Reconstruction of the cervical spinal cord based on motor function restoration and mitigation of oxidative stress and inflammation through eNOS/Nrf2 signaling pathway using ibuprofen-loaded nanomicelles

Motor disfunction and oxidative and inflammatory stress after spinal cord injuries (SCIs) occur as a result of primary mechanical damage and secondary degeneration process. In the present study, we aimed to examine the protective effect of fabricated ibuprofen- polyethylene glycol (PEG)/polylactide acid (PLA) diblock copolymer nanomicelles on reconstruction of motor-evoked potential (MEP) of cervical spinal cord, the posterior limb function, ROS and RNS levels, expression of inflammation cytokines, and enzymatic and non-enzymatic antioxidant systems after an experimental SCI. Also, qPCR assay was employed to assess eNOS and Nrf2 at the mRNA level. It was shown that that the drug loading and entrapment efficiency of fabricated nanomicelles were around 9.3% and 72.09%, respectively. Also, the average size and zeta potential of blank PEG-PLA diblock copolymer nanomicelles and drug-loaded nanomicelles were 32.4 ± 2.18 nm, 36.2 ± 2.01 nm and −21.73 ± 4.21 mV, −34.48 ± 3.38 M, respectively. Moreover, ibuprofen-PEG/PLA diblock copolymer nanomicelles revealed a slight burst release within the first 20 h, followed by a continuous release phase over 12 h. It was seen that in control group, MEP amplitude decreased to 17.41 ± 3.75 mV at 1 h after surgery, whereas MEP amplitudes in ibuprofen- and ibuprofen-PEG/PLA -nanomicelles- treated animals were remarkably increased in comparison with the control group, and this enhancement was more pronounced for ibuprofen-PEG/PLA -treated animals. Finally, it was determined that compared with those in the SCI group, the spinal cord function score, SOD, CAT and GSH levels in the ibuprofen-PEG/PLA -nanomicelles- treated group were significantly increased, whereas ROS, RNS, TNF-α, IL-Iβ and IL-6 levels and eNOS and Nrf2 mRNA levels were significantly reduced. In conclusion, this study indicates that the ibuprofen-PEG/PLA -nanomicelles provide significant improvement in the motor function restoration and mitigation of inflammation and oxidative stress stimulated by SCI through eNOS/Nrf2 signaling pathway.