Repeated post-exercise administration with a mixture of leucine and glucose alters the plasma amino acid profile in Standardbred trotters

Abstract

BackgroundThe branched chain amino acid leucine is a potent stimulator of insulin secretion. Used in combination with glucose it can increase the insulin response and the post exercise re-synthesis of glycogen in man. Decreased plasma amino acid concentrations have been reported after intravenous or per oral administration of leucine in man as well as after a single per oral dose in horses. In man, a negative correlation between the insulin response and the concentrations of isoleucine, valine and methionine have been shown but results from horses are lacking. This study aims to determine the effect of repeated per oral administration with a mixture of glucose and leucine on the free amino acid profile and the insulin response in horses after glycogen-depleting exercise.MethodsIn a crossover design, after a glycogen depleting exercise, twelve Standardbred trotters received either repeated oral boluses of glucose, 1 g/kg body weight (BW) at 0, 2 and 4 h with addition of leucine 0.1 g/kg BW at 0 and 4 h (GLU+LEU), or repeated boluses of water at 0, 2 and 4 h (CON). Blood samples for analysis of glucose, insulin and amino acid concentrations were collected prior to exercise and over a 6 h post-exercise period. A mixed model approach was used for the statistical analyses.ResultsPlasma leucine, isoleucine, valine, tyrosine and phenylalanine concentrations increased after exercise. Post-exercise serum glucose and plasma insulin response were significantly higher in the GLU+LEU treatment compared to the CON treatment. Plasma leucine concentrations increased after supplementation. During the post-exercise period isoleucine, valine and methionine concentrations decreased in both treatments but were significantly lower in the GLU+LEU treatment. There was no correlation between the insulin response and the response in plasma leucine, isoleucine, valine and methionine.ConclusionsRepeated post-exercise administration with a mixture of leucine and glucose caused a marked insulin response and altered the plasma amino acid profile in horses in a similar manner as described in man. However, the decreases seen in plasma amino acids in horses seem to be related more to an effect of leucine and not to the insulin response as seen in man.

Detection and Serogrouping of Dichelobacter nodosus Infection by Use of Direct PCR from Lesion Swabs To Support Outbreak-Specific Vaccination for Virulent Footrot in Sheep

“…Although real-time PCR is generally regarded as being more sensitive than conventional PCR, these results demonstrate that high rates of detection, along with high specificity, can be achieved with a conventional PCR assay with an appropriate procedure for sample collection and DNA preparation. The difference between culture detection and direct PCR detection of the 16S rRNA gene reported here is less marked than the differences that have been reported before (23,25); however, the rates of detection by culture reported in those studies (27% and 43%, respectively) were much lower than the rates achieved in this study (76.8% to 78.0%). We opted to use a conventional 16S rRNA gene PCR assay (24) because the objective of this study was to develop a direct testing procedure to use with the conventional fimA PCR (17), and the products of the two reactions could be visualized conveniently on the same agarose gel.…”

“…Procedures for sample collection, sample transport, and DNA preparation were optimized first for a PCR assay targeting the 16S rRNA gene of D. nodosus. Previously reported primers (24) were used; however, the assay was modified and a customized touchdown thermal cycling program was developed to enhance its sensitivity and specificity; this was prompted by reports of poor sensitivity and of nonspecific PCR products in previous studies (23,25).…”

“…Primers and reaction conditions were as reported previously (24); however, a customized touchdown thermal cycling program was developed consisting of an initial denaturation step of 95°C for 3 min, followed by 2 cycles of 95°C for 30 s, 60°C for 30 s, and 72°C for 30 s; 2 cycles of 95°C for 30 s, 58°C for 30 s, and 72°C for 30 s; 10 cycles of 95°C for 30 s, 55°C for 30 s, and 72°C for 30 s; and 15 cycles of 95°C for 30 s, 58°C for 30 s, and 72°C for 30 s and a final extension step of 72°C for 4 min. This was prompted by previous reports of poor sensitivity and nonspecific PCR products associated with the use of these primers under the cycling conditions reported by La Fontaine et al (24) or under modified cycling conditions (23,25). Amplification was performed in a Bio-Rad T100 thermal cycler (Bio-Rad, Gladesville, Australia).…”

“…While direct (culture-independent) tests for D. nodosus infection had long been sought (21) and, more recently, have been reported using both conventional and real-time PCR platforms targeting the 16S rRNA, pnpA, rpoD, and aprV2 and aprB2 genes (22)(23)(24)(25)(26)(27)(28)(29), the diagnostic performances of these tests can vary (20,23,25,30), and there are no reports of direct PCR-based serogrouping methods validated against a reference test at the flock level. That these could be developed is suggested by reports of PCR amplification followed by cloning and sequencing (31,32) or of PCR-single-strand conformational polymorphism analysis (33) of class I-and class II-specific regions of the fimA gene.…”

Using energy budgets to combine ecology and toxicology in a mammalian sentinel species

“…Mink inhabit coastal areas, have restricted home-ranges, and as fish-eating mammals they typically occupy high trophic levels and bioaccumulate local pollutants16. For these reasons the mink has been recognized as an ideal sentinel species to address integrative issues of exposure and effect to environmental toxicants1718. Indeed, the mink has been used extensively as a classic model in mammalian toxicology for effects of many toxicants on various health endpoints, including reproduction and growth192021.…”