Purpose: Angiopoietin-like 7 (ANGPTL7), abundantly expressed in cornea, plays a major role in maintaining corneal avascularity. Although the cornea is avascular and contains multiple sensory nerves (trigeminal nerve), the effects of ANGPTL7 on the trigeminal nerve have not been completely defined. In this study, we determined if ANGPTL7 induces axon elongation of cultured rat trigeminal ganglion (TG) cells.
Materials and methods: The trigeminal nerve was isolated and cultured from euthanized rats. Recombinant ANGPTL7 was added to the cultured trigeminal nerve and allowed to react over a 24-h period. Immunostaining with antiphosphoneurofilament H (pNFH) antibody and antisubstance P antibody was performed, and the specimens were observed under a fluorescence microscope. After imaging, the number of pNFH-positive cells or the number of double-positive cells of pNFH and substance P was quantified, and the cell body diameter and axon length were measured.
Results: Aα/β/δ fibers stained with anti-pNFH antibody, Aδ and C fibers stained with anti-substance P antibody, and double-positive Aδ fibers were compared with the control. In comparison with the control group, the number of cells in which axonal outgrowth was promoted was abundant in the group in which ANGPTL7 was added, and axon outgrowth promoting effect because of ANGPTL7 was observed.
Conclusion: Thus, ANGPTL7 might stimulate axon elongation of TG cells.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 124: 982-986, 2020.