Tyrosine Hydroxylase Immunohistochemistry Research Articles

A study of monoamine neuronal systems of schizophrenic patients: Using forensic autopsy brains

Studies on autopsy brains of mental illnesses are essential for psychiatric research. Brain materials from forensic autopsy cases have been valuable research resource. We introduced some characteristic neuronal structures of schizophrenic post-mortem brains and normal controls detected using both forensic and pathological autopsy cases and immunohistochemical method. Dopamine-related neuronal structures in schizophrenic cases were investigated by using immunohistochemistry for tyrosine hydroxylase (TH), aromatic l-amino acid decarboxylase (AADC) and phenylethanolamine- N-methyltransferase (PNMT). At the level of the striatum, the number of AADC-positive, but TH-negative neurons ( d-neurons) reduced in schizophrenics compared with controls. In the brainstem structures, we described some morphological findings characteristic to catecholaminergic neurons of the ventral tegmental area of schizophrenic cases and reduction of the number of medullary catecholaminergic neurons. These results might be in accordance with recent reports describing neural stem cell dysfunction in schizophrenic brains. The authors also introduced the first systematic psychiatric brain bank in Japan, the Fukushima Psychiatric Brain Bank, constructed in 1997, and mentioned the necessity for arrangement of brain bank systems to further promote the psychiatric brain research.

Nuclear organization and morphology of cholinergic, putative catecholaminergic and serotonergic neurons in the brain of the rock hyrax, Procavia capensis

The nuclear subdivisions of the cholinergic, putative catecholaminergic and serotonergic systems within the brain of the rock hyrax ( Procavia capensis) were identified following immunohistochemistry for acetylcholinesterase, tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems by comparing those of the rock hyrax to published studies of other mammals. The rock hyrax belongs to the order Hyracoidea and forms part of the Afroplacentalia mammalian cohort. For the most part, the nuclear organization of these three systems closely resembled that described for many other mammalian species. The nuclear organization of the serotonergic system was identical to that seen in all eutherian mammals. The nuclear organization of the putative catecholaminergic system was very similar to that seen in rodents except for the lack of a C3 nucleus and the compact division of the locus coeruleus (A6c). In addition, the diffuse locus coeruleus (A6d) appeared to contain very few tyrosine hydroxylase immunoreactive (TH+) neurons. The cholinergic system showed many features in common with that seen in both rodents and primates; however, there were three differences of note: (1) cholinergic neurons were observed in the anterior nuclei of the dorsal thalamus; (2) cholinergic parvocellular nerve cells, probably representing interneurons, forming subdivisions of the laterodorsal and pedunculopontine tegmental nuclei were observed at the midbrain/pons interface; and (3) a large number of cholinergic nerve cells in the periventricular grey of the medulla oblongata were observed. Thus, while there are many similarities to other mammalian species, the nuclear organization of these systems in the rock hyrax shows specific differences to what has been observed previously in other mammals. These differences are discussed in both a functional and phylogenetic perspective.

Observation of fetal brain in a rat valproate-induced autism model: a developmental neurotoxicity study

Prenatal exposure to chemicals is well known to induce developmental abnormalities in the central nervous system of children. Developmental neurotoxicity (DNT) tests are important to identify neurotoxic agents and prevent neurodevelopmental disorders. We have investigated DNT, focusing on the fetal brain shortly after chemical exposure. To demonstrate a usefulness of a study focusing on the fetal brain in DNT tests, we assessed the fetal brain in a rat valproate-induced autism model. Rats were treated with sodium valproate (VPA, 800mg/kg) orally on gestational day (GD) 9 or 11 (VPA9 or VPA11), and the fetal brains were examined on GD16 using immunohistochemistry for serotonin (5-HT), tyrosine hydroxylase (TH), and TuJ1 (neuron specific class III β-tubulin). Hypoplasia of the cortical plate was induced in both VPA9 and VPA11 groups. Abnormal migration of TH-positive and 5-HT neurons, possibly due to the appearance of an abnormally running nerve tract in the pons, was observed only in the VPA11 group. In addition, when we compared the incidence of these abnormalities between pregnant rats mated in our own animal facility (in-house group), and rats purchased pregnant (supplier group), the supplier group was much more sensitive, especially to the pons abnormality. Shipping stress may affect the reproducibility of VPA-induced DNT. The present results demonstrate that examination of the GD16 fetal brain was useful for detecting and characterizing abnormal development of the brain after VPA exposure. Further discussion was made with reference to the findings in children with autism.

Unilateral axonal or terminal injection of 6-hydroxydopamine causes rapid-onset nigrostriatal degeneration and contralateral motor impairments in the rat

Unilateral injection of the catecholamine neurotoxin 6-hydroxydopamine into the axons or terminals of the nigrostriatal pathway is commonly used to model Parkinson’s disease in experimental animals. Although the terminal lesion paradigm is considered to induce a more progressive lesion when compared to the axonal lesion, few studies have directly compared the early time-course for lesion development in these two models. Thus, this experiment sought to establish the temporal pattern of nigrostriatal degeneration and emergence of contralateral motor impairment in these models. Young adult male Lister Hooded rats were used. After baseline testing on a battery of spontaneous motor tests, standard stereotaxic techniques were used to inject 6-hydroxydopamine into the nigrostriatal axons or terminals at the level of the medial forebrain bundle or striatum respectively. From the day after lesion surgery, a subset of the rats was tested for motor performance, while another subset was used for immunohistochemical analysis. Quantitative tyrosine hydroxylase immunohistochemistry revealed that although both lesions caused a similar temporal pattern of immunopositive cell loss from the substantia nigra, the terminal lesion caused a more rapid loss of immunopositive terminals from the striatum. Despite these differences in striatal dopaminergic deafferentation, both lesion types caused a profound loss of contralateral motor function from the first day after lesion surgery. These findings illustrate the rapidity of the neuropathological and behavioural consequences of either axonal or terminal injection of 6-hydroxydopamine into the nigrostriatal pathway, and further highlight the need for a more progressive model of human Parkinson’s disease.

Inhibition of pontine noradrenergic A7 cells reduces hypoglossal nerve activity in rats

Noradrenergic (NE) excitatory drive maintains activity of hypoglossal (XII) motoneurons during wakefulness. In predisposed persons, sleep-related decrements of NE cell activity may contribute to hypotonia of upper airway muscles innervated by XII motoneurons. The goal of this study was to determine whether NE neurons of the pontine A7 group, an anatomically identified source of NE projections to the XII nucleus, provide significant, endogenous NE excitatory drive to XII motoneurons. In anesthetized rats, we microinjected clonidine (0.75 mM, 20–40 nl), an α 2-adrenergic receptor agonist that inhibits pontine NE cells, aiming at the A7 region. Nine injections were placed within 0.4 mm from the A7 group identified using tyrosine hydroxylase immunohistochemistry: they reduced XII nerve activity by 31.3±2.8% (standard error) and decreased the central respiratory rate by 6%. Another 21 injections, including eight placed near NE cells of the sub-coeruleus region, were made at distances over 0.5 mm from the A7 group and they did not alter either XII nerve activity or respiratory rate. In control experiments, clonidine injections into the A7 group preceded by injections of an α 2-receptor antagonist, RS-79948, did not change XII nerve activity. Four experiments with unilateral clonidine injections into the A7 region and with Fos immunohistochemistry used as a marker of cell activity revealed that the percentage of Fos-positive A7 cells was significantly reduced on the injected side. There was also a significant positive correlation between Fos expression in A7 cells and XII nerve activity. Thus, decrements of NE excitatory drive from the A7 group may significantly reduce XII nerve activity. In obstructive sleep apnea patients, in whom the muscles innervated by XII motoneurons act as upper airway dilators, this may contribute to sleep-related respiratory disorders.

Emotional, cognitive and neurochemical alterations in a premotor stage model of Parkinson's disease

In addition to classic motor symptoms, Parkinson's disease (PD) is characterized by cognitive and emotional deficits, which have been demonstrated to precede motor impairments. The present study addresses the question of whether a partial degeneration of dopaminergic neurons using 6-hydroxydopamine (6-OHDA) in rats is able to induce premotor behavioral signs. The time-course of nigrostriatal damage was evaluated by tyrosine hydroxylase immunohistochemistry and the levels of dopamine, noradrenaline, and 5-HT in various brain regions were analyzed by high performance liquid chromatography (HPLC). Behavioral tests that assessed a variety of psychological functions, including locomotor activity, emotional reactivity and depression, anxiety and memory were conducted on 6-OHDA lesioned rats. Bilateral infusion of 6-OHDA in the striatum of rats caused early (1 week) damage of dopaminergic terminals in striatum and in cell bodies in substantia nigra pars compacta. The nigrostriatal lesion was accompanied by early loss of dopamine in the striatum, which remained stable through a 3-week period of observation. In addition, a late (3 weeks) loss of dopamine in the prefrontal cortex, but not in the hippocampus, was seen. Additional noradrenergic and serotonergic alterations were observed after 6-OHDA administration. The results indicated that 6-OHDA lesioned rats show decreased sucrose consumption and an increased immobility time in the forced swimming test, an anhedonic-depressive-like effect. In addition, an anxiogenic-like activity in the elevated plus maze test and cognitive impairments were observed on the cued version of the Morris water maze and social recognition tests. These findings suggest that partial striatal dopaminergic degeneration and parallel dopaminergic, noradrenergic and serotonergic alterations in striatum and prefrontal cortex may have caused the emotional and cognitive deficits observed in this rat model of early phase PD.

Effect of locus coeruleus denervation on levodopa-induced motor fluctuations in hemiparkinsonian rats

Parkinson's disease (PD) is characterized not only by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) but also by a degeneration of locus coeruleus (LC) noradrenergic neurons. It has been suggested that deficient LC noradrenergic mechanisms might play a critical role in symptomatology and in the progression of PD. However, the effect of LC depletion on levodopa-induced motor complications, such as the motor fluctuations, is still unknown. Male Sprague-Dawley rats received 50 mg/kg intraperitoneal (i.p.) of [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine] (DSP-4) or saline 7 days before the day of 6-hydroxydopamine (6-OHDA, 8 microg) administration in the medial forebrain bundle. Four weeks later, animals were treated with levodopa (25 mg/kg with benserazide, twice at day, i.p.) for 22 days. Rotational behavior was measured on days 1 and 22 of levodopa administration. Tyrosine hydroxylase (TH) immunohistochemistry was performed to evaluate the neurodegeneration in the SNc and LC. Striatal dopamine transporter (DAT) immunohistochemistry was performed to evaluate DA depletion. As expected, levodopa administration decreased the duration of the motor response in the vehicle-pretreated group (P < 0.01). A potentiation of levodopa-induced shortening in the duration of motor response was not achieved after LC depletion since no significant differences were observed in the duration of rotational behavior between these two groups on day 22. In addition, LC depletion did not potentiate either the total number of rotations or the maximal peak of rotation induced by levodopa treatment. These results suggest that LC depletion might not be involved in the pathophysiology of levodopa-induced motor fluctuations.

Cardiac sympathetic denervation correlates with clinical and pathologic stages of Parkinson's disease

Attention has been drawn to cardiac sympathetic denervation in Parkinson's disease (PD) based on clinical studies using [123I] metaiodobenzylguanidine scintigraphy; however, the histologic correlates and time course of cardiac sympathetic denervation are poorly understood. To address these issues, we used tyrosine hydroxylase (TH) immunohistochemistry to detect cardiac sympathetic nerve fibers in the epicardium of 4 normal controls, 11 cases with incidental Lewy bodies (iLBs), and 14 cases of PD. Cardiac sympathetic innervation was significantly less in PD than in normal controls and cases with iLBs (P < 0.05). There was also a decrease in TH-immunoreactive fibers in iLB cases compared to normal controls (P < 0.01). TH-immunoreactive fibers correlated with the PD stage (r = -0.75, P < 0.001), as well as with Hoehn & Yahr clinical stage (r = -0.61, P < 0.001), and disease duration (r = -0.63, P < 0.001). Immunohistochemistry for alpha-synuclein showed neurites in epicardium in PD and iLB cases, but not in normal controls. The density of alpha-synuclein neurites correlated with Braak PD stage (r = 0.38, P < 0.05), Hoehn & Yahr clinical stage (r = 0.44, P < 0.05), and disease duration (r = 0.42, P < 0.05). This study demonstrates that cardiac sympathetic degeneration and alpha-synuclein pathology is present in presymptomatic phase of PD, and that both increase with disease duration and severity.

Nuclear organization and morphology of cholinergic, putative catecholaminergic and serotonergic neurons in the brain of the Cape porcupine ( Hystrix africaeaustralis): Increased brain size does not lead to increased organizational complexity

The distribution, morphology and nuclear organization of the cholinergic, putative catecholaminergic and serotonergic systems within the brain of the Cape porcupine ( Hystrix africaeaustralis) were identified following immunohistochemistry for choline acetyltransferase, tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems in the Cape porcupine in comparison with previous studies of these systems in other rodents. The Cape porcupine is the largest rodent in which these systems have been examined and has an adult body mass of 10–24 kg and an average brain mass of approximately 37 g, around 15 times larger than the laboratory rat. The Cape porcupines were taken from the wild and while these differences, especially that of mass, may lead to the prediction of a significant difference in the nuclear organization or number within these systems, all the nuclei observed in all three systems in the laboratory rat and in other rodents had direct homologues in the brain of the Cape porcupine. Moreover, there were no additional nuclei in the brain of the Cape porcupine that are not found in the laboratory rat or other rodents studied and vice versa. It is noted that the medial septal nucleus of the Cape porcupine appeared qualitatively to have a reduced number of neurons in comparison to the laboratory rat and other rodents. The locus coeruleus of the laboratory rat differs in location to that observed for the Cape porcupine and several other rodent species. The Cape porcupine is distantly related to the laboratory rat, but still a member of the order Rodentia; thus, changes in the organization of these systems appears to demonstrate a form of constraint related to the phylogenetic level of the order.

Regional‐specific regulation of BDNF and trkB correlates with nigral dopaminergic cell sprouting following unilateral nigrostriatal axotomy

Axotomy is a powerful stimulus of axon growth and plastic changes. We investigated the potential role of BDNF/trkB signaling in the sprouting of dopaminergic nigral axons in response to axotomy of the medial forebrain bundle. Tyrosine hydroxylase immunohistochemistry revealed the existence of sprouting mechanisms in the axotomized substantia nigra (SN). Time-course changes of trkB mRNA expression demonstrated a robust increase in an area projecting from the rostral tip of the SN to the glial scar, which coincided with evidence of nigral dopaminergic sprouting. In addition, we found an early loss of this messenger in areas related to the knife cut, which recovered by 7 days postlesion. TrkB down-regulation appeared to be associated to the lesion-induced local damage, as it was restricted to an area showing Fluoro-Jade B- and TUNEL positive cells. In trkB-depleted areas, an inverse correlation between mRNA expressions of BDNF and trkB was apparent. Specific induction of BDNF mRNA was mostly seen in border of areas devoid of trkB mRNA. In contrast, in the areas exhibiting trkB mRNA expression, no BDNF mRNA was detected. We suggest that trkB levels could be a determinant element in regulating BDNF expression. Finally, the search for molecules involved in either promoting or inhibiting axonal growth, demonstrated up-regulation of GAP-43 and Nogo-A mRNA at sites close to the knife transections as early as 1 day postlesion. However, overall, Nogo-A induction was more robust than that seen for GAP-43.

Nuclear organization and morphology of cholinergic, putative catecholaminergic and serotonergic neurons in the brains of two species of African mole-rat

The distribution, morphology and nuclear subdivisions of the cholinergic, putative catecholaminergic and serotonergic systems within the brains of two species of African mole-rat (Cape dune mole-rat – Bathyergus suillus; highveld mole-rat – Cryptomys hottentotus pretoriae) were identified following immunohistochemistry for acetylcholinesterase, tyrosine hydroxylase and serotonin. The aim of the present study was to investigate possible differences in the complement of nuclear subdivisions of these systems by comparing those of the mole-rats to published studies of other rodents. The mole-rats used exhibit a major reduction of the visual system and live a subterranean lifestyle. These wild caught animals also have differing social systems, the Cape dune mole-rat is strictly solitary whereas the highveld mole-rat occurs in social familial units. While these differences, especially that of phenotype, may lead to the prediction of significant differences in the nuclear complement of these systems, we found that all nuclei identified in all three systems in the laboratory rat and other rodents had direct homologs in the brains of the mole-rats studied. There were no additional nuclei in the brains of the mole-rats that are not found in the laboratory rat or other rodents and vice versa. The mole-rats are phylogenetically distant from the laboratory rat, but are still part of the order Rodentia. We conclude that changes in the nuclear organization of the systems studied appear to demonstrate a form of constraint related to the phylogenetic level of the order.

Estrogen enhances the number of nigral dopaminergic neurons of adult male mice without affecting nigral neuroglial number and morphology

Emerging evidence indicate the modulating effects of estrogen on dopaminergic neurons in the substantia nigra pars compacta (SNpc). One of the mechanisms underlying the effect of estrogen is through neuroglia. To determine whether estrogen affects the number of dopaminergic neurons and reactive astrocytes and microglia in the SNpc of male mice, 14-week-old C57Bl/6 male mice were injected with 17beta-estradiol (E2) or vehicle for 10.5 days. On day 11 all mice were killed and the SNpc were collected and processed for lectin (GSI-B4) histochemistry, tyrosine hydroxylase (TH) immunohistochemistry or glial fibrillary acidic protein (GFAP) immunohistochemistry. Quantitative studies demonstrated that E2 significantly increases the number of TH-immunoreactive (IR) neurons in the SNpc but the hormone induces no change either in cell number or cell morphology of GFAP-IR astroglia and GSI-B4(+ve) microglia. These observations suggest that E2 can influence the number of nigral dopaminergic neurons of male mice and possibly protects dopaminergic neuronal loss during normal aging and in Parkinson's disease.

Neurochemistry of the afferents to the rat cochlear root nucleus: Possible synaptic modulation of the acoustic startle

Afferents to the primary startle circuit are essential for the elicitation and modulation of the acoustic startle reflex (ASR). In the rat, cochlear root neurons (CRNs) comprise the first component of the acoustic startle circuit and play a crucial role in mediating the ASR. Nevertheless, the neurochemical pattern of their afferents remains unclear. To determine the distribution of excitatory and inhibitory inputs, we used confocal microscopy to analyze the immunostaining for vesicular glutamate and GABA transporter proteins (VGLUT1 and VGAT) on retrogradely labeled CRNs. We also used reverse transcription–polymerase chain reaction (RT-PCR) and immunohistochemistry to detect and localize specific neurotransmitter receptor subunits in the cochlear root. Our results show differential distributions of VGLUT1- and VGAT-immunoreactive endings around cell bodies and dendrites. The RT-PCR data showed a positive band for several ionotropic glutamate receptor subunits, M1–M5 muscarinic receptor subtypes, the glycine receptor α1 subunit (GlyRα1), GABAA, GABAB, and subunits of α2 and β-noradrenergic receptors. By immunohistochemistry, we confirmed that CRN cell bodies exhibit positive immunoreaction for the glutamate receptor (GluR) 3 and NR1 GluR subunits. Cell bodies and dendrites were also positive for M2 and M4, and GlyRα1. Other subunits, such as GluR1 and GluR4 of the AMPA GluRs, were observed in glial cells neighboring unlabeled CRN cell bodies. We further confirmed the existence of noradrenergic afferents onto CRNs from the locus coeruleus by combining tyrosine hydroxylase immunohistochemistry and tract-tracing experiments. Our results provide valuable information toward understanding how CRNs might integrate excitatory and inhibitory inputs, and hence how they could elicit and modulate the ASR.

A nitric oxide synthase inhibitor decreases 6-hydroxydopamine effects on tyrosine hydroxylase and neuronal nitric oxide synthase in the rat nigrostriatal pathway

There is evidence that nitric oxide plays a role in the neurotransmitter balance within the basal ganglia and in the pathology of Parkinson's disease. In the present work we investigated in striatal 6-hydroxydopamine (6-OHDA) lesioned rats the effects of a nitric oxide synthase (NOS) inhibitor, NG-nitro- l-arginine ( l-NOARG), given systemically on both the dopaminergic (DA) neuronal loss and the neuronal NOS cell density. We analyzed the DA neuronal loss through tyrosine hydroxylase immunohistochemistry (TH). The nitrergic system was evaluated using an antibody against the neuronal NOS (nNOS) isoform. Treatment with the l-NOARG significantly reduced 6-OHDA-induced dopaminergic damage in the dorsal striatum, ventral substantia nigra and lateral globus pallidus, but had no effects in the dorsal substantia nigra and in the cingulate cortex. Furthermore, l-NOARG reduced 6-OHDA-induced striatal increase, and substantia nigra compacta decrease, in the density of neuronal nitric oxide synthase positive cells. These results suggest that nitric oxide synthase inhibition may decrease the toxic effects of 6-OHDA on dopaminergic terminals and on dopamine cell bodies in sub-regions of the SN and on neuronal nitric oxide synthase cell density in the rat brain.

The effect of glucocorticoids on bradykinesia induced by immobilization stress

It is well known that the release of glucocorticoids from the adrenal gland is increased in response to many types of stressors and plays a principal role in stress responses. We have shown that the synthesis of prostaglandins (PGs) in the brain is increased under several stress conditions including immobilization (IMO), and that endogenous glucocorticoids counteract this stress-induced PG synthesis. It was also recently reported that IMO damages dopaminergic (DA) neurons in the substantia nigra (SN), which is known to cause symptoms similar to Parkinson's disease (PD). The present study was therefore undertaken to determine the role of glucocorticoids in modulating the signs of PD induced by IMO. The pole test, in which each mouse was placed head upward at the top of a pole and the time taken to turn downward and to arrive on the floor was recorded, and immunohistochemistry for tyrosine hydroxylase (TH) in the SN were performed to evaluate bradykinesia and injury of DA neurons, respectively. Intact and adrenalectomized (ADX) mice were immobilized for 2 h twice, 1 day apart. Both bradykinesia and a decrease in the number of TH-immunoreactive cells in the SN were observed in ADX mice, but not in intact mice, following IMO. These effects of IMO on ADX mice were restored by treatment with corticosterone or indomethacin, a PG synthesis inhibitor. These results suggest that glucocorticoids play a role in preventing the detrimental effect of IMO on nigral DA neurons and resulting bradykinesia, and that this effect of IMO involves PG-mediated mechanisms.

Hemiparkinsonian rats rotate toward the side with the weaker dopaminergic neurotransmission

Rats with unilateral lesion of the substantia nigra pars compacta (SNpc) have been used as a model of Parkinson's disease. Depending on the lesion protocol and on the drug challenge, these rats rotate in opposite directions. The aim of the present study was to propose a model to explain how critical factors determine the direction of these turns. Unilateral lesion of the SNpc was induced with 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Separate analysis showed that neither the type of neurotoxin nor the site of lesion along the nigrostriatal pathway was able to predict the direction of the turns these rats made after they were challenged with apomorphine. However, the combination of these two factors determined the magnitude of the lesion estimated by tyrosine-hydroxylase immunohistochemistry and HPLC-ED measurement of striatal dopamine. Very small lesions did not cause turns, medium-size lesions caused ipsiversive turns, and large lesions caused contraversive turns. Large-size SNpc lesions resulted in an increased binding of [3H]raclopride to D2 receptors, while medium-size lesions reduced the binding of [3H]SCH-23390 D1 receptors in the ipsilateral striatum. These results are coherent with the model proposing that after challenged with a dopamine receptor agonist, unilaterally SNpc-lesioned rats rotate toward the side with the weaker activation of dopamine receptors. This activation is weaker on the lesioned side in animals with small SNpc lesions due to the loss of dopamine, but stronger in animals with large lesions due to dopamine receptor supersensitivity.

Striatal β-Amyloid Deposition in Parkinson Disease With Dementia

Dementia is common in Parkinson disease (PD), although its anatomic and pathologic substrates remain undefined. Recently, striatal abnormalities in Lewy body diseases have been described, but their clinical relevance is not clear. Thirty PD cases from the United Kingdom Parkinson's Disease Society Tissue Bank were grouped as demented (PDD; n = 16) and nondemented (PD; n = 14) based on a review of clinical records. The extent of alpha-synuclein, tau, and amyloid beta peptide (Abeta) deposition in the caudate nucleus, putamen, and nucleus accumbens was assessed. All cases showed severe dopaminergic striatal terminal denervation based on tyrosine hydroxylase immunohistochemistry. Alpha-synuclein and tau deposition in the striatum were rare in both groups, but the Abeta burden was significantly greater in the striatum of PD cases with dementia than present in the nondemented PD group. Striatal Abeta deposition was type-independent of Alzheimer disease changes in the cortex and was minimal in nondemented PD cases. We conclude that Abeta deposition in the striatum strongly correlates with dementia in PD.

Adjunctive use of the non‐ionic surfactant Poloxamer 188 improves fetal dopaminergic cell survival and reinnervation in a neural transplantation strategy for Parkinson's disease

Although neural transplantation of fetal dopaminergic cells is a promising therapy for Parkinson's disease, poor transplanted cell survival limits its efficacy. In the present study it was hypothesized that the use of Poloxamer 188 (P188), a non-ionic surfactant, during cell preparation and transplantation may protect cells from associated mechanical injury and thus improve transplanted cell survival in a rat model of Parkinson's disease. Fetal rat dopaminergic tissue was dissociated in media with or without P188 and then cultured for 1 week or transplanted into the striatum of rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic pathway. Fetal dopaminergic cell survival and reinnervation of the host brain were examined using tyrosine hydroxylase immunohistochemistry and stereological quantification. The number of surviving tyrosine hydroxylase-immunoreactive cells in vitro and in vivo was significantly increased by 2.2-fold by incubating fetal dopaminergic cells with P188 during tissue dissociation. Furthermore, the striatal reinnervation in parkinsonian rats that received intrastriatal transplants of P188-exposed dopaminergic cells was significantly enhanced (1.8-fold increase) compared with rats that received non-P188-treated cells. In conclusion, P188 protects fetal dopaminergic cells from mechanical injury by increasing cell survival and enhances dopaminergic fibre outgrowth into the transplanted striatum. Use of P188 may thus be an important adjunct to improve the clinical efficacy of neural transplantation for Parkinson's disease.

Neuroprotective Effects of Delta-9-Tetrahydrocannabinol in a Marmoset Parkinson Model

The present medication in Parkinson's disease (PD) is unable to stop or slow down the progression of the dis- ease. Therefore pharmacological intervention at crucial steps in the neuronal cell death processes would be a better stra- tegy. Cannabinoids are potent neuroprotective compounds in models of oxidative stress and excitotoxicity and offer po- tential protection in models of PD. Therefore the present study determines the neuroprotective effects of � 9 - tetrahydrocannabinol (� 9 -THC) in the marmoset 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model on beha- vior and pathology. Twelve marmoset monkeys were treated with a total cumulative dose of 6 mg/kg MPTP in 9 days. Seven of these animals received simultaneously a daily oral dose of � 9 -THC (4 mg/kg) and five animals received simulta- neously vehicle for 27 days. The parkinsonian symptoms were observed daily and locomotor activity and hand-eye coor- dination were tested once a week during the experimental period. Postmortem, dopamine levels in the striatum were ana- lyzed and tyrosine hydroxylase immunohistochemistry was applied to determine viable dopaminergic neurons in the sub- stantia nigra. � 9 -THC has no protective effects on any parameter. These negative results might be related to the severity of the cell death induction by MPTP in relation to the low dose of � 9 -THC used in this Parkinson model.

Increased progenitor cell proliferation and astrogenesis in the partial progressive 6-hydroxydopamine model of Parkinson’s disease

The existence of endogenous progenitor cells in the adult mammalian brain presents an exciting and attractive alternative to existing therapeutic options for treating neurodegenerative diseases such as Parkinson’s disease (PD). However, prior to designing endogenous cell therapies, the effect of PD neuropathology on endogenous progenitor cell proliferation and their neurogenic potential must be investigated. This study examined the effect of dopaminergic cell loss on the proliferation and differentiation of subventricular zone- (SVZ) and midbrain-derived progenitor cells in the adult rodent brain, using the partial progressive 6-hydroxydopamine (6-OHDA) lesion model of PD. Cell proliferation and differentiation were assessed with 5-bromo-2′-deoxyuridine (BrdU) labeling and immunohistochemistry for cell type-specific markers. Tyrosine hydroxylase immunohistochemistry demonstrated a complete loss of nigrostriatal projections in the striatum and a subsequent progressive loss of dopamine (DA) cells in the SN. Quantification indicated that 6-OHDA lesion–induced cell degeneration produced a significant increase in BrdU immunoreactivity in the SVZ, ipsilateral to the lesioned hemisphere from 3 to 21 days post-lesion, compared with sham-lesioned animals. Similarly, in the striatum we observed a significant increase in the total number of BrdU positive cells in 6-OHDA-lesioned animals at all time points examined. More importantly, a significant increase in midbrain-derived BrdU positive cells was demonstrated in 6-OHDA-lesioned animals 28 days post-lesion. While we did not detect neurogenesis, BrdU labeled cells co-expressing the astrocytic marker glial fibrillary acidic protein (GFAP) were widely distributed throughout the 6-OHDA-lesioned striatum at all time points. In contrast, BrdU-labeled cells in the SN of 6-OHDA-lesioned animals did not co-express neural markers. These results demonstrate that DA-ergic neurodegeneration in the partial progressive 6-OHDA-lesioned rat brain increases SVZ- and midbrain-derived progenitor cell proliferation. While, newborn striatal progenitors undergo robust astrogenesis, newborn midbrain-derived progenitors remain in an undifferentiated state suggesting local environments differentially regulate endogenous progenitor cell populations in PD.