Expression of purinergic P2X receptor subtypes 1, 2, 3 and 7 in equine laminitis.

The research investigates the expression of certain purinergic P2X receptors in horses with chronic-active laminitis, revealing variations in the expression of these receptors and changes in vein thickness in comparison with non-laminitic horses.

Research Objective and Methodology

• The aim of the study was to examine the expression of purinergic P2X receptor subtypes 1, 2, 3, and 7 within various parts of the equine anatomy. This was done in an attempt to understand their role in chronic-active laminitis, a painful and difficult to treat condition in horses.
• The researchers studied these receptors in the hoof, palmar digital vessels and nerves, dorsal root ganglia, and spinal cord of horses with chronic-active laminitis and compared the results with those of the non-laminitic horses.
• A total of 5 laminitic and 5 control non-laminitic horses were included in the study.
• The researchers used a technique called immunohistochemical analysis, using antibodies against P2X receptor subtypes 1-3 and 7. This method allowed the researchers to observe the presence of these P2X receptors within various tissues.

Results and Observations

• In laminitic horses, the study found a reduction in the thickness of the tunica media layer of the palmar digital vein as a proportion of the whole vessel diameter. This implies changes in vascular properties that could be related to the disease mechanism in laminitis.
• P2X receptor subtype 3 was expressed in the smooth muscle layer (tunica media) of the palmar digital artery of horses with laminitis but was absent in non-laminitic horses. This might contribute to the pathophysiology of the disease.
• There was a strong expression of P2X receptor subtype 7 in proliferating, partially keratinised, epidermal cells of the secondary epidermal lamellae in the hooves of horses with laminitis but none in the horses without laminitis. This indicates that the changes in expression and localization of purinergic receptors might be a potential factor associated with the condition.

Significance of the study

• The research suggests that chronic inflammation and pain experienced by horses with chronic-active laminitis might be due to changes in the purinergic P2X receptors and alterations in vascular properties.
• Further investigation of these receptors could provide insight into the mechanisms of laminitis and might potentially lead to the development of more effective treatments for this debilitating condition in horses.