The SLC38 family of transporters has in total 11 members in humans and they encode amino acid transporters called sodium-coupled amino acid transporters (SNAT). To date, five SNATs have been characterized and functionally subdivided into systems A (SLC38A1, SLC38A2, and SLC38A4) and N (SLC38A3 and SLC38A5) showing the highest transport for glutamine and alanine. Here we present identification of a novel glutamine transporter encoded by the Slc38a7 gene, which we propose should be named SNAT7. This transporter has L-glutamine as the preferred substrate but also transports other amino acids with polar side chains, as well as L-histidine and L-alanine. The expression pattern and substrate profile for SLC38A7 shows highest similarity to the known system N transporters. Therefore, we propose that SLC38A7 is a novel member of this system. We used in situ hybridization and immunohistochemistry with a custom-made antibody to show that SLC38A7 is expressed in all neurons, but not in astrocytes, in the mouse brain. SLC38A7 is unique in being the first system N transporter expressed in GABAergic and also other neurons. The preferred substrate and axonal localization of SLC38A7 close to the synaptic cleft indicates that SLC38A7 could have an important function for the reuptake and recycling of glutamate.Solute carriers (SLCs), 3 are the largest group of transporters in the human genome (1, 2). Many of the SLCs are coupled transporters with important functions in cellular processes, including roles as transporters for amino acids and neurotransmitter cycling, whereas others are passive transporters or exchangers (2-4). It has been suggested that there are close to 100 SLC transporters for amino acids in the human genome, of these around 60 have been characterized regarding substrate and the rest are postulated as probable amino acid transporters (5). This large number indicates the importance of having a regulated membrane transport of amino acids over the cell membrane as well as over mitochondrial and vesicular membranes. The SLCs have been categorized into at least 46 different families with varied biochemical properties (5) and recently two more families have been identified (6). In mammals, phylogenetic classification of SLCs show that the SLC proteins form four major phylogenetic groups, termed ␣, ␤, ␥, and ␦, with proteins in each group having a common evolutionary origin. The ␤-group includes the SLC32, SLC36, and SLC38 families and is the second largest phylogenetic cluster of amino acid transporters. Some members of the ␤-group are known to be expressed in the brain and most are located in the plasma membrane, whereas SLC32A1 is found in neuronal vesicles. Yet, others are still orphans and very little is known about their tissue distribution, functional characteristics, or substrate specificity (5, 7).The SLC38 family consists of 11 members. The orphans SLC38A7-11 were only recently identified and have thus far not been characterized regarding their substrate of transport (7), whereas the other members, SLC38A1-6, ...

Acute sleep loss increases food intake in adults. However, little is known about the influence of acute sleep loss on portion size choice, and whether this depends on both hunger state and the type of food (snack or meal item) offered to an individual. The aim of the current study was to compare portion size choice after a night of sleep and a period of nocturnal wakefulness (a condition experienced by night-shift workers, e.g. physicians and nurses). Sixteen men (age: 23 ± 0.9 years, BMI: 23.6 ± 0.6 kg/m(2)) participated in a randomized within-subject design with two conditions, 8-h of sleep and total sleep deprivation (TSD). In the morning following sleep interventions, portion size, comprising meal and snack items, was measured using a computer-based task, in both fasted and sated state. In addition, hunger as well as plasma levels of ghrelin were measured. In the morning after TSD, subjects had increased plasma ghrelin levels (13%, p=0.04), and chose larger portions (14%, p=0.02), irrespective of the type of food, as compared to the sleep condition. Self-reported hunger was also enhanced (p<0.01). Following breakfast, sleep-deprived subjects chose larger portions of snacks (16%, p=0.02), whereas the selection of meal items did not differ between the sleep interventions (6%, p=0.13). Our results suggest that overeating in the morning after sleep loss is driven by both homeostatic and hedonic factors. Further, they show that portion size choice after sleep loss depend on both an individual's hunger status, and the type of food offered.

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Objective: To investigate if acute sleep deprivation affects food purchasing choices in a mock supermarket. Design and Methods: On the morning after one night of total sleep deprivation (TSD) or after one night of sleep, 14 normal-weight men were given a fixed budget (300 SEK-approximately 50 USD). They were instructed to purchase as much as they could out of a possible 40 items, including 20 high-caloric foods (>2 kcal/g) and 20 low-caloric foods (<2 kcal/g). The prices of the high-caloric foods were then varied (75%, 100% (reference price), and 125%) to determine if TSD affects the flexibility of food purchasing. Before the task, participants received a standardized breakfast, thereby minimizing the potential confound produced by hunger. In addition, morning plasma concentrations of the orexigenic hormone ghrelin were measured under fasting conditions. Results: Independent of both type of food offered and price condition, sleep-deprived men purchased significantly more calories (19%) and grams (118%) of food than they did after one night of sleep (both P < 0.05). Morning plasma ghrelin concentrations were also higher after TSD (P < 0.05). However, this increase did not correlate with the effects of TSD on food purchasing. Conclusions: This experiment demonstrates that acute sleep loss alters food purchasing behavior in men.Obesity (2013) 21, E555-E560.

Obesity is a serious and growing health concern worldwide. Watching television (TV) represents a condition during which many habitually eat, irrespective of hunger level. However, as of yet, little is known about how the content of television programs being watched differentially impacts concurrent eating behavior. In this study, eighteen normal-weight female students participated in three counter-balanced experimental conditions, including a ‘Boring’ TV condition (art lecture), an ‘Engaging’ TV condition (Swedish TV comedy series), and a no TV control condition during which participants read (a text on insects living in Sweden). Throughout each condition participants had access to both high-calorie (M&Ms) and low-calorie (grapes) snacks. We found that, relative to the Engaging TV condition, Boring TV encouraged excessive eating (+52% g, P = 0.009). Additionally, the Engaging TV condition actually resulted in significantly less concurrent intake relative to the control ‘Text’ condition (−35% g, P = 0.05). This intake was driven almost entirely by the healthy snack, grapes; however, this interaction did not reach significance (P = 0.07). Finally, there was a significant correlation between how bored participants were across all conditions, and their concurrent food intake (beta = 0.317, P = 0.02). Intake as measured by kcals was similarly patterned but did not reach significance. These results suggest that, for women, different TV programs elicit different levels of concurrent food intake, and that the degree to which a program is engaging (or alternately, boring) is related to that intake. Additionally, they suggest that emotional content (e.g. boring vs. engaging) may be more associated than modality (e.g. TV vs. text) with concurrent intake.