Intragastric preloads of l-tryptophan reduce ingestive behavior via oxytocinergic neural mechanisms in male mice.

Human and laboratory animal studies suggest that dietary supplementation of a free essential amino acid, l-tryptophan (TRP), reduces food intake. It is unclear whether an acute gastric preload of TRP decreases consumption and whether central mechanisms underlie TRP-driven hypophagia. We examined the effect of TRP administered via intragastric gavage on energy- and palatability-induced feeding in mice. We sought to identify central mechanisms through which TRP suppresses appetite. Effects of TRP on consumption of energy-dense and energy-dilute tastants were established in mice stimulated to eat by energy deprivation or palatability. A conditioned taste aversion (CTA) paradigm was used to assess whether hypophagia is unrelated to sickness. c-Fos immunohistochemistry was employed to detect TRP-induced activation of feeding-related brain sites and of oxytocin (OT) neurons, a crucial component of satiety circuits. Also, expression of OT mRNA was assessed with real-time PCR. The functional importance of OT in mediating TRP-driven hypophagia was substantiated by showing the ability of OT receptor blockade to abolish TRP-induced decrease in feeding. TRP reduced intake of energy-dense standard chow in deprived animals and energy-dense palatable chow in sated mice. Anorexigenic doses of TRP did not cause a CTA. TRP failed to affect intake of palatable yet calorie-dilute or noncaloric solutions (10% sucrose, 4.1% Intralipid or 0.1% saccharin) even for TRP doses that decreased water intake in thirsty mice. Fos analysis revealed that TRP increases activation of several key feeding-related brain areas, especially in the brain stem and hypothalamus. TRP activated hypothalamic OT neurons and increased OT mRNA levels, whereas pretreatment with an OT antagonist abolished TRP-driven hypophagia. We conclude that intragastric TRP decreases food and water intake, and TRP-induced hypophagia is partially mediated via central circuits that encompass OT.

Evaluating the efficacy of different types of stem cells in preserving gut barrier function in necrotizing enterocolitis.

BACKGROUND: Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in premature infants. Increased intestinal permeability is central to NEC development. We have shown that stem cells (SCs) can reduce the incidence and severity of NEC. Our current goal was to investigate the efficacy of four different types of SC in preservation of gut barrier function during NEC. MATERIALS AND METHODS: We compared (1) amniotic fluid-derived mesenchymal SC, (2) bone marrow-derived mesenchymal SC, (3) amniotic fluid-derived neural SC, and (4) enteric neural SC. Premature rat pups received an intraperitoneal injection of 2 × 106 SC or phosphate-buffered saline only and were then subjected to experimental NEC. Control pups were breastfed and not subjected to NEC. After 48 h, animals received a single enteral dose of fluorescein isothiocyanate -labeled dextran (FD70), were sacrificed 4 h later, and serum FD70 concentrations determined. RESULTS: Compared to breastfed, unstressed pups with intact gut barrier function and normal intestinal permeability (serum FD70 concentration 2.22 ± 0.271 µg/mL), untreated pups exposed to NEC had impaired barrier function with significantly increased permeability (18.6 ± 4.25 µg/mL, P = 0.047). Pups exposed to NEC but treated with SC had significantly reduced intestinal permeability: Amniotic fluid-derived mesenchymal SC (9.45 ± 1.36 µg/mL, P = 0.017), bone marrow-derived mesenchymal SC (6.73 ± 2.74 µg/mL, P = 0.049), amniotic fluid-derived neural SC (8.052 ± 1.31 µg/mL, P = 0.0496), and enteric neural SC (6.60 ± 1.46 µg/mL, P = 0.033). CONCLUSIONS: SCs improve gut barrier function in experimental NEC. Although all four types of SC reduce permeability equivalently, SC derived from amniotic fluid may be preferable due to availability at delivery and ease of culture, potentially enhancing clinical translation.

Whey-Adapted versus Natural Cow's Milk Formulation: Distinctive Feeding Responses and Post-Ingestive c-Fos Expression in Laboratory Mice.

The natural 20:80 whey:casein ratio in cow's milk (CM) for adults and infants is adjusted to reflect the 60:40 ratio of human milk, but the feeding and metabolic consequences of this adjustment have been understudied. In adult human subjects, the 60:40 CM differently affects glucose metabolism and hormone release than the 20:80 CM. In laboratory animals, whey-adapted goat's milk is consumed in larger quantities. It is unknown whether whey enhancement of CM would have similar consequences on appetite and whether it would affect feeding-relevant brain regulatory mechanisms. In this set of studies utilizing laboratory mice, we found that the 60:40 CM was consumed more avidly than the 20:80 control formulation by animals motivated to eat by energy deprivation and by palatability (in the absence of hunger) and that this hyperphagia stemmed from prolongation of the meal. Furthermore, in two-bottle choice paradigms, whey-adapted CM was preferred against the natural 20:80 milk. The intake of the whey-adapted CM induced neuronal activation (assessed through analysis of c-Fos expression in neurons) in brain sites promoting satiation, but importantly, this activation was less pronounced than after ingestion of the natural 20:80 whey:casein CM. Activation of hypothalamic neurons synthesizing anorexigenic neuropeptide oxytocin (OT) was also less robust after the 60:40 CM intake than after the 20:80 CM. Pharmacological blockade of the OT receptor in mice led to an increase in the consumption only of the 20:80 CM, thus, of the milk that induced greater activation of OT neurons. We conclude that the whey-adapted CM is overconsumed compared to the natural 20:80 CM and that this overconsumption is associated with weakened responsiveness of central networks involved in satiety signalling, including OT.

The Statin Target Hmgcr Regulates Energy Metabolism and Food Intake through Central Mechanisms.

The statin drug target, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), is strongly linked to body mass index (BMI), yet how HMGCR influences BMI is not understood. In mammals, studies of peripheral HMGCR have not clearly identified a role in BMI maintenance and, despite considerable central nervous system expression, a function for central HMGCR has not been determined. Similar to mammals, Hmgcr is highly expressed in the Drosophila melanogaster brain. Therefore, genetic and pharmacological studies were performed to identify how central Hmgcr regulates Drosophila energy metabolism and feeding behavior. We found that inhibiting Hmgcr, in insulin-producing cells of the Drosophila pars intercerebralis (PI), the fly hypothalamic equivalent, significantly reduces the expression of insulin-like peptides, severely decreasing insulin signaling. In fact, reducing Hmgcr expression throughout development causes decreased body size, increased lipid storage, hyperglycemia, and hyperphagia. Furthermore, the Hmgcr induced hyperphagia phenotype requires a conserved insulin-regulated α-glucosidase, target of brain insulin (tobi). In rats and mice, acute inhibition of hypothalamic Hmgcr activity stimulates food intake. This study presents evidence of how central Hmgcr regulation of metabolism and food intake could influence BMI.

Effect of Oxytocin on Hunger Discrimination.

Centrally and peripherally administered oxytocin (OT) decreases food intake and activation of the endogenous OT systems, which is associated with termination of feeding. Evidence gathered thus far points to OT as a facilitator of early satiation, a peptide that reduces the need for a meal that has already begun. It is not known, however, whether OT can diminish a feeling of hunger, thereby decreasing a perceived need to seek calories. Therefore, in the current project, we first confirmed that intraperitoneal (i.p.) OT at 0.3-1 mg/kg reduces food intake in deprived and non-deprived rats. We then used those OT doses in a unique hunger discrimination protocol. First, rats were trained to discriminate between 22- and 2-h food deprivation (hungry vs. sated state) in a two-lever operant procedure. After rats acquired the discrimination, they were food-restricted for 22 h and given i.p. OT before a generalization test session. OT did not decrease 22-h deprivation-appropriate responding to match that following 2-h food deprivation, thus, it did not reduce the perceived level of hunger. In order to better understand the mechanisms behind this ineffectiveness of OT, we used c-Fos immunohistochemistry to determine whether i.p. OT activates a different subset of feeding-related brain sites under 22- vs. 2-h deprivation. We found that in sated animals, OT induces c-Fos changes in a broader network of hypothalamic and brain stem sites compared to those affected in the hungry state. Finally, by employing qPCR analysis, we asked whether food deprivation vs. sated state have an impact on OT receptor expression in the brain stem, a CNS "entry" region for peripheral OT. Fasted animals had significantly lower OT receptor mRNA levels than their ad libitum-fed counterparts. We conclude that OT does not diminish a feeling of hunger before a start of a meal. Instead OT's anorexigenic properties are manifested once consumption has already begun which is-at least to some extent-driven by changes in brain responsiveness to OT treatment in the hungry vs. fed state. OT should be viewed as a mediator of early satiation rather than as a molecule that diminishes perceived hunger.

Palatability of Goat's versus Cow's Milk: Insights from the Analysis of Eating Behavior and Gene Expression in the Appetite-Relevant Brain Circuit in Laboratory Animal Models.

Goat's (GM) and cow's milk (CM) are dietary alternatives with select health benefits shown in human and animal studies. Surprisingly, no systematic analysis of palatability or preference for GM vs. CM has been performed to date. Here, we present a comprehensive investigation of short-term intake and palatability profiles of GM and CM in laboratory mice and rats. We studied consumption in no-choice and choice scenarios, including meal microstructure, and by using isocaloric milks and milk-enriched solid diets. Feeding results are accompanied by qPCR data of relevant genes in the energy balance-related hypothalamus and brain stem, and in the nucleus accumbens, which regulates eating for palatability. We found that GM and CM are palatable to juvenile, adult, and aged rodents. Given a choice, animals prefer GM- to CM-based diets. Analysis of meal microstructure using licking patterns points to enhanced palatability of and, possibly, greater motivation toward GM over CM. Most profound changes in gene expression after GM vs. CM were associated with the brain systems driving consumption for reward. We conclude that, while both GM and CM are palatable, GM is preferred over CM by laboratory animals, and this preference is driven by central mechanisms controlling eating for pleasure.

Randomized, Crossover Study of Immersive Virtual Reality to Decrease Opioid Use During Painful Wound Care Procedures in Adults.

The objective of this study was to evaluate the effect of immersive virtual reality (IVR) distraction therapy during painful wound care procedures in adults on the amount of opioid medications required to manage pain. A convenience sample of consenting, adult inpatients requiring recurrent painful wound care procedures was studied. Using a within-subject, randomized controlled trial study design, 2 sequential wound procedures were compared, 1 with IVR distraction therapy and 1 without IVR. Total opioid medications administered before and during the wound procedures were recorded and pain and anxiety were rated before and after the 2 wound procedures. The IVR intervention included the wearing of virtual reality goggles and participation in an immersive, computer generated, interactive, 3-dimensional virtual world program. Data were analyzed with Student's t test and chi-square analysis, with P < 0.05 considered significant. A total of 18 patients were studied, with 12 completing both study wound procedures and 6 completing a single wound procedure. The amount of opioid administered before each of the 2 wound procedures was similar with and without IVR. Total opioid administration during the dressing procedures with IVR was significantly less than when no IVR was used, 17.9 ± 6.0 and 29.2 ± 4.5 mcg/kg fentanyl, respectively (t = -2.7; df = 14; P = 0.02). Two of 15 patients (11%) requested more than 1 opioid rescue dose with IVR and 9 of 15 patients (60%) requested more than 1 rescue dose without IVR. Seventy-five percentage of participants stated that they would want to use IVR with future dressing changes. Pain and anxiety scores were similar for the wound procedures with and without IVR (P > 0.05). IVR significantly reduced the amount of opioid medication administered during painful wound care procedures when IVR was used compared with no IVR. Since pain scores were similar before and after the wound procedures with IVR and without IVR, the 39% reduction in opioid medication during IVR supports its use as a pain distraction therapy during painful procedures.

Identification of central mechanisms underlying anorexigenic effects of intraperitoneal L-tryptophan.

A free essential amino acid, L-tryptophan (TRP), administered through a diet or directly into the gut, decreases food intake by engaging neural mechanisms. The ability of intragastric TRP to cross into the general circulation and through the blood-brain barrier, at least partly underlies hypophagia. It is unclear although, whether TRP's anorexigenic effects and accompanying neural processes occur in the absence of the initial action of TRP on the gut mucosa. Here, we addressed this issue by using a fundamental approach of examining effects of intraperitoneally administered TRP on feeding and neuronal activation in rats. We found that 30 mg/kg, intraperitoneal, TRP decreases deprivation-induced intake of standard chow and thirst-driven water intake. A 100 mg/kg dose was necessary to suppress consumption of palatable chow and of sucrose and saccharin solutions in nondeprived animals. Intraperitoneally TRP did not induce a conditioned taste aversion; thus, its anorexigenic effects were unrelated to sickness/malaise. c-Fos mapping in feeding-related brain sites revealed TRP-induced changes in the dorsal vagal complex, hypothalamic paraventricular and supraoptic nuclei and in the basolateral amygdala. TRP enhanced activation of hypothalamic neurons synthesizing an anorexigen, oxytocin (OT). Pharmacological blockade of the OT receptor with a blood-brain barrier -penetrant antagonist, L-368,899, attenuated TRP-induced decrease in deprivation-induced chow intake, but not in thirst-driven water consumption. We conclude that TRP triggers anorexigenic action and underlying neural responses even when it does not directly contact the gut mucosa. TRP requires OT to decrease energy intake, whereas OT is nonobligatory in TRP's effects on drinking behavior.

Single visit surgery for pediatric ambulatory surgical procedures: a satisfaction and cost analysis.

BACKGROUND: Single visit surgery (SVS) consists of same-day pre-operative assessment and operation with telephone post-operative follow-up. This reduces family time commitment to 1 hospital trip rather than 2-3. We began SVS for ambulatory patients with clear surgical indications in 2013. We sought to determine family satisfaction, cost savings to families, and institutional financial feasibility of SVS. METHODS: SVS patients were compared to age/case matched conventional surgery (CS) patients. Satisfaction was assessed by post-operative telephone survey. Family costs were calculated as the sum of lost revenue (based on median income) and transportation costs ($0.50/mile). RESULTS: Satisfaction was high in both groups (98% for SVS vs. 93% for CS; p=0.27). 40% of CS families indicated that they would have preferred SVS, whereas no SVS families indicated preference for the CS option (p<0.001). Distance from the hospital did not correlate with satisfaction. Estimated cost savings for an SVS family was $188. Reimbursement, hospital and physician charges, and day-of-surgery cancellation rates were similar. CONCLUSIONS: SVS provides substantial cost savings to families while maintaining patient satisfaction and equivalent institutional reimbursement. SVS is an effective approach to low-risk ambulatory surgical procedures that is less disruptive to families, facilitates access to pediatric surgical care, and reduces resource utilization. TYPE OF STUDY: Cost Effectiveness Study. LEVEL OF EVIDENCE: Level II.