Effects of time of day and the wingate test on appetite perceptions, food intake and plasma levels of adipokines

It has been demonstrated that several aspects of adipose-related physiology including adipokine release, exhibit daily oscillations. Physical exercise exerts a strong influence on adipokine release and a possible reverse disruption of peripheral circadian clocks. The aim of this study was to establish the effects of time of day and the Wingate test on appetite perception, food intake and plasma levels of adipokines. Twenty-four moderately active non-smoking males (mean ± S.D. age: 27.1 ± 3.1 years; height: 1.79 ± 0.1 m; weight: 76.1 ± 11.7 kg) were recruited for this study and divided in two groups; one fed with an ad libitum test meal and another one without an ad libitum test meal. Each subject participated in the following studies performed at 11:00 and 23:00 hours on separate days: 1) Exercise study (ES): a 30-second Wingate Anaerobic Test (WAnT), and 2) sedentary study (SS). Subjects rated their appetite perceptions (hunger and prospective food consumption) on a 100-milimeter visual analogue scale (VAS) at baseline, after exercise, after test meal and during the postprandial/control period. At those time points blood samples were obtained for the measurement of plasma leptin, visfatin and apelin concentrations. Appetite perception and energy intake results at test meal decreased in response to WAnT in comparison with sedentary subjects. Time of day had no statistically significant effect on energy intake but the appetite perception score after test meal at 24:00 hours was statistically higher than that after test meal at 12:00 hours. No significant differences in the tested plasma adipokine concentrations between the trials existed at baseline, however, all plasma adipokine levels at 24:00 hours were higher than those at 12:00 hours. Plasma apelin concentrations after WAnT were significantly higher than its pre-exercise value at 12:00 hours, unlike those at 24:00 hours. Sedentary experiments showed a modest, yet significant, rise in plasma apelin levels after the test meal at 12:00 hours but not after the one at 24:00 hours. There were no significant changes in plasma leptin concentrations after exercise or test meal but a significant decrease in plasma visfatin concentrations after exercise intervention both at the 12:00 hours test and the 24:00 hours test has been observed. Test meals caused a significant rise in visfatin concentrations in sedentary, but not exercise series, in the daytime and nighttime tests. We conclude that time of day is an important aspect to consider in the relationships between exercise, metabolism and appetite. Further studies are needed to explain the specific mechanisms underlying the effects of acute exercise on postprandial physiology at different times of the day.

Single nucleotide polymorphisms in the CXCR1 gene and its association with clinical mastitis incidence in Polish Holstein-Friesian cows

The aim of this study was to identify the association between single nucleotide polymorphisms (SNPs) in the bovine chemokine receptor (CXCR1) gene and the resistance or susceptibility of cows to mastitis. The analysis of the CXCR1 polymorphism was carried out using polymerase chain reaction restriction fragment length polymorphism analysis for six SNP mutations (c.+291C>T, c.+365T>C, c.+816C>A, c.+819G>A, +1093C>T, and +1373C>A), of which four were located within the coding region and two in the 3'UTR region of the CXCR1 gene. Genetic material from 146 Polish Holstein-Friesian cows was analyzed after dividing into two groups depending on the incidence of clinical mastitis. Identified polymorphisms were in linkage disequilibrium and formed two linkage groups. Three haplotypes (CCCATA, TTAGCC, CTCGCC), forming six haplotype combinations, were detected. The logistic regression showed a significant association between the CC genotype at c.+365T>C and susceptibility of cows to clinical mastitis (P = 0.047). The frequency of haplotype combination 1/1 (CCCATA/CCCATA) was not significantly higher in cows susceptible to mastitis (P = 0.062). Of the identified SNP mutations, only c.+365T>C is a nonsynonymous mutation that induces a change in the coded protein [GCC (Ala) to GTC (Val) at the 122nd amino acid]. This amino acid change can result in changes in receptor function, which may be a reason for the increased mastitis incidence observed in cows with polymorphism at this site.