Region-specific mouse brain ganglioside distribution revealed by an improved isobaric aminoxyTMT labeling strategy with automated data processing

Gangliosides are specialized glycosphingolipids most abundant in the central nervous system. Their complex amphiphilic structure is essential to the formation of membrane lipid rafts and for molecular recognition. Dysfunction of lipid rafts and ganglioside metabolism has been linked to cancer, metabolic disorders, and neurodegenerative disorders. Changes in ganglioside concentration and diversity during the progression of disease have made them potential biomarkers for early detection and shed light on disease mechanisms. Chemical derivatization facilitates whole ion analysis of gangliosides while improving ionization, providing rich fragmentation spectra, and enabling multiplexed analysis schemes such as stable isotope labeling. In this work, we report improvement to our previously reported isobaric labeling methodology for ganglioside analysis by increasing buffer concentration and removing solid-phase extraction desalting for a more complete and quantitative reaction. Identification and quantification of gangliosides are automated through MS-DIAL with an in-house ganglioside derivatives library. We have applied the updated methodology to relative quantification of gangliosides in six mouse brain regions (cerebellum, pons/medulla, midbrain, thalamus/hypothalamus, cortex, and basal ganglia) with 2 mg tissue per sample, and region-specific distributions of 88 ganglioside molecular species are described with ceramide isomers resolved. This method is promising for application to comparative analysis of gangliosides in biological samples.

Noncoding RNAs and Midbrain DA Neurons: Novel Molecular Mechanisms and Therapeutic Targets in Health and Disease

Midbrain dopamine neurons have crucial functions in motor and emotional control and their degeneration leads to several neurological dysfunctions such as Parkinson’s disease, addiction, depression, schizophrenia, and others. Despite advances in the understanding of specific altered proteins and coding genes, little is known about cumulative changes in the transcriptional landscape of noncoding genes in midbrain dopamine neurons. Noncoding RNAs—specifically microRNAs and long noncoding RNAs—are emerging as crucial post-transcriptional regulators of gene expression in the brain. The identification of noncoding RNA networks underlying all stages of dopamine neuron development and plasticity is an essential step to deeply understand their physiological role and also their involvement in the etiology of dopaminergic diseases. Here, we provide an update about noncoding RNAs involved in dopaminergic development and metabolism, and the related evidence of these biomolecules for applications in potential treatments for dopaminergic neurodegeneration.

Simultaneous voltammetric detection of glucose and lactate fluctuations in rat striatum evoked by electrical stimulation of the midbrain

Glucose and lactate provide energy for cellular function in the brain and serve as an important carbon source in the synthesis of a variety of biomolecules. Thus, there is a critical need to quantitatively monitor these molecules in situ on a time scale commensurate with neuronal function. In this work, carbon-fiber microbiosensors were coupled with fast-scan cyclic voltammetry to monitor glucose and lactate fluctuations at a discrete site within rat striatum upon electrical stimulation of the midbrain projection to the region. Systematic variation of stimulation parameters revealed the distinct dynamics by which glucose and lactate responded to the metabolic demand of synaptic function. Immediately upon stimulation, extracellular glucose and lactate availability rapidly increased. If stimulation was sufficiently intense, concentrations then immediately fell below baseline in response to incurred metabolic demand. The dynamics were dependent on stimulation frequency, such that more robust fluctuations were observed when the same number of pulses was delivered at a higher frequency. The rates at which glucose was supplied to, and depleted from, the local recording region were dependent on stimulation intensity, and glucose dynamics led those of lactate in response to the most substantial stimulations. Glucose fluctuated over a larger concentration range than lactate as stimulation duration increased, and glucose fell further from baseline concentrations. These real-time measurements provide an unprecedented direct comparison of glucose and lactate dynamics in response to metabolic demand elicited by neuronal activation. Graphical abstract.

Differential regional and cellular distribution of TFF3 peptide in the human brain

TFF3 is a member of the trefoil factor family (TFF) predominantly secreted by mucous epithelia. Minute amounts are also expressed in the immune system and the brain. In the latter, particularly the hypothalamo-pituitary axis has been investigated in detail in the past. Functionally, cerebral TFF3 has been reported to be involved in several processes such as fear, depression, learning and object recognition, and opiate addiction. Furthermore, TFF3 has been linked with neurodegenerative and neuropsychiatric disorders (e.g., Alzheimer's disease, schizophrenia, and alcoholism). Here, using immunohistochemistry, a systematic survey of the TFF3 localization in the adult human brain is presented focusing on extrahypothalamic brain areas. In addition, the distribution of TFF3 in the developing human brain is described. Taken together, neurons were identified as the predominant cell type to express TFF3, but to different extent; TFF3 was particularly enriched in various midbrain and brain stem nuclei. Besides, TFF3 immunostaining staining was observed in oligodendroglia and the choroid plexus epithelium. The wide cerebral distribution should help to explain its multiple effects in the CNS.

The neuroprotective potential of sinapic acid in the 6-hydroxydopamine-induced hemi-parkinsonian rat

Parkinson's disease (PD) is a neurodegenerative movement disorder due to selective loss of dopaminergic neurons of mesencephalic substantia nigra pars compacta (SNC) with debilitating motor symptoms. Current treatments for PD afford symptomatic relief with no prevention of disease progression. Due to the antioxidant and neuroprotective potential of sinapic acid, this study was conducted to evaluate whether this agent could be of benefit in an experimental model of early PD in rat. Unilateral intrastriatal 6-hydroxydopamine (6-OHDA)-lesioned rats were pretreated p.o. with sinapic acid at doses of 10 or 20 mg/kg. One week after surgery, apomorphine caused significant contralateral rotations, a significant reduction in the number of Nissl-stained and tyrosine hydroxylase (TH)-positive neurons and a significant increase of iron reactivity on the left side of SNC. Meanwhile, malondialdehyde (MDA) and nitrite levels in midbrain homogenate significantly increased and activity of superoxide dismutase (SOD) significantly reduced in the 6-OHDA-lesioned group. In addition, sinapic acid at a dose of 20 mg/kg significantly improved turning behavior, prevented loss of SNC dopaminergic neurons, lowered iron reactivity, and attenuated level of MDA and nitrite. These results indicate the neuroprotective potential of sinapic acid against 6-OHDA neurotoxicity that is partially due to the attenuation of oxidative stress and possibly lowering nigral iron level.

Lesion profiles and gliosis in the brainstem of 135 Swiss Cows with Bovine Spongiform Encephalopathy (BSE)

Lesion profiles are considered to be an important tool for the comparison of the various animal and human spongiform encephalopathies and to obtain information upon prion strain variations. Histological and immunohistochemical reactions (PrPsc, GFAP) in 13 brain areas at 4 levels in the brainstem from 135 BSE-positive and 45 BSE-negative cases were retrospectively evaluated. In this retrospective study a lesion profile based on histological features was worked out on the basis of BSE cases originating from Switzerland over a period of ten years. They were confirmed post mortem by histology and immunohistology. Our findings were reviewed in comparison with lesion profiles published in England. No striking differences comparing type and quality of lesions in the relevant areas between the Swiss and the English cases were evident. Moreover, the lesion profiles and the character of the lesions did not differ between animals born before or after the offal feeding ban, which supports the hypothesis that the Swiss epidemic is sustained by the same single, stable strain of the BSE agent, which is probably the same as in the English epidemic. There was a good correlation between PrPsc accumulation and spongiform changes, in particular in those areas which were morphologically most affected. Astrocytosis in BSE was quantified. A significant rise in GFAP-positive cells could be shown comparing the brain stem nuclei of BSE affected with BSE-unaffected cattle, despite considerable variation between the cases and between the nuclei. The observed astrocytosis did correlate with vacuolation of the neuropil and of perikarya as well as with PrPsc accumulation.

Mechanisms explaining transitions between tonic and phasic firing in neuronal populations as predicted by a low dimensional firing rate model

Several firing patterns experimentally observed in neural populations have been successfully correlated to animal behavior. Population bursting, hereby regarded as a period of high firing rate followed by a period of quiescence, is typically observed in groups of neurons during behavior. Biophysical membrane-potential models of single cell bursting involve at least three equations. Extending such models to study the collective behavior of neural populations involves thousands of equations and can be very expensive computationally. For this reason, low dimensional population models that capture biophysical aspects of networks are needed. The present paper uses a firing-rate model to study mechanisms that trigger and stop transitions between tonic and phasic population firing. These mechanisms are captured through a two-dimensional system, which can potentially be extended to include interactions between different areas of the nervous system with a small number of equations. The typical behavior of midbrain dopaminergic neurons in the rodent is used as an example to illustrate and interpret our results. The model presented here can be used as a building block to study interactions between networks of neurons. This theoretical approach may help contextualize and understand the factors involved in regulating burst firing in populations and how it may modulate distinct aspects of behavior.

Early expression of axon guidance molecules in the embryonic chick mesencephalon and pretectum

Early axon tracts in the developing vertebrate brain are established along precise paths. Yet, little is known about axon guidance processes at early stages of rostral brain development. Using whole mount in situ hybridisation in combination with immunohistochemistry, we have analysed the expression patterns of Slits, Netrins, Semaphorins and the respective receptors during the formation of the early axon scaffold, particularly focusing on the pretectal-mesencephalic boundary. Many of these guidance molecules are expressed in close correlation with the growing tracts, and the nuclei of the corresponding neurons often express the respective receptors. The expression patterns of Slits and Netrins implicate them with the positioning of the longitudinal tracts along the dorsoventral axis, while Semaphorins could provide guidance at specific choice points. Our study provides a catalogue of gene expression for future studies on axon guidance mechanisms in the early brain.

Effect of dioxins on regulation of tyrosine hydroxylase gene expression by aryl hydrocarbon receptor: a neurotoxicology study

BACKGROUND

Dioxins and related compounds are suspected of causing neurological disruption. Epidemiological studies indicated that exposure to these compounds caused neurodevelopmental disturbances such as learning disability and attention deficit hyperactivity disorder, which are thought to be closely related to dopaminergic dysfunction. Although the molecular mechanism of their actions has not been fully investigated, a major participant in the process is aryl hydrocarbon receptor (AhR). This study focused on the effect of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on the regulation of TH, a rate-limiting enzyme of dopamine synthesis, gene expression by AhR.

METHODS

N2a-Rbeta cells were established by transfecting murine neuroblastoma Neuro2a with the rat AhR cDNA. TH expression induced by TCDD was assessed by RT-PCR and Western blotting. Participation of AhR in TCDD-induced TH gene expression was confirmed by suppressing AhR expression using the siRNA method. Catecholamines including dopamine were measured by high-performance liquid chromatography. A reporter gene assay was used to identify regulatory motifs in the promoter region of TH gene. Binding of AhR with the regulatory motif was confirmed by an electrophoretic mobility shift assay (EMSA).

RESULTS

Induction of TH by TCDD through AhR activation was detected at mRNA and protein levels. Induced TH protein was functional and its expression increased dopamine synthesis. The reporter gene assay and EMSA indicated that AhR directly regulated TH gene expression. Regulatory sequence called aryl hydrocarbon receptor responsive element III (AHRE-III) was identified upstream of the TH gene from -285 bp to -167 bp. Under TCDD exposure, an AhR complex was bound to AHRE-III as well as the xenobiotic response element (XRE), though AHRE-III was not identical to XRE, the conventional AhR-binding motif.

CONCLUSION

Our results suggest TCDD directly regulate the dopamine system by TH gene transactivation via an AhR-AHRE-III-mediated pathway. The AhR- mediated pathway could have a particular AhR-mediated genomic control pathway transmitting the effects of TCDD action to target cells in the development of dopaminergic disabilities.

Prenatal development of NMDA receptor composition and function in trigeminal neurons

The prenatal development of neural circuits for rhythmical oral-motor behaviors used for feeding is essential for the survival of the newborn mammal. The N-methyl-D-aspartate (NMDA) receptor plays a critical role in brainstem circuits underlying postnatal oral-motor behaviors. To understand a role for the NMDA receptor in the emergence of sucking behavior we conducted physiological and immunohistochemical experiments using fetal rats. Physiology experiments examined the development of the NMDA dose response of the brainstem circuit responsible for generating rhythmical trigeminal activity by recording trigeminal motor outputs using an in vitro preparation. The high dose of NMDA agonist bath application affected the mean cycle duration of rhythmical trigeminal activity (RTA) at both embryonic day (E) 18-19 and E20-21 in comparison with standard concentration of NMDA agonist. NMDA receptor immunohistochemistry studies, using antibodies directed against subunits NR1, NR2A, NR2B, NR3A and NR3B were performed to determine the prenatal regulation of NMDA subunits in trigeminal motoneurons (Mo5), and mesencephalic trigeminal neurons (Me5) between E17 to E20. In Mo5, NR1, NR2A, NR2B and NR3A immunoreactivity was observed throughout the time frame sampled. NR3B immunoreactivity was not observed in Mo5 or Me5. In Mo5, there was a significant decrease in the percentage of NR2B immunoreactive neurons between E17 and E20, and a concurrent increase in the NR2A/NR2B ratio between E17 and E20. In Me5, NR1, NR2A and NR3A immunoreactivity was observed throughout the time frame sampled; a significant decrease in the percentage of NR2A immunoreactive neurons between E17 and E20, and NR3A immunoreactive neurons between E17 and E18 occurred. The timing of subunit changes between E17 and E18 is coincident with the prenatal emergence of rhythmical jaw movements, and in vitro rhythmical trigeminal activity, shown in earlier studies. Our data suggest that NMDA receptor plays an important role in the development and function of prenatal oral-motor circuits.

Nonserotonergic projection neurons in the midbrain raphe nuclei contain the vesicular glutamate transporter VGLUT3

The brainstem raphe nuclei are typically assigned a role in serotonergic brain function. However, numerous studies have reported that a large proportion of raphe projection cells are nonserotonergic. The identity of these projection cells is unknown. Recent studies have reported that the vesicular glutamate transporter VGLUT3 is found in both serotonergic and nonserotonergic neurons in both the median raphe (MR) and dorsal raphe (DR) nuclei. We injected the retrograde tracer cholera toxin subunit B into either the dorsal hippocampus or the medial septum (MS) and used triple labeled immunofluorescence to determine if nonserotonergic raphe cells projecting to these structures contained VGLUT3. Consistent with previous studies, only about half of retrogradely labeled MR neurons projecting to the hippocampus contained serotonin, whereas a majority of the retrogradely labeled nonserotonergic cells contained VGLUT3. Similar patterns were observed for MR cells projecting to the MS. About half of retrogradely labeled nonserotonergic neurons in the DR contained VGLUT3. Additionally, a large number of retrogradely labeled cells in the caudal linear and interpeduncular nuclei projecting to the MS were found to contain VGLUT3. These data suggest the enigmatic nonserotonergic projection from the MR to forebrain regions may be glutamatergic. In addition, these results demonstrate a dissociation between glutamatergic and serotonergic MR afferent inputs to the MS and hippocampus suggesting divergent and/or complementary roles of these pathways in modulating cellular activity within the septohippocampal network.

Effects of anthocyanins on psychological stress-induced oxidative stress and neurotransmitter status

There is strong evidence that oxidative stress participates in the etiology of neurodegenerative diseases such as Parkinson's, and Alzheimer's diseases. Moreover, emotional stress effects in the central nervous system play a vital role in homeostasis. The protective effect of anthocyanins on the cerebral oxidative stress was studied using the whiskers cut model. In mice, such treatment causes psychological or emotional distress leading to oxidative stress in tissues. To investigate the in vivo antioxidant activity of anthocyanins, an extract of Vaccinium myrtillis L., an anthocyanin mixture, was orally administered (100 mg/kg of body weight.) to mice for 7 days, and then psychological stress was assessed by cutting off their whiskers. Whisker removal increased both protein carbonyl formation and lipid peroxidation in the brain, heart, kidney, and liver. Further, the levels of oxidative markers showed regional differences in the brain. Concomitantly, dopamine neurotransmitter levels were altered in both the midbrain and the brain cortex. Orally administered anthocyanins were also active in the brain, suppressing stress-induced cerebral oxidative stress and dopamine abnormalities in distressed mice. These effects of anthocyanin treatment suggest their possible usefulness for the treatment of cerebral disorders related to oxidative stress.

Engaging in paced mating, but neither exploratory, anti-anxiety, nor social behavior, increases 5alpha-reduced progestin concentrations in midbrain, hippocampus, striatum, and cortex

Sequential actions of 17beta-estradiol (E(2)) and progesterone (P(4)) in the hypothalamus and the P(4) metabolite, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), in the midbrain ventral tegmental area (VTA) respectively mediate the initiation and intensity of lordosis of female rats and may also modulate anxiety and social behaviors, through actions in these, and/or other brain regions. Biosynthesis of E(2), P(4), and 3alpha,5alpha-THP can also occur in brain, independent of peripheral gland secretion, in response to environmental/behavioral stimuli. The extent to which engaging in tasks related to reproductive behaviors and/or mating increased E(2) or progestin concentrations in brain was investigated. In Experiment 1, proestrous rats were randomly assigned to be tested in individual tasks, including the open field, elevated plus maze, partner preference, social interaction, or no test control, in conjunction with paced mating or no mating. Engaging in paced mating, but not other behaviors, significantly increased dihydroprogesterone (DHP) and 3alpha,5alpha-THP levels in midbrain, hippocampus, striatum, and cortex. In Experiment 2, proestrous rats were tested in the combinations of the above tasks (open field and elevated plus maze, partner preference, and social interaction) with or without paced mating. As in Experiment 1, only engaging in paced mating increased DHP and 3alpha,5alpha-THP concentrations in midbrain, hippocampus, striatum, and cortex. Thus, paced mating enhances concentrations of 5alpha-reduced progestins in brain areas associated with reproduction (midbrain), as well as exploration/anxiety (hippocampus and striatum) and social behavior (cortex).

Distribution and characterization of estrogen receptor G protein-coupled receptor 30 in the rat central nervous system

The G protein-coupled receptor 30 (GPR 30) has been identified as the non-genomic estrogen receptor, and G-1, the specific ligand for GPR30. With the use of a polyclonal antiserum directed against the human C-terminus of GPR30, immunohistochemical studies revealed GPR30-immunoreactivity (irGPR30) in the brain of adult male and non-pregnant female rats. A high density of irGPR30 was noted in the Islands of Calleja and striatum. In the hypothalamus, irGPR30 was detected in the paraventricular nucleus and supraoptic nucleus. The anterior and posterior pituitary contained numerous irGPR30 cells and terminal-like endings. Cells in the hippocampal formation as well as the substantia nigra were irGPR30. In the brainstem, irGPR30 cells were noted in the area postrema, nucleus of the solitary tract, and dorsal motor nucleus of the vagus; a cluster of cells were prominently labeled in the nucleus ambiguus. Tissue sections processed with pre-immune serum showed no irGPR30, affirming the specificity of the antiserum. G-1 (100 nM) caused a large increase of intracellular calcium concentrations [Ca(2+) ](i) in dissociated and cultured rat hypothalamic neurons, as assessed by microfluorometric Fura-2 imaging. The calcium response to a second application of G-1 showed a marked homologous desensitization. Our result shows a high expression of irGPR30 in the hypothalamic-pituitary axis, hippocampal formation, and brainstem autonomic nuclei; and the activation of GPR30 by G-1 is associated with a mobilization of calcium in dissociated and cultured rat hypothalamic neurons.

A new model to study compensatory mechanisms in MPTP-treated monkeys exhibiting recovery

The cardinal symptoms in Parkinson's disease (PD), akinesia, rigidity and tremor, are only observed when the striatal level of dopamine is decreased by 60-80%. During the preclinical phase of PD, compensatory mechanisms are probably involved in delaying the appearance of motor symptoms. In a MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) monkey model of PD, a spontaneous recovery has been reported after initial intoxication suggesting that compensatory mechanisms are activated in this model as well. Assuming that mechanisms are similar in these phenomena, the study of recovery in monkeys following MPTP intoxication may enable identification of compensatory mechanisms involved in the preclinical phase of PD. In order to maximize the temporal similarity between PD and the MPTP model, we assessed a new progressive monkey model in which spontaneous recovery is expressed systematically and to characterize it based on (1) its behavioural features, and (2) the presence of compensatory mechanisms revealed by an immunohistological approach comparing dopaminergic and serotoninergic innervation between monkeys either exhibiting behavioural recovery or stable motor symptoms. This immunohistological study focused on the substantia nigra, striatum and pallidum, and their anatomical and functional subdivisions: sensorimotor, associative and limbic. The behavioural analysis revealed that with progressive MPTP intoxication motor symptoms were initially expressed in all monkeys. Observable recovery from these symptoms occurred in all monkeys (7/7) within 3-5 weeks after the last MPTP injection, and most exhibited a full recovery. In contrast, acute intoxication induced stable motor symptoms. Despite this obvious behavioural difference, immunohistological methods revealed that the loss of dopaminergic cell bodies in substantia nigra was substantial and similar in both MPTP-treated groups. However, quantification of fibres revealed that recovered monkeys displayed more dopaminergic and serotoninergic fibres than those with stable motor symptoms in sensorimotor and associative territories of striatum and more dopaminergic fibres in internal pallidum. This study provides a new model of PD where all monkeys expressed functional recovery from motor symptoms despite a large dopaminergic neuronal loss. The immunohistological results suggest that both dopamine and serotonin could be implicated in the compensatory mechanisms.

Activation of apoptosis signal regulating kinase 1 (ASK1) and translocation of death‐associated protein, Daxx, in substantia nigra pars compacta in a mouse model of Parkinson's disease: protection by α‐lipoic acid

Parkinson's disease (PD), a neurodegenerative disorder, causes severe motor impairment due to loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). MPTP, a neurotoxin that causes dopaminergic cell loss in mice, was used in an animal model to study the pathogenic mechanisms leading to neurodegeneration. We observed the activation of apoptosis signal regulating kinase (ASK1, MAPKKK) and phosphorylation of its downstream targets MKK4 and JNK, 12 h after administration of a single dose of MPTP. Further, Daxx, the death-associated protein, translocated to the cytosol selectively in SNpc neurons seemingly due to MPTP mediated down-regulation of DJ-1, the redox-sensitive protein that binds Daxx in the nucleus. Coadministration of alpha-lipoic acid (ALA), a thiol antioxidant, abolished the activation of ASK1 and phosphorylation of downstream kinases, MKK4, and JNK and prevented the down-regulation of DJ-1 and translocation of Daxx to the cytosol seen after MPTP. ALA also attenuated dopaminergic cell loss in SNpc seen after subchronic MPTP treatment. Our studies demonstrate for the first time that MPTP triggers death signaling pathway by activating ASK1 and translocating Daxx, in vivo, in dopaminergic neurons in SNpc of mice and thiol antioxidants, such as ALA terminate this cascade and afford neuroprotection.

Overexpression of pitx3 upregulates expression of BDNF and GDNF in SH-SY5Y cells and primary ventral mesencephalic cultures

The transcription factor Pitx3 plays an important role in the development of midbrain to promote the growth and differentiation of dopamine neurons. The present study has demonstrated that overexpression of Pitx3 in SH-SY5Y cells and primary ventral mesencephalic (VM) cultures significantly increased the mRNA levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), and remarkably elevated the protein levels of these two neurotrophic factors. Our data provide the first evidence that pitx3-expressing cells are able to upregulate the expression of BDNF and GDNF. Therefore, Pitx3 might be a good target for the treatment of Parkinson's disease.

Long-term consequences of human alpha-synuclein overexpression in the primate ventral midbrain

Overexpression of human alpha-synuclein (alpha-syn) using recombinant adeno-associated viral (rAAV) vectors provides a novel tool to study neurodegenerative processes seen in Parkinson's disease and other synucleinopathies. We used a pseudotyped rAAV2/5 vector to express human wild-type (wt) alpha-syn, A53T mutated alpha-syn, or the green fluorescent protein (GFP) in the primate ventral midbrain. Twenty-four adult common marmosets (Callithrix jacchus) were followed with regular behavioural tests for 1 year after transduction. alpha-Syn overexpression affected motor behaviour such that all animals remained asymptomatic for at least 9 weeks, then motor bias comprising head position bias and full body rotations were seen in wt-alpha-syn expressing animals between 15 and 27 weeks; in the later phase, the animals overexpressing the A53T alpha -syn, in particular, showed a gradual worsening of motor performance, with increased motor coordination errors. Histological analysis from animals overexpressing either the wt or A53T alpha -syn showed prominent degeneration of dopaminergic fibres in the striatum. In the ventral midbrain, however, the dopaminergic neurodegeneration was more prominent in the A53T group than in the WT group suggesting differential toxicity of these two proteins in the primate brain. The surviving cell bodies and their processes in the substantia nigra were stained by antibodies to the pathological form of alpha-syn that is phosphorylated at Ser position 129. Moreover, we found, for the first time, ubiquitin containing aggregates after overexpression of alpha-syn in the primate midbrain. There was also a variable loss of oligodendroglial cells in the cerebral peduncle. These histological and behavioural data suggest that this model provides unique opportunities to study progressive neurodegeneration in the dopaminergic system and deposition of alpha-syn and ubiquitin similar to that seen in Parkinson's disease, and to test novel therapeutic targets for neuroprotective strategies.

Molecular programming of stem cells into mesodiencephalic dopaminergic neurons

In a screen for homeobox transcription factors expressed in the embryonic ventral midbrain, Andersson et al. recently identified Lmx1a and Msx1. Using in ovo electroporation in chick embryos, they showed that these factors are crucial for initiating the differentiation of neuroepithelial progenitor neurons into mesodiencephalic dopaminergic (mdDA) neurons. Lmx1a also initiated a developmental program that drove an mdDA phenotype in mouse embryonic stem cells. This indicates that these factors can be exploited in cell-replacement strategies for treatment of Parkinson's disease.

Quantitative genetic analysis of brain copper and zinc in BXD recombinant inbred mice

Copper and zinc are trace nutrients essential for normal brain function, yet an excess of these elements can be toxic. It is important therefore that these metals be closely regulated. We recently conducted a quantitative trait loci (QTL) analysis to identify chromosomal regions in the mouse containing possible regulatory genes. The animals came from 15 strains of the BXD/Ty recombinant inbred (RI) strain panel and the brain regions analyzed were frontal cortex, caudate-putamen, nucleus accumbens and ventral midbrain. Several QTL were identified for copper and/or zinc, most notably on chromosomes 1, 8, 16 and 17. Genetic correlational analysis also revealed associations between these metals and dopamine, cocaine responses, saccharine preference, immune response and seizure susceptibility. Notably, the QTL on chromosome 17 is also associated with seizure susceptibility and contains the histocompatibility H2 complex. This work shows that regulation of zinc and copper is under polygenic influence and is intimately related to CNS function. Future work will reveal genes underlying the QTL and how they interact with other genes and the environment. More importantly, revelation of the genetic underpinnings of copper and zinc brain homeostasis will aid our understanding of neurological diseases that are related to copper and zinc imbalance.

Non-cannabinoid CB1, non-cannabinoid CB2 antinociceptive effects of several novel compounds in the PPQ stretch test in mice

The analgesic and anti-hyperalgesic effects of cannabinoid- and vanilloid-like compounds, plus the fatty acid amide hydrolase (FAAH) inhibitor Cyclohexylcarbamic acid 3'-carbamoyl-biphenyl-3-yl ester (URB597), and acetaminophen, were evaluated in the phenyl-p-quinone (PPQ) pain model, using different routes of administration in combination with opioid and cannabinoid receptor antagonists. All the compounds tested produced analgesic effects. Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide ((R)-methanandamide) were active by three routes of administration: i.p., s.c. and, p.o. Delta(9)-THC produced ED(50)s of 2.2 mg/kg (0.3-15.6) i.p., 9 mg/kg (4.3-18.9) s.c., and 6.4 mg/kg (5.5-7.6) p.o. Similarly, (R)-methanandamide yielded ED(50)s of 2.9 mg/kg (1-8) i.p., 11 mg/kg (7-17) s.c., and 11 mg/kg (0.9-134) p.o. N-vanillyl-arachidonyl-amide (arvanil) was active by two routes, producing ED(50)s of 4.7 mg/kg (3.0-7.4) s.c. and 0.06 mg/kg (0.02-0.2) i.p. Palmitoylethanolamide, URB597, and acetaminophen were active i.p., resulting in ED(50)s of 3.7 mg/kg (3.2-4.2), 22.9 mg/kg (11.1-47.2), and 160 mg/kg (63-405), respectively. None of the cannabinoid or opioid receptor antagonists tested blocked the compounds evaluated, with two exceptions: the antinociceptive effects of Delta(9)-THC and URB597 were completely blocked by SR141716A, a cannabinoid CB(1) receptor antagonist. Western immunoassays performed using three opioid receptor antibodies, a cannabinoid CB(1) receptor antibody and a transient receptor potential vanilloid type 1(TRPV(1)) receptor antibody, yielded no change in receptor protein levels after short-term arvanil, (R)-methanandamide or Delta(9)-THC administration. These data suggest that all the compounds tested, except Delta(9)-THC and URB597, produced analgesia via a non-cannabinoid CB(1), non-cannabinoid CB(2) pain pathway not yet identified.

Prefrontal cortical projections to the midbrain in primates: evidence for a sparse connection

Frontal cortical efferent fibers are thought to have important regulatory influence on cortico-basal ganglia (BG) circuits. The cortico-midbrain (substantia nigra/ventral tegmental area, SN/VTA) pathway has received particular attention in psychiatric diseases, most notably schizophrenia. Work in rodents demonstrates that the prefrontal cortico (PFC)-midbrain pathway plays a central role in regulating the firing pattern of dopamine (DA) neurons. These findings have led to some important hypotheses concerning PFC/BG interaction in schizophrenia. Descending PFC projections to the SN/VTA have been primarily documented in the rodent. The aim of this study was to determine the degree and organization of PFC afferents to these areas in the Macaque monkey. Anterograde tracer injections were made into discrete orbital, cingulate, and dorsolateral prefrontal areas. Projections were charted to the SN and VTA. Overall, there were very few fibers in the ventral midbrain following injections confined to specific areas of the PFC. To determine the relationship of the descending fibers to the midbrain DA neurons, sections were double stained for the tracer molecules and for tyrosine hydroxylase. In all cases, the prefrontal projections and the TH-positive cells did not appear to be in close juxtaposition. The results show a very limited projection from the PFC to the midbrain DA neurons in primates, terminating both within the SN proper as well as in the VTA. They arise from a broad region of the PFC, including the DLPF, cingulate, and orbital cortices. However, despite the relative lack of cortical input to the midbrain cells, these neurons are rich in glutamate receptors in primates. Thus, while, based on these anatomical studies, direct cortical control of DA neurons remains debatable in primates; the cortex may directly impact other sources of glutamatergic control.

Identification of intrinsic determinants of midbrain dopamine neurons

The prospect of using cell replacement therapies has raised the key issue of whether elucidation of developmental pathways can facilitate the generation of therapeutically important cell types from stem cells. Here we show that the homeodomain proteins Lmx1a and Msx1 function as determinants of midbrain dopamine neurons, cells that degenerate in patients with Parkinson's disease. Lmx1a is sufficient and required to trigger dopamine cell differentiation. An early activity of Lmx1a is to induce the expression of Msx1, which complements Lmx1a by inducing the proneural protein Ngn2 and neuronal differentiation. Importantly, expression of Lmx1a in embryonic stem cells results in a robust generation of dopamine neurons with a "correct" midbrain identity. These data establish that Lmx1a and Msx1 are critical intrinsic dopamine-neuron determinants in vivo and suggest that they may be essential tools in cell replacement strategies in Parkinson's disease.

Molecular cloning and differential expression of three GnRH mRNAs in discrete brain areas and lymphocytes in red drum

Three gonadotropin releasing hormones, seabream GnRH (GnRH-I), chicken GnRH-II (GnRH-II) and salmon GnRH (GnRH-III) cDNAs were isolated from the brain of the red drum, Sciaenops ocellatus. The GnRH cDNA sequences of red drum showed more similarity to those of Atlantic croaker, sea bass and sea bream. The real-time quantitative RT-PCR study revealed expression of GnRH-I and GnRH III mRNAs in the olfactory bulb plus telencephalon (OB+TEL), and preoptic-anterior hypothalamic area (POAH), indicating an overlap of the GnRH-I and GnRH-III systems in these forebrain regions. However, GnRH-II mRNA expression was detected only in the midbrain tegmentum (MT). The GnRH-I mRNA expression in the POAH in fish undergoing gonadal recrudescence was significantly higher than that in gonadally immature individuals, suggesting involvement of the POAH GnRH-I in gonadal maturation. On the other hand, GnRH-III mRNA expression was significantly higher in the OB+TEL region compared with that in the POAH. Moreover, the demonstration of GnRH-I mRNA and peptide expression in red drum lymphocytes indicates that the GnRH-I is synthesized in these cells of the immune system similar to the situation in mammals.

Riboflavin-like inmunoreactive fibers in the monkey brain

Using an antiserum directed against the vitamin riboflavin, we studied the distribution of riboflavin-like immunoreactive structures in the monkey brain. In the mesencephalon, at the level of the mesencephalic-diencephalic junction, single riboflavin-like immunoreactive fibers were observed in its dorsal part, whereas a low density of immunoreactive fibers was found below the surface of the section and close to substantia nigra, and a high density was observed above the substantia nigra and close to the medial geniculate nucleus. In the thalamus, single riboflavin-like immunoreactive fibers were found in the ventral regions of the lateral posterior and the medial geniculate nuclei; a low density in the region located above the medial and lateral geniculate nuclei and a high density in the ventral part of the pulvinar nucleus and in the region extending from this latter to the caudate nucleus. Immunoreactive fibers were not observed in the medulla oblongata, pons, cerebellum, hypothalamus, basal ganglia and cerebral cortex. Moreover, no riboflavin-like immunoreactive cell bodies were observed in the monkey brain. The distribution of riboflavin-like immunoreactive fibers in the monkey suggests that this vitamin could be involved in several physiological mechanisms.

Distribution of somatostatin immunoreactivity in the brain of the snake Bothrops jararaca

The distribution of perikarya and fibers containing somatostatin was studied in the brain of the snake Bothrops jararaca by means of immunohistochemistry using an antiserum against synthetic somatostatin. Immunoreactive perikarya and fibers were localized in telencephalic, diencephalic and mesencephalic areas. In the telencephalon, numerous immunoreactive perikarya were found in the medial, dorsomedial, dorsal and lateral cortex, mainly in the deep plexiform layer, less so in the cellular layer, but not in the superficial plexiform layer. Immunoreactive perikarya were also observed in the dorsal ventricular ridge, the nucleus of the diagonal band of Broca, amygdaloid complex, septum and lamina terminalis. In the diencephalon, labelled cells were observed in the paraventricular, periventricular hypothalamic and in the recessus infundibular nuclei. In the mesencephalon, immunoreactive perikarya were seen in the mesencephalic reticular formation, reticular nucleus of the isthmus and torus semicircularis. Labelled fibers ran along the diencephalic floor and the inner zone of the median eminence, and ended in the neural lobe of the hypophysis. Other fibers were observed in the outer zone of the median eminence close to the portal vessels and in the septum, lamina terminalis, retrochiasmatic nucleus, deep layers of the tectum, periventricular gray and granular layer of the cerebellum. Our data suggest that somatostatin may function as a mediator of adenohypophysial secretion as well as neurotransmitter and/or neuromodulator which can regulate the neurohypophysial peptides in the snake B. jararaca.

The role of Pitx3 in survival of midbrain dopaminergic neurons

Dopamine belongs to the most intensively studied neurotransmitters of the brain, because of its implications in psychiatric and neurological disorders. Although, clinical relevance of midbrain dopaminergic (mDA) neurons is well recognized and dopaminergic dysfunction may have a genetic component, the genetic cascades underlying developmental processes are still largely unknown. With the advances in molecular biology, mDA neurons and their involvement in psychiatric and neurological disorders are now subject of studies that aim to delineate the fundamental neurobiology of these neurons. These studies are concerned with developmental processes, cell-specific gene expression and regulation, molecular pharmacology, and genetic association of dopamine-related genes and mDA-associated disorders. Several transcription factors implicated in the post-mitotic mDA development, including Nurr1, Lmx1b, Pitx3, and En1/En2 have contributed to the understanding of how mDA neurons are generated in vivo. Furthermore, these studies provide insights into new strategies for future therapies of Parkinson's Disease (PD) using stem cells for engineering DA neurons in vitro. Here, we will discuss the role of Pitx3 in molecular mechanisms involved in the regional specification, neuronal specification and differentiation of mDA neurons.

Distribution, depletion and recovery of docosahexaenoic acid are region-specific in rat brain

The present study examined: (i) age-induced regional changes in fatty acid composition of brain phospholipids; (ii) alpha-linolenic acid deficiency-induced regional depletion and recovery of DHA in the brain. DHA and arachidonic acid (AA) did not distribute evenly in the brain. In weaning and adult rats, the region with the highest DHA percentage was the cortex whereas the medulla had the lowest DHA percentage. In the aged rats, both the cortex and cerebellum were the regions with the highest DHA percentage whereas in the neonatal rats, the striatum had the greatest percentage of DHA, and the hypothalamus and hippocampus had the least percentage of DHA. Regarding AA, the hippocampus was the region that had the highest percentage whereas the medulla was the region with the lowest percentage except for the neonatal rats, whose cerebellum, hypothalamus, striatum and midbrain had AA percentage lower than hippocampus and cortex. DHA was not proportionally depleted in various regions of brain when the rats were maintained on an n-3-deficient diet for two generations. The results demonstrated that the cortex, hippocampus, striatum, cerebellum and hypothalamus had DHA depleted by >71 %, whereas the midbrain and medulla had only 64 and 57 % DHA depleted, respectively. The most important observation was that the diet reversal for 12 weeks resulted in complete DHA recovery in all regions except for the medulla where the recovery was only 62 %. It was concluded that the location of DHA, n-3 deficiency-induced DHA depletion and reversibility of DHA deficiency across the brain were region-specific.

Sharpening of directional responses along the auditory pathway of the oyster toadfish, Opsanus tau

Our previous studies have shown that the peripheral auditory system of the toadfish encodes the direction of a sound source. Here, we compare directional responses of peripheral saccular afferents, cells in the descending octaval nucleus (DON) of the medulla, and the torus semicircularis (TS) of the midbrain. Recording locations in the brain were labeled with neurobiotin to confirm the site. To compare directional responses among cells, we calculated an index [sharpening ratio (SR)] that weights the relative strength of responses to the best direction for that cell and to the adjacent stimulus angles tested. Unsharpened saccular afferents tend to have a cosinusoidal directional response pattern (DRP) with an expected SR of 0.87. In DON, more than 60% of the cells exhibited directional sharpening (defined as SR <0.8). In TS, more than 80% of the cells exhibited directional sharpening. We conclude that directional auditory sharpening first occurs in DON and some additional sharpening occurs in the ascending pathway to the midbrain, particularly in azimuth. The sharpening of directional selectivity is likely to be an important component of the neural computations underlying directional hearing.

Localization of nitric oxide synthase in the central complex and surrounding midbrain neuropils of the locust Schistocerca gregaria

Nitric oxide (NO), generated enzymatically by NO synthase (NOS), acts as an important signaling molecule in the nervous systems of vertebrates and invertebrates. In insects, NO has been implicated in development and in various aspects of sensory processing. To understand better the contribution of NO signaling to higher level brain functions, we analyzed the distribution of NOS in the midbrain of a model insect species, the locust Schistocerca gregaria, by using NADPH diaphorase (NADPHd) histochemistry after methanol/formalin fixation; results were validated by NOS immunohistochemistry. NADPHd yielded much higher sensitivity and resolution, but otherwise the two techniques resulted in corresponding labeling patterns throughout the brain, except for intense immunostaining but only weak NADPHd staining in median neurosecretory cells. About 470 neuronal cell bodies in the locust midbrain were NADPHd-positive positive, and nearly all major neuropil centers contained dense, sharply stained arborizations. We report several novel types of NOS-expressing neurons, including small ocellar interneurons and antennal sensory neurons that bypass the antennal lobe. Highly prominent labeling occurred in the central complex, a brain area involved in sky-compass orientation, and was analyzed in detail. Innervation by NOS-expressing fibers was most notable in the central body upper and lower divisions, the lateral accessory lobes, and the noduli. About 170 NADPHd-positive neurons contributed to this innervation, including five classes of tangential neuron, two systems of pontine neuron, and a system of columnar neurons. The results provide new insights into the neurochemical architecture of the central complex and suggest a prominent role for NO signaling in this brain area.

Quantitative morphometry of granular ‘dot-like’ ubiquitin-immunoreactivity in the crus cerebri in asphyxiation and fire fatalities

In the central nervous system (CNS), a variety of ubiquitinated structures have been reported, usually as pathological alterations of the brain related to degenerative diseases or aging. However, previous studies showed an increase in the ubiquitin (Ub)-immunoreactive intranuclear inclusion of the pigmented neurons of the substantia nigra in the midbrain in asphyxiation and fire fatalities in the adult subjects. The aim of the present study was to examine granular 'dot-like' Ub-immunoreactivity in the crus cerebri (cortico-spinal tracts) in related fatalities (over 35 years of age, n=169), including fatal asphyxiation (n=27), drownings (n=14), fire fatalities (n=60), and control groups (n=68). Dot-like Ub-immunoreactivity was clearly observed in the descending tract of the crus cerebri. Morphometric analysis of the positive granular area (dot-like Ub-area) showed a higher value in strangulation and fire fatalities and a lower value in hemorrhagic and head injury deaths, as was observed for the inclusion-type neuronal Ub-positivity. However, there was a difference between those markers: a low value was seen for the inclusion-type neuronal Ub-positivity in hanging and drownings, and a difference in the dot-like Ub-area was detected between fire fatalities with lower and higher COHb levels. Our findings suggested the possible usefulness of these markers for examination of CNS stress responses in traumas, at least in middle-aged and elderly victims and a partial difference in stress reaction between the cortico-spinal tracts and dopaminergic neurons.

Immunocytochemical localization and ontogenic development of alpha-melanocyte-stimulating hormone (alpha-MSH) in the brain of a pleuronectiform fish, barfin flounder

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a pituitary hormone derived by post-translational processing from proopiomelanocortin and is involved in background adaptation in teleost fish. It has also been reported to suppress food intake in mammals. Here, we examined the immunocytochemical localization of alpha-MSH in the brain and pituitary of a pleuronectiform fish, the barfin flounder (Verasper moseri), as a first step in unraveling the possible function of alpha-MSH in the brain. The ontogenic development of the alpha-MSH system was also studied. In the pituitary, alpha-MSH-immunoreactive (ir) cells were preferentially detected in the pars intermedia. In the brain, alpha-MSH-ir neuronal somata were located in the nucleus tuberis lateralis of the basal hypothalamus, and alpha-MSH-ir fibers were located mainly in the telencephalon, hypothalamus, and midbrain. Alpha-MSH-ir neuronal somata did not project their axons to the pituitary. The alpha-MSH-ir neurons differed from those immunoreactive to melanin-concentrating hormone. Alpha-MSH cells in the pituitary and alpha-MSH-ir neuronal somata in the brain were first detected 1 day and 5 days after hatching, respectively. The distribution of alpha-MSH-ir cells, neuronal somata, and fibers showed a pattern similar to that in adult fish 30 days after hatching. These results indicate that the functions of alpha-MSH in the brain and pituitary are different and that alpha-MSH plays physiological roles in the early development of the barfin flounder.

Behavioral effects of 8-OH-DPAT injections into pontine and mesencephalic areas containing 5-HT-immunoreactive perikarya in the pigeon

This study examined the distribution of 5-HT-immunoreactive perikarya (5-HT-IRp) and the effects of local injections of 8-OH-DPAT into 5-HT-IRp-containing pontine and mesencephalic regions on feeding and drinking behaviors in free-feeding pigeons. When infused into the midline 5-HT-IRp-containing areas, 8-OH-DPAT (6.1 nmol) reliably elicited drinking and, to a lesser extent, feeding responses during the first hour after injection. These responses were significantly higher than the ingestive indexes observed (1) after vehicle (ascorbic acid 0.1%, 200 nl) injections at the same sites and (2) after 8-OH-DPAT injections into adjacent sites devoid of 5-HT-IRp. Increases in drinking were proportionally higher than those observed in feeding and a significant negative correlation was observed between water and food after midline 8-OH-DPAT injections. Similar dipsogenic responses were observed after injections of different 8-OH-DPAT doses (0.6, 2.0, and 6.1 nmol). Pretreatment with local injections of p-MPPI (an antagonist of 5-HT1A receptors) attenuated the ingestive responses evoked by 8-OH-DPAT injections. Injections of 8-OH-DPAT into lateral 5-HT-IRp-containing sites evoked only inconsistent and weak ingestive responses. These results indicate that 5-HT1A receptor-mediated circuits located in the midline superior raphe system of the pigeon may play an important role in mechanisms controlling water intake, similar to that observed in mammals.

Fluvoxamine, a selective serotonin reuptake inhibitor, suppresses tetrahydrobiopterin levels and dopamine as well as serotonin turnover in the mesoprefrontal system of mice

RATIONALE

Tetrahydrobiopterin (BH4) is a coenzyme of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), rate-limiting enzymes of monoamine biosynthesis. According to the monoamine hypothesis of depression, antidepressants will restore the function of the brain monoaminergic system, and BH4 concentration.

OBJECTIVE

To investigate the effects of fluvoxamine on BH4 levels and dopamine (DA) and serotonin (5-HT) turnover in the mesoprefrontal system, incorporating two risk factors of depression, social isolation and acute environmental change.

METHODS

Male ddY mice (6W) were divided into two housing groups, i.e. group-housing (eight animals per cage; 35 days), and isolation-housing (one per cage; 35 days), SC injected with fluvoxamine (20 or 40 mg/kg; days 29-35), and exposed to 20-min novelty stress (day 35). The levels of BH4, DA, homovanilic acid (HVA), 5-HT, and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the prefrontal cortex and midbrain.

RESULTS

Under the group-housing condition, novelty stress significantly increased BH4 levels in both regions, and the HVA/DA ratio in the midbrain, whereas it did not change any parameters in either region under the isolation-housing condition. In the prefrontal cortex, fluvoxamine significantly decreased the 5-HIAA/5-HT ratio under the group-housing condition, and BH4 levels and the HVA/DA ratio under the isolation-housing condition. In the midbrain, fluvoxamine significantly decreased all parameters, except for an increasing in the 5-HIAA/5-HT ratio under the isolation-housing condition.

CONCLUSION

Isolation-housing suppressed the increase of BH4 levels and DA turnover elicited by novelty stress. Fluvoxamine suppressed BH4 levels, and DA and 5-HT turnover. Fluvoxamine may have altered DA turnover by suppressing BH4 levels.

Age-related metabolic changes in the upper brainstem tegmentum by MR spectroscopy

Several neurodegenerative disorders have a profound metabolic and structural impact on the brainstem. MR spectroscopy provides metabolic information non-invasively and has the potential to characterize the changes associated with normal aging and differentiate them from neurodegenerative alterations. The present work was aimed at studying the upper brainstem tegmentum at the midbrain and pontine levels in 57 adult normal volunteers, aged 23-79 years, with long-echo time proton MR spectroscopy to evaluate possible regional differences and the effect of age. Higher ratios of N-acetyl aspartate (NAA)/total creatine (Cr) and choline-containing compounds (Cho)/Cr were observed in the pons compared to the midbrain, resulting from higher net NAA and Cho content. In the midbrain, there was a linear decline of NAA and Cho with age in subjects over 50, most probably related to neuronal tissue loss. In the pons, such an aging effect was not observed, with subjects over 50 showing higher Cr and Cho than the under-50 subjects. Our findings provided evidence of regional differences and suggest different effects of age on the two studied brainstem segments, hitherto undescribed.

Elevated midbrain serotonin transporter availability in mixed mania: a case report

BACKGROUND

Results obtained from brain imaging studies indicate that serotonin transporter (SERT) and dopamine transporter (DAT) densities are altered in major depression. However, no such studies have been published on current mania or hypomania.

CASE PRESENTATION

In this single photon emission computed tomography (SPECT) study with [123I]nor-beta-CIT we present a case with simultaneous symptoms of major depression and hypomania. She had an elevated serotonin transporter availability (SERT) in the midbrain and elevated dopamine transporter availability (DAT) in the striatum, which normalised in a one-year follow-up period during which she received eight months of psychodynamic psychotherapy.

CONCLUSIONS

To our knowledge, this is the first report on SERT and DAT associated with mania. In our case the availability of both SERT in the midbrain and DAT in the striatum were elevated at baseline and declined during psychotherapy, while the SERT and DAT of the depressed controls increased during psychotherapy. Symptoms of hypomania in the case were alleviated during psychotherapy. Clinical recovery was also reflected in the Hamilton Depression Rating Scale (HDRS) scores.

[The activity of ethanol- and aldehyde-oxidizing enzymes of the brain in ethanol intoxication]

The distributed activity of alcohol dehydrogenase (ADG) and aldehyde dehydrogenase (AldDG) was histochemically studied in neurons of locus coeruleus, nuclei of raphe, substantia nigra and in cerebellar cortex in death or intoxication of ethanol (IE). The enzymatic activity was found to be changing depending on whether there was IE or not. Both higher ADG and lower AldDG were registered in the examined brain sections, which differ by mediatory structure of the neuronic centers. The detected regularities can be used within the forensic medical diagnosis of IE.

Olfactory impairment and Parkinson's disease-like symptoms observed in the common marmoset following administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

OBJECTIVE

Although olfactory disturbance appears to occur in the early stages of Parkinson's disease (PD) in humans, little is known about its mechanism. The aim of this study was to make a PD model using injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the common marmoset and to discover the mechanism of olfactory disturbance in this animal.

MATERIAL AND METHODS

Olfactory disturbance induced by MPTP in the common marmoset was observed by behavioral, biochemical and immunohistochemical means.

RESULTS

Administration of MPTP caused common marmosets to enter an akinetic state within a few days and to show signs of impaired olfactory function. Biochemical study showed a decrease in dopamine levels, especially in tissue samples from the caudate nucleus and putamen. Immunohistochemical analysis revealed a lack of tyrosine hydroxylase immunoreactivity, not only in the substantia nigra, caudate nucleus and putamen but also in the olfactory tubercle.

CONCLUSION

These results demonstrate that MPTP causes both PD-like symptoms and olfactory disturbance in the common marmoset. The olfactory disturbance observed in these animals may be due to the lack of dopamine in the olfactory tubercle.

Immunohistochemical distribution of neuropeptide Y in the mesencephalon and rhombencephalon of carp, Cyprinus carpio L. (Cyprinidae: Teleostei)

The localization of neuropeptide Y (NPY)-immunoreactive elements was investigated in the mesencephalon and rhombencephalon of carp, Cyprinus carpio, by using antisera raised against porcine NPY and the immunoperoxidase technique. Concurrently, to identify the distribution of NPY-immunoreactivity, we developed an atlas of the studied areas based on Nissl-stained sections. The NPY-immunoreactive (NPY-ir) elements were located in many zones of the mesencephalon and rhombencephalon. In the mesencephalon, positive fibers were the most abundant elements while neurons were scarce. The rhombencephalon rostral part was characterized by a low to moderate fiber density, distributed in the ventro-medial and ventro-lateral region. Differently the caudal part of the rhombencephalon exhibited several NPY-ir elements. In particular, a high density of immunoreactivity was located in the gustatory area at the level of the nucleus (n.) originis nervi glossopharyngei, in the n. nervi vagi, and in the vagal lobe. The latter can be considered a valid neuroanatomical model for the study of gustatory signal processing in vertebrates. Our results regarding the primary gustatory centers give neuroanatomical support to the view that NPY may act as a neurotransmitter and/or a neuromodulator in a wide neural network for feeding behavior control.

Role of extracellular signal-regulated kinase in the ventral tegmental area in the suppression of the morphine-induced rewarding effect in mice with sciatic nerve ligation

We recently reported that micro-opioid receptor agonist morphine failed to induce its rewarding effects in rodents with sciatic nerve injury. In the present study, we investigated whether a state of neuropathic pain induced by sciatic nerve ligation could change the activities of the extracellular signal-regulated kinase (ERK) and p38 in the mouse lower midbrain area including the ventral tegmental area (VTA), and these changes could directly affect the development of the morphine-induced rewarding effect in mice. The sciatic nerve ligation caused a long-lasting and profound thermal hyperalgesia. A dose-dependent place preference induced by s.c. administration of morphine was observed in sham-operated mice, but not in sciatic nerve-ligated mice. We found here for the first time that nerve injury produces a sustained and significant reduction in protein levels of phosphorylated-ERK and -p38 in cytosolic preparations of the mouse lower midbrain. The inhibition of ERK activity by i.c.v. pre-treatment with either PD98059 or U0126 impaired the morphine-induced place preference. In contrast, i.c.v. treatment with a specific inhibitor of p38, SB203580, did not interfere with the morphine-induced rewarding effect. Immunohistochemical study showed a drastic reduction in phosphorylated-ERK immunoreactivity within tyrosine hydroxylase-positive cells of the VTA. These results suggest that a sustained reduction in the ERK-dependent signalling pathway in dopamine cells of the VTA may be implicated in the suppression of the morphine-induced rewarding effect under neuropathic pain.

Progressive sensorimotor impairment is not associated with reduced dopamine and high energy phosphate donors in a model of ataxia-telangiectasia

Ataxia-telangiectasia (A-T) is a genetic disease, associated with progressive motor impairment and a lack of functional ATM protein. It has been reported that immunoreactive tyrosine hydroxylase and dopamine transporter are reduced in an Atm-/- mouse model of A-T. These observations led to a hypothesis that A-T is associated with loss of nigrostriatal dopamine and prompted the launch of clinical trials to evaluate a therapeutic utility of the anti-parkinsonian drug, l-DOPA. To test for dopamine depletion more directly, we measured regional levels of monoamines and their metabolites in the Atm-/- mouse brain. We also measured levels of NAD+, a cofactor for dopamine biosynthesis and substrate of the DNA damage surveillance enzyme, poly(ADP-ribose) polymerase (PARP). Constitutive activation of PARP has been posited to cause NAD+ depletion. We observed no reduction in monoamine transmitters and no depletion of NAD+, or other high energy phosphate donors in the adult Atm-/- cerebellum, striatum, or ventral mesencephalon. However, our studies did reveal a progressive sensorimotor impairment in Atm-/- mice that may serve as a relevant proxy for progressive neurological impairment in the human disease. Our results call into question the involvement of dopamine in A-T and the therapeutic strategy of enhancing dopaminergic function with l-DOPA.

Activation of the dorsal periaqueductal gray in the rat induces Fos-like immunoreactivity in select non-cholinergic mesopontine neurons

Autonomic responses evoked from the dorsal periaqueductal gray (dPAG) have been reported to be mediated in part by acetylcholine release in the medulla. To identify the possible origin of cholinergic neurons activated by dPAG stimulation, the pattern of Fos-like immunoreactivity (FLI) in the mesopontine cholinergic cell groups was examined in three groups of urethane anesthetized rats. Relative to surgery (n=6) and blood pressure control groups (n=6), chemical disinhibition of the dPAG (n=10) induced a significant increase in FLI in the lateral dorsal tegmental nucleus (LDTg) but not the pedunculopontine tegmental nucleus. LDTg neurons stained for choline acetyltransferase immunoreactivity however did not co-label for FLI. Other pontomesencephalic regions outside of the dPAG demonstrating a significant increase in FLI relative to controls included the lateral and ventrolateral columns of the PAG, the cuneiform nucleus, dorsal raphe, and the microcellular tegmental nucleus. These findings suggest that acetylcholine release in during dPAG stimulation does not originate from mesopontine neurons.

Comparative distribution of estrogen receptor α and β immunoreactivities in the forebrain and the midbrain of the female guinea pig

Estrogen plays an important role in regulating gonadotropin secretion and reproductive behavior. The estrogen receptor alpha (ERalpha) was believed to be the only receptor which mediated the actions of the hormone until the identification of a novel ER called ERbeta. In the present study, the map of ERalpha immunoreactive (IR) neurons was compared with the distribution pattern of ERbeta-IR neurons in the forebrain and midbrain of ovariectomized guinea pigs using immunocytochemistry. The immunoreactivities appeared to be mainly nuclear in their subcellular distribution. Both ERalpha- and ERbeta-like immunoreactivities were highly expressed in the bed nucleus of the stria terminalis and the ventrolateral hypothalamic nucleus but were found to be differentially expressed in discrete subregions of the amygdaloid complex. A large number of intensely labeled ERalpha cells were observed throughout the rostrocaudal extent of the preoptic region, whereas only a few ERbeta-IR neurons were found in the periventricular preoptic nucleus bordering the third ventricle or scattered in the medial preoptic area. In contrast, only ERalpha-immunoreactivity was seen in the septum, and in the magnocellular supraoptic, paraventricular, arcuate, and premammillary nuclei. In the midbrain, neurons containing ERalpha were observed throughout the rostrocaudal extent of the gray matter, whereas ERbeta was only detected within the dorsal raphe nucleus. These observations provide evidence of a distinct neuroanatomical pattern for the two subtypes of the ER which may have different roles in regulating behavior and the neuroendocrine mechanisms of reproduction. Species similarities and differences in the distributions of ERalpha and ERbeta immunoreactivities are discussed.

The effect of chronic aluminum(III) administration on the nervous system of aged rats: Clues to understand its suggested role in Alzheimer's disease

The effect of chronic aluminum intake has been investigated in the brain of aged male Wistar rats to assess the potential role of the accumulation of this metal ion on the development of neurodegenerative features observed in Alzheimer's disease. AlCl3 x 6 H2O (2g/L) was administered to experimental animals for 6 months in the drinking water. The total content of Al (microg/g fresh tissue) was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES), while the content of Cu, Zn and Mn was determined by flame AAS in the prosencephalon + mesencephalon, pons-medulla and cerebellum of control and Al(III)-treated animals. The area occupied by mossy fibres in the CA3 field of the hippocampus was estimated by a computer-assisted morphometric method following Timm's preferential staining. In Al(III)-treated rats the concentration of Cu, Zn and Mn did not increase significantly (p < 0.5) in prosencephalon + mesencephalon, nor in pons-medulla (p < 0.5) except for Cu (p < 0.05) in pons-medulla. In the cerebellum the only significant increase was seen for Zn (p < 0.01) while no change was observed for Cu and Mn. The area occupied by the mossy fibres in the hippocampal CA3 field was significantly increased (+32%) in aged Al(III)-treated rats. Since Cu, Zn and Mn are essential components of the cytosolic and mitochondrial superoxide dismutases, it is possible that the increased content of these ions in aged Al(III)-treated rats represents an increased amount of genetic expression of these antioxidant enzymes. Considering that the positivity to Timm's reaction is based on the presence of free or loosely bound Zn2+ ions within synaptic terminals and that Zn2+ ions are reported to be accumulated by hippocampal neurons when tissue injury occurs, the increased area of the mossy fibres in CA3 field of Al(III)-treated rats could indicate increased hippocampal damage in these animals. Taken together, the present findings indicate that the aging CNS is particularly susceptible to Al(III) toxic effects which may increase the cell load of oxidative stress and may contribute, as an aggravating factor, to the development of neurodegenerative events as observed in Alzheimer's disease.

Rubratoxin B elicits antioxidative and DNA repair responses in mouse brain

Rubratoxin B (RB) is a mycotoxin with potential neurotoxic effects that have not yet been characterized. Based on existing evidence that RB interferes with mitochondrial electron transport to produce oxidative stress in peripheral tissues, we hypothesized that RB would produce oxidative damage to macromolecules in specific brain regions. Parameters of oxidative DNA damage and repair, lipid peroxidation, and superoxide dismutase (SOD) activity were measured across six mouse brain regions 24 h after administration of a single dose of RB. Lipid peroxidation and oxidative DNA damage were either unchanged or decreased in all brain regions in RB-treated mice compared with vehicle-treated mice. Concomitant with these decreased indices of oxidative macromolecular damage, SOD activity was significantly increased in all brain regions. Oxyguanosine glycosylase activity (OGG1), a key enzyme in the repair of oxidized DNA, was significantly increased in three brain regions--cerebellum (CB), caudate/putamen (CP), and cortex (CX)--but not in the hippocampus (HP), midbrain (MB), and pons/medulla (PM). The RB-enhanced OGG1 catalytic activity in these brain regions was not due to increased OGG1 protein expression, but was a result of enhanced catalytic activity of the enzyme. In conclusion, specific brain regions responded to an acute dose of RB by significantly altering SOD and OGG1 activities to maintain the degree of oxidative DNA damage equal to, or less than, that of normal steady-state levels.

A nuclear microscopic and histochemical study of iron concentrations and distribution in the midbrain of two age groups of monkeys unilaterally injected with MPTP

The present study was carried out to elucidate the concentration and distribution of iron in the substantia nigra of two age groups of monkeys after experimental hemi-Parkinsonism induced by unilateral internal carotid injections of MPTP. Iron levels and distribution were detected using the nuclear microscope, which is able to provide structural and quantitative elemental analysis of biological tissue down to the parts per million (ppm) level of analytical sensitivity. Five weeks after unilateral lesioning with MPTP, we observed a 30-65% loss of neurons in the injected substantia nigra of each monkey, compared with the contralateral control 'non-lesioned' side. In monkeys less than 7 years of age, the iron was distributed fairly uniformly and showed little evidence of focal deposits. In monkeys greater than 7 years of age, we observed many dense focal deposits of iron in the substantia nigra. A comparison between iron distributions in nuclear microscopic scans and cell distributions in the same sections stained by the Nissl technique showed that areas containing high iron concentrations were present not where large-diameter neurons with abundant Nissl substance (presumed dopaminergic neurons) were located but in a region ventral to these cell bodies, i.e., in the substantia nigra pars reticulata. These distributions were present on the control side as well as the MPTP-injected side. Since a previous study has shown that unilateral MPTP injection results in lesions of the substantia nigra of the same side but negligible injury to the opposite side, this implies that the iron deposits existed in the older monkeys before MPTP injections (i.e. they occurred normally). The accumulation of iron in the substantia nigra with age suggests the possibility of localised damage to neurons through the catalysis of free radicals.

Retinal ganglion cell projections to the hamster suprachiasmatic nucleus, intergeniculate leaflet, and visual midbrain: bifurcation and melanopsin immunoreactivity

The circadian clock in the suprachiasmatic nucleus (SCN) receives direct retinal input via the retinohypothalamic tract (RHT), and the retinal ganglion cells contributing to this projection may be specialized with respect to direct regulation of the circadian clock. However, some ganglion cells forming the RHT bifurcate, sending axon collaterals to the intergeniculate leaflet (IGL) through which light has secondary access to the circadian clock. The present studies provide a more extensive examination of ganglion cell bifurcation and evaluate whether ganglion cells projecting to several subcortical visual nuclei contain melanopsin, a putative ganglion cell photopigment. The results showed that retinal ganglion cells projecting to the SCN send collaterals to the IGL, olivary pretectal nucleus, and superior colliculus, among other places. Melanopsin-immunoreactive (IR) ganglion cells are present in the hamster retina, and some of these cells project to the SCN, IGL, olivary pretectal nucleus, or superior colliculus. Triple-label analysis showed that melanopsin-IR cells bifurcate and project bilaterally to each SCN, but not to the other visual nuclei evaluated. The melanopsin-IR cells have photoreceptive characteristics optimal for circadian rhythm regulation. However, the presence of moderately widespread bifurcation among ganglion cells projecting to the SCN, and projection by melanopsin-IR cells to locations distinct from the SCN and without known rhythm function, suggest that this ganglion cell type is generalized, rather than specialized, with respect to the conveyance of photic information to the brain.

Presence of functional ATP and dinucleotide receptors in glutamatergic synaptic terminals from rat midbrain

Glutamatergic terminals from rat midbrain were characterized by immunolocalization of synaptophysin and the vesicular glutamate transporters, either VGLUT1 or VGLUT2. Terminals containing these markers represent about 31% (VGLUT1) and 16% (VGLUT2) of the total synaptosomal population. VGLUT1-positive glutamatergic terminals responded to ATP or P1,P 5-di(adenosine-5') pentaphosphate (Ap5A) with an increase in the intrasynaptosomal calcium concentration as measured by a microfluorimetric technique in single synaptosomes. Roughly 20% of the VGLUT1-positive terminals responded to ATP, 13% to Ap5A and 11% to both agonists. Finally 56% of the terminals labeled with the anti-VGLUT1 antibody did not show any calcium increase in response to ATP or Ap5A. A similar response distribution was also observed in the VGLUT2-positive terminals. The Ca2+ responses induced by ATP and Ap5A in the glutamatergic terminals could be selectively inhibited by pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, 80 micro m) and P1,P 5-di(inosine-5') pentaphosphate (Ip5I, 100 nm), respectively. Both ATP and Ap5A, once assayed in the presence of extrasynaptosomal calcium, were able to induce a concentration-dependent glutamate release from synaptosomal populations, EC50 values being 21 micro m and 38 micro m for ATP and Ap5A, respectively. Specific inhibition of glutamate release was obtained with PPADS on the ATP effect and with Ip5I on the dinucleotide response, indicating that separate receptors mediate the secretory effects of both compounds.