Systemic and local responses of cytokines and tissue histology following intramammary lipopolysaccharide challenge in dairy cows.

During bovine mastitis, immune responses include the release of cytokines and the recruitment of leukocytes, resulting in profound structural and functional changes in the mammary gland. Our aims were to delineate systemic and local cytokine responses and to quantify histological changes in the mammary tissue of lactating cows after acute intramammary lipopolysaccharide (LPS) challenge. Ten multiparous dairy cows were paired to either treatment (TRT) or control (CON) groups. For TRT cows, one side of the udder was randomly assigned to receive treatment with LPS (50 µg in 10 mL of saline, TL) into both the front and rear quarters; the contralateral quarters received saline (10 mL). Udder-halves of CON cows were similarly assigned randomly to receive either saline (10 mL, CS) or no infusion (untreated). Temporal changes in the concentrations of 15 cytokines in the blood (0, 3, 6, 12, and 24 h relative to the LPS infusion) and in mammary tissue (0, 3, and 12 h) were determined, as were concomitant changes in mammary histology. The cytokines IL-6, IL-10, MCP-1, and MIP-1ß showed a systemic response as their concentrations were significantly different in the plasma of TRT cows as compared with CON cows after LPS challenge. The cytokines IL-1α, IL-1ß, IL-6, IL-8, IL-17A, IL-36RA, IP-10, MCP-1, MIP-1α, MIP-1ß, TNF-α, and VEGF-A showed a local response in TL glands, and 8 cytokines, IL-1ß, IL-6, IL-10, IL-17A, IL-36RA, IP-10, MIP-1ß, and VEGF-A showed systemic changes in the nonchallenged mammary glands adjacent to LPS-infused glands. Endotoxin challenge evoked changes in the histology of mammary tissue that included a 5.2- and 7.2-fold increases in the number of neutrophils in alveolar lumens at 3 h and 12 h, respectively. In summary, LPS challenge induced specific local and systemic responses in cytokine induction and elicited neutrophil infiltration in bovine mammary tissue.

Serum gastrin concentrations in dogs with primary hyperparathyroidism.

BACKGROUND: Hypercalcemia has been associated with hypergastrinemia in humans. Hypergastrinemia could be responsible for gastrointestinal (GI) signs in dogs with primary hyperparathyroidism (PHPT). HYPOTHESIS/OBJECTIVES: (a) Determine whether hypergastrinemia occurs in dogs with PHPT, (b) assess for potential correlations among ionized calcium (iCa), parathyroid hormone (PTH), and serum gastrin concentrations, and (c) determine whether gastrin concentrations decrease after management of PHPT. ANIMALS: Phase 1: 151 client-owned dogs at the time of PHPT diagnosis, Phase 2: 24 dogs that underwent treatment for PHPT. METHODS: Dogs with azotemia, concurrent disease, or those receiving acid suppressants were excluded. Twenty-four treated dogs had baseline and repeat quantification of serum gastrin, PTH, and iCa concentrations 4 weeks after treatment. The effect of treatment on gastrin, iCa, and PTH concentrations was assessed using Wilcoxon signed rank sum tests. Fisher exact testing was used to compare the proportion of dogs with hypergastrinemia in dogs with and without GI signs. RESULTS: Twenty-seven of 151 PHPT dogs (17.9%) had increased pre-treatment serum gastrin concentrations (median, 45.0 ng/L; interquartile range [IQR], 20.0 ng/L). Gastrin concentrations were not correlated with iCa (P = .92) or PTH (P = .60). Treatment of PHPT decreased PTH (P < .001) and iCa concentrations (P < .001), but not gastrin concentrations (P = .15). The proportion of dogs with hypergastrinemia with and without GI signs did not differ (P = 1.00). CONCLUSIONS AND CLINICAL IMPORTANCE: Mild increases in serum gastrin concentrations may be seen in dogs with PHPT, but this finding is independent of the presence of GI signs.

Bacterial Endotoxin Induces Oxidative Stress and Reduces Milk Protein Expression and Hypoxia in the Mouse Mammary Gland.

The aim of this study was to investigate the mechanisms underlying the reduced milk production during mastitis. We hypothesized that bacterial endotoxin induces hypoxia, oxidative stress, and cell apoptosis while inhibiting milk gene expression in the mammary gland. To test this hypothesis, the left and right sides of the 4th pair of mouse mammary glands were alternatively injected with either lipopolysaccharide (LPS, E. coli 055: B5, 100 µL of 0.2 mg/mL) or sterile PBS through the teat meatus 3 days postpartum. At 10.5 and 22.5 h postinjection, pimonidazole HCl, a hypoxyprobe, was injected intraperitoneally. At 12 or 24 h after the LPS injection, the 4th glands were individually collected (n = 8) and analyzed. LPS treatment induced mammary inflammation at both 12 and 24 h but promoted cell apoptosis only at 12 h. Consistently, H2O2 content was increased at 12 h (P < 0.01), but dropped dramatically at 24 h (P < 0.01) in the LPS-treated gland. Nevertheless, the total antioxidative capacity in tissue tended to be decreased by LPS at both 12 and 24 h (P = 0.07 and 0.06, respectively). In agreement with these findings, LPS increased or tended to increase the mRNA expression of antioxidative genes Nqo1 at 12 h (P = 0.05) and SLC7A11 at 24 h (P = 0.08). In addition, LPS inhibited mammary expression of Csn2 and Lalba across time and protein expression of Csn1s1 at 24 h (P < 0.05). Furthermore, hypoxyprobe staining intensity was greater in the alveoli of the PBS-treated gland than the LPS-treated gland at both 12 and 24 h, demonstrating a rise in oxygen tension by LPS treatment. In summary, our observations indicated that while intramammary LPS challenge incurs inflammation, it induces oxidative stress, increases cell apoptosis and oxygen tension, and differentially inhibits the milk protein expression in the mammary gland.

Nicotine-induced behavioral sensitization in an adult rat model of attention deficit/hyperactivity disorder (ADHD).

Attention deficit hyperactivity disorder (ADHD) is associated with increased risk of tobacco dependence. Nicotine, the main psychoactive component of tobacco, appears to be implicated in ADHD-related tobacco dependence. However, the behavioral responsiveness to nicotine of the prevalent animal model of ADHD, the spontaneously hypertensive rat (SHR), is currently underinvestigated. The present study examined the activational effects of acute and chronic nicotine on the behavior of adult male SHRs, relative to Wistar Kyoto (WKY) controls. Experiment 1 verified baseline strain differences in open-field locomotor activity. Experiment 2 tested for baseline strain differences in rotational behavior using a Rotorat apparatus. Adult SHR and WKY rats were then exposed to a 7-day regimen of 0.6mg/kg/d s.c. nicotine, or saline, prior to each assessment. A separate group of SHRs underwent similar training, but was pre-treated with mecamylamine, a cholinergic antagonist. Nicotine sensitization, context conditioning, and mecamylamine effects were then tested. Baseline strain differences were observed in open-field performance and in the number of full rotations in the Rotorat apparatus, but not in the number of 90° rotations or direction changes. In these latter measures, SHRs displayed weaker nicotine-induced rotational suppression than WKYs. Both strains expressed nicotine-induced sensitization of rotational activity, but evidence for strain differences in sensitization was ambiguous; context conditioning was not observed. Mecamylamine reversed the effects of nicotine on SHR performance. These findings are consistent with the hypothesis that a reduced aversion to nicotine (expressed in rats as robust locomotion) may facilitate smoking among adults with ADHD.