Application of Noninvasive Method for Assessing the Neuroprotective Effect of Magnolol

Abstract

Purpose:: An approach of NMDA(N-methyl-D- aspartate)-induced retinitis was used to study the neuroprotective effects of magnolol.

Methods:: Rex rabbits with pigment iris were used as tested animals in the study. After intravenous (IV) administration of sodium fluorescein, blood samples were withdrawn and analyzed to characterize the pharmacokinetics of fluorescein. In addition, various doses (4.5, 10, and 15 mg/Kg BW) of magnolol were given by IV administration prior to intravitreal injection of NMDA induced retinitis. A noninvasive method was used to directly determine the distribution of fluorescein in vitreous using an ocular fluorometer. A PK/PD model was established to evaluate following ocular pharmacokinetic parameters, including: k_in (the rate constant of fluorescein permeating blood-retina-barrier into vitreous), k_out (the rate constant of fluorescein into systemic circulation), MRT (the mean residence time of fluorescein in vitreous), and permeability coefficient (P) of blood-retina-barrier.

Results:: As the results, the parameters of k_in, MRT, and P were dose-dependent on the injected amount of magnolol, and the penetration of fluorescein into vitreous through blood-retina-barrier was significantly reduced.

Conclusions:: It indicated that magnolol is a potential optic neuroprotectant in the animal model of NMDA-induced retinitis.

Keywords: neuroprotection • apoptosis/cell death • visual impairment: neuro-ophthalmological disease