointestinal satiety factors. Sclafani was one of the first investigators to demonstrate DIO in rats as a result of exposure to multiple palatable food items (the "supermarket diet"), and concluded that diet palatability was the primary factor responsible for DIO. Sclafani went on to investigate the potency of specific carbohydrate and fat stimuli for inducing hyperphagia, and in so doing discovered that post-ingestive nutrient effects contribute to the elevated intake of palatable food items. To further investigate this effect, he devised an intragastric infusion system which allowed the introduction of nutrients into the gut paired with the oral intake of flavored solutions, an apparatus her termed the "electronic esophagus". Sclafani coined the term "appetition" to describe the effect of intestinal nutrient sensing on post-ingestive appetite stimulation. Sclafani's productivity in the research areas he chose to investigate has been nothing short of extraordinary, and his studies are characterized by inventive hypothesizing and meticulous experimental design. His results and conclusions, to our knowledge, have never been contradicted.

Central effects of insulin detemir on feeding, body weight, and metabolism in rats.

Insulin detemir (DET) is a basal insulin analog that, in contrast to other long-acting forms of insulin, has significant weight-gain-sparing effects in diabetic patients. We hypothesized that this effect of DET may be due to its enhanced catabolic action in the central nervous system. We investigated the long-term effects of single third ventricular (3V) microinjections of equimolar doses of DET and regular insulin in normal male rats on feeding, body weight, energy expenditure (EE), and respiratory quotient (RQ). Also, in acute testing, we assessed the ability of lower doses of DET to alter feeding, EE, and RQ when microinjected directly into the paraventricular nucleus (PVN). The anabolic peptide ghrelin served as a positive control in acute testing. 3V administration of both DET (0.5-2.0 mU) and regular insulin (2.0-8.0 mU) significantly reduced feeding and body weight over 48 and 120 h, respectively, with DET yielding greater inhibitory effects. DET also stimulated greater elevations of EE and reductions of RQ over 72 and 48 h postinjection, respectively. In acute (4 h) testing, microinjections of DET (0.5 mU) into the PVN reduced feeding, increased EE, and reduced RQ, while ghrelin (100 pmol) had the opposite effects. When administered sequentially into the PVN, DET (0.25 and 0.5 mU) reversed ghrelin-induced feeding, EE, and RQ effects. These data support the notion that the weight-sparing effect of DET is at least in part based on its central catabolic action and that enhanced EE and reduced RQ may participate in this effect.

Using Caenorhabditis elegans as a Model for Obesity Pharmacology Development.

The Caenorhabditis elegans model is a rapid and inexpensive method to address pharmacologic questions. We describe the use of C. elegans to explore 2 pharmacologic questions concerning candidate antiobesity drugs and illustrate its potential usefulness in pharmacologic research: (1) to determine a ratio of betahistine-olanzapine that blocks the olanzapine-induced intestinal fat deposition (IFD) as detected by Nile red staining and (2) to identify the mechanism of action of a pharmaceutical candidate AB-101 that reduces IFD. Olanzapine (53 µg/mL) increased the IFD (12.1 ± 0.1%, P < 0.02), which was blocked by betahistine (763 µg/mL, 39.3 ± 0.01%, P < 0.05) in wild-type C. elegans (N2). AB-101 (1.0%) reduced the IFD in N2 (P < 0.05), increased the pharyngeal pumping rate (P < 0.05), and reversed the elevated IFD induced by protease inhibitors atazanavir and ritonavir (P < 0.05). AB-101 did not affect IFD in a ACS null mutant strain acs-4(ok2872) III/hT2[bli-4(e937) let-?(q782) qIs48](I;III) suggesting an involvement of the lipid oxidation pathway and an upregulation of CPT-1. Our studies suggest that C. elegans may be used as a resource in pharmacologic research. This article is intended to stimulate a greater appreciation of its value in the development of new pharmaceutical interventions.

Sugar-induced cephalic-phase insulin release is mediated by a T1r2+T1r3-independent taste transduction pathway in mice.

Sensory stimulation from foods elicits cephalic phase responses, which facilitate digestion and nutrient assimilation. One such response, cephalic-phase insulin release (CPIR), enhances glucose tolerance. Little is known about the chemosensory mechanisms that activate CPIR. We studied the contribution of the sweet taste receptor (T1r2+T1r3) to sugar-induced CPIR in C57BL/6 (B6) and T1r3 knockout (KO) mice. First, we measured insulin release and glucose tolerance following oral (i.e., normal ingestion) or intragastric (IG) administration of 2.8 M glucose. Both groups of mice exhibited a CPIR following oral but not IG administration, and this CPIR improved glucose tolerance. Second, we examined the specificity of CPIR. Both mouse groups exhibited a CPIR following oral administration of 1 M glucose and 1 M sucrose but not 1 M fructose or water alone. Third, we studied behavioral attraction to the same three sugar solutions in short-term acceptability tests. B6 mice licked more avidly for the sugar solutions than for water, whereas T1r3 KO mice licked no more for the sugar solutions than for water. Finally, we examined chorda tympani (CT) nerve responses to each of the sugars. Both mouse groups exhibited CT nerve responses to the sugars, although those of B6 mice were stronger. We propose that mice possess two taste transduction pathways for sugars. One mediates behavioral attraction to sugars and requires an intact T1r2+T1r3. The other mediates CPIR but does not require an intact T1r2+T1r3. If the latter taste transduction pathway exists in humans, it should provide opportunities for the development of new treatments for controlling blood sugar.

Success and failures of telehealth during COVID-19 should inform digital applications to combat obesity.

Background: In response to the COVID-19 pandemic, telehealth digital applications (apps) permitted the delivery of health care to millions of individuals, including those with poor access to health services. Aim: To review a body of evidence demonstrating that telehealth and mobile health (mHealth) apps can promote clinically meaningful weight loss, and thus hold potential to increase access to treatment and weight loss care for individuals suffering from obesity. Results: Data from COVID-19 pandemic revealed that access to telehealth and mHealth remains a challenge for underserved communities that are disproportionately affected by obesity. Conclusions: The development of telehealth and mHealth for obesity treatment must be informed by the success and failures of telehealth during the COVID-19 pandemic. Failure to do so, risks alienating the very populations that stand most to benefit from telehealth and mHealth apps for obesity treatment.

In vivo MRI quantification of individual muscle and organ volumes for assessment of anabolic steroid growth effects.

This study aimed to develop a quantitative and in vivo magnetic resonance imaging (MRI) approach to investigate the muscle growth effects of anabolic steroids. A protocol of MRI acquisition on a standard clinical 1.5 T scanner and quantitative image analysis was established and employed to measure the individual muscle and organ volumes in the intact and castrated guinea pigs undergoing a 16-week treatment protocol by two well-documented anabolic steroids, testosterone and nandrolone, via implanted silastic capsules. High correlations between the in vivo MRI and postmortem dissection measurements were observed for shoulder muscle complex (R=0.86), masseter (R=0.79), temporalis (R=0.95), neck muscle complex (R=0.58), prostate gland and seminal vesicles (R=0.98), and testis (R=0.96). Furthermore, the longitudinal MRI measurements yielded adequate sensitivity to detect the restoration of growth to or towards normal in castrated guinea pigs by replacing circulating steroid levels to physiological or slightly higher levels, as expected. These results demonstrated that quantitative MRI using a standard clinical scanner provides accurate and sensitive measurement of individual muscles and organs, and this in vivo MRI protocol in conjunction with the castrated guinea pig model constitutes an effective platform to investigate the longitudinal and cross-sectional growth effects of other potential anabolic steroids. The quantitative MRI protocol developed can also be readily adapted for human studies on most clinical MRI scanner to investigate the anabolic steroid growth effects, or monitor the changes in individual muscle and organ volume and geometry following injury, strength training, neuromuscular disorders, and pharmacological or surgical interventions.

Weight Cycling Increases Longevity Compared with Sustained Obesity in Mice.

OBJECTIVE: Despite the known health benefits of weight loss among persons with obesity, observational studies have reported that cycles of weight loss and regain, or weight cycling, are associated with increased mortality. To study whether weight loss must be sustained to achieve health and longevity benefits, we performed a randomized controlled feeding study of weight cycling in mice. METHODS: In early adult life, obese mice were randomized to ad libitum feeding to sustain obesity, calorie restriction to achieve a "normal" or intermediate body weight, or weight cycling (repeated episodes of calorie restriction and ad libitum refeeding). Body weight, body composition, and food intake were followed longitudinally until death. A subsample of mice was collected from each group for determination of adipose cell size, serum analytes, and gene expression. RESULTS: Weight loss significantly reduced adipose mass and adipocyte size in both sexes, whereas weight cycling animals regained body fat and cell size during refeeding. Sustained weight loss resulted in a dose-dependent decrease in mortality compared with ad libitum feeding. CONCLUSIONS: Weight cycling significantly increased life-span relative to remaining with obesity and had a similar benefit to sustained modest weight loss.

Phase I study of vandetanib with radiation therapy with or without cisplatin in locally advanced head and neck squamous cell carcinoma.

BACKGROUND: Vandetanib, added to cisplatin and radiation therapy (RT) overcomes chemoradiation therapy (CRT) and epidermal growth factor receptor (EGFR) inhibitor resistance in head and neck squamous cell carcinoma (HNSCC) lines and models. METHODS: Patients with previously untreated HNSCC received vandetanib daily for 14 days (starting dose 100 mg) and then vandetanib + RT (2.2 Gy/day, 5 days/week) for 6 weeks (regimen 1) or vandetanib + RT (2 Gy/day, 5 days/week) + cisplatin (30 mg/m(2) weekly) for 7 weeks (regimen 2). The primary objective was the maximum tolerated dose (MTD) of vandetanib with RT +/- cisplatin. RESULTS: Of 33 treated patients, 30 completed therapy (regimen 1, n = 12; regimen 2, n = 18). MTD in regimen 2 was 100 mg (3 dose limiting toxicities [DLTs] at 200 mg), whereas regimen 1 was stopped because of poor recruitment (1 DLT at 200 mg). Most common grade ≥3 adverse events (AEs) were dysphagia (30%), stomatitis (33%), and mucosal inflammation (27%). Five patients discontinued vandetanib because of AEs. CONCLUSION: Vandetanib with CRT was feasible.

Spexin is a novel human peptide that reduces adipocyte uptake of long chain fatty acids and causes weight loss in rodents with diet-induced obesity.

OBJECTIVE: Microarray studies identified Ch12:orf39 (Spexin) as the most down-regulated gene in obese human fat. Therefore, we examined its role in obesity pathogenesis. METHODS: Spexin effects on food intake, meal patterns, body weight, respiratory exchange ratio (RER), and locomotor activity were monitored electronically in C57BL/6J mice or Wistar rats with diet-induced obesity (DIO). Its effects on adipocyte [(3)H]-oleate uptake were determined. RESULTS: In humans, Spexin gene expression was down-regulated 14.9-fold in obese omental and subcutaneous fat. Circulating Spexin changed in parallel, correlating (r = -0.797) with Leptin. In rats, Spexin (35 µg/kg/day SC) reduced caloric intake ∼32% with corresponding weight loss. Meal patterns were unaffected. In mice, Spexin (25 µg/kg/day IP) significantly reduced the RER at night, and increased locomotion. Spexin incubation in vitro significantly inhibited facilitated fatty acid (FA) uptake into DIO mouse adipocytes. Conditioned taste aversion testing (70 µg/kg/day IP) demonstrated no aversive Spexin effects. CONCLUSIONS: Spexin gene expression is markedly down-regulated in obese human fat. The peptide produces weight loss in DIO rodents. Its effects on appetite and energy regulation are presumably central; those on adipocyte FA uptake appear direct and peripheral. Spexin is a novel hormone involved in weight regulation, with potential for obesity therapy.

Dietary components in the development of leptin resistance.

Classically, leptin resistance has been associated with increased body fat and circulating leptin levels, and the condition is believed to contribute to the onset and/or maintenance of obesity. Although a great deal is known about the central nervous system mechanisms mediating leptin resistance, considerably less is known about the role of diet in establishing and maintaining this altered hormonal state. An exciting new finding has recently been published demonstrating the existence of leptin resistance in normal-weight rats with lean leptin levels by feeding them a high-concentration-fructose diet. This finding has opened the possibility that specific macronutrients may be capable of inducing leptin resistance, independently of the amount of body fat or circulating leptin present in the treated animals. This review describes several lines of research that have recently emerged indicating that specific types of dietary sugars and fats are capable of inducing leptin resistance in experimental rodent models. The results further show that diet-induced leptin resistance is capable of increasing energy intake and elevating body weight gain under appropriate dietary challenges. It appears that biological mechanisms on multiple levels may underlie the dietary induction of leptin resistance, including alterations in the leptin blood-to-brain transport system, in peripheral glucose metabolism, and in central leptin receptor signaling pathways. What is clear from the findings reviewed here is that diet-induced leptin resistance can occur in the absence of elevated circulating leptin levels and body weight, rendering it a potential cause and/or predisposing factor to excess body weight gain and obesity.

In vivo MRI evaluation of anabolic steroid precursor growth effects in a guinea pig model.

Anabolic steroids are widely used to increase skeletal muscle (SM) mass and improve physical performance. Some dietary supplements also include potent steroid precursors or active steroid analogs such as nandrolone. Our previous study reported the anabolic steroid effects on SM in a castrated guinea pig model with SM measured using a highly quantitative magnetic resonance imaging (MRI) protocol. The aim of the current study was to apply this animal model and in vivo MRI protocol to evaluate the growth effects of four widely used over-the-counter testosterone and nandrolone precursors: 4-androstene-3 17-dione (androstenedione), 4-androstene-3beta 17beta-diol (4-androsdiol), 19-nor-4-androstene-3beta-17beta-diol (bolandiol) and 19-nor-4-androstene-3 17-dione (19-norandrostenedione). The results showed that providing precursor to castrated male guinea pigs led to plasma steroid levels sufficient to maintain normal SM growth. The anabolic growth effects of these specific precursors on individual and total muscle volumes, sexual organs, and total adipose tissue over a 10-week treatment period, in comparison with those in the respective positive control testosterone and nandrolone groups, were documented quantitatively by MRI.

Prolonged decrease of adipocyte size after rosiglitazone treatment in high- and low-fat-fed rats.

OBJECTIVE: The anti-diabetic thiazolidinediones (TZDs) stimulate adipocyte differentiation and decrease mean adipocyte size. However, whether these smaller, more insulin-sensitive adipocytes maintain their size after TZD therapy is discontinued has not been studied. RESEARCH METHODS AND PROCEDURES: Adult female Sprague-Dawley rats were fed a low-fat (10% fat) diet or, to elevate body weight (BW), a high-fat (HF) diet (45% fat) for 6 weeks. Rats were initially randomized to groups (n = 12) fed either low-fat or HF diets, with or without the TZD rosiglitazone (ROSI; 5 mg/kg per day), for 6 weeks. ROSI was then discontinued, and all animals were fed HF for another 6 weeks before sacrifice. Retroperitoneal (RP) adipose tissue morphology was determined from tissue collected by serial biopsies before and after 6 weeks of ROSI treatment and at sacrifice. RESULTS: Measures of BW and adiposity did not differ among groups 6 weeks after stopping ROSI treatment. However, during treatment, ROSI in both diets significantly decreased RP adipocyte size and increased RP DNA content, and these effects continued to be observed after discontinuing treatment. ROSI administration also decreased circulating insulin, leptin, and triglycerides and increased circulating adiponectin levels; however, these effects were reversed on stopping treatment. DISCUSSION: These results demonstrated that TZD-induced effects on adipocyte size and number were maintained after discontinuing treatment, even with consumption of an obesigenic diet. However, additional studies are needed to determine whether TZD-treated animals eventually achieve an adipocyte size similar to that of untreated animals at the expense of a higher BW.

Acute insulin-induced elevations of circulating leptin and feeding inhibition in lean but not obese rats.

Insulin has been shown to stimulate leptin mRNA expression acutely in rat adipose tissue, but its short-term effects on circulating leptin levels, and subsequent feeding behavior, have not been well described. We used 11-mo-old female selectively bred obesity-resistant (OR) and obesity-prone (OP) Sprague-Dawley rats maintained on laboratory chow to investigate this question. At testing, body weights and basal leptin levels of the OP rats were significantly elevated compared with the OR rats. In the 3-h fasted state, injection of 2.0 U insulin/kg ip resulted in significant elevations of plasma leptin at 4 h postinjection in both OP and OR groups (hour 4, +2.50 and +5.98 ng/ml, respectively). In separate feeding tests with the same groups, intake of laboratory chow pellets was significantly inhibited during hours 2-4 after 2.0 U/kg of insulin in the OR (-80.1%, P < 0.05), but not in the OP group, compared with intake after saline injections. In feeding tests with palatable moderately high-fat pellets after 2.0 and 3.0 U insulin/kg ip, significant decreases between hours 2 and 4 in intake were seen in the OR group only (-41.0 and -68.3%, respectively). Thus feeding inhibition coincides with insulin-induced elevations of plasma leptin in lean but not obese Sprague-Dawley rats. Our data suggest that elevations of leptin within the physiological range may contribute to short-term inhibition of food intake in rats and that this process may be stimulated by feeding-related insulin release.

Ghrelin is an orexigenic and metabolic signaling peptide in the arcuate and paraventricular nuclei.

Ghrelin is a 28-amino acid acylated peptide and is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). The GHS-R is expressed in hypothalamic nuclei, including the arcuate nucleus (Arc) where it is colocalized with neuropeptide Y (NPY) neurons. In the present study, we examined the effects of ghrelin on feeding and energy substrate utilization (respiratory quotient; RQ) following direct injections into either the arcuate or the paraventricular nucleus (PVN) of the hypothalamus. Ghrelin was administered at the beginning of the dark cycle at doses of 15-60 pmol to male and female rats. In feeding studies, food intake was measured 2 and 4 h postinjection. Separate groups of rats were injected with ghrelin, and the RQ (VCO(2)/VO(2)) was measured using an open circuit calorimeter over a 4-h period. Both Arc and PVN injections of ghrelin increased food intake in male and female rats. Ghrelin also increased RQ, reflecting a shift in energy substrate utilization in favor of carbohydrate oxidation. Because these effects are similar to those observed after PVN injection of NPY, we then assessed the impact of coinjecting ghrelin with NPY into the PVN. When rats were pretreated with very low doses of ghrelin (2.5-10 pmol), NPY's (50 pmol) effects on eating and RQ were potentiated. Overall, these data are in agreement with evidence suggesting that ghrelin functions as a gut-brain endocrine hormone implicated in the regulation of food intake and energy metabolism. Our findings are also consistent with a possible interactive role of hypothalamic ghrelin and NPY systems.

Intentional weight loss reduces mortality rate in a rodent model of dietary obesity.

OBJECTIVE: We used a rodent model of dietary obesity to evaluate effects of caloric restriction-induced weight loss on mortality rate. Research Measures and Procedures: In a randomized parallel-groups design, 312 outbred Sprague-Dawley rats (one-half males) were assigned at age 10 weeks to one of three diets: low fat (LF; 18.7% calories as fat) with caloric intake adjusted to maintain body weight 10% below that for ad libitum (AL)-fed rat food, high fat (HF; 45% calories as fat) fed at the same level, or HF fed AL. At age 46 weeks, the lightest one-third of the AL group was discarded to ensure a more obese group; the remaining animals were randomly assigned to one of three diets: HF-AL, HF with energy restricted to produce body weights of animals restricted on the HF diet throughout life, or LF with energy restricted to produce the body weights of animals restricted on the LF diet throughout life. Life span, body weight, and leptin levels were measured. RESULTS: Animals restricted throughout life lived the longest (p < 0.001). Life span was not different among animals that had been obese and then lost weight and animals that had been nonobese throughout life (p = 0.18). Animals that were obese and lost weight lived substantially longer than animals that remained obese throughout life (p = 0.002). Diet composition had no effect on life span (p = 0.52). DISCUSSION: Weight loss after the onset of obesity during adulthood leads to a substantial increase in longevity in rats.

High-resolution magnetic resonance imaging tracks changes in organ and tissue mass in obese and aging rats.

Magnetic resonance imaging (MRI) has the ability to discriminate between various soft tissues in vivo. Whole body, specific organ, total adipose tissue (TAT), intra-abdominal adipose tissue (IAAT), and skeletal muscle (SM) weights determined by MRI were compared with weights determined by dissection and chemical analysis in two studies with male Sprague-Dawley rats. A 4.2-T MRI machine acquired high-resolution, in vivo, longitudinal whole body images of rats as they developed obesity or aged. Weights of the whole body and specific tissues were determined using computer image analysis software, including semiautomatic segmentation algorithms for volume calculations. High correlations were found for body weight (r = 0.98), TAT (r = 0.99), and IAAT (r = 0.98) between MRI and dissection and chemical analyses. MRI estimated the weight of the brain, kidneys, and spleen with high accuracy (r > 0.9), but overestimated IAAT, SM, and liver volumes. No differences were detected in organ weights using MRI and dissection measurements. Longitudinal MRI measurements made during the development of obesity and aging accurately represented changes in organ and tissue mass.