Changes in free amino acid concentrations in the blood, brain and muscle of heat-exposed chicks

1. An experiment was conducted to analyse the changes in free amino acid concentrations in the blood, brain and muscle of chicks in response to 15 or 30 min exposure to high ambient temperature (HT). 2. Food intake and body weight were not affected, while rectal temperature was significantly increased by short-term HT exposure. 3. Several free amino acid concentrations increased in the blood, brain and muscle even with short-term HT, whereas levels of a few amino acids declined significantly. As well as the nonessential amino acids, essential amino acids also significantly increased with exposure to HT. 4. 3-Methylhistidine, a marker of proteolysis, significantly declined in the muscle of HT chicks, implying a reduction of protein breakdown under HT. 5. These results indicate that alteration of protein metabolism may occur in chicks even with short-term heat exposure

Orally Administered D-Aspartate Depresses Rectal Temperature and Alters Plasma Triacylglycerol and Glucose Concentrations in Broiler Chicks

L-Aspartate (L-Asp), D-aspartate (D-Asp) or their chemical conjugates plays important physiological roles in regulating food intake, plasma metabolites and thermoregulation in animals. However, there are very few studies available in layers and no reports have been found in broilers. Broilers are very important commercial birds for meat production, so effects of L- or D-Asp in broilers would provide new physiological insight of this strain. Therefore, the purpose of this study was to determine the effect of oral administration of L- or D-Asp on feed intake, rectal temperature and some plasma metabolites in broiler chicks. Broiler chicks (5 days old) were orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp. At 120 min after administration of L- or D-Asp, the blood was immediately collected through the jugular vein. The rectal temperature of chicks was measured at 30, 60 and 120min after administration using a digital thermometer with an accuracy of ±0.1℃, by inserting the thermistor probe in the rectum to a depth of 2cm. A repeated-measures two-way ANOVA was applied for the analysis of feed intake and rectal temperature. Plasma metabolites were statistically analyzed by one-way ANOVA and regression equations. The study showed that oral administration of both L- and D-Asp did not alter feed intake. However, D-Asp, but not L-Asp, dose-dependently decreased the rectal temperature in chicks. It was also found that DAsp increased plasma glucose and decreased triacylglycerol concentrations. The changes in plasma metabolites further indicate that D-Asp treatment modulates the energy metabolism in broiler chicks. In conclusion, D-Asp may be a beneficial nutrient not only for layers but also for broilers, since orally administered D-Asp lowered rectal temperature without reducing feed intake

Metabolism of amino acids differs in the brains of Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii)

Abstract Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii) belong to the same genus of phodopus. Roborovskii hamster shows high locomotor activity and low level of dopamine (DA) in the brain. Administration of L-tyrosine, a precursor of DA, decreases locomotor activity in Roborovskii hamsters. However, the amino acid metabolism in relation to the hyperactivity is not yet well known. In the present study, L- and D-amino acid concentrations in the brain, liver, and plasma in Djungarian and Roborovskii hamsters were investigated during day and night times to explain the possible difference in hyperactivity between them. Most of the examined amino acids were higher in the night time when hamsters are active compared to those in day time. L- and D-tyrosine concentrations were higher in the liver of Roborovskii hamsters than in Djungarian hamsters. Furthermore, brain concentration of D-tyrosine was higher in the Roborovskii than in Djungarian hamsters, but no significant difference was observed for L-tyrosine concentrations between the two species. These results suggest that the conversion of L-tyrosine to D-tyrosine in the brain of Roborovskii hamster may be higher than in Djungarian hamster, which may cause low DA concentration and hyperactivity in Roborovskii hamster. On the other hand, L- and D-serine, which are known as sedative factors, were lower in Roborovskii hamsters than Djungarian hamster. These results suggest that species-specific regulation in amino acid metabolism may contribute to hyperactivity in Roborovskii hamsters.</jats:p

Central injection of L- and D-aspartate attenuates isolation-induced stress behavior in chicks possibly through different mechanisms

Intracerebroventricular (i.c.v.) injection of L- and D-aspartate (L- and D-Asp) has been shown to have a sedative effect with and without a hypnotic effect, respectively, in neonatal chicks experiencing isolation stress. However, the mechanisms of the different stress-attenuating functions of L- and D-Asp have not yet been fully clarified. In the present study, we investigated the involvement of the N-methyl-Daspartate (NMDA) receptor in order to reveal the receptor-mediated function of L- and D-Asp. To reveal whether L-and D-Asp act through the NMDA receptor, (þ)–MK-801, which is an antagonist of NMDA receptors, was used in the current study. In experiment 1, the chicks were injected i.c.v. with either saline, (þ)–MK-801, L-Asp or L-Asp plus (þ)–MK-801. The sedative and hypnotic effects induced by L-Asp were blocked by co-administration with (þ)–MK-801. In experiment 2, the chicks were injected i.c.v. with either saline, (þ)–MK-801, D-Asp or D-Asp plus (þ)–MK-801. Importantly, the sedative effects induced by D-Asp were shifted to hypnotic effects by co-administration with (þ)–MK-801. Taken together, L-Asp could induce sedative and hypnotic effects for stress behaviors through the NMDA receptor, but the attenuation of stress behaviors by D-Asp might be via simultaneous involvement of other receptors besides the NMDA receptor in this process. These differences may explain the different functional mechanisms of L- and D-Asp in the central nervous system

Oral administration of D-aspartate, but not L-aspartate, depresses rectal temperature and alters plasma metabolites in chicks

Aims: L-Aspartate (L-Asp) and D-aspartate (D-Asp) are physiologically important amino acids in mammals and birds. However, the functions of these amino acids have not yet been fully understood. In this study, we therefore examined the effects of L-Asp and D-Asp in terms of regulating body temperature, plasma metabolites and catecholamines in chicks. Main methods: Chicks were first orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp to monitor the effects of these amino acids on rectal temperature during 120 min of the experimental period. Key findings: Oral administration of D-Asp, but not of L-Asp, linearly decreased the rectal temperature in chicks. Importantly, orally administered D-Asp led to a significant reduction in body temperature in chicks even under high ambient temperature (HT) conditions. However, centrally administered D-Asp did not significantly influence the body temperature in chicks. As for plasma metabolites and catecholamines, orally administered D-Asp led to decreased triacylglycerol and uric acid concentrations and increased glucose and chlorine concentrations but did not alter plasma catecholamines. Significance: These results suggest that oral administration of D-Asp may play a potent role in reducing body temperature under both normal and HT conditions. The alteration of plasma metabolites further indicates that D-Asp may contribute to the regulation of metabolic activity in chicks

Plasma Triacylglycerol and Glucose Concentrations in Broiler Chicks Orally Administered D-Aspartate Depresses Rectal Temperature and Alters Plasma Triacylglycerol and Glucose Concentrations in Broiler Chicks

Both L-aspartate (L-Asp) and D-aspartate (D-Asp) play important physiological roles in animals. However, there are very few studies available in birds and no reports have been found in broilers. Broilers are very important commercial birds for meat production, so effects of L- or D-Asp in broilers would provide new physiological insight of this strain. Therefore, the purpose of this study was to determine the effect of oral administration of L- or D-Asp on food intake, body temperature and some plasma metabolites in broiler For Peer Review chicks. Broiler chicks were orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp. We confirmed that oral administration of both For Peer Review L- and D-Asp did not alter food intake. However, D-Asp, but not L-Asp, For Peer Review dose-dependently decreased the rectal temperature in chicks. It was also found that For Peer Review D-Asp increased plasma glucose and decreased triacylglycerol concentrations. T changes in plasma metabolites further indicate that D-Asp treatment modulates energy metabolism in broiler chicks. In conclusion, D-Asp may be a beneficial n for broilers, since orally administered D-Asp lowered body temperature without reducing food intake