RESUMEN
Postpartum uterine infections of dairy cows promote a local and systemic inflammation and interfere with reproductive efficiency. The aim of this study was to evaluate the effect of steroid hormones including progesterone (P4) and estradiol (E2) on the systemic inflammatory response of cows after being challenged with an intrauterine infusion of lipopolysaccharide (LPS). For this, a hemogram and serum dosage of haptoglobin (Hp) in eight primiparous Gir cows ovariectomized were performed on day (day 0) and after 24 h (day +1). Four cows (n = 4) were challenged (day 0) with 20 mL of 0.9% NaCl + 12.5 µg/kg LPS, and four cows (n = 4) were challenged (day 0) with 20 mL of 0.9% NaCl. For this, the study was divided in four experimental groups as: (1) Control group: without any hormonal treatment before day 0; (2) Group 24 h - E2: 1 mg of estradiol benzoate 24 h before (day -1); (3) Group 24 h - P4: 2.0 g of P4 device 24 h before (day -1); (4) Group 14 d - P4: 2.0 g of P4 device 14 days before (day -14). In the systemic response to LPS, there was an increase in Hp (control group; 24 h - P4 group; 14 d - P4 group), and on day +1 the Hp of 14 d - P4 group was higher when compared to the other groups. On day 0, the 14 d - P4 group had an increase in circulating leukocytes and lymphocytes cells than the control group (P < 0.01). On day +1 after LPS-challenge the 14 d - P4 group showed a decrease in circulating lymphocytes, eosinophils, and monocytes (P < 0.05). A neutrophilia with left shift in the two treatments with P4 (day +1), in addition to a thrombocytopenia and lower platelets compared to the 24 h - E2 group (P < 0.05) (day 0) were recorded. It was concluded that ovariectomized cows challenged with LPS, previously submitted to steroid hormones induce a systemic inflammatory response. Also, the systemic response is more intense after previous prolonged exposure to P4 and less intense after exposure to E2. This study provided important information relating the effect of ovarian steroids on the systemic inflammatory response of cows challenged with intrauterine LPS.
