Central GABAA receptor mediates taurine-induced hypothermia and possibly reduces food intake in thermo-neutral chicks and regulates plasma metabolites in heat-exposed chicks.

The aim of this study was to examine the central action of taurine on body temperature and food intake in neonatal chicks under control thermoneutral temperature (CT) and high ambient temperature (HT). Intracerebroventricular injection of taurine caused dose-dependent hypothermia and reduced food intake under CT. The mRNA expression of the GABAA receptors, GABAAR-α1 and GABAAR-γ, but not that of GABABR, significantly decreased in the diencephalon after central injection of taurine. Subsequently, we found that picrotoxin, a GABAAR antagonist, attenuated taurine-induced hypothermia. Central taurine significantly decreased the brain concentrations of 3-methoxy-4-hydroxyphenylglycol, a major metabolite of norepinephrine; however, the concentrations of serotonin, dopamine, and the epinephrine metabolites, 3,4-hydroxyindoleacetic acid and homovanillic acid, were unchanged. Although hypothermia was not observed under HT after central injection of taurine, plasma glucose and uric acid levels were higher, and plasma sodium and calcium levels were lower, than those in chicks under CT. In conclusion, brain taurine may play a role in regulating body temperature and food intake in chicks through GABAAR. The changes in plasma metabolites under heat stress suggest that brain taurine may play an important role in maintaining homeostasis in chicks.

Artificial neural network modeling for Congo red adsorption on microwave-synthesized akaganeite nanoparticles: optimization, kinetics, mechanism, and thermodynamics.

This work aims to synthesize akaganeite nanoparticles (AKNPs) by using microwave and use them to adsorb Congo red dye (CR) from the aqueous solution. The AKNPs with an average particle size of about 50 nm in width and 100 nm in length could be fabricated in 20 min. The effects of pH, CR initial concentration, adsorption time, and adsorbent dosage on the adsorption process were investigated and the artificial neural network (ANN) was used to analyze the adsorption data. The various ANN structures were examined in training the data to find the optimal model. The structure with training function, TRAINLM; adaptation learning function, LARNGDM; transfer function, LOGSIG (in hidden layer) and PURELIN (in output layer); and 10 neutrons in hidden layer having the highest correlation (R2 = 0.996) and the lowest MSE (4.405) is the optimal ANN structure. The consistency between the experimental data and the data predicted by the ANN model showed that the behavior of the adsorption process of CR onto AKNPs under different conditions can be estimated by the ANN model. The adsorption kinetics was studied by fitting the data into pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The results showed that the adsorption kinetics obeyed the pseudo-second-order model and governed by several steps. The adsorption isotherms at the different temperatures were studied by fitting the data to Langmuir, Freundlich, and Temkin isotherm models. The R2 obtained from the Langmuir model was above 0.9 and the highest value in three of four temperatures, suggesting that the adsorption isotherms were the best fit to the Langmuir model and the maximum adsorption capacity was estimated to be more than 150 mg/g. Thermodynamic studies suggested that the adsorption of CR onto AKNPs was a spontaneous and endothermic process and physicochemical adsorption. The obtained results indicated the potential application of microwave-synthesize AKNPs for removing organic dyes from aqueous solutions.

Intracerebroventricular injection of L-arginine and D-arginine induces different effects under an acute stressful condition.

Central administration of L-arginine was reported to attenuate stress responses in neonatal chicks. The present study aimed to elucidate the differential effects of centrally administered L-arginine and its enantiomer, D-arginine, on the stress response in chicks and the associated mechanisms. Intracerebroventricular injection of L-arginine attenuated acute isolation stress by inducing sleep-like behavior, while central administration of D-arginine potentiated the stress response, reducing the time spent standing motionless with eyes open and increasing distress vocalizations compared to the control. The brain concentrations of amino acids and monoamines following L- and D-arginine administration during stress were also determined. L-Arginine significantly increased the mesencephalic L-glutamine concentration. D-Arginine administration did not affect the levels of L-arginine or other amino acids in the examined brain regions. 3,4-Dihydroxyphenylacetic acid (DOPAC) level and dopamine (DA) metabolic rate (DOPAC/DA) were significantly higher in the diencephalon in the D-arginine group compared to the L-arginine group, while the mesencephalic DA level was significantly lower in the D-arginine group compared to the control. In vitro experiment using the brain slice culture demonstrated that extracellular perfusion of D-arginine significantly elevated the mRNA expression level of monoamine oxidase B, the major enzyme involved in DA metabolism, in the locus coeruleus region of the brainstem. In conclusion, in neonatal chicks, central administration of D-arginine exerted a stimulant effect on the stress response, in contrast to the stress-attenuating effects of L-arginine, partly through an effect on brain dopaminergic metabolism and not through competition with the L-stereoisomer.

Hypothermia induced by central injection of sucralose potentially occurs via monoaminergic pathways in the hypothalamus of chicks.

Oral administration of sucralose has been reported to stimulate food intake through inducing hypothalamic neuropeptide Y (NPY) in mice and fruit flies. However, the underlying mechanisms of action of sucralose in hypothermia and NPY and monoamine regulation remain unknown. The aim of the present study was to investigate central effects of sucralose on body temperature, NPY, and monoamine regulation, as well as its peripheral effects, in chicks. In Experiment 1, 5-day-old chicks were centrally injected with 1 µmol of sucralose, other sweeteners (erythritol and glucose), or saline. In Experiment 2, chicks were centrally injected with 0.2, 0.4, and 1.6 µmol of sucralose or saline. In Experiment 3, chicks were centrally injected with 0.8 µmol of sucralose or saline, with a co-injection of 100 µg fusaric acid (FA), an inhibitor of dopamine-ß-hydroxylase, to examine the role dopamine in sucralose induced hypothermia. In Experiment 4, 7-16-day-old chicks were orally administered with 75, 150, and 300 mg/2 ml distilled water or sucralose, daily. We observed that the central injection of sucralose, but not other sweeteners, decreased body temperature (P < .05) in chicks; however, the oral injection did not influence body temperature, food intake, and body weight gain. Central sucralose administration decreased dopamine and serotonin and stimulated dopamine turnover rate in the hypothalamus significantly (P < .05). Notably, sucralose co-injection with FA impeded sucralose-induced hypothermia. Sucralose decreases body temperature potentially via central monoaminergic pathways in the hypothalamus.

Oral Administration of Watermelon Rind Extract to Induce Hypothermia in Chicks.

Oral administration of l-citrulline (l-Cit) caused hypothermia, but l-Cit is not recommended in poultry diets in Japan. Watermelon is a natural source of l-Cit. The objective of this study is to examine the effect of watermelon waste, i.e., watermelon rind (WR) on the body temperature and plasma free amino acids of chicks. In Experiment 1, 14-day-old chicks were subjected to acute oral administration of WR extract (WRE) (2 ml) under control thermoneutral temperature (CT). In Experiment 2, 15-day-old chicks were orally administered 1.6 ml of either WRE, lowdose l-Cit (7.5 mmol/10 ml), or high-dose l-Cit (15 mmol/10 ml) under CT. In both experiments, rectal temperature (RT) and plasma free amino acids were analyzed. In Experiment 3, after dual oral administration of (1.6 ml) WRE or l-Cit (15 mmol/10 ml), 15-day-old chicks were exposed to high ambient temperature (HT; 35±1°C, 2 h) to monitor changes in RT. Acute oral administration of WRE significantly reduced RT under CT. The degree of RT reduction by WRE was similar to that by high l-Cit. Moreover, RT was significantly low at HT owing to the oral administration of WRE. However, the reduced RT was difficult to explain by the content of Cit in WRE alone. In conclusion, WRE could be used as a dietary ingredient to reduce body temperature for imparting thermotolerance in chicks.

Dried Watermelon Rind Mash Diet Increases Plasma l-Citrulline Level in Chicks.

Heat stress is an increasing concern in poultry industry as it can cause a rise in the body temperature of chickens. Recently, we reported that l-citrulline (l-Cit) is a potential hypothermic agent that could improve thermotolerance in chicks. However, synthetic l-Cit has not yet been approved for inclusion in animal diets. l-Cit was first isolated from watermelon. Watermelon rind (WR), an agricultural waste product, contains more l-Cit than the flesh of the fruit. In the current study, the chemical composition and l-Cit content of WR dried powder (WRP) were determined. WRP was mixed with water at a ratio of 4:5 (wt/v) to make WRP mash, and then mixed with a commercial starter diet to prepare a 9% WRP mash diet. The WRP mash diet was fed to 3- to 15-day-old chicks and daily food intake, body weight, and changes in rectal temperature were measured. At the end of the experiment, blood was collected from the chicks to analyze plasma l-Cit and other free amino acids. The chemical analysis of WRP revealed a variety of components including 19.1% crude protein. l-Cit was the most abundant free amino acid in WRP (3.18 mg/g). Chronic supplementation of the WRP mash diet significantly increased compensatory food intake, plasma l-Cit, l-ornithine, and l-tyrosine in chicks. WRP mash diet did not affect the body temperature of the chicks. In conclusion, WRP mash diet supplementation increased plasma l-Cit concentration in chicks. The increase in plasma l-Cit concentrations suggest that WR could be used as a natural source of l-Cit in chicks to ameliorate the adverse effects of heat stress.

In ovoL-leucine administration stimulates lipid metabolisms in heat-exposed male, but not female, chicks to afford thermotolerance.

Thermal manipulation declined embryonic brain and liver concentrations of leucine (Leu). L-Leu in ovo injection afforded thermotolerance in male broiler chicks. This study aimed to examine the role of in ovo injection of L-Leu in metabolic functions, and differences between male and female broiler chicks in thermotolerance. L-Leu injection was performed in ovo on embryonic day (ED) 7 to reveal its role in metabolic activity in embryos and in post-hatch male and female broiler chicks under heat stress. To examine the metabolic activity of embryos, oxygen (O2) consumption, carbon dioxide (CO2) production, heat production and plasma metabolites were analyzed. Rectal temperature, food intake and plasma metabolites were also analyzed in heat-exposed (35 ± 1°C for 180min) male and female broiler chicks. It was found that O2 consumption, heat production, and plasma triacylglycerol (TG) and non-esterified fatty acid (NEFA) concentrations in ED 14 embryos were significantly increased by in ovo injection of L-Leu in comparison with the controls. Plasma glucose concentration was significantly increased in both male and female chicks under heat stress, but in ovo injection of L-Leu attenuated the increase in male chicks. In contrast, plasma TG, NEFA, and ketone body concentrations were significantly higher in male chicks injected in ovo with L-Leu, but not in similarly injected female chicks, compared with control chicks, all under heat stress. Rectal temperature and food intake were significantly lower in male, but not female, chicks under heat stress injected in ovo with L-Leu. In conclusion, in ovoL-Leu administration enhanced the prenatal metabolic rate and lipid metabolisms, which possibly appeared as sex-dependent fashion to facilitate thermotolerance in males. A reduction in heat production through lowered food intake in heat-exposed male, but not female chicks injected in ovo with L-Leu may help to afford thermotolerance in male broiler chicks under heat stress.

Central NPY-Y5 sub-receptor partially functions as a mediator of NPY-induced hypothermia and affords thermotolerance in heat-exposed fasted chicks.

Exposure of chicks to a high ambient temperature (HT) has previously been shown to increase neuropeptide Y (NPY) mRNA expression in the brain. Furthermore, it was found that NPY has anti-stress functions in heat-exposed fasted chicks. The aim of the study was to reveal the role of central administration of NPY on thermotolerance ability and the induction of heat-shock protein (HSP) and NPY sub-receptors (NPYSRs) in fasted chicks with the contribution of plasma metabolite changes. Six- or seven-day-old chicks were centrally injected with 0 or 375 pmol of NPY and exposed to either HT (35 ± 1°C) or control thermoneutral temperature (CT: 30 ± 1°C) for 60 min while fasted. NPY reduced body temperature under both CT and HT NPY enhanced the brain mRNA expression of HSP-70 and -90, as well as of NPYSRs-Y5, -Y6, and -Y7, but not -Y1, -Y2, and -Y4, under CT and HT A coinjection of an NPYSR-Y5 antagonist (CGP71683) and NPY (375 pmol) attenuated the NPY-induced hypothermia. Furthermore, central NPY decreased plasma glucose and triacylglycerol under CT and HT and kept plasma corticosterone and epinephrine lower under HT NPY increased plasma taurine and anserine concentrations. In conclusion, brain NPYSR-Y5 partially afforded protective thermotolerance in heat-exposed fasted chicks. The NPY-mediated reduction in plasma glucose and stress hormone levels and the increase in free amino acids in plasma further suggest that NPY might potentially play a role in minimizing heat stress in fasted chicks.