Diurnal and Acute Stress-Induced Changes in Distribution of Peripheral Blood Leukocyte Subpopulations
ABSTRACT In this study, we examined hormonal regulation of the distribution profiles of leukocyte subpopulations in the peripheral blood of rats. Flow cytometric analysis revealed significant and selective changes in the numbers and the percentages of peripheral blood leukocyte subpopulations which were a function of diurnal variations in hormone secretion and hormonal changes induced by acute stress. Changes in numbers and percentages of leukocyte subpopulations, which varied with time of day, were similar to changes observed under stress conditions. At the beginning of the rat's active period, and after 1 h of restraint stress, there was a significant reduction in numbers of leukocytes and lymphocytes. This reduction was primarily accounted for by a decrease in numbers of B cells, natural killer cells, monocytes (diurnal study), and helper T cells (diurnal study). There was also a significant decrease in the percentage of lymphocytes which was mirrored by an increase in the percentage of neutrophils in the peripheral blood. Peripheral blood leukocyte numbers were inversely related to plasma corticosterone levels. These results suggest that the endocrine system plays a role in the regulation of immune cell turnover and/or redistribution between immune compartments under conditions of normal daily experiences, namely, the diurnal cycle, and mild acute stress. They also suggest that these effects are selective for certain subpopulations of leukocytes.
SourceAvailable from: Claus Bech[Show abstract] [Hide abstract]
ABSTRACT: In recent decades, data loggers and radio- and satellite transmitters have become an important technological part of research on free living animals. Loggers to track movements and behaviour are especially useful in seabird studies, as seabirds often travel considerable distances at sea where visual observations are challenging. The potential negative effects of these devices on mortality, behaviour and reproduction of birds have received some attention, but few studies have investigated the physiological effects of instrument attachment. In the present study, effects of global positioning system (GPS) loggers on black-legged kittiwakes Rissa tridactyla were investigated by obtaining behavioural and physiological parameters of stress (nest attendance, plasma levels of the avian stress hormone corticosterone [CORT], relative leucocyte counts, body mass and reproductive success) during 2 d of GPS-deployment. GPS-equipped kittiwakes had significantly elevated levels of CORT at recapture and also significantly extended the duration of feeding trips compared to controls. Kittiwakes with low body condition index (BCI) attended nests less than controls, and this pattern was more pronounced among GPS-equipped birds. The study underlines the need to take device effects into consideration when instrumenting seabirds. Potentially, effects may become more evident in birds with low body condition or in years where food is limited, and results from GPS-equipped birds should be viewed with this in mindMarine Ecology Progress Series 02/2015; 521:237-248. DOI:10.3354/meps11140 · 2.64 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Birds undergo pronounced physiological changes during the reproduction, which may be linked to their parental efforts. Examining these changes may supply information about the birds’ energy expenditure during the particular phases of breeding and help to understand birds’ decisions about their subsequent parental investments. In this study, we measured a number of variables, i.e. body mass (scaled mass index, SMI), baseline corticosterone (CORT) and prolactin (PRL) concentrations and leucocyte profile [basically heterophils-to-lymphocytes (H/L) ratio], during the prelaying, incubation and chick rearing periods in 191 little auks (Alle alle), small Arctic seabirds. We expected the changes in the physiological variables to reflect the energy demands, i.e. the highest levels during chick rearing, moderate ones during incubation and the lowest ones prior to egg laying. Unexpectedly, we found SMI to be the highest during the incubation period, whereas lower and similar to each other values were recorded during the prelaying and chick rearing periods. Also, CORT unexpectedly peaked in the prelaying period, declined during incubation and remained at the incubation level during the chick rearing period. In accordance with our expectations, the PRL concentration was five times higher during the incubation than the chick rearing period and H/L ratio followed the pattern of the CORT changes. Consequently, there is no straightforward interpretation of the observed patterns of changes. Evidently, there are factors other than parental efforts per se that account for the dynamics of physiological changes. We found no sex differences in any of the variables investigated, which indicates that male and female parental investments are very similar.Polar Biology 01/2015; DOI:10.1007/s00300-015-1687-y · 2.07 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: This study investigated effects of dietary Aloe vera on growth performance, some haemato-biochemical parameters and disease resistance against Streptococcus iniae in tilapia (GIFT). Five groups were designed including a basal diet (control) and 100% A. vera powder incorporated in fish feed at 0.5% 1%, 2%, and 4%/kg feed, which were administered for 8 weeks. Fish fed 0.5%, 1%, and 2% A. vera supplemented diet significantly improved (p<0.05) weight gain, absolute growth rate and specific growth rate. Feed intake significantly increased in fish fed with A. vera diet at 1% and 2%/kg feed. Feed efficiency ratio, feed conversion ratio, and hepatosomatic index were significantly enhanced in 4% A. vera supplemented fish over unsupplemented ones (p<0.05). Several haemato-biochemical indices were examined before and after fish were challenged with S. iniae pathogen containing 7.7x10(6) CFU cells mL(-1). A. vera supplemented fish showed a significant increase (p<0.05) in red blood cells, haematocrits (Hb), hemoglobin (Hb), white blood cells (WBC), neutrophils, monocytes, eosinophils, serum total protein, glucose and cortisol after challenge when compared to unsupplemented ones. Meanwhile, 4% A. vera supplemented fish showed a decrease (p<0.05) in RBC, Hb, Ht, WBC, and mean corpuscular hemoglobin (MCH) after challenge compared to unsupplemented ones and other supplemented ones. In addition, lower mean corpuscular volume values (MCV) (p<0.05) were observed in fish fed with A. vera diet at 2% and 4% A. vera/kg feed than those fed unsupplemented diet. Unchallenged fish fed 0.5%, 1%, and 2% A. vera showed significantly higher values (p<0.05) of mean corpuscular hemoglobin concentration (MCHC) than those fed unsupplemented diet and 4% A. vera supplemented diet. There was a significant increase (p<0.05) in the neutrophil to lymphocyte ratio (N/L) within experimental groups after challenge; N/L ratio in A. vera unsupplemented fish and those supplemented with A. vera diet at 1%/kg feed increased significantly (p<0.05) throughout challenge period; while those fed 4% A. vera supplemented diet maintained higher values at all experimental stages among groups. There was a significant correlation (p<0.05, r = 0.53) between N/L ratio and glucose concentration, 96 hours after challenge. Aloe had no significant effect (p>0.05) on the survival of the fish when compared to the control; no mortality was recorded in challenge trial. Overall, our results indicated that dietary aloe supplementation could improve growth, feed utilization, and haemato-biochemical parameters of cultured tilapia. Copyright © 2015. Published by Elsevier Ltd.Fish & Shellfish Immunology 03/2015; DOI:10.1016/j.fsi.2015.03.002 · 3.03 Impact Factor