Health Literacy among Japanese College Students: Association with Healthy Lifestyle and Subjective Health Status.

The improvement of health literacy (HL) is a critical issue for college students who are in the transitional period to adulthood and are establishing their subsequent lifestyles. The present study aimed to evaluate the current state of HL among college students and to explore the factors that influence HL. Moreover, it investigated the relationship between HL and health conditions. For this study, the researchers conducted an online survey of college students. The questionnaire consisted of the Japanese version of the 47-item European Health Literacy Survey Questionnaire (HLS-EU-Q47), which is a self-assessment tool for HL that covers the major health issues of college students and health-related quality of life. The study analyzed 1049 valid responses. Based on the HLS-EU-Q47 total score, 85% of the participants exhibited problematic or unsatisfactory HL levels. Participants who reported high levels of healthy lifestyles obtained high HL scores. High levels of HL were associated with high levels of subjective health. Results from quantitative text analysis suggested that specific mindsets were correlated with high levels of competency in appraising health information among male students. In the future, educational intervention programs for college students need to be established to improve HL levels.

Eating Perception, Nutrition Knowledge and Body Image among Para-Athletes: Practical Challenges in Nutritional Support.

Limited information exists on dietary practices in para-athletes. The aim of this study was to clarify the actual situation of para-athletes' dietary practice and to sort out the factors (i.e., eating perception, nutrition knowledge, and body image), that may hinder their dietary practices, and explored the practical challenges in nutritional support and improving nutrition knowledge for para-athletes. Thirty-two Japanese para-athletes (22 men) and 45 collegiate student athletes without disabilities (27 men) participated in the online survey. The questionnaire included demographic characteristics, eating perception, dietary practices, and nutrition knowledge. The Japanese version of the body appreciation scale was used to determine their body image. Para-athletes who answered that they knew their ideal amount and way of eating showed significantly higher body image scores (r = 0.604, p < 0.001). However, mean score for nutrition knowledge of para-athletes were significantly lower than collegiate student athletes (19.4 ± 6.8 vs. 24.2 ± 6.1 points, p = 0.001). Both groups did not identify a dietitian as the source of nutrition information or receiving their nutrition advice. The results indicate para-athletes have unique eating perceptions and inadequate nutrition knowledge. Future interventions are needed to examine nutritional supports and education in relation to the role of dietitians.

Efficient Attenuation of Dextran Sulfate Sodium-Induced Colitis by Oral Administration of 5,6-Dihydroxy-8Z,11Z,14Z,17Z-eicosatetraenoic Acid in Mice.

5,6-dihydroxy-8Z,11Z,14Z,17Z-eicosatetraenoic acid (5,6-DiHETE) is an eicosapentaenoic acid-derived newly discovered bioactive anti-inflammatory lipid mediator having diverse functions. Here, we assessed the potential of orally administered 5,6-DiHETE in promoting healing of dextran sulfate sodium (DSS)-induced colitis in mice. We measured the plasma concentrations of 5,6-DiHETE in untreated mice before and 0.5, 1, 3, and 6 h after its oral administration (150 or 600 µg/kg) in mice. Mice developed colitis by DSS (2% in drinking water for 4 days), and 5,6-DiHETE (150 or 600 µg/kg/day) was orally administered from day 9 to 14. Next, the faecal hardness and bleeding were assessed, and the dissected colons on day 14 via H&E staining. The plasma concentration of 5,6-DiHETE reached 25.05 or 44.79 ng/mL 0.5 h after the administration of 150 or 600 µg/kg, respectively, followed by a gradual decrease. The half-life of 5,6-DiHETE was estimated to be 1.25-1.63 h. Diarrhoea deteriorated after day 3 and peaked on day 5, followed by a gradual recovery. Histological assessment on day 14 showed DSS-mediated granulocyte infiltration, mucosal erosion, submucosal edema, and cryptal abscesses in mice. Oral administration of 150 or 600 µg/kg/day of 5,6-DiHETE accelerated the recovery from the DSS-induced diarrhoea and significantly ameliorated colon inflammation. The therapeutic effect of 600 µg/kg/day 5,6-DiHETE was slightly stronger than that by 150 µg/kg/day. Our study reveals attenuation of DSS-induced colitis in mice by the oral administration of 5,6-DiHETE dose-dependently, thereby suggesting a therapeutic potential of 5,6-DiHETE for inflammatory bowel disease.

Increase in diastolic blood pressure induced by fragrance inhalation of grapefruit essential oil is positively correlated with muscle sympathetic nerve activity.

Fragrance inhalation of essential oils is widely used in aromatherapy, and it is known to affect blood pressure (BP) and heart rate (HR) via autonomic control of circulation. In this study, we aimed to test the hypothesis that the changes in hemodynamics with fragrance inhalation were observed along with changes in muscle sympathetic nerve activity (MSNA). In study 1, thirteen healthy men were exposed to fragrance stimulation of grapefruit essential oil for 10 min, and BP, HR, and MSNA were continuously measured. In study 2, another nine healthy men were exposed to the same fragrance stimulation; responses in BP and HR were continuously measured, and plasma noradrenaline and cortisol concentrations were determined. We found that diastolic BP increased significantly during fragrance inhalation, while the other variables remained unchanged in both studies. Although MSNA burst frequency, burst incidence, and total activity remained unchanged during fragrance inhalation, we found a significant linear correlation between changes in diastolic BP in the last 5 min of fragrance inhalation and changes in MSNA burst frequency. The plasma cortisol concentration decreased significantly at 10 min of fragrance inhalation, though the noradrenaline concentration remained unchanged. These results suggest, for the first time, that changes in BP with fragrance inhalation of essential oil are associated with changes in MSNA even with decreased stress hormone.

Aerobic Exercise Training with Brisk Walking Increases Intestinal Bacteroides in Healthy Elderly Women.

This study examined the effect of an exercise intervention on the composition of the intestinal microbiota in healthy elderly women. Thirty-two sedentary women that were aged 65 years and older participated in a 12-week, non-randomized comparative trial. The subjects were allocated to two groups receiving different exercise interventions, trunk muscle training (TM), or aerobic exercise training (AE). AE included brisk walking, i.e., at an intensity of ≥ 3 metabolic equivalents (METs). The composition of the intestinal microbiota in fecal samples was determined before and after the training period. We also assessed the daily physical activity using an accelerometer, trunk muscle strength by the modified Kraus-Weber (K-W) test, and cardiorespiratory fitness by a 6-min. walk test (6MWT). K-W test scores and distance achieved during the 6MWT (6MWD) improved in both groups. The relative abundance of intestinal Bacteroides only significantly increased in the AE group, particularly in subjects showing increases in the time spent in brisk walking. Overall, the increases in intestinal Bacteroides following the exercise intervention were associated with increases in 6MWD. In conclusion, aerobic exercise training that targets an increase of the time spent in brisk walking may increase intestinal Bacteroides in association with improved cardiorespiratory fitness in healthy elderly women.

The effects of aging on the distribution of cerebral blood flow with postural changes and mild hyperthermia.

PURPOSE: Cerebral blood flow (CBF) would be impaired with dual stresses of heat and orthostatic changes, even if those stresses are mild, in the elderly with declined cardio- and cerebrovascular functions with aging. To test the hypothesis, we compared the response of blood flow in the internal carotid artery (ICA) and vertebral artery (VA) to dual stresses of heat and orthostatic changes between the elderly and young individuals. METHODS: Nine elderly and eight young healthy men (71.3 ± 3.0 and 23.3 ± 3.1 years, mean ± SD, respectively) underwent measurements of blood flow in the ICA, VA and external carotid artery (ECA) via ultrasonography. The measurements were obtained in sitting and supine positions under normothermic (NT) and mildly hyperthermic (HT) conditions (ambient temperature 28 °C). Esophageal temperatures increased from NT (36.4 ± 0.2 °C, mean ± SE) to HT (37.4 ± 0.2 °C) with lower legs immersion in 42 °C water. RESULTS: With heat stress, ECA blood flow increased in both postures in both age groups (effect of heat, p < 0.001), whereas ICA blood flow remained unchanged. With postural changes from supine to sitting, ECA blood flow remained unchanged whereas ICA blood flow decreased (effect of posture, p = 0.027) by 18% in NT in the young and by 20% in HT in the elderly. VA blood flow remained unchanged under both heat stress and postural changes. CONCLUSIONS: The CBF is impaired under dual stresses of heat and orthostatic changes in healthy aged individuals, even if the levels of the stresses are mild.

Hematopoietic prostaglandin D synthase-derived prostaglandin D2 ameliorates adjuvant-induced joint inflammation in mice.

Although prostaglandins (PGs) are known to be involved in the progression of arthritis, the role of PGD2 remains unclear. In this study, we evaluated the role of PGD2 in joint inflammation using genetically modified mice. Injection of complete Freund's adjuvant (CFA) increased the production of PGD2 and induced paw swelling and cartilage erosion in wild-type (WT) mice. These phenomena were accompanied with an increase in the mRNA levels of TNF-α, IL-6, IL-1ß, and matrix-degrading metalloproteinase-9. Knockdown of hematopoietic PGD synthase (H-PGDS) abolished the PGD2 production and exacerbated all of the arthritic manifestations in the inflamed paw. Immunostaining revealed that infiltrating macrophages strongly expressed H-PGDS in the CFA-injected paw. Morphologic studies revealed vascular hyperpermeability and angiogenesis in the inflamed WT paw. H-PGDS deficiency was accelerated, whereas daily administration of a PGD2 receptor D prostanoid (DP) agonist attenuated the CFA-induced hyperpermeability and angiogenesis. We further confirmed that DP deficiency exacerbated, whereas the administration of the DP agonist improved, the CFA-induced arthritic manifestations. The findings demonstrate that H-PGDS-derived PGD2 ameliorates joint inflammation by attenuating vascular permeability and subsequent angiogenesis and indicates the therapeutic potential of a DP agonist for arthritis.-Tsubosaka, Y., Maehara, T., Imai, D., Nakamura, T., Kobayashi, K., Nagata, N., Fujii, W., Murata, T. Hematopoietic prostaglandin D synthase-derived prostaglandin D2 ameliorates adjuvant-induced joint inflammation in mice.

Inhibitory Effects of Intranasal Administration of Insulin on Fat Oxidation during Exercise Are Diminished in Young Overweight Individuals.

It remains unknown whether the high insulin (INS) levels in the brain affect fat oxidation during exercise. We examined the effects of the intranasal administration of INS, which increases the INS concentration in the cerebrospinal fluid when peripheral effects are lacking, on the maximum fat oxidation rate (maxFOR) and its intensity (FATmax) during exercise in 15 young normal-weight (N group) and eight young overweight (O group) individuals. On two separate days, either INS or placebo (PL) was randomly administered intranasally before a graded exercise test. Indirect calorimetry was used to assess maxFOR and FATmax during exercise. Blood INS and glucose levels did not change after INS administration. In the N group, maxFOR and FATmax were significantly smaller in the INS trial than in the PL trial. MaxFOR was significantly smaller in the O group than in the N group and was not influenced by INS administration. Exercise-induced elevation in blood epinephrine levels tended to be reduced by INS administration only in the N group. Intranasal INS administration reduces fat oxidation during exercise without any peripheral effects, possibly by suppressing sympathetic nerve activity. This inhibitory effect is diminished in overweight subjects, suggesting that cerebral insulin effects are attenuated in this population.

Effects of 2-Year Cognitive⁻Motor Dual-Task Training on Cognitive Function and Motor Ability in Healthy Elderly People: A Pilot Study.

We aimed to examine the effect of 2-year cognitive⁻motor dual-task (DT) training on cognitive functions and motor ability of healthy elderly people without marked cognitive impairment. From the 25 participants of our 12-week DT trial conducted in 2014, we recruited 8 subjects who voluntarily participated in a new DT training program once a week for 2 years (exercise (EX) group). Their cognitive functions were evaluated by the Modified Mini-Mental State (3MS) examination and the Trail Making Test, and results were compared with those of the 11 subjects who discontinued the training and did not perform any types of exercise for 2 years (non-exercise (NO) group). Subjects in the NO group showed deterioration in the 3MS examination results, especially in the cognitive domain of attention. Meanwhile, participation in DT training maintained the scores in almost all domains of cognitive function, as well as the total 3MS scores. However, both groups had impaired quadriceps muscle strength and motor ability after the 2-year observation period. These results suggest that participating in exercise program comprising DT training for 2 years may be beneficial for maintaining the broad domains of cognitive function in healthy elderly people, although further verification is needed.

Effects of skin surface cooling before exercise on lactate accumulation in cool environment.

PURPOSE: We assessed whether plasma lactate accumulation increased and the lactate threshold (LT) declined when the skin temperature was lowered by whole body skin surface cooling before exercise in cool, but not temperate, conditions, and whether the lowered LT was associated with sympathetic activation or lowered plasma volume (PV) by cold-induced diuresis. METHODS: Ten healthy subjects performed a graded maximal cycling exercise after pre-conditioning under three different conditions for 60 min. Ambient temperature (using an artificial climatic chamber) and water temperature in a water-perfusion suit controlled at 25 and 34 °C in temperate-neutral (Temp-Neut); 25 and 10 °C in temperate-cool (Temp-Cool); and at 10 and 10 °C in cool-cool (Cool-Cool) conditions, respectively. Esophageal (Tes) and skin temperatures were measured; plasma lactate ([Lac]p) and noradrenaline concentrations ([Norad]p), and relative change in PV (%ΔPV) were determined before and after pre-conditioning and during exercise, and LT was determined. RESULTS: After pre-conditioning, Tes was not different among trials, whereas the mean skin temperature was lower in Cool-Cool and Temp-Cool than in Temp-Neut (P < 0.001). During exercise, [Lac]p and [Norad]p were higher (P = 0.009 and P < 0.001, respectively) and LT was lower (P = 0.013) in Cool-Cool than in the other trials. The %ΔPV was not different among trials. LT was correlated with [Norad]p during exercise (R = 0.50, P = 0.005). CONCLUSIONS: Whole body skin surface cooling before exercise increases lactate accumulation and decreases LT with sympathetic activation when exercise is performed in a cool, but not in a temperate, environment.

Molecular detection of Mycoplasma haemomuris subspecies using dnaK-targeted real-time PCR with SYBR Green I and melting curve analysis.

Hemoplasmas cause severe infections in mammals, but these pathogens are difficult to detect and identify at the species and subspecies level because of the need for time-consuming sequence based methods. Here, we used real-time PCR with SYBR Green I targeting of the dnaK gene followed by standard melting curve analysis to achieve rapid detection and differentiation of the Mycoplasma haemomuris subspecies 'Candidatus Mycoplasma haemomuris subsp. musculi' and 'Candidatus M. haemomuris subsp. ratti'. The melting temperatures of the PCR products, 84.63 ± 0.14 °C for 'Candidatus M. haemomuris subsp. musculi', and 80.72 ± 0.16 °C for 'Candidatus M. haemomuris subsp. ratti', provided clear differentiation between them. Murine hemoplasma DNA samples, which were used as references, were confirmed for species by an analysis of 16S rRNA sequences. The protocol described herein provides a new rapid detection and identification method suitable for use with two recognized subspecies of M. haemomuris.

Thermal sensation during mild hyperthermia is modulated by acute postural change in humans.

Thermal sensation represents the primary stimulus for behavioral and autonomic thermoregulation. We assessed whether the sensation of skin and core temperatures for the driving force of behavioral thermoregulation was modified by postural change from the supine (Sup) to sitting (Sit) during mild hyperthermia. Seventeen healthy young men underwent measurements of noticeable increase and decrease (±0.1 °C/s) of skin temperature (thresholds of warm and cold sensation on the skin, 6.25 cm2 of area) at the forearm and chest and of the whole-body warm sensation in the Sup and Sit during normothermia (NT; esophageal temperature (Tes), ∼36.6 °C) and mild hyperthermia (HT; Tes, ∼37.2 °C; lower legs immersion in 42 °C of water). The threshold for cold sensation on the skin at chest was lower during HT than NT in the Sit (P < 0.05) but not in Sup, and at the forearm was lower during HT than NT in the Sup and further in Sit (both, P < 0.05), with interactive effects of temperature (NT vs. HT) × posture (Sup vs. Sit) (chest, P = 0.08; forearm, P < 0.05). The threshold for warm sensation on the skin at both sites remained unchanged with changes in body posture or temperature. The whole-body warm sensation was higher during HT than NT in both postures and higher in the Sit than Sup during both NT and HT (all, P < 0.05). Thus, thermal sensation during mild hyperthermia is modulated by postural change from supine to sitting to sense lesser cold on the skin and more whole-body warmth.

Forced respiration during the deeper water immersion causes the greater inspiratory muscle fatigue in healthy young men.

[Purpose] The purpose of the present study was to evaluate the effect of water immersion at different water depths on respiratory function and the effect of inspiratory load breathing (ILB) during water immersion at different water depths on respiratory muscle strength evaluated by maximum inspiratory and expiratory pressures (PImax and PEmax, respectively). [Subjects] Eight healthy men participated randomly in three trials. [Methods] All sessions were conducted with the participants in a sitting position immersed in a water bath. We evaluated respiratory function, PImax and PEmax during submersion at three different levels of water depth (umbilicus; 4th-rib; or clavicle, CL) and after subsequent 15-min ILB. [Results] Decreases in vital capacity and expiratory reserve volume from baseline by water immersion were significantly greater in the CL trial than those in the other trials. In the CL trial, PImax was immediately reduced after ILB compared to that at baseline, and the reduction was significantly greater than those in the other trials. PEmax was not affected by ILB in any of the trials. [Conclusion] Forced respiration during deeper water immersion caused greater inspiratory muscle fatigue in healthy young men.

Lower thermal sensation in normothermic and mildly hyperthermic older adults.

PURPOSE: It is important to know how thermal sensation is affected by normal aging under conditions that elevate core body temperature for the prevention of heat-related illness in older people. We assessed whether thermal sensation under conditions of normothermia (NT) and mild hyperthermia (HT) is lowered in older adults. METHODS: Seventeen younger (23 ±  3 years) and 12 older (71 ±  3 years) healthy men underwent measurements of the cold and warmth detection thresholds ( ± 0.1 °C/s) of their chest and forearm skin, and whole body warmth perception under NT (esophageal temperature, T es, ~36.5 °C) and HT (T es, ~37.3 °C; lower legs immersed in 42 °C water) conditions. RESULTS: Warmth detection threshold at the forearm was increased in older compared with younger participants under both NT (P = 0.006) and HT (P = 0.004) conditions. In contrast, cold detection threshold at the forearm was decreased in older compared with younger participants under NT (P = 0.001) but not HT (P = 0.16). Mild hyperthermia decreased cold detection threshold at forearm in younger participants (P = 0.001) only. There were no effects of age and condition on warmth and cold detection thresholds at chest. Whole body warmth perception increased during HT compared with NT in both groups (both, P < 0.001), and older participants had lower values than the younger group under NT (P = 0.001) and HT (P = 0.051). CONCLUSIONS: Skin warmth detection thresholds at forearm and whole body warmth perception under NT and HT and skin cold detection thresholds at forearm under NT deteriorated with aging.

Treadmill walking in water induces greater respiratory muscle fatigue than treadmill walking on land in healthy young men.

The purpose of the present study was to investigate the effect of walking in water on respiratory muscle fatigue compared with that of walking on land at the same exercise intensity. Ten healthy males participated in 40-min treadmill walking trials on land and in water at an intensity of 60% of peak oxygen consumption. Respiratory function and respiratory muscle strength were evaluated before and after walking trials. Inspiratory muscle strength and forced expiratory volume in 1 s were significantly decreased immediately after walking in water, and expiratory muscle strength was significantly decreased immediately and 5 min after walking in water compared with the baseline. The decreases of inspiratory and expiratory muscle strength were significantly greater compared with that after walking on land. In conclusion, greater inspiratory and expiratory muscle fatigue was induced by walking in water than by walking on land at the same exercise intensity in healthy young men.

A method for estimating the glomerular filtration rate in conscious monkeys.

To establish a method for estimating the glomerular filtration rate (GFR) in conscious monkeys, the radiographic contrast medium iodixanol and the standard agent inulin were coadministered as tracers to male cynomolgus monkeys (Macaca fascicularis) as a bolus injection; blood was collected after 60, 90 and 120 min. An equation based on a single-blood-sample method derived from Jacobsson's formula was prepared using the data from healthy and saline- and gentamicin-treated monkeys by a multisample strategy with iodixanol. The GFR using the equation with iodixanol was in agreement with that from the multisample method with inulin or iodixanol. When the GFR decreased to more than 60% of the basal reference level, serum creatinine concentrations tended to increase, whereas serum blood urea nitrogen concentrations fluctuated. The results suggest that the single-sample-blood method with iodixanol is a practical tool for estimating the monkey GFR in a toxicological research setting therefore minimizing animal sufferings.

The effect of cognitive-motor dual-task training on cognitive function and plasma amyloid ß peptide 42/40 ratio in healthy elderly persons: a randomized controlled trial.

BACKGROUND: Physical activity reduces the incidence and progression of cognitive impairment. Cognitive-motor dual-task training, which requires dividing attention between cognitive tasks and exercise, may improve various cognitive domains; therefore, we examined the effect of dual-task training on the executive functions and on plasma amyloid ß peptide (Aß) 42/40 ratio, a potent biomarker of Alzheimer's disease, in healthy elderly people. METHODS: Twenty-seven sedentary elderly people participated in a 12-week randomized, controlled trial. The subjects assigned to the dual-task training (DT) group underwent a specific cognitive-motor dual-task training, and then the clinical outcomes, including cognitive functions by the Modified Mini-Mental State (3MS) examination and the Trail-Making Test (TMT), and the plasma Aß 42/40 ratio following the intervention were compared with those of the control single-task training (ST) group by unpaired t-test. RESULTS: Among 27 participants, 25 completed the study. The total scores in the 3MS examination as well as the muscular strength of quadriceps were equally improved in both groups after the training. The specific cognitive domains, "registration & recall", "attention", "verbal fluency & understanding", and "visuospatial skills" were significantly improved only in the DT group. Higher scores in "attention", "verbal fluency & understanding", and "similarities" were found in the DT group than in the ST group at post-intervention. The absolute changes in the total (8.5 ± 1.6 vs 2.4 ± 0.9, p = 0.004, 95 % confidence interval (CI) 0.75-3.39) and in the scores of "attention" (1.9 ± 0.5 vs -0.2 ± 0.4, p = 0.004, 95 % CI 2.25-9.98) were greater in the DT group than in the ST group. We found no changes in the TMT results in either group. Plasma Aß 42/40 ratio decreased in both groups following the training (ST group: 0.63 ± 0.13 to 0.16 ± 0.03, p = 0.001; DT group: 0.60 ± 0.12 to 0.25 ± 0.06, p = 0.044), although the pre- and post-intervention values were not different between the groups for either measure. CONCLUSIONS: Cognitive-motor dual-task training was more beneficial than single-task training alone in improving broader domains of cognitive functions of elderly persons, and the improvement was not directly due to modulating Aß metabolism.

Inhibition of the functional interplay between endoplasmic reticulum (ER) oxidoreduclin-1α (Ero1α) and protein-disulfide isomerase (PDI) by the endocrine disruptor bisphenol A.

Bisphenol A (BPA) is an endocrine disruptor that may have adverse effects on human health. We recently isolated protein-disulfide isomerase (PDI) as a BPA-binding protein from rat brain homogenates and found that BPA markedly inhibited PDI activity. To elucidate mechanisms of this inhibition, detailed structural, biophysical, and functional analyses of PDI were performed in the presence of BPA. BPA binding to PDI induced significant rearrangement of the N-terminal thioredoxin domain of PDI, resulting in more compact overall structure. This conformational change led to closure of the substrate-binding pocket in b' domain, preventing PDI from binding to unfolded proteins. The b' domain also plays an essential role in the interplay between PDI and ER oxidoreduclin 1α (Ero1α), a flavoenzyme responsible for reoxidation of PDI. We show that BPA inhibited Ero1α-catalyzed PDI oxidation presumably by inhibiting the interaction between the b' domain of PDI and Ero1α; the phenol groups of BPA probably compete with a highly conserved tryptophan residue, located in the protruding ß-hairpin of Ero1α, for binding to PDI. Consistently, BPA slowed down the reoxidation of PDI and caused the reduction of PDI in HeLa cells, indicating that BPA has a great impact on the redox homeostasis of PDI within cells. However, BPA had no effect on the interaction between PDI and peroxiredoxin-4 (Prx4), another PDI family oxidase, suggesting that the interaction between Prx4 and PDI is different from that of Ero1α and PDI. These results indicate that BPA, a widely distributed and potentially harmful chemical, inhibits Ero1-PDI-mediated disulfide bond formation.

Thermoregulatory responses are attenuated after fructose but not glucose intake.

PURPOSE: We examined whether plasma hyperosmolality induced by oral monosaccharide intake attenuated thermoregulatory responses and whether the responses were different between fructose and glucose. METHODS: Ten healthy young subjects performed three trials in a sitting position in an artificial climate chamber (ambient temperature, 28°C; relative humidity, 40%). After resting for 10 min, the subjects drank 300 mL of water alone (control), or 300 mL of water supplemented with 75 g fructose or 75 g glucose. Twenty minutes later, they were heated passively by immersing the lower legs in water at 42°C for 60 min. Plasma osmolality (Posm), sodium ([Na+]p) and insulin concentrations ([Ins]p), and percent change in plasma volume (%ΔPV) were measured, and esophageal temperature (Tes) thresholds for cutaneous vasodilation (THCVC) and sweating (THSR) at the forearm were determined. RESULTS: Posm was significantly increased by fructose and glucose intake compared with water alone, although %ΔPV and [Na+]p were not significantly different among the three trials. [Ins]p was significantly higher after glucose intake than after fructose or water alone. THCVC and THSR were significantly higher after fructose intake than after glucose intake, which showed similar values to water intake. CONCLUSIONS: These results suggest that the Tes threshold for thermoregulation is elevated after fructose intake, indicating the attenuation of thermoregulatory responses, whereas it is not attenuated after glucose intake. These results provide a novel insight to better determine the carbohydrate component of oral rehydration fluids for preventing dehydration and/or heat disorders.

Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.

BACKGROUND: Central administration of γ-amino butyric acid (GABA) induces lower body temperature in animals in hot ambient air. However, it is still unknown whether oral GABA administration affects temperature regulation at rest in a hot environment in humans. Therefore, in the present study, we specifically hypothesized that systemic administration of GABA in humans would induce hypothermia in a hot environment and that this response would be observed in association with decreased heat production. METHODS: Eight male participants drank a 200-ml sports drink with 1 g of GABA (trial G) or without GABA (trial C), then rested for 30 minutes in a sitting position in a hot environment (ambient air temperature 33°C, relative humidity 50%). RESULTS: We found that changes in esophageal temperature from before drinking the sports drink were lower in trial G than in trial C (-0.046 ± 0.079°C vs 0.001 ± 0.063°C; P < 0.05), with lower heat production calculated by oxygen consumption (41 ± 5 W/m2 vs 47 ± 8 W/m2; P < 0.05). CONCLUSIONS: In this study, we have demonstrated that a single oral administration of GABA induced a larger decrease in body core temperature compared to a control condition during rest in a hot environment and that this response was concomitant with a decrease in total heat production.