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To study behavioral character and changes of neuronal activity in the basal ganglia of rat model of levodopa-induced dyskinesia, unilateral 6-hydroxydopamine lesioned rat model of Parkinson disease (PD) was treated with levodopa/benserazide twice daily for 4 weeks and the behavior observed on the 1st, 3rd, 4th, 7th, 9th, 10th, 14th, 21st and 28th day. The animals were sacrificed and immunohistochemical technique was used to measure the changes of Fos expression in the caudate putamen (CPU), globus pallidus (GP) and sensorimotor area of cerebral cortex 2 h after the last treatment. The results showed that pulsatile treatment with a subthreshold dose of levodopa gradually induced abnormal involuntary movement (AIM), including stereotypy (limb dyskinesia, axial dystonia and masticatory dyskinesia) towards the side contralateral to the dopamine-denervated striatum and increased contraversive rotation. The motor pattern of each subtype was highly stereotypic across individual rats, and the proportion of each subtype was not consistent among individual rats. Fos positive nuclei in the CPU and GP were increased by levodopa acute administration, and more remarkably in the CPU, but not in the cerebral cortex. After repeated levodopa treatment. Fos positive nuclei were reduced remarkably in the CPU, but were increased in the GP and cerebral cortex. It was concluded that the neural mechanisms underlying levodopa induced AIM in rat model of PD was very similar to those seen in levodopa-induced dyskinesia (LID) in PD patients and MPTP-lesioned monkeys, and increased striatopallidal neuronal activity might be involved in occurrence of LID.

To investigate the distribution of possible novel mutations from parkin gene in variant subset of patients with Parkinson's disease (PD) in China and explore whether parkin gene plays an important role in the pathogenesis of PD, 70 patients were divided into early-onset group and late-onset group; 70 healthy subjects were included as controls. Genomic DNA from 70 normal controls and from those of PD patients were extracted from peripheral blood leukocytes by using standard procedures. Mutations of parkin gene (exon 1-12) in all the subjects were screened by PCR-single strand conformation polymorphism (SSCP), and further sequencing was performed in the samples with abnormal SSCP results, in order to confirm the mutation and its location. A new missense mutation Gly284Arg in a patient and 3 abnormal bands in SSCP electrophoresis from samples of another 3 patients were found. All the DNA variants were sourced from the samples of the patients with early-onset PD. It was concluded that Parkin point mutation also partially contributes to the development of early-onset Parkinson's disease in Chinese.

To study the effect of glutamate on the intracellular calcium signal of pure cultured rat astrocytes and the role of NMDA and AMPA receptors in the procedure, the change of calcium signal was investigated by monitoring the fluctuation of intracellular Ca2+ concentration ([Ca2+]i) on the basis of Fura-2 single cell fluorescent ratio (F345/F380). The changes in the effect of glutamate on the intracellular calcium signal were observed after blockage of NMDA and (or) AMPA receptors. It was found that L-glutamate could induce an increased [Ca2+]i in most of the cells in concentration- and time-dependent manner. D-(-)-2-amino-5-phosphonopentanoic acid (D-AP-5, a selective antagonist of the NMDA receptor) and 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX, a selective antagonist of the AMPA receptor) could abolish the effects of NMDA and AMPA respectively. The treatment of D-AP-5 and CNQX simultaneously or respectively could attenuate the effect of L-glutamate at varying degrees. All these indicated that glutamate could modulate intracellular Ca2+ of pure cultured rat astrocytes through different pathways. The activation of NMDA and AMPA receptors took part in the complex mechanisms.

The protective effect of puerarin on the Parkinson disease (PD) mice with decreased estrogen level was investigated in order to develop a new potential medicine as a substitute for estrogen for preventing and treating PD. By using immunohistochemical method of avidinbiotin peroxidase complex (ABC), the distribution of the cells positive for tyrosine hydroxylase (TH) and fibres in the substantia nigra of the mouse were observed. These mice were divided into three groups randomly: group A, normal-female-mouse models; group B containing three subgroups, B1 (normal saline), B2 (estrogen), B3 (puerarin); group C containing three sub groups, C1 (normal saline), C2 (estrogen), C3 (puerarin). By using TUNEL the numbers of apoptosis cells in every visual field was counted and the difference between the experimental group and control group was compared. The results showed the numbers of the cells positive for TH were more and the numbers of apoptosis cells were less in the normal-female-mouse models group than in the group of model made after ovariosteresis and the group of model made before ovariosteresis (P < 0.05), respectively. However, there was no significant difference, between the group given estrogen/puerarin and the controls, and between the group given estrogen and given puerarin. (P > 0.05). It was suggested that puerarin may have protective effect on the nigral neurons to PD. Moreover, the protective effect might serve as a surrogate of estrogen and be associated with the apoptosis.

In order to observe neuronal toxical effect of Levodopa and investigate if using Levodopa together with Ginkgo Bilobar Extract (EGb) would be an workable method to treat Parkinson disease, rat models of Parkinson disease (PD) were made by injecting 6-OHDA stereotaxically to right side of the mesencephic ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Rotational behavioral observation, TUNEL, immunocytochemistry, Nissl's body staining were performed to measure the difference between group treated by Levodopa (50 mg/kg every day for 3 days, 5 days, 7 days, L-dopa group) and group treated by Levodopa combined with EGb (100 mg/kg every day, E-D group). The results showed that in the L-dopa group, the numbers of apoptosis of substantial nigra, rings of rotational behavior were more than those in the E-D group (P < 0.05). The numbers of Nissl's cells in L-dopa group were fewer than in E-D group (P < 0.05). The results suggested that Levodopa had neur toxic effect and EGb may decrease the toxicity of levodopa. The combined use of EGb with Levodopa may be a workable method to treat PD and may be better than using Levodopa alone.

To investigate the changes in the expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta 2 (TGFbeta2) in glomus cell grafts of carotid body in the rat model of 6-hydroxydopamine-induced Parkinson disease, immunohistochemical staining of bFGF and TGFbeta2 in the sections of striate body was done on the 2nd, 4th and 12th week after transplantation. The results showed that on the 2nd week after transplantation, bFGF and TGFbeta2 were not detectable in the glumous cell grafts. On the 4th week after graft, bFGF and TGFbeta2 immunoreactivity was increased within the grafts and at the graft-host interface but was restricted only to astrocytes. In the striatum surrounding the graft, bFGF was expressed persistently, while TGFbeta2 showed transient expression. It was suggested that the transient expression of TGFbeta2 was likely due more to the trauma imposed by the graft procedure than to an intrinsic. The deficiency in astrocytic bFGF early after graft may be responsible for the poor survival of grafted glomus cells of carotid body.

Objective: To study the effect of Ginkgo biloba extract on rats during ischemia/reperfusion and its influence on intracellular calcium in hippocampal neurons., Methods: Model of intraluminal occlusion of the middle cerebral artery (MCAO) was used to prepare the ischemia/reperfusion cortex tissue. Concentration of MDA was determined by measuring thiobarbituric acid-reactive substance. GSH-PX was quantified using the thiobarbituric acid (TBA) technique. SOD was assayed througha xanthine method. Endogenous amino acids were quantified by high performance liquid chromatographic (HPLC) analysis. Primary culturs of hippocampal neurons were prepared for a free intracellular calcium ([Ca(2+)]I) assay by Fura-2 based single cell microfluoremetric technique., Results: Comparing control and treatment groups, the concentration of SOD and GSH-PX were higher, whereas that of MDA was much lower; the concentration of glutamate and aspartate decreased and that of GABA increased markedly at all time point (P < 0.01), Gly also decreased at some time points (P < 0.05). The differences were significant between the groups of 10 mg/kg, 15 mg/kg and the groups of 5 mg/kg. When 1 x 10(-5) mol/L glutamate was applied with 25 micro g/ml ginkgo biloba extract to cultured neurons, the increase in [Ca(2+)]I was lower than that caused by applying glutamate alone. Its peak value was much lower and increased phase was longer, its declining phase was shorter. After returning to baseline, the application of 1 x 10(-5) mol/L glutamate could induce the reaction to recover., Conclusions: Ginkgo biloba extract could protect damaged neurons by keeping the balance of inhibitory/excitatory aminoacids, enhancing the free radical scavengers system, and inhibiting the effect of glutamate on [Ca(2+)]I.

To explore the relationship between beta-amyloid (A beta) and the pathogenesis of Alzheimer disease (AD), after injection of beta-amyloid into the rat brain, the apoptosis of nerve cells and acetylcholine (Ach) content in rat hippocampus were examined by employing TUNEL technique and base hydroxylamine colorimetry respectively. The influence of age and glucocorticoid on the neurotoxic effect of A beta was also analyzed. A beta peptide could strongly induce the apoptosis of neurons in hippocampus, cortex and striate body (P < 0.05 or P < 0.01). In addition, the senility and glucocorticoid pre-treatment could enhance the toxic effect of A beta (P < 0.05 or P < 0.01). It is concluded that A beta may play an important role in the pathogenesis of Alzheimer disease via its induction of apoptosis of neurons and by decreasing the content of the Ach.

To investigate the effects of time interval and cumulative dosage of repetitive mild cellular hypoxia on shape of neurodegeneration and neuroprotection in mice, population spike amplitude (PSA) was measured during hypoxia and posthypoxic recovery in hippocampal slices from untreated control and mice pretreated in vivo with a single or repeatedly intraperitoneal injection of 3-nitropropionate (3-NP). Posthypoxic recovery of PSA was dose-dependent in single pretreated slices, with maximal recovery on pretreatment attained with 20 mg/kg 3-NP (82 +/- 32%, P < 0.01). Upon 5 and 9 treatments with 20 mg/kg 3-NP (dosage interval 3 days), PSA recovered to (38 +/- 9)% with the difference being not significant vs control group and (72 +/- 45)% with the difference being significant (P < 0.05 to control, P < 0.05 to 5 treatments), respectively. In contrast, with 2 days time interval, recovery after 5 and 9 treatments was (30 +/- 25)% and (16 +/- 14)%, respectively (without significant difference from control). Continued neuroprotection was also observed upon increase of dosage interval to 4 and 5 days. It was suggested that repetitive chemical hypoxia is a model for neurodegenerative disease and continued neuroprotection depending on time interval between repetitive hypoxic episodes rather than cumulative dosage. At appropriate time intervals increased neuronal hypoxic tolerance could be induced with number of hypoxic episodes.

To observe the effects of heterograft of glomus cells of carotid body on hemiparkinsonian rat models, rats with unilateral 6-hydroxydopamine (6-OHDA)-induced lesions of the right dopaminergic neurons of substantia nigra received intrastriatal glomus cells heterograft. Apomorphine-induced rotation was monitored for 30 min at various time points after grafting. The striata were cut and examined for dopamine content by HPLC and for immunohistochemical staining of tyrosine hydroxylase positive neurons (TH+) at the end of the experiments. The results showed that apomorphine-induced rotational behavior was significantly reduced for 12 weeks and the dopamine contents were significantly elevated after grafting (P < 0.01), and TH+ cells survived better. The present study demonstrates that intrastriatal heterograft of glomus cells within carotid body in rats with 6-OHDA-elicited lesions could reduce apomorphine-induced rotational behavior and elevate the dopamine contents and numbers of TH+ cell surviving within striatum, and can serve as a new and effective alternative for Parkinson disease.