Abstract: Objective To explore the feasibility of retrobulbar vein injection of nanoparticles in nude mice. Methods Eight healthy adult nude mice were randomly divided into two groups with four in each group. Superparamagnetic iron oxide nanoparticles (SPIO) were intravenously injected via tail vein and retrobulbar vein, respectively. Magnetic resonance (MR) FSE T2WI were performed on liver of nude mice. The signal intensity (SI) of the liver and adjacent muscles were measured, and the change rate of SI were calculated. Results All the 8 nude mice were punctured successfully. It took an average of 8 minutes 30 seconds and 3.7 times for tail vein puncture, which was larger than that of retrobulbar vein puncture which took an average of 3 minutes 50 seconds and 2.3 times. The liver SI enhancement is consistent between retrobulbar vein injection and tail vein injection. The SI change rate at 0 minute, 5 minute, 10 minute, 30 minute, 1 hour and 2 hour were 66.78%±5.62%, 72.92%±8.41%, 73.08%±7.68%, 74.06%±7.44%, 74.61%±6.28%, 73.66%±4.52% respectively in tail vein injection and 69.29%±7.53%, 74.86%±5.84%, 77.54%±6.47%, 78.85%±8.23%, 79.05%±4.65%, 77.99%±7.73% respectively in retrobulbar vein injection. The difference was not statistically significant (P>0.05). Conclusion The intravenous administration of nanoparticles via retrobulbar vein is simpler and efficient, it may be used as a method apart from the tail vein injection .

Key words: Nude mice, Intravenous administration, Nanoparticles, Retrobulbar vein