Upregulation of G-protein Coupled Receptor 120 in Rats Following Spinal Cord Injury.

G protein-coupled receptors (GPCRs) are fundamental mediators of a wide array of processes including proliferation, immune cell function and neural signaling. GPR120 is a GPCR present within the spleen, lungs, adipose tissue and intestines that is stimulated by endogenous free fatty acids (FFAs). Whether GPR120 is expressed or functionally relevant in the central nervous system (CNS), however, has yet to be directly examined. Herein, a rat spinal cord injury (SCI) model was established and used to explore the expression of GPR120 in SCI. Western blotting and immunohistochemical staining revealed that GPR120 was detectable in the spinal tissues of healthy rats, and the levels rose following SCI and reached the peak on day 3, whereafter they declined to basal levels within two weeks post-SCI. Dual immunofluorescent staining revealed detectable GPR120 expression in astrocytes, microglia and a limited number of neurons. Following SCI, GPR120 upregulation was primarily evident in astrocytes. After injury, colocalization between GPR120 and the proliferative marker PCNA was also detected. Together, these results offer new insights regarding the dynamics of spinal cord GPR120 expression and suggest that it may play important roles in the CNS following SCI.