Changes in tryptophan and kynurenine concentrations in pig plasma after in vivo immune activation and controlled tissue trauma

Abstract

The main purpose of this thesis is to describe the changes in plasma concentrations of kynurenine and tryptophan in pig plasma after an LPS - injection and a surgical procedure. Pigs are frequently exposed to stressors, such as infections and tissue trauma in production settings. From other species we know that changes in amino acid metabolism is linked to changes in mood and behavior. However, the time-course of changes in amino-acid metabolism has rarely been described in pigs and doing so is an important step towards understanding how immunological stressors can change pig physiology, mood and behavior. The pigs were exposed to two different events that triggered a stress response and activated the immune system; 1) surgery to insert a permanent central venous catheter and 2) an injection of LPS. We measured the amount of kynurenine and tryptophan in their plasma. In addition, we had data on the CRP levels in the same plasma samples. The effect of surgery and LPS on these physiological variables were analyzed in JMP. As predicted, there was an increase in the amount of kynurenine and a decrease in the amount of tryptophan over time in relation to LPS. However, tissue trauma and LPS did not have the same effect on the kyn/trp ratio, which was not as predicted. Our results also showed that there was an association between CRP, tryptophan and kynurenine as predicted.