Preparation of Neuropeptide Nanoparticle and Its Mechanism in Corneal Nerve Regeneration in Substance P-Neurokinin 1 Receptor Signaling Pathway

Abstract

The multiple emulsion method was applied to prepare the 1.5 mL solution of ciliary neurotrophic factor (CNTF), and dichloromethane solution with 2.5% polylactic acid (PLA) was added into the CNTF solution during the colostrum process, and then, polyethylene glycol solution was added into the mixed solution under ultrasonic conditions to form multiple emulsion; finally, it was stirred magnetically and centrifuged to obtain CNTF nanoparticles. The transmission electron microscope (TEM) was applied to characterize the prepared nanoparticles that detected their drug loading rate, encapsulation rate, and their drug release in vitro and in vivo. In the demonstration of neuropeptide nanoparticles participating in corneal nerve regeneration in the substance p-neurokinin 1 receptor (SP-NK-1R) signaling pathway, it was to detect the gene expression in the trigeminal ganglion cells based on the different groups like normal group, advanced glycation end products (AGE)/Stattic group, and AGE + CNTF/Stattic + CNTF group. In the characterization experiment of CNTF nanoparticles, their surfaces were smooth, they evenly distributed, and the average drug loading rate reached 1.27% ± 0.032%; the nanoparticles were able to continuously release CNTF molecules within 30 hours; what’s more, CNTF group (low concentration to high concentration) and CNTF nanoparticles group (low concentration to high concentration) could both enhance the expression of mouse optic nerve cells. Compared to AGE group, the expressions of substance p-signal transducer and activator of transcription 3 (p-STAT3) in trigeminal ganglion cells increased after adding CNTF and CNTF nanoparticles, respectively (P < 0.05); and the expression of p-STAT3 increased remarkably after the addition of CNTF nanoparticles (P < 0.05), with an obvious increase on the growth of nerve axon. On the other hand, it had the same results as the above, compared with Stattic group.