Microglia and astrocyte activation in the spinal cord of lame horses.

This research examines the spinal reactions of horses experiencing painful lameness, looking specifically at changes in microglial and astrocyte responses. Using various methods, the study identified differences in the presence and form of these cells within the lameness-affected areas compared to non-affected areas.

Methodology

• The researchers used a sample of five adult horses, which had either acute or chronic unilateral lameness and were already scheduled for euthanasia.
• To assess lameness, the team performed a visual evaluation as per clinical guidelines. The location of the lameness was also confirmed post-euthanasia through dissection and radiography.
• Once the horses were euthanized, spinal cord samples were collected for further study.
• The team utilized ionized calcium binding adaptor molecule 1 (Iba-1) for the detection and characterization of microglia in the dorsal horn section of the spinal cord. These are immune cells active in responses to injury or disease.
• Similarly, they deployed glial fibrillary acidic protein (GFAP) as a marker to identify astrocytes in the dorsal horn, which are star-shaped cells that provide support and nutrition, maintain ion balance, and repair damage to the central nervous system.

Findings

• Results showed that Iba-1 expression was more prevalent in the dorsal horn section of the spinal cord on the same side as the affected limb, compared to the side that was not affected.
• However, the GFAP marker did not show an increased activity of astrocytes on the dorsal horn side that corresponded with the distal limb lesion of affected horses.
• For horses with acute lameness, the microglia mostly had a spherical shape. However, horses with chronic lameness presented microglia with varied morphologies.
• Astrocytes, whether in cases of acute or chronic lameness, showed small bodies and large branches, with greater GFAP localization in the main branches.

Conclusions

• The researchers concluded that both Iba-1 and GFAP can be used as functional and morphological markers of spinal microglial cells and astrocytes in horses with lameness.
• They also noted similarities between the localization patterns found in horses and those previously recorded in rodents, where microglia and astrocytes tend to reside mainly within the first three laminae of the spinal cord.