Effects of naloxone on calcium turnover in cows affected by milk fever.

Milk fever is a metabolic disorder of calcium homeostasis that affects about 2 to 6% of postpartum cows. Current therapy is based on the administration of calcium gluconate. On the basis of the clinical signs, and given that endorphins increase at parturition, we supposed that endogenous opioid peptides (EOP) could be responsible for this pathology. In this study, cows with milk fever were administered the opiate antagonist, Naloxone (Nx; experiment 1) or Nx with calcium salts (experiment 2). In experiment 1, Nx induced the recovery of affected cows. The effects of Nx therapy, expressed in terms of proportion of recovered cows, of cows recovering in less than 30 min and cows requiring repeated treatments, were not statistically different than those obtained by means of calcium administration (17/17, 100%; 10/17, 59% and 7/17, 41% vs. 33/35, 94%; 22/35, 63% and 11/35, 31%, respectively; NS). In experiment 2, a significantly higher ratio of cows recovered in less than 30 min in the group of animals treated with Nx in association with calcium salts, compared with the group of cows treated with the calcium traditional therapy (106/118, 90% for calcium-Nx treated cows vs. 34/62, 55% for calcium-treated cows). Moreover, in the group of cows treated with calcium-Nx, the number of cows requiring repeated treatments was significantly reduced and no unrecovered cows were observed. The results support the idea that high EOP levels interfere with inward movement of calcium through the cell membrane and with calcium activity. The association of calcium and Nx at low dosage is a safe method to treat milk fever in cows and reduces muscular complications

Oxytocin plus antibiotics: A synergism of potentiation to enhance bovine uterine contractility

This in vitro study investigates the modulatory effect of three antibiotics (amoxicillin, enrofloxacin, and rifaximin) on contractility of the bovine uterine tissue, in follicular and luteal phases. The evaluation of the effects of these antibiotics (104 M) was performed on oxytocin-induced contractility. The decision to test these antibiotics with the oxytocin (106 M) comes from the reported ability of these combinations of hinder the antibiotic resistance and the formation of bacterial biofilms. The procedures were carried out in isolated organ bath, and the contractile functionality of the strip throughout the experiment was evaluated after a dose of carbachol (105 M). The results demonstrate the different modulatory activity of these antibiotics, on the plateau of contraction induced by oxytocin, in both phases of the estrus cycle. The differing individual antibiotic effects of our testing made it possible to identify, only in some cases. Rifaximin in the follicular phase and enrofloxacin in both phases of the estrous cycle, induced a synergistic enhancement (potentiation) of uterine strip contraction induced by oxytocin. This result is thought important because these associations might enable, in vivo, a simultaneous increase of uterine cleaning and the antimicrobial action on bacteria in planktonic form and of those organized in biofilms

Concentrations of free radicals and beta-endorphins in repeat breeder cows

Repeat breeding (RB) is one of the major problems that affect the reproductive efficiency and economy of milk production in dairy animals. So far, the etiopathogenesis of this pathology has not been defined completely. Stress has been hypothesized to be a cause of impaired reproductive efficiency. Stress may cause an overproduction of beta-endorphins and free radicals; in particular, reactive oxygen species (ROS). The aim of this work is to determine the concentrations of these substances in RB cows and to evaluate the correlation with the serum level of progesterone. The study was performed on 60 dairy cows: 26 RB and 34 control cows. Blood samples were collected on day 12 and day 16, after artificial insemination (AI) in all subjects, in order to assess the concentrations of progesterone, free radicals and beta-endorphins. The stressors, free radicals and beta-endorphins, that we considered, were higher in repeat breeders (day 12, 93.32(±1.91) UCarr and 0.50(±0.03) ng/ml; day 16, 94.42(±1.91) UCarr and 0.61(±0.03) ng/ml), with a lower level of progesterone, which probably is responsible for failure to conceive. The stress factors (free radicals and beta-endorphins) may actually enhance each other and induce an inhibition of progesterone synthesis in repeat breeders

Follicular development in pregnant cows after the administration of equine Chorionic Gonadotropin (eCG): a new insight

The follicular development in the cow occurs in a wave-like pattern, and it takes place also during pregnancy. In the cow, Equine Chorionic Gonadotropin (eCG) is used for superovulation, but a decrease in total fertility has been reported, likely because of its immunogenic properties in species other than equine. In this regard, immune response has been implicated in follicular growth, ovulation, and placental development. So, aims of our study are to test the safety of eCG administered during pregnancy and characterize the ovarian activity, the quality of oocytes, the hormonal status, and interleukin levels in eCG-treated pregnant cows

Effects of Mefepronic Acid (2-Phenoxy-2-Methyl Propionic Acid) on Hepatic Metabolism and Reproductive Parameters in Postpartum Dairy Cows.

This study investigates the effects of mefepronic acid (MA), a PPAR-α agonist, on hepatic metabolic functions and reproduction of postpartum dairy cows. Sixty Friesian cows were divided into Group A (administered 5g of MA IM, within 24 hrs after calving, on the 3rd and 5th day postpartum) and Group B (control). All the cows were blood sampled within 24 hrs of calving (Day 0), on Day 3, 5, 10, 15, 30, and 40 postpartum. On plasma, metabolic and biochemical parameters were determined. Liver biopsies were performed on Day 0, 15 and 30 for the evaluation of hepatic lipid and glycogen content. Reproductive parameters were also evaluated. In Group A, blood HDL, glucose and cholesterol increased till the end of the study, in accordance with the histological results. PPAR-α immunopositive cells increased in liver slices of Group A, too. Reproductive parameters improved in Group A. This study highlights the beneficial effects of mefepronic acid on the hepatic metabolism and reproductive parameters of post-partum dairy cows

Influence of hCG on inducible nitric oxide synthase gene expression in ram testicular arteries

Background. Experimental evidence suggests a relationship between the vasodilatory effect of hCG and the NOS system in the testis. The influence of hCG administration on testicular vascular NOS gene expression has not been fully investigated. Objective: This study aimed to evaluate the presence of the nitric oxide syntheses gene in ram testicular arteries and the influence of hCG administration on its expression. Materials and methods: Both testicular arteries of sixteen rams were extracted before and after i.v. administration of 5000 IU of hCG or placebo. The expression of the iNOS gene was investigated by real time PCR. Data were analyzed by means of Wilcoxon and Mann-Whitney tests. A p value of < 0.05 was considered statistically significant. Results: PCR revealed the presence of iNOS mRNA in all basal samples but the expression of the iNOS gene was significantly reduced in all arteries obtained 24 h after the administration of either hCG or placebo. A significant reduction in the expression of iNOS gene was observed in the testicular arteries extracted after 24 h in both treated and placebo groups. On the other hand hCG stimulation did not significantly influence iNOS expression following its administration compared to a placebo. Conclusion: Ram testicular arteries express the iNOS gene but hCG stimulation did not significantly influence iNOS expression. A significant reduction in the expression of this gene was observed in the testicular arteries extracted after 24 h in both treated and placebo groups, suggesting that iNOS expression on the testicular artery could be influenced by the spermatic vessel ligation of the controlateral testis

Functional Expression of the Extracellular Calcium Sensing Receptor (CaSR) in Equine Umbilical Cord Matrix Size-Sieved Stem Cells

The present study investigates the effects of high external calcium concentration ([Ca(2+)](o)) and the calcimimetic NPS R-467, a known calcium-sensing receptor (CaSR) agonist, on growth/proliferation of two equine size-sieved umbilical cord matrix mesenchymal stem cell (eUCM-MSC) lines. The involvement of CaSR on observed cell response was analyzed at both the mRNA and protein level.A large (>8 µm in diameter) and a small (<8 µm) cell line were cultured in medium containing: 1) low [Ca(2+)](o) (0.37 mM); 2) high [Ca(2+)](o) (2.87 mM); 3) NPS R-467 (3 µM) in presence of high [Ca(2+)](o) and 4) the CaSR antagonist NPS 2390 (10 µM for 30 min.) followed by incubation in presence of NPS R-467 in medium with high [Ca(2+)](o). Growth/proliferation rates were compared between groups. In large cells, the addition of NPS R-467 significantly increased cell growth whereas increasing [Ca(2+)](o) was not effective in this cell line. In small cells, both higher [Ca(2+)](o) and NPS R-467 increased cell growth. In both cell lines, preincubation with the CaSR antagonist NPS 2390 significantly inhibited the agonistic effect of NPS R-467. In both cell lines, increased [Ca(2+)](o) and/or NPS R-467 reduced doubling time values.Treatment with NPS R-467 down-regulated CaSR mRNA expression in both cell lines. In large cells, NPS R-467 reduced CaSR labeling in the cytosol and increased it at cortical level.In conclusion, calcium and the calcimimetic NPS R-467 reduce CaSR mRNA expression and stimulate cell growth/proliferation in eUCM-MSC. Their use as components of media for eUCM-MSC culture could be beneficial to obtain enough cells for down-stream purposes