Evaluation of the possible role of prostaglandin F(2 alpha) in laminitis induced in horses by nasogastric administration of black walnut heartwood extract.
Authors: Noschka, Moore, Peroni, Lewis, Lewis, Robertson
Journal: American journal of veterinary research
Summary
# Editorial Summary This 2010 study examined whether prostaglandin F(2α) (PGF(2α))—a potent inflammatory mediator—contributes to the vascular changes occurring during early laminitis development, using a well-established black walnut heartwood extract (BWHE) model that reliably triggers clinical disease in horses. Researchers administered BWHE or placebo to ten horses, measuring plasma PGF(2α) concentrations and isolating laminar blood vessels to test their contractile responses to increasing PGF(2α) concentrations, both before and after blocking specific prostanoid receptors with pharmacological antagonists. Plasma PGF(2α) levels rose significantly in BWHE-treated horses alongside a concurrent decrease in white blood cell count, and whilst PGF(2α) proved a potent constrictor of laminar veins in healthy controls, the magnitude of this venoconstriction was substantially reduced in laminitic horses—an unexpected finding suggesting altered vascular responsiveness during disease development. When researchers blocked the thromboxane-prostanoid receptor (SQ 29,548), control laminae exhibited a small dilatory response to PGF(2α), whereas BWHE-treated laminae showed no such response, indicating fundamental changes in receptor signalling pathways in early laminitis. The findings suggest PGF(2α) warrants serious consideration as a mediator of the microvascular dysfunction characteristic of laminitis's prodromal phase, with potential therapeutic implications: targeting prostanoid synthesis or receptor signalling might represent a preventative strategy during high-risk periods, though further investigation into which receptors are most promising and whether intervention proves efficacious in clinical contexts remains essential before practitioners could consider this approach.
Read the full abstract on PubMed
Practical Takeaways
- •PGF(2α) antagonism may represent a preventive strategy for acute laminitis in horses exposed to BWHE or other inflammatory triggers
- •Selective targeting of prostanoid receptors in laminar vasculature could preserve vascular function during the early inflammatory stages of laminitis
- •Monitor for laminitis risk when horses have access to black walnut wood or extract; consider prostaglandin modulation as adjunctive therapy
Key Findings
- •Plasma PGF(2α) concentrations increased in horses administered BWHE, concurrent with decreased WBC count
- •PGF(2α) acted as a potent selective contractile agonist for laminar veins in control horses but caused less venoconstriction in BWHE-treated horses
- •After SQ 29,548 preincubation, laminar veins from control horses showed small dilation to PGF(2α) while BWHE-treated horses showed no response
- •PGF(2α) did not act as a contractile agonist for laminar arteries in either control or BWHE-treated horses