Synaptic innervation of midbrain dopaminergic neurons by glutamate-enriched terminals in the squirrel monkey

The excitatory amino acid, glutamate, has long been thought to be a transmitter that plays a major role in the control of the firing pattern of midbrain dopaminergic neurons. The present study was aimed at elucidating the anatomical substrate that underlies the functional interaction between glutamatergic afferents and midbrain dopaminergic neurons in the squirrel monkey. To do this, we combined preembedding immunocytochemistry for tyrosine hydroxylase and calbindin D-28k with postembedding immunostaining for glutamate. On the basis of their ultrastructural features, three types (so-called types I, II, and III) of glutamate-enriched terminals were found to form asymmetric synapses with dendrites and perikarya of midbrain dopaminergic neurons. The type I terminals accounted for more than 70% of the total population of glutamate-enriched boutons in contact with dopaminergic cells in the dorsal and ventral tiers of the substantia nigra pars compacta as well as in the ventral tegmental area, whereas 5–20% of the glutamatergic synapses with dopaminergic neurons involved the two other types of terminals. The major finding of our study is that the glutamate-enriched boutons were involved in 70% of the axodendritic synapses in the ventral tegmental area. In contrast, less than 40% of the boutons in contact with dopaminergic dendrites were immunoreactive for glutamate in the dorsal and ventral tiers of the substantia nigra pars compacta. Approximately 50% of the terminals in contact with the perikarya of the different populations of midbrain dopaminergic neurons displayed glutamate immunoreactivity. In conclusion, our findings provide the first evidence that glutamate-enriched terminals form synapses with midbrain dopaminergic neurons in primates. The fact that the proportion of glutamatergic boutons in contact with dopaminergic cells is higher in the ventral tegmental area than in the substantia nigra pars compacta suggests that the different groups of midbrain dopaminergic neurons are modulated differently by extrinsic glutamatergic afferents in primates. © 1996 Wiley-Liss, Inc.     

Cholecystokinin: Corelease with dopamine from nigrostriatal neurons in the cat

Halothane-anaesthetized cats were implanted with push-pull cannulae to demonstrate the in vivo release of cholecystokinin-like immunoreactivity (CCK-LI) in the substantia nigra and the ipsilateral caudate nucleus. The spontaneous and the calcium-dependent potassium-evoked release of CCK-LI were observed in both structures. In addition, the local application of tetrodotoxin (10-6 M) reduced the spontaneous release of the peptide. 6-OHDA lesions made in the substantia nigra pars compacta led to a complete destruction of nigrostriatal dopaminergic neurons. CCK-LI levels were not affected in the caudate nucleus but were reduced substantially in the substantia nigra. The activation of dopaminergic cells induced by the nigral application of alpha-methyl-para-tyrosine (10-4 M) stimulated the release of CCK-LI and dopamine in the ipsilateral caudate nucleus, whilst opposite effects were seen in the substantia nigra. Similar results were obtained when dopaminergic transmission was blocked in the caudate nucleus suggesting that the evoked release of CCK-LI by the alpha-methyl-para-tyrosine treatment originates from dopaminergic nerve terminals and not from other CCK-LI containing fibres in response to released dopamine. Dopamine (10-7 M) as well as the D1 agonist SKF 38393 (10-5 M) stimulated CCK-LI release when applied into the caudate nucleus while the D2 agonist, LY 171555 (10-6 M) slightly reduced peptide release. The local application of cholecystokinin-8 sulfate (CCK-8S) (10-8 M, for 30 min) into the substantia nigra pars compacta increased the firing rate of dopaminergic cells and stimulated the release of newly synthesized 3H-dopamine from dendrites and nerve terminals. These results suggest, but do not definitively prove, that, in the cat, CCK-LI and dopamine are coreleased from nigrostriatal mixed dopaminergic/CCK-LI neurons and that CCK-LI released from dendrites is, like dopamine, involved in the regulation of the activity of these cells.     

Substance P-dopamine relationship in the rat substantia nigra: a light and electron microscopy study of double immunocytochemically labeled materials

The synaptic relationships between substance P-containing terminals and dopaminergic neurons (immunoreactive for tyrosine hydroxylase) in the substantia nigra were studied at both light and electron microscopic levels using a pre-embedding double-labeling immunocytochemical method. Many substance P-containing terminals were found to form synapses directly with dendrites and somata of nigral dopaminergic neurons. Since most of the substance P-containing axon terminals arise from the striatum, this result suggests that striatal substance P neurons can have monosynaptic influence on nigral dopaminergic neurons.     

Sparing of orexin‐A and orexin‐B neurons in the hypothalamus and of orexin fibers in the substantia nigra of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐treated macaques

Several studies conducted in patients with Parkinson's disease have reported that the degeneration of substantia nigra dopaminergic neurons, which are essential for motor control, is associated with the loss of hypothalamic orexin neurons, which are involved in sleep regulation. In order to better explore the mutual interactions between these two systems, we wished to determine in macaques: (i) if the two orexin peptides, orexin‐A and orexin‐B, are distributed in the same hypothalamic cells and if they are localized in nerve terminals that project onto nigral dopaminergic neurons, and (ii) if there is a loss of orexin neurons in the hypothalamus and of orexin fibers innervating nigral dopaminergic neurons in macaques rendered parkinsonian by 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) intoxication. We showed that virtually all cells stained for orexin‐A in the hypothalamus co‐expressed orexin‐B. Numerous terminals stained for both orexin‐A and orexin‐B immunoreactivity that innervated the whole extent of the ventral tegmental area and substantia nigra pars compacta were found in close proximity to tyrosine hydroxylase‐immunoreactive dendrites. These data indicate that orexin‐A and orexin‐B peptides are in a position to play a role in controlling the activity of nigral dopaminergic neurons. However, no loss of orexin‐A or orexin‐B neurons in the hypothalamus and no loss of orexin fibers in the substantia nigra pars compacta was found in MPTP‐treated macaques when compared with control macaques. We conclude that a relatively selective dopaminergic lesion, such as that performed in MPTP‐treated macaques, is not sufficient to induce a loss of hypothalamic orexin neurons.     

Endogenous brain-derived neurotrophic factor protects dopaminergic nigral neurons against transneuronal degeneration induced by striatal excitotoxic injury

Injury to the central nervous system causes atrophy or death of connecting neurons and can modify the expression of neurotrophic factors. We observed transneuronal upregulation of brain-derived neurotrophic factor (BDNF) expression in the rat ipsilateral substantia nigra pars compacta after a striatal lesion induced by kainate. This effect is developmentally regulated because the enhancement of nigral BDNF expression was only observed when striatal lesion was performed on postnatal day (P) 15 and in adulthood, but not at P7. Interestingly, the lack of regulation of BDNF was coincident with the transynaptic degeneration of nigral neurons after striatal excitotoxic injury. Hence, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta decreased when the lesion was performed at P7, but not at P15 or at P30. The analysis of the functional significance of this BDNF upregulation was done using trkB-IgG fusion proteins. After striatal injury, blockade of endogenous BDNF by trkB fusion proteins induced an atrophy of the dopaminergic neurons of the pars compacta. The injection of trkB-IgG fusion proteins did not modify the effects of kainate in the substantia nigra pars reticulata. Thus, our results show that BDNF exerts an autocrine/paracrine protective effect selectively on dopaminergic neurons against the loss of trophic support from the target striatum.     

Immunoreactive substance P in the substantia nigra of the monkey: light and electron microscopic localization

The microscopic localization of immunoreactive substance P in the monkey substantia nigra was investigated by the peroxidase antiperoxidase method. Immunoreactive substance P was identified in the substantia nigra pars compacta and pars reticulata in numerous myelinated and unmyelinated fibers, and within axon terminals which contained intensely labeled granular vesicles and formed predominantly axodendritic synapses. These morphologic results are consistent with known excitatory effects of SP on nigral neurons.     

Demonstration of the nigrostriatal projection by silver staining after nigral injections of 6-hydroxydopamine

Lesions of the substantia nigra of rats were made by local injections of 6-hydroxydopamine. The degenerative changes in the brain were studied by means of the Fink-Heimer technique. Survival times of 2 or 3 days were optimal for the demonstration of degeneration. Extensive necrotic changes were observed in neurons of the substantia nigra pars compacta following 6-hydroxydopamine injections; control injections did not produce necrosis. Dense fields of terminal degeneration were observed in the caudate of the 6-hydroxydopamine treated rats but not in the caudates of the control animals. A comparison was made on the amount of degeneration present in the ventral nucleus of the thalamus after three types of lesions: (a) nigral injection of 6-hydroxydopamine; (b) nigral injection of carrier solution (control); and (c) electrolytic lesion of the substantia nigra. Lesions (a) and (b) produced only small amounts of thalamic degeneration, while lesion (c) produced extensive terminal degeneration in the ventral thalamic nucleus. The toxic effects of nigral injections of 6-hydroxydopamine were confined to the dopaminergic neurons of the substantia nigra pars compacta; nondopaminergic neurons of the substantia nigra pars reticulata, and their thalamic projection field, appeared normal in silver stains.     

Ultrastructural single- and double-label immunohistochemical studies of substance P-containing terminals and dopaminergic neurons in the substantia nigra in pigeons.

The vast majority of striatonigral projection neurons in pigeons contain substance P (SP), and the vast majority of SP-containing fibers terminating in the substantia nigra arise from neurons in the striatum. To help clarify the role of striatonigral projection neurons, we conducted electron microscopic single- and double-label immunohistochemical studies of SP+ terminals and/or dopaminergic neurons (labeled with either anti-dopamine, DA, or anti-tyrosine hydroxylase, TH) in pigeons to determine: (1) the synaptic organization of SP+ terminals, (2) the synaptic organization of TH+ perikarya and/or dendrites, and (3) the synaptic relationship between SP+ terminals and TH+ neurons in the substantia nigra. Tissue single-labeled for SP revealed numerous SP+ terminals contacting thin unlabeled dendrites in the substantia nigra, but few SP+ terminals were observed contacting perikarya or large-diameter dendrites. SP+ terminals contained round, densely packed, clear vesicles, and often contained one or more dense-core vesicles. Synaptic junctions between SP+ terminals and their targets were more often symmetric (86%) than asymmetric. In tissue single-labeled for DA, we observed few terminals contacting DA+ perikarya, whereas terminals contacting DA+ dendrites were more abundant. Terminals contacting DA+ structures comprised at least four different morphologically distinct types based on the morphology of the clear synaptic vesicles and the type of synaptic junction. One type of terminal contained round clear vesicles and made symmetric synapses, and thus resembled the predominant type of SP+ terminal. The second type contained round clear vesicles and made asymmetric synapses, the third type contained medium-size pleomorphic clear vesicles and made symmetric synapses, and the fourth type contained small pleomorphic clear vesicles and made symmetric synapses. The presence of contacts between SP+ terminals and dopaminergic dendrites in the substantia nigra was directly demonstrated in tissue double-labeled for SP (by the peroxidase-antiperoxidase procedure, or PAP, with diaminobenzidine) and TH (by either the silver-intensified immunogold procedure or the PAP procedure with benzidine dihydrochloride). SP+ terminals commonly contacted thin TH+ dendrites in the substantia nigra, but few SP+ terminals contacted large-diameter TH+ dendrites or perikarya. Synapses between SP+ terminals and TH+ neurons were always symmetric. TH+ dendrites also were contacted by terminals not labeled for SP, which were more abundant than were SP+ terminals. Non-TH+ neurons were also contacted by both SP+ terminals and non-SP+ terminals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Neurotensin terminals form synapses primarily with neurons lacking detectable tyrosine hydroxylase immunoreactivity in the rat substantia nigra and ventral tegmental area.

A light and electron microscopic double antigen localization technique was employed to examine the fine structural relationship between neurotensin-containing axon terminals and dopaminergic neurons in the substantia nigra and ventral tegmental area of the rat. At the light microscopic level, neurotensin-immunoreactive terminals were densely distributed throughout the substantia nigra pars compacta and ventral tegmental area in close proximity to tyrosine hydroxylase-immunoreactive somata and dendrites. On electron microscopic examination, direct synaptic connections were identified between neurotensin-immunoreactive axon terminals and tyrosine hydroxylase-immunopositive perikarya and dendrites. However, only 8.2% and 8.8% of the neurotensin-immunoreactive axonal profiles detected in the substantia nigra and ventral tegmental area, respectively, were found in direct apposition with tyrosine hydroxylase-immunostained elements. In turn, only 9.3% and 10.0% of tyrosine hydroxylase immunoreactive dendrites sampled from the substantia nigra and ventral tegmental area, respectively, were seen in contact with neurotensin immunopositive axon terminals. However, neurotensin-immunoreactive and tyrosine hydroxylase-immunolabelled elements were frequently identified in close anatomical proximity (less than 5 microns) to one another. These results are interpreted in light of the selective association of neurotensin receptors with dopaminergic neurons in the substantia nigra and ventral tegmental area to suggest a predominantly parasynaptic mechanism of action for neurotensin in the ventral midbrain.     

D2 Dopamine receptor blockade results in sprouting of DA axons in the intact animal but prevents sprouting following nigral lesions

Recently it was demonstrated that sprouting of dopaminergic neurons and a microglial and astrocyte response follows both partial lesions of the substantia nigra pars compacta and blockade of the D2 dopamine receptor. We therefore studied the effects of the combination of these two treatments (lesioning and D2 dopamine receptor blockade). Haloperidol administration caused a 57% increase in dopaminergic terminal tree size (measured as terminal density per substantia nigra pars compacta neuron) and an increase of glia in the striatum. Following small to medium nigral lesions (less than 60%), terminal tree size increased by 51% on average and returned density of dopaminergic terminals to normal. In contrast, administration of haloperidol for 16 weeks following lesioning resulted in reduced dopaminergic terminal density and terminal tree size (13%), consistent with absent or impaired sprouting. Glial cell numbers increased but were less than with lesions alone. When haloperidol was administered after the striatum had been reinnervated through sprouting (16-32 weeks after lesioning), terminal tree size increased up to 150%, similar to the effect of haloperidol in normal animals. By examining the effect of administering haloperidol at varying times following a lesion, we concluded that a switch in the effect of D2 dopamine receptor blockade occurred after dopaminergic synapses began to form in the striatum. We postulate that when synapses are present, D2 dopamine receptor blockade results in increased terminal density, whereas prior to synapse formation D2 dopamine receptor blockade causes attenuation of a sprouting response. We speculate that D2 dopamine receptors located on growth cones 'push' neurites toward their targets, and blockade of these receptors could lead to attenuation of sprouting.     

Topographical study of the distribution of gamma-aminobutyric acid (GABA) in the human substantia nigra. A case study.

The topographical distribution of gamma-aminobutyric acid (GABA) in the substantia nigra of a 28-year-old male 4 h after death was investigated. In a preliminary study the entire substantia nigra was dissected from transverse sections. The results showed that there was no correlation between the GABA concentration and the number of melanin-rich nigral cell bodies. This was especially so in the rostral third of the substantia nigra. Using the method of Miyata and Otsuka, transverse sections (150 mum) of the rostral, middle and caudal substantia nigra were cut into 500 mum X 500 mum square blocks which were assayed for GABA by an enzymatic method. In the rostral substantia nigra the GABA distribution was markedly uneven. The highest concentration of GABA was found in the pars reticulata. Within the pars reticulata the highest levels of GABA clearly occurred in two separate regions, a medial and a lateral. In the middle and caudal substantia nigra the GABA distribution was again uneven; however, the highest GABA levels were divided between the pars reticulata and the pars compacta. The results support the view that in the substantia nigra the greatest part of the GABA content is due to the presence of striato-nigral nerve terminals which are known to synapse with the dendrites of the substantia nigra dopamine neurons. In the rostral substantia nigra the concentration of GABA within the pars reticulata is in keeping with the presence of dendrites of such neurons in this region. Presumably on this basis it can be assumed that in the middle and caudal substantia nigra the dendrites are oriented in a more rostro-caudal direction.     

GABAergic synaptic interactions in the substantia nigra

The substantia nigra receives a strong GABAergic input from the ipsilateral striatum and globus pallidus. Nigral GABAergic synaptic interactions have been described in the pars compacta (SNC) and pars reticulata (SNR) but not in the pars lateralis (SNL). The SNR and particularly the SNL are the nodal points of the GABAergic nigrotectal pathway. The present study analyzes the synaptic connections of GABAergic and dopaminergic neurons in each of the divisions of the substantia nigra by employing a double-labeling immunocytochemical technique at the light and electron microscope levels. Glutamic acid decar☐ylase (GAD)-containing terminals make symmetrical synaptic contacts with dopaminergic neurons in the SNC and SNR. Neurons that contain GAD also receive a GABAergic input in the SNR and SNL. The proportion of GAD-GAD contacts appears to be highest in the SNL where virtually all GAD-positive terminals are found to be in synaptic contact with or apposed to GAD positive profiles. This study demonstrates a strong GABAergic input onto nigral dopaminergic neurons and GABAergic neurons in the SNR and SNL. This GABAergic influence which is ontensibly striatal or pallidal in origin is particularly prominent in relation to the SNL-mediated nigro-collicular pathway.     

5-HT1D receptors in the guinea pig brain: pre- and postsynaptic localizations in the striatonigral pathway

The caudate-putamen, globus pallidus and substantia nigra pars reticulata of the guinea pig contain high densities of the 5-HT1D receptor subtype. The cellular localization of these sites in the striatonigral pathway was investigated using receptor autoradiography and selective neurotoxin lesions. In guinea pigs with unilateral 6-hydroxydopamine lesions of the nigral dopaminergic cells, no significant decrease was observed in any of the components of the striatonigral pathway. In contrast, when quinolinic acid was injected in the caudate-putamen, marked reductions in [3H]5-HT binding were seen in the caudate-putamen, the globus pallidus and the substantia nigra pars reticulata, on the side ipsilateral to the lesion. These data, which are comparable to previous results in human pathologies where similar cell populations are known to degenerate (Parkinson disease and Huntington's chorea), indicate a presynaptic localization of 5-HT1D receptors on the terminals of the striatal neurons projecting to the pars reticulata of the substantia nigra. In addition, these receptors could be located on the cell bodies or dendrites of these neurons in the striatum, postsynaptically to serotoninergic fibers.     

Electrophysiologically identified nigral dopaminergic neurons intracellularly labeled with HRP: light-microscopic analysis

Intracellular recordings were obtained in vivo from neurons of the rat substantia nigra, pars compacta. Neurons that were identified as dopaminergic by a variety of electrophysiological criteria, including antidromic activation from ipsilateral neostriatum or globus pallidus, were microiontophoretically injected with horseradish peroxidase and examined at the level of the light microscope. Dopaminergic neurons were of medium size and had ovoid, polygonal, or fusiform cell bodies that emitted from 3-6 primary dendrites. Much of the sparse and relatively unbranched dendritic arborization of these neurons remained within pars compacta, except for 1 or 2 large dendrites that were directed ventrally or ventrolaterally into pars reticulata, roughly perpendicular to the plane of the pars compacta. In coronal sections, the dendrites of ovoid- or polygonal-shaped pars compacta neurons were oriented mainly along the dorsoventral axis, whereas fusiform-shaped neurons had dendrites that were oriented primarily mediolaterally. Although some of the dendrites of dopaminergic neurons exhibited variations in diameter, most were not markedly varicose. Dendrites were sometimes sparsely invested with spinelike appendages or other dendritic extrusions, particularly along their distal portions. The axons of dopaminergic pars compacta neurons were emitted from primary or proximal secondary dendrites, and were extremely fine processes, 0.5 micron or less in diameter. No local axon collaterals were observed.     

Leucine5-enkephalin afferents to midbrain dopaminergic neurons: Light and electron microscopic examination

The relationship between leucine⁵-enkephalin-containing nerve terminals and midbrain dopaminergic neurons was studied in the adult rat by light and electron microscopy. For light microscopy, alternate midbrain sections were immunostained with rabbit polyclonal antibodies against leucine⁵-enkephalin and tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique. Leucine⁵-enkephalin stained fibers and terminals were observed with varying density in the retrorubral field (dopaminergic nucleus A8 region), substantia nigra pars compacta (dopaminergic nucleus A9 region), and ventral tegmental area and related nuclei (dopaminergic nucleus A10 region). For electron microscopy, midbrain sections were immunostained with a mouse monoclonal antibody against leucine⁵-enkephalin and a rabbit polyclonal antibody against tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique and silver-intensified colloidal gold reactions, respectively. The nucleus A10 area was examined at the electron microscopic level, and there were (a) both symmetric (75%) and asymmetric (25%) synapses made between leucine⁵-enkephalin axon terminals and dopaminergic dendrites, and also synaptic contacts with unlabeled dendrites; (b) leucine⁵-enkephalin synaptic contacts with dopaminergic dendrites that were covered with astrocytic membranes; and (c) leucine⁵-enkephalin appositions with unlabeled nerve terminals that made synaptic contacts with dopaminergic dendrites, suggestive of axo-axonic connections. These findings provide the structural basis for both direct and indirect control of A10 dopaminergic neurons by enkephalin-containing nerve terminals. © 1993 Wiley-Liss, Inc.     

Glutamate transporter 1-expressing glia in the rat substantia nigra—Morphometric analysis and relationships to synapses

Glial cells have a major role in protecting neurons against various forms of stress. Especially, astrocytes mediate the bulk of glutamate clearance in the brain via specific membrane transporters (GLAST and GLT1), thereby preventing the occurrence of excitotoxic events. Although glutamate-mediated mechanisms are thought to contribute to nigral dopaminergic neuron degeneration in Parkinson's disease, detailed information on the organization of glia in the substantia nigra is still lacking. The present study was performed to provide quantitative information on the organization of astroglia and on the relationships between astrocytes and excitatory synapses in the rat substantia nigra. Using immunolabeling of GLT1 and confocal imaging, we found that the substantia nigra was filled with a dense meshwork of immunoreactive astrocyte processes. Stereological analysis performed on electron microscope images revealed that the density of immunoreactive astrocyte plasma membranes was substantial, close to 1 μm²/μm³, in the substantia nigra neuropil, both in the pars compacta and the pars reticulata. Excitatory synapses had on average two thirds of their perimeters free from glia, a disposition that may favor transmitter spillover. The density of glutamatergic synapses, as quantified on confocal images by the simultaneous detection of bassoon and of vesicular glutamate transporter 1 or 2, was very low (0.01 and 0.025 per μm³ in the reticulata and compacta subdivisions, respectively). Thus the ratio of GLT1-expressing glial membrane surface to glutamatergic synapses was very high (40–100 μm²), suggesting an efficient regulation of extracellular glutamate concentrations.     

Differential expression patterns of mGluR1 alpha in monkey nigral dopamine neurons

The expression pattern of metabotropic glutamate receptor 1alpha (mGluR1alpha) was immunohistochemically investigated in substantia nigra dopaminergic neurons of the macaque monkey. In normal monkeys, mGluR1alpha immunoreactivity was weakly observed in the dorsal tier of the substantia nigra pars compacta (SNc-d) where calbindin-D28k-containing dopaminergic neurons invulnerable to parkinsonian degeneration are specifically located. On the other hand, mGluR1alpha was strongly expressed in the ventral tier of the substantia nigra pars compacta (SNc-v). In monkeys treated with the parkinsonism-inducing drug, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), mGluR1alpha expression was decreased in dopaminergic neurons in the SNc-v that were spared its toxic action. These results suggest that mGluR1alpha expression may be involved at least partly in the vulnerability of dopaminergic neurons to parkinsonian insults.     

蛋白酶体抑制剂诱导大鼠黑质变性伴包涵体形成

目的 观察蛋白酶体抑制剂Lactacystin诱导大鼠黑质变性伴包涵体形成及运动行为学的改变,探讨蛋白酶体功能下降在帕金森病(PDl发病机制中的作用. 方法 24只SD大鼠采用随机数字表法分为kactacystin实验组和生理盐水组.每组12只,Lactacystin实验组将蛋白酶体抑制剂Lactacystin立体定向注射人大鼠左侧黑质致密部(SNc).生理盐水组注射等体积生理盐水;观察大鼠自主行为和阿朴吗啡(APO)诱导的旋转行为的改变;Nissl染色法观察SNc病理改变;免疫组化法观察SNc及纹状体酪氨酸羟化酶(TH)和SNc中α-共核蛋白的表达;透射电镜观察SNc超微结构的改变. 结果 Lactacystin实验组大鼠给药7 d后出现自发性活动减少、动作缓慢、震颤、且症状逐步加重.APO可诱导出向健侧的旋转运动;Nissl染色发现Lactacystin实验组左侧SNc神经元数量减少,尼氏体结构松散;免疫组化结果表明21 d后Lactacystin实验组左侧SNc出现变性,TH免疫阳性神经元数量减少,α-共核蛋白表达增强,纹状体内TH免疫阳性纤维数量减少;电镜观察到蛋白质聚集形成的包涵体. 结论 Lactacystin单侧SNc注射可以诱导大鼠黑质变性伴包涵体形成及大鼠行为改变.蛋白酶体功能下降可能在PD发病机制中起重要作用.