ABSTRACT
Objective To investigate the effects of levodopa/benserazide-loaded poly-lactide-coglycolide (PLGA) microspheres on motor deficits and levodopa-induced dyskinesia in a rat model of Parkinson' s disease (PD) and to explore the mechanisms underlying this effects.Methods The content of levodopa/benserazide released from the microspheres was determined by high-performance liquid chromatography.The rat model of PD was induced by 6-OHDA injections.Then the valid PD rats were treated with levodopa ( 12 mg/kg,s.c.)/benserazide ( 15 mg/kg,s.c.) or microspheres.Forepaw adjusting steps were measured on 1,4,7,10 and 14 days after treatment.After 2 weeks of treatment,the abnormal involuntary movements (AIM) were measured.Phosphorylated dopamine,cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) at threonine 34 levels were determined by immunohistochemistry and Western blot respectively.In addition,the levels of △FosB were measured by Western blot.Results In vivo release test showed that 76.2％ of levodopa and 83.6％ benserazide were released from the microspheres on day 7.Forepaw adjusting steps showed that the scores of forepaw adjusting steps in microspheres-treated PD rats were ( 5.8 ± 1.6 ) and ( 5.2 ± 1.5 ) respectively on 10 and 14 days of treatment,which were increased compared to levodopa-treaded PD rats (2.4 ± 1.1 and 1.2 ± 0.5 ; t =4.12,5.43,all P ＜0.01 ).The AIM scores of microspheres-treated rats ( 16.0 ±2.1 ) were decreased significantly compared to levodopa-treated rats ( 26.0 ± 3.2 ) on day 14 ( t =6.59,P ＜ 0.01 ).Immunohistochemistry indicated that the phosphorylated levels of DARPP-32 in microspheres-treated rats ( (3.7 ± 1.3 ) × 104 )were decreased significantly compared to levodopa-treated rats ( (7.9 ± 2.2) × 104 ; t =2.95,P ＜ 0.05 ).In addition,Western blot showed that the levels of phosphorylated DARPP-32 and △FosB were 119.4％ ± 11.3％ and 149.3％ ± 12.3％ respectively,which were decreased significantly compared to levodopatreated rats ( 184.8％ ± 13.7％ and 300.4％ ± 14.2％ ; t =4.12,2.91,all P ＜ 0.05 ).Conclusions Microspheres can be used to improve the motor deficits and reduce the expression of dyskinesia in PD rats.This may be due to the continuous release of levodopa/beserazide from the microspheres,which leads to continuous stimulation of PD rats and reduces the levels of phosphorylated DARPP-32 and △FosB in the striata of these rats.
ABSTRACT
OBJECTIVE: To characterize morphology and drug release kinetics of protein-loaded poly(?-caprolactone)/poly(ethylene glycol)/poly(?-caprolactone) amphiphilic block copolymeric (PCE) microspheres, and elucidate the mechanistic details regarding protein release. METHODS: BSA-loaded PCE microspheres were prepared using a water-in-oil-in-water, followed by solvent evaporation. Morphology of the polymer microspheres was observed using scanning electron microscopy. Protein loading capacity and encapsulation efficiency were determined by extracting the proteins from the microspheres and measured using MicroBCA method. Protein release kinetics was characterized by cumulative release against the date of release incubation. RESULTS: The protein-loaded PCE microspheres were spherical and possess smooth surface under SEM. Protein loading capacity and encapsulation efficiency in the microspheres were independent of PCE molecular weight. However, the kinetic features of the protein release varied significantly with PCE molecular weight, suggesting a diffusion-degradation combined release mechanism. For the microspheres made of larger molecular weight PCE 4000, the portion of protein release attributed to diffusion from the polymer matrix was remarkably less than that from microspheres of small molecular weight PCE. In vitro release profile can be simulated using a diffusion-degradation model(Q=k1t1/2+k2t+k3t2+k4t3)(r=0.997). CONCLUSION: PCE microsphere formulation can offer sustainedrelease of proteins with initial burst and incomplete release reduced to acceptable level.
ABSTRACT
Object To develop a resonance scattering spectral(RSS) method for the determination of total flavone in Shuxuening Tablet, and study the cause of RSS enhancement. Methods The BSA Mo (Ⅵ) qucercetin (Qu) system was investigated by RSS method. Results There were two resonance sacttering peaks at 470 and 525 nm. The Qu concentration in the range of 0-2 4 mg/L is linear to the resonance scattering intensity I 470 nm , with a detection limit of 0 3 mg/L. Conclusion This method is simple, sensitive and suitable for the determination of total flavone in Shuxuening Tablet. The spectral results demonstrate that the formation of [BSA Mo Qu] n associated particle and the interface between the particle solid phase and water phase results to its enhanced RSS.