The aim of the present study was to investigate the use of
18F-fallypride micro-positron emission tomography (micro-PET) imaging in the evaluation of the early therapeutic efficacy of
L-dopa in the treatment of
Parkinson's disease (PD) and the underlying mechanism.
18F-fallypride was synthesized and its specific binding with
dopamine (DA) receptors in normal mouse brain was studied. Following the establishment of a mouse model of PD, the animals were divided into normal control, PD model and
L-dopa treatment groups. General behavior, swimming test, locomotor activity counts, transmission electron microscopy, immunohistochemical analysis, high performance liquid chromatography-electrochemical detection and
18F-fallypride micro-PET imaging were used to study intergroup differences and the correlation between the changes of striatal uptake of
18F-fallypride and the therapeutic efficacy. The general behavioral features of PD model mice were similar to the clinical symptoms of PD patients and were alleviated
after treatment. The swimming time, locomotor activity and frequency of standing posture of PD model mice were lower than those of the control mice, but had no difference from those of the control mice after
L-dopa treatment. The number of
tyrosine hydroxylase-positive neurons and the striatal contents of
glutathione peroxidase,
superoxide dismutase, DA and its metabolites 3,5-dihydroxyphenylacetic
acid and
homovanillic acid in the PD group were lower than those in the control group, but were significantly improved following the treatment; the significant reduction in
DOPAC/DA and HVA/DA ratios post treatment suggested that the rate of DA metabolism decreased significantly. The striatal
malondialdehyde content in the PD group increased compared with that in the control group, but was reduced after
L-dopa treatment. Micro-PET imaging indicated that the uptake of
18F-fallypride in the mouse striatum of the PD group was lower than that of the control group and was significantly increased after the treatment. The mechanism of treatment of PD with
L-dopa in mice may involve increasing the number of TH-positive cells and DA receptor levels, as well as reducing the rate of DA metabolism; such changes can be noninvasively observed in vitro by
18F-fallypride imaging.