NK-1 receptor is involved in the decreased movement in a rat chronic acid reflux oesophagitis model

BACKGROUND: We previously reported that rats with reflux oesophagitis (RE) show a decrease in voluntary movement, which could be used as a measure of chronic visceral symptoms. However, what mediates these symptoms is still unknown, and pain-related neuropeptides or their receptors in oesophageal mucosa are possibly related to the symptom generation of oesophagitis. In the present study, we investigated the role of NK-1 receptor (NK-1R) as a mediator of oesophagitis symptoms.

METHODS: Chronic RE was surgically induced using rats. The degree or severity of oesophageal symptoms was evaluated by assessing voluntary movement, which was monitored using an infrared sensor system. The NK-1R antagonist, L-732,138, was administered and changes in voluntary movement were assessed. Ten days after surgery, the rats were killed to examine the oesophagus. NK-1R and tachykinin-1 mRNA were detected by real-time RT-PCR. NK-1R protein expression was examined by Western blotting.

KEY RESULTS: Voluntary movement of the oesophagitis model rats was significantly lower than that of the sham-operated rats on day 10. The size of oesophageal mucosal erosion did not correlate with the amount of voluntary movement. The amount of NK-1R protein and mRNA in the oesophageal tissue was significantly higher at both the erosion and non-erosion sites. The amount of tachykinin-1 mRNA in oesophageal tissue at the non-erosion sites was significantly higher in oesophagitis rats. The voluntary movement of oesophagitis rats was significantly increased by the administration of L-732,138.

CONCLUSIONS & INFERENCES: The NK-1R and related neuropeptides are possibly involved in the decrease in voluntary movement of RE.