Plasma corticosterone (CORT) measures are a common procedure to detect stress responses in rodents. However, the procedure is invasive and can influence CORT levels, making it less than ideal for monitoring CORT circadian rhythms. In the current paper, we examined the applicability of a non-invasive fecal CORT metabolite measure to assess the circadian rhythm. We compared fecal CORT metabolite levels to circulating CORT levels, and analyzed change in the fecal circadian rhythm following an acute stressor (i.e. blood sampling by tail veil catheter). Fecal and blood samples were collected from male adolescent rats and analyzed for CORT metabolites and circulating CORT respectively. Fecal samples were collected hourly for 24 h before and after blood draw. On average, peak fecal CORT metabolite values occurred 7-9 h after the plasma CORT peak and time-matched fecal CORT values were well correlated with plasma CORT. As a result of the rapid blood draw, fecal production and CORT levels were altered the next day. These results indicate fecal CORT metabolite measures can be used to assess conditions that disrupt the circadian CORT rhythm, and provide a method to measure long-term changes in CORT production. This can benefit research that requires long-term glucocorticoid assessment (e.g. stress mechanisms underlying health)., P. K. Thanos ... [et al.]., and Obsahuje seznam literatury
Adenosine 5'-triphosphate (ATP), phosphocreatine (PCr), creatine (Cr), inorganic phosphate (Pi), lactate (LAC), pyruvate (PYR) and glycogen as glucose (GLG) were determined and free adenosine 5'-diphosphate (ADP) was calculated from ATP:creatine phosphokinase (CPK) reaction in the gracilis muscle of cold-acclimated rats in vivo, and in completely isolated muscles under medium perfusion and superfusion in vitro, using the freezeclamping method. The mean in vivo levels (wmol/g w.w.) were: ATP 4.8, PCr 12.0, Cr 7.8, Pi 1.6, LAC 1.6, PYR 0.09, GLG 22.9, ADP 0.62 x 10-3. Isolation of the muscle (about 11 min of anoxia followed by perfusion in the air with a high pC>2 medium) decreased macroergic phosphate levels (ATP 3.0 , PCr 8.3). In isolated muscles perfused with a high pC>2 medium (99 kPa O2, perfusion rate 70 /rl/min) and simultaneously superfused with a low p02 medium (6.2 kPa O2, 2.3 ml/min) at 28 °C in vitro the levels of metabolites were (wmol/g w.w.): ATP 3.1, PCr 8.5, Cr 5.6, Pi 0.9, LAC 2.1, PYR 0.19, GLG 6.6, ADP 0.44 x 10-3. The mean steady oxygen uptake of the isolated muscle was 97 nmol O2 x min-1 x g-1 w.w. Thus, the levels of macroergic phosphates and their derivatives are lower after isolation and perfusion of the muscle, but the creatine charge [PCr]/([PCr]-f[Cr]] remains stable (0.61 in vivo versus 0.60 in the isolated muscle). This indicates that the steady-state and high energy status of the isolated perfused-superfused gracilis muscle is maintained.
The microanatomy of several oribatid and one acaridid mite was studied to determine the role of free cells (haemocytes) in mites. Mites from the field as well as laboratory cultures were observed and analyzed histologically using Masson triple stain. The mites were offered various foods and kept in fluctuating moisture conditions. The presence of haemocytes was significantly correlated with the transport between internal organs of various substance. Three types of transport were recorded: (i) enzymes into the alimentary tract, including the incorporation of haemocytes into the gut walls. This process seemed to be correlated with the amount and type of food and frequently with the presence of internal extraintestinal bacteria associated with mesenchyma; (ii) metabolites, like guanine from mesenchyma into the alimentary tract followed by expulsion from the body via the gut. This process is correlated with food of high nitrogen content or dry conditions; (iii) resorption of nutrients from eggs during an induced quiescent state under unfavourable conditions by small haemocytes.