Influence of dexamethasone on leukocytes of calves from the nuclear transfer technique

Abstract

Animal cloning has gained great importance in veterinary medicine, not only by adding a great technological involvement to the vet, but also by the positive financial impact on agribusiness. However, even if cloning techniques improved, many cattle clones don't resist the first month of life, especially in function of disturbs from physiology, biochemistry or immunological causes that can affect the neonate clone. The aim of this work was to evaluate qualitatively and quantitatively the leukocytes of calves from the nuclear transfer technique (TN) and the influence of dexamethasone, used as an inducer of childbirth, in these cells, in order to evaluate the role of these factors in the early hours of the clone. Blood collections were performed (3 to 5 ml) jugular vein puncture, 15 calves cloned in a company in the State of São Paulo in Brazil. There was no prior selection of animals as to gender or race. All the clones were born during the period established for the experiment were subject to collections, that occurred immediately after delivery (0 hours – (T0)), 24 (T1) and 48 hours (T2) after delivery. Three other collections were made at intervals of 7 days (T3, T4 and T5). The making of the blood smear was performed by wedge or sliding technique, followed by staining the blades by the use of fast panótico, established by Romanowsky. The samples were evaluated by microscopic analysis of cellular elements. For the total count was used the technique of counting Chamber Neubauer manual, having solution of Turk as a diluent. The differential count was done with 100 cells in the body of the blade looped. Data were analyzed by PROC MIXED (SAS, version 9.2, 2010), for comparison of means was used the Tukey test, and were considered statistical differences when < P 0.05. Of animals evaluated, 2 died before completing 24 hours, while other 2, after completing 48 hours. Of the 15 clones evaluated, dexamethasone was used as a labor inducer in 10 of them, of which 9 were born by Cesarean and 1 of natural childbirth. The remaining 5 clones induced with dexamethasone, 3 were born by Cesarean and 2 of natural childbirth. At the time of birth (collects 12:00 am) not induced group presented higher values of myeloid precursors (6.74 ± 1.03) that induced Group (1.60 ± 0.32) (P = 0.009), however, 12:00 am after birth, this difference was not apparent (not induced; 1.18 ± 2.74; induced 1.76 ± 0.41) (P = 0.838). Mieloides precursors are found in the peripheral circulation, in cases of inflammation or injury. The fact the Group has made fewer of those induced precursors, may be indicative of the action of dexamethasone as fetal maturation inducer, demonstrating the potential of this drug to contribute positively to the health of the clone in the first hours of life.