Immunolocalization of IGF-I and PCNA in mammary tissue of cows treated with an immunomodulator at the end of lactation

DALLARD, B.; SALVETTI, N.; ORTEGA, H.; LORENTE, J.A.; CALVINHO, L.F.

La Plata. Buenos Aires

Congreso; IX Congreso Argentino de Ciencias Morfológicas; 2004

Facultad de Ciencias Veterinarias. Universidad Nacional de La Plata

The expression of insulin-like growth factor I (IGF-I) and cellular proliferation detected by presence of PCNA (proliferation cell nuclear antigen) was evaluated by immunohistochemistry (IHC) during the involution of bovine mammary glands treated with an immunomodulator. Six Holstein cows at the end of lactation were used. Animals were randomly assigned to each of three treatment groups. Two groups were infused intramammarily in all quarters with an immunomodulator containing 0.45 and 0.73 µmoles of lipopolysaccharide (LPS) of Escherichia coli, whereas two cows remained as uninfused controls. Milking was interrupted after infusion and animals were slaughtered 11 days post-inoculation. Tissue samples were taken from two zones in each quarter and were fixed in 10% neutral buffered formalin. IGF-I and PCNA were detected by IHC using the streptavidin-peroxidase method. Image analysis was performed using Image Pro-Plus 4.1.0.1®. At 11 days of involution, significant differences in the percentage (%) of immunostaining areas for IGF-I among control and treated groups with different dose of LPS were observed, with a larger % in controls. Index of cellular proliferation analysis was expressed as percentage of PCNA intensely positive cells. No differences in expression of PCNA among control and treated groups were detected. We conclude that the application of the intramammary immunomodulator at drying-off was associated with a decrease in the IGF-I expression (antiapoptotic factor) and did not interfere with mammary epithelial cell proliferation.