IBYME   02675
INSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Circulating IGF-1 levels and mammary gland development in antiparasitic treated and untreated prepubertal Holstein heifers
Autor/es:
PERRI, AF; LICOFF, N; MEJIA, ME; FORMIA, N; ORNSTEIN, A; BECU-VILLALOBOS, D; ORTEGA, H.; DALLARD, B.; ISABEL MARIA LACAU
Lugar:
Buenos Aires
Reunión:
Conferencia; Conference of the World Association for the Advancement of Veterinary Parasitology; 2011
Institución organizadora:
World Association for the Advancement of Veterinary Parasitology
Resumen:
We have previously showed that gastrointestinal nematode parasites delayed puberty onset and decreased circulating IGF-1 levels in dairy cattle. As this growth factor is essential to mammary parenchyma development during prepuberty, we wish to investigate whether anthelmintic treatment in naturally infected grazing dairy heifer calves can increase IGF-1 levels and improve mammary development.  Forty female Holstein calves were randomly assigned, at birth, to an untreated control group (C) or to the treated group (T) which received monthly, from birth onward, the following drugs: ivermectin (0.63 mg/Kg), fenbendazol (7.5 mg/Kg) and/or levamisol (10 mg/Kg). All the heifers were raised together on infected pastures, and supplemented with milk, concentrate or corn according to age. At 20, 30, 40 and 70 weeks of age blood and fecal samples were taken for serum IGF-I determination by RIA and nematode egg counting (EPG) in feces. Mammary biopsies were taken to 6 heifers in each group, using a Tru-Core® Biopsy Needle (Medical Device Technologies, Inc.), for histological and immunohistochemical studies. EPG counts in feces decreased with age (P = 0.027) and were higher in C than T heifers (P = 0.020). IGF-1 levels increased with age (P = 0.003) and were higher in T than C heifers (P = 0.042). Mammary slices stained with Hematoxilin-Eosin and immunolabeled with PCNA and Estrogen receptor alpha antibodies (monoclonal anti PCNA clon PC10 - Santa Cruz Sc 56 and monoclonal anti Estrogen receptor Clon 1D5 Bio Genex, respectively) were analyzed with the Image Pro Plus 3.0 software.  Two way ANOVA for repeated sampling was performed to compare image parameters between groups. Mammary samples from T heifers had higher ratio of parenchyma/total area (P = 0.036), PCNA index (P = 0.037) and expression of estrogen-receptor alpha (P = 0.006), compared with C heifers; no effect of age was evidenced for any of those parameters.  We conclude that lowering parasite burden to naturally infected prepubertal dairy heifers induces a higher mammary parenchymal development and cell proliferation, as well as a higher density of parenchymal estrogen receptors, in association with increased circulating IGF-1 levels.