Diurnal variations and effects of fasting on blood constituents in minipigs

Diurnal rhythms in peripheral blood immune cell numbers of domestic pigs

Diurnal rhythms within the immune system are considered important for immune competence. Until now, they were mostly studied in humans and rodents. However, as the domestic pig is regarded as suitable animal model and due to its importance in agriculture, this study aimed to characterize diurnal rhythmicity in porcine circulating leukocyte numbers. Eighteen pigs were studied over periods of up to 50 h. Cosinor analyses revealed diurnal rhythms in cell numbers of most investigated immune cell populations in blood. Whereas T cell, dendritic cell, and eosinophil counts peaked during nighttime, NK cell and neutrophil counts peaked during daytime. Relative amplitudes of cell numbers in blood differed in T helper cell subtypes with distinctive differentiation states. Mixed model analyses revealed that plasma cortisol concentration was negatively associated with cell numbers of most leukocyte types, except for NK cells and neutrophils. The observed rhythms mainly resemble those found in humans and rodents.

Effects of fasting on hematologic and clinical chemical values in cynomolgus monkeys (Macaca fascicularis)

BACKGROUND

Fasting is an important pre-analytical factor that may affect clinical pathology parameters in toxicological and pharmacological studies. Little information is available on how fasting affects clinical pathology parameters in cynomolgus monkeys (Macaca fascicularis).The aim of this study was to evaluate the influence of fasting on clinical pathology parameters in healthy adult cynomolgus monkeys.

METHODS

Five female and six male cynomolgus monkeys were fasted for 0, 8, 16, and 24 hours. Changes in body weight (BW), core hematologic, and serum clinical chemical parameters were evaluated.

RESULTS

The BW significantly decreased after 24 hours of fasting. Significant decreases in red blood cell count, hemoglobin, hematocrit, and mean corpuscular volume and increases in mean cell hemoglobin and mean cell hemoglobin concentration were observed at 16 hours in males. In females, increasing the duration of fasting caused a significant time-dependent increase in platelets. Blood urea nitrogen showed significant decreases in female and male monkeys after fasting. Alkaline phosphatase increased in females after fasting. Aspartate transaminase significantly increased both in females and males at 8 hours. In females, alanine transaminase and lactate dehydrogenase significantly increased at 8 hours. Albumin significantly decreased in males 24 hours, but increased in females 16 hours after fasting. Serum glucose and triglyceride were not affected by fasting. Serum calcium decreased and inorganic phosphorus increased in males after fasting.

CONCLUSION

These results suggested that clinical pathology data would vary after fasting. The decision to feed or fast before blood collection for clinical pathology tests should be made based on careful consideration.