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Intraductal Injection of LPS as a Mouse Model of Mastitis: Signaling Visualized via an NF-κB Reporter Transgenic
Published on: September 4, 2012
Retinoid protects rats against neutrophil-induced oxidative stress in acute experimental mastitis
Beibei Gu1, Yumin Zhu, Wei Zhu
1College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China. beibei.gu@163.com
Abstract:
Activated polymorphonuclear neutrophilic leukocytes (PMN) are able to produce large quantities of bactericidal molecules such as reactive oxygen species (ROS) that are associated with tissue damage in models of inflammatory mastitis. In this study, the putative protective effect of retinoid was evaluated in a lipopolysaccharide (LPS) induced mastitis model in rats. Commencing at 10 d of gestation, retinoid (dissolved in olive oil) or an equal volume of olive oil were administered daily by gavage to pregnant rats until parturition. LPS or pyrogen-free physiological saline were infused into the mammary gland 72 h after parturition. At pre-infusion (defined as 0 h) and at 2, 4, 8, 16 and 24 h post-infusion, six rats from each group were euthanized. Retinoid administration decreased PMN accumulation in mammary alveoli, significantly decreased the level of TNF-alpha in mammary tissues and IL-8 in serum at the different time points. ROS release was significantly increased after LPS infusion and was reduced by retinoid at 16 h PI. Retinoid reduced N-acetyl-beta-D-glucosaminidase (NAGase) activity in both serum and mammary tissue at 8 h PI. Intercellular adhesion molecule 1 (ICAM-1) mRNA expression reached its peak value earlier in retinoid treated rats than in the control group. Overall, the results suggest that activated PMN play an important role in the pathogenesis of acute mastitis and retinoid administration may be an effective tool for protecting mammary tissue against PMN-induced oxidative stress during LPS-induced acute mastitis.
Insights
Retinoid administration reduced inflammatory responses and tissue damage in a rat model of acute mastitis. This suggests retinoids can protect mammary tissue from polymorphonuclear leukocyte-induced oxidative stress.
Area of Science:
- Veterinary Medicine
- Immunology
- Pharmacology
Background:
- Activated polymorphonuclear leukocytes (PMN) produce reactive oxygen species (ROS), contributing to tissue damage in inflammatory mastitis.
- Lipopolysaccharide (LPS) is a common inducer of experimental mastitis models.
Purpose of the Study:
- To evaluate the protective effect of retinoid in a lipopolysaccharide (LPS)-induced mastitis model in rats.
- To investigate retinoid's impact on PMN accumulation, inflammatory markers, and oxidative stress.
Main Methods:
- Pregnant rats were treated with retinoid or olive oil from day 10 of gestation until parturition.
- LPS or saline was infused into the mammary gland 72 hours postpartum.
- PMN, TNF-alpha, IL-8, ROS, NAGase, and ICAM-1 expression were assessed at various time points post-infusion.
Main Results:
- Retinoid decreased PMN accumulation, TNF-alpha in mammary tissue, and IL-8 in serum.
- Retinoid reduced ROS release at 16 hours post-infusion and NAGase activity at 8 hours.
- Intercellular adhesion molecule 1 (ICAM-1) mRNA peaked earlier in retinoid-treated rats.
Conclusions:
- Activated PMN are crucial in acute mastitis pathogenesis.
- Retinoid administration may protect mammary tissue from PMN-induced oxidative stress in LPS-induced mastitis.
