AUTHOR=Zhang Yu , Zhao Jun , Hu Nan , Wang Jing , Chen Xi , Wang Kaiyuan , Yin Yiqing 

TITLE=Motilin and its receptor are expressed in the dorsal horn in a rat model of acute incisional pain: Intrathecal motilin injection alleviates pain behaviors

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1104862

DOI=10.3389/fnins.2023.1104862

ISSN=1662-453X

ABSTRACT=Aims: To observe the effects of intrathecal administration of motilin on pain behavior and expression of motilin/motilin receptor (MTLR) in the spinal cord of a rat model of acute incisional pain. 
Methods: An incisional pain model was established in rats using a unilateral plantar incision. The rats were also injected intrathecally with 1, 5, or 25 µg of motilin. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were determined. Motilin/MTLR expression in the spinal cord was detected by western blotting and immunofluorescence. The expression of motilin in the spinal cord, stomach, duodenum, and plasma was determined by ELISA.
Results: Motilin/MTLR were detected in the spinal cord. Spinal cord motilin/MTLR expression peaks 2 h after modeling (P<0.05) and start to decrease at 24 h (P<0.05) to almost reach baseline levels at 72 h. The changes in gastric, duodenal, plasma, and spinal cord motilin levels correlated with MWT and TWL (all R2>0.82). The intrathecal injection of 1, 5, or 25 µg of motilin could increase the pain threshold of rats with incisional pain at 72 h in a dose-dependent manner.
Conclusion: This study showed for the first time that motilin/MTLR are expressed in rats’ spinal dorsal horn. Acute pain increased motilin/MTLR expression in the spinal dorsal horn. Also for the first time, this study showed that motilin intrathecal injection alleviates pain in rat models of acute incisional pain. These results suggest that motilin/MTLR could be a novel target for the management of acute pain.