Modulation of peripheral markers of the serotoninergic system in healthy horses.

The research article investigates the changes in levels of serotonin, a neurotransmitter, in the bloodstream and platelets of healthy horses, before and after they eat. Particular attention is paid to the increases in serotonin in both aspects after the horses have fed.

Research Methodology

• The researchers carried out their experiments using blood samples from 12 clinically healthy horses. These samples were obtained both before and after the horses had been fed.
• Once the samples were obtained, they were deproteinized, which involves removing proteins from a sample to allow for a more precise analysis of the other components.
• The researchers specifically measured serotonin in two aspects: platelet-rich plasma (PRP) and platelet-poor plasma (PPP). By subtracting the amount of free serotonin in PPP (f5-HT) from the serotonin in PRP, they were able to determine the amount of serotonin in platelets (p5-HT).

Results

• The findings revealed this level of serotonin significantly increased following the horses’ meals, both in the bloodstream and in platelets.
• The measurements of free serotonin to platelet serotonin ratio did not show any changes post feeding.

Implications

• The researchers speculated that the spike in total circulating serotonin could stimulate peristaltic activity — the process that moves food through the digestive system. This increase could also explain the elevation in free serotonin levels.
• An additional theory proposed by the team was that a higher uptake of serotonin by platelets could possibly indicate increased activity of serotonergic neurons, the nerve cells that release serotonin.
• The findings support the understanding that serotonin is released from enterochromaffin cells, which are found in the digestive system, when they are mechanically and chemically stimulated — potentially by the act of eating or the presence of food.
• Notably, the study also demonstrated the practicality of using high performance liquid chromatography (HPLC) to measure levels of free and platelet serotonin in equine plasma.