Sex steroid hormones, the estrous cycle, and rapid modulation of glutamatergic synapse properties in the striatal brain regions with a focus on 17β-estradiol and the nucleus accumbens

The striatal brain regions encompassing the nucleus accumbens core (NAcc), shell (NAcs) and caudate-putamen (CPu) regulate cognitive functions including motivated behaviors, habit, learning, and sensorimotor action, among others. Sex steroid hormone sensitivity and sex differences have been documented in all of these functions in both normative and pathological contexts, including anxiety, depression and addiction. The neurotransmitter glutamate has been implicated in regulating these behaviors as well as striatal physiology, and there are likewise documented sex differences in glutamate action upon the striatal output neurons, the medium spiny neurons (MSNs). Here we review the available data regarding the role of steroid sex hormones such as 17β-estradiol (estradiol), progesterone, and testosterone in rapidly modulating MSN glutamatergic synapse properties, presented in the context of the estrous cycle as appropriate. Estradiol action upon glutamatergic synapse properties in female NAcc MSNs is most comprehensively discussed. In the female NAcc, MSNs exhibit development period-specific sex differences and estrous cycle variations in glutamatergic synapse properties as shown by multiple analyses, including that of miniature excitatory postsynaptic currents (mEPSCs). Estrous cycle-differences in NAcc MSN mEPSCs can be mimicked by acute exposure to estradiol or an ERα agonist. The available evidence, or lack thereof, is also discussed concerning estrogen action upon MSN glutamatergic synapse in the other striatal regions as well as the underexplored roles of progesterone and testosterone. We conclude that there is strong evidence regarding estradiol action upon glutamatergic synapse function in female NAcs MSNs and call for more research regarding other hormones and striatal regions.

Subcortical connections of area V4 in the macaque

Area V4 has numerous, topographically organized connections with multiple cortical areas, some of which are important for spatially organized visual processing, and others which seem important for spatial attention. Although the topographic organization of V4's connections with other cortical areas has been established, the detailed topography of its connections with subcortical areas is unclear. We therefore injected retrograde and anterograde tracers in different topographical regions of V4 in nine macaques to determine the organization of its subcortical connections. The injection sites included representations ranging from the fovea to far peripheral eccentricities in both the upper and lower visual fields. The topographically organized connections of V4 included bidirectional connections with four subdivisions of the pulvinar, two subdivisions of the claustrum, and the interlaminar portions of the lateral geniculate nucleus, and efferent projections to the superficial and intermediate layers of the superior colliculus, the thalamic reticular nucleus, and the caudate nucleus. All of these structures have a possible role in spatial attention. The nontopographic, or converging, connections included bidirectional connections with the lateral nucleus of the amygdala, afferent inputs from the dorsal raphe, median raphe, locus coeruleus, ventral tegmentum and nucleus basalis of Meynert, and efferent projections to the putamen. Any role of these structures in attention may be less spatially specific.

Mineral composition of and the relationships between them of human basal ganglia in very old age

Trace elements and the relationships among them were investigated by direct chemical analysis in three basal ganglia regions in very old age individuals and age- and gender-related differences were assessed. After ordinary dissections at Nara Medical University were finished, the caudate nucleus, putamen, and globus pallidus belonging to the basal ganglia were removed from the identical cerebra of the subjects who consisted of 22 men and 23 women, ranging in age from 70 to 101 years (average age = 83.3 ± 7.5 years). After incineration with nitric acid and perchloric acid, the element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that the Ca, P, and Mg contents increased significantly in the putamen with aging and the Mg content increased significantly in the globus pallidus with aging, but no elements increased significantly in the caudate nucleus with aging. Regarding the relationships among elements in the basal ganglia, extremely significant direct correlations were found among the Ca, P, and Mg contents in the putamen. These results suggested that slight calcification occurred in the putamen in very old age. With regard to seven elements of Ca, P, S, Mg, Zn, Fe, and Na, it was examined whether there were significant correlations among the caudate nucleus, putamen, and globus pallidus. It was found that there were extremely significant direct correlations among all of the three basal ganglia in the P content. Likewise, with regard to the Fe content, there were extremely or very significant direct correlations among all of the three basal ganglia. Regarding the gender difference in elements, it was found that the Ca content of the caudate nucleus was significantly higher in women than in men.

Profiling and sequencing of gangliosides from human caudate nucleus by chip-nanoelectrospray mass spectrometry

Gangliosides (GGs), sialic acid-containing glycosphingolipids are involved in many brain functions at the cell and molecular level. Compositional and structural elucidation of GGs in mixtures extracted from human brain is essential for correlating their profile with the specialized function of each brain area in health and disease. As a part of our ongoing study on GG expression and structure in different healthy and diseased brain regions, in this work, a preliminary investigation of GGs in a specimen of human caudate nucleus (CN) was carried out using an advanced mass spectrometry (MS) technique. By chip-nanoelectrospray MS performed on a NanoMate robot coupled to a high capacity ion trap instrument, 81 GG components were detected in human CN in only 1.5 min of signal acquisition. Although the native GG mixture from CN was found dominated by mono-, di- and trisialylated GGs with a slight dominance of disialylated forms (GD), four tetrasialylated structures (GQ) and two pentasialylated (GP) species were also identified. Additionally, species with unusually long fatty acid chains, exceeding 30 carbon atoms in their ceramide (Cer) composition, and several glycoforms modified by fucosyl (Fuc), O-acetyl (O-Ac) and/or lactonization were discovered. By tandem MS (MS(2) ) using collision-induced dissociation, two atypical mono and disialylated species with long-chain fatty acids in their Cer could be confirmed and structurally characterized. These results may be a starting point for new GG-based approaches in the study of CN functions and ethiopathogenesis of CN-related neurodegenerative disorders.

Dopamine receptor alterations in female rats with diet-induced decreased brain docosahexaenoic acid (DHA): interactions with reproductive status

Decreased tissue levels of n-3 (omega-3) fatty acids, particularly docosahexaenoic acid (DHA), are implicated in the etiologies of non-puerperal and postpartum depression. This study examined the effects of a diet-induced loss of brain DHA content and concurrent reproductive status on dopaminergic parameters in adult female Long-Evans rats. An alpha-linolenic acid-deficient diet and breeding protocols were used to produce virgin and parous female rats with cortical phospholipid DHA levels 20-22% lower than those fed a control diet containing adequate alpha-linolenic acid. Decreased brain DHA produced a significant main effect of decreased density of ventral striatal D(2)-like receptors. Virgin females with decreased DHA also exhibited higher density of D(1)-like receptors in the caudate nucleus than virgin females with normal DHA. These receptor alterations are similar to those found in several rodent models of depression, and are consistent with the proposed hypodopaminergic basis for anhedonia and motivational deficits in depression.

[Glutamate increase in the associative striatum in schizophrenia: a longitudinal magnetic resonance spectroscopy preliminary study]

OBJECTIVE

To compare glutamate levels (Glu) found in the dorsal-caudate nucleus (a dopamine rich region) and in the cerebellum (a low dopamine region) among: 1) schizophrenia patients undergoing an acute psychotic episode, 2) after receiving antidopaminergic treatment (Risperidone), and 3) healthy controls.

METHODS

Fourteen drug-free patients with schizophrenia and fourteen healthy controls were included. Patients underwent two proton magnetic resonance spectroscopy (1H-MRS) studies, one prior to treatment and the second after 6-weeks of daily Risperidone treatment. Controls underwent one 1H-MRS study. Glutamate levels were normalized according to the relative concentration of Creatine (Cr).

RESULTS

The dorsal-caudate nucleus among schizophrenia patients showed higher levels of Glu/Cr during the drug-free condition (t = -2.16, p = 0.03) and after antipsychotic treatment (t = 2.12, p = 0.04) compared with controls. No difference was observed in the cerebellum between the drug-free, post-treatment and controls conditions.

CONCLUSIONS

Our results suggest that the Glu increase observed in the dorsal-caudate in schizophrenia is illness-mediated and does not change after 6-weeks of antipsychotic treatment. Moreover, the lack of change detected in the cerebellum suggests that the Glu increase in schizophrenia is not ubiquitous within the brain and that may be associated with dopamine target regions.

Immunolocalization of NMDA receptor subunit NR3B in selected structures in the rat forebrain, cerebellum, and lumbar spinal cord

N-methyl-D-aspartate (NMDA) receptors have been implicated in many neurological disorders. Although NMDA receptors are best known for their high calcium permeability, the recently discovered NR3 subunits, NR3A and NR3B, have been shown to reduce the calcium permeability of the NMDA receptor. Thus, NR3 subunits may be important players in modulating synaptic plasticity in neurons. Although NR3B expression in the rodent and human brain has been studied, little is known about its distribution in different cell types. Here we used immunolabeling with a specific NR3B antibody together with antibodies against established neurochemical markers to determine the cellular and subcellular localization of NR3B. The nucleus was concurrently stained with NR3B immunolabeling to show that NR3B is widely expressed by many cells in each brain region. Our findings indicate that NR3B is widely expressed in the structures examined in the rat forebrain (hippocampus, cerebral cortex, caudoputamen, and nucleus accumbens), cerebellum, and lumbar sections of the spinal cord. Within these regions NR3B was found to be expressed in all the substructures of the hippocampus (CA1, CA3, dentate gyrus), the various layers of the cerebral cortex, projection neurons and interneurons of the striatum, different cell types of the cerebellum, and motor neurons of the spinal cord. Furthermore, when stained with NR1-the obligatory subunit responsible for forming functional NMDA receptors-the distribution of NR3B appears to be as ubiquitous as NR1. Taken together, our data suggest that there may be a population of NR3B-containing NMDA receptors conferring new functional roles in the mammalian central nervous system.

Pathological tau burden and distribution distinguishes progressive supranuclear palsy-parkinsonism from Richardson's syndrome

Clinical syndromes associated with progressive supranuclear palsy-tau pathology now include progressive supranuclear palsy-parkinsonism (PSP-P), in addition to classic Richardson's syndrome (RS) and pure akinesia with gait freezing (PAGF). Although pathological heterogeneity of progressive supranuclear palsy (PSP) has also been established, attempts to correlate this with clinical findings have only rarely provided conclusive results. The aim of this study was to investigate whether regional variations in the types of tau lesions or differences in overall tau load may explain the clinical differences between the RS, PSP-P and PAGF. Quantitative tau pathology assessment was performed in 17 brain regions in 42 cases of pathologically diagnosed PSP (22 RS, 14 PSP-P and 6 PAGF). Neurofibrillary tangles, tufted astrocytes, coiled bodies and thread pathology were quantitated and a grading system was developed separately for each region. Using these grades the overall tau load was calculated in each case. To establish a simplified system for grading the severity of tau pathology, all data were explored to identify the minimum number of regions that satisfactorily summarized the overall tau severity. The subthalamic nucleus, substantia nigra and globus pallidus were consistently the regions most severely affected by tau pathology. The mean severity in all regions of the RS group was higher than in PSP-P and PAGF, and the overall tau load was significantly higher in RS than in PSP-P (P = 0.002). Using only the grade of coiled body + thread lesions in the substantia nigra, caudate and dentate nucleus, a reliable and repeatable 12-tiered grading system was established (PSP-tau score: 0, mild tau pathology, restricted distribution; >7, severe, widespread tau pathology). PSP-tau score was negatively correlated with disease duration (Spearman's rho −0.36, P = 0.028) and time from disease onset to first fall (Spearman's rho −0.49, P = 0.003). The PSP-tau score in PSP-P (median 3, range 0–5) was significantly lower than in RS (median 5, range 2–10, Mann–Whitney U, P < 0.001). The two cases carrying the tau-H2 protective allele had the two lowest PSP-tau scores. We have identified significant pathological differences between the major clinical syndromes associated with PSP-tau pathology and the restricted, mild tau pathology in PSP-P supports its clinical distinction from RS. The grading system we have developed provides an easy-to-use and sensitive tool for the morphological assessment of PSP-tau pathology and allows for consideration of the clinical diversity that is known to occur in PSP.

Functional gene expression differences between inbred alcohol-preferring and -non-preferring rats in five brain regions

The objective of this study was to determine if there are innate differences in gene expression in selected CNS regions between inbred alcohol-preferring (iP) and -non-preferring (iNP) rats. Gene expression was determined in the nucleus accumbens (ACB), amygdala (AMYG), frontal cortex (FC), caudate-putamen (CPU), and hippocampus (HIPP) of alcohol-naïve adult male iP and iNP rats, using Affymetrix Rat Genome U34A microarrays (n = 6/strain). Using Linear Modeling for Microarray Analysis with a false discovery rate threshold of 0.1, there were 16 genes with differential expression in the ACB, 54 in the AMYG, 8 in the FC, 24 in the CPU, and 21 in the HIPP. When examining the main effect of strain across regions, 296 genes were differentially expressed. Although the relatively small number of genes found significant within individual regions precluded a powerful analysis for over-represented Gene Ontology categories, the much larger list resulting from the main effect of strain analysis produced 17 over-represented categories (P < .05), including axon guidance, gliogenesis, negative regulation of programmed cell death, regulation of programmed cell death, regulation of synapse structure function, and transmission of nerve impulse. Co-citation analysis and graphing of significant genes revealed a network involved in the neuropeptide Y (NPY) transmitter system. Correlation of all significant genes with those located within previously established rat alcohol QTLs revealed that of the total of 313 significant genes, 71 are located within such QTLs. The many regional and overall gene expression differences between the iP and iNP rat lines may contribute to the divergent alcohol drinking phenotypes of these rats.

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.

Disminución del transportador de dopamina estriatal en primeros episodios psicóticos de pacientes esquizofrénicos tratados con risperidona

Extrapyramidal symptoms and Parkinsonism (PS) are side effects commonly observed with antipsychotic treatment. However, about 24% of never-treated schizophrenic patients may suffer from PS, which contrast with that 1% observed from the general population. 123I-FP-CIT SPECT has probe useful to differentiate degenerative from non-degenerative PS, so it could be interesting using it for establishing the functional state of presynaptic dopamine neurons of these patients.

AIM

To determine the dopamine transporter binding (DAT) in a homogeneous group of first-episode schizophrenic patients.

METHODS

An open, transversal study. Thirty schizophrenic in-patients and 15 healthy subjects were recruited. Patients were treated with similar doses of risperidone and all subjects were scanned with 123I-FP-CIT. Extrapyramidal symptoms and psychopathological status was assessed by Simpson-Angus, CGI and PANSS. Semi-quantitative analyses of SPECT images were performed using ROIs placed in caudate nucleus, anterior, medium and posterior putamen and occipital cortex.

RESULTS

Whole striatum 123I-FP-CIT binding ratio was significantly lower in patients than healthy subjects (t = 2.56, p < 0.014). This was observed in whole putamen (t = 2.66, p < 0.011), anterior (t = 2.35, p < 0.023), medium (t = 2.38, p < 0.022) and posterior putamen (t = 2.09, p < 0.042). No differences were observed in caudate nucleus (t = 1.81, p = 0.076). Females obtained higher binding ratios than males (t = -3.13, p < 0.003). No correlation was observed between 123I-FP-CIT binding ratios and clinical scales.

CONCLUSION

In our series, first episode schizophrenic patients treated with risperidone have a decrease striatal DAT binding assessed with 123I-FP-CIT SPECT. This alteration could be related to their own schizophrenia disease or be secondary to the antipsychotic treatment.

Comparison of ethanol preference and neurochemical measures of mesolimbic dopamine and adenosine systems across different strains of mice

BACKGROUND

To extend the known phenotype of strains commonly used in the development of mutant mice, ethanol, saccharin, and caffeine preferences were examined in C57Bl/6J, CD-1, and hybrid C57Bl/6J x CD-1 mice. As dopaminergic mechanisms are inherently involved in the neuronal processing of many drugs of abuse (including ethanol), and an important role for adenosine-dopamine interactions has also been reported, the dopaminergic and purinergic neurochemical profiles of mice were compared against the consummatory phenotype observed.

METHODS

Ethanol (5% v/v), saccharin (0.1% w/v), and caffeine (0.1% w/v) consumption and preference were examined using a 2-bottle free-choice paradigm. Dopamine and adenosine receptor and transporter mRNA and protein density were quantified using in situ hybridization histochemistry and in vitro autoradiography, respectively.

RESULTS

C57Bl/6J and hybrid C57Bl/6J x CD-1 mice demonstrated a clear ethanol preference, voluntarily consuming large quantities of ethanol when given the choice between drinking vessels containing either ethanol or water. Conversely, CD-1 mice were characterized as ethanol-avoiding under the present paradigm. Differences in D(1) receptor mRNA between the strains were consistent with the observed behavioral differences in ethanol preference. The high ethanol-preferring phenotype of C57Bl/6J mice could not be directly linked to alterations in dopamine transporter neurochemistry and/or enkephalin levels as proposed by earlier researchers. Ethanol-seeking behavior appeared to correlate with D2 receptor expression, however, with evidence that ethanol-preferring mice also exhibit an increased density of D2 receptors within limbic dopaminergic projection nuclei. Interestingly, strain differences in the expression of the ethanol-sensitive nucleoside transporter paralleled differences in ethanol consumption, a novel finding consonant with purinergic involvement in dopamine-related behaviors.

CONCLUSIONS

This study has highlighted the relevance of alterations in dopamine receptor expression and purinergic modulation within the mesolimbic pathway and predisposition toward the development of ethanol-seeking behavior.

Tissue-specific deletion patterns of the mitochondrial genome with advancing age

Aging is a multifactorial process and a lot of theories have been put forward to explain the deterioration of organ function with advancing age. The free radical hypothesis developed by Harman is amongst the most prominent today and has been focused on mitochondrial aging in the last decades. Applying a long PCR approach we screened human skeletal muscle, heart, caudate nucleus and cerebellum of 50 individuals for large-scale deletions of mitochondrial DNA (mtDNA). The most important observation of our study was the detection of age dependent tissue specific deletion patterns of mtDNA. The pattern of the same tissue of different individuals was more similar than the pattern of different tissues of the same individuals. Whereas deletions were barely detectable in cerebellar tissue, in caudate nucleus a specific banding pattern with deletions of 4-8 kb was already observed around the age of thirty. However, the increase of these large-scale deletions in number and variety over lifetime was more pronounced in skeletal muscle or heart. Our data support the notion that different tissues accumulate mtDNA damage in a specific manner. Although functional consequences of mitochondrial deletions are clearly supported by experimental data on the single-cell level in model organisms and mammals, their role regarding impaired function of organs with advancing age in humans remains unresolved.

Altered glutathione redox state in schizophrenia

Altered antioxidant status has been reported in schizophrenia. The glutathione (GSH) redox system is important for reducing oxidative stress. GSH, a radical scavenger, is converted to oxidized glutathione (GSSG) through glutathione peroxidase (GPx), and converted back to GSH by glutathione reductase (GR). Measurements of GSH, GSSG and its related enzymatic reactions are thus important for evaluating the redox and antioxidant status. In the present study, levels of GSH, GSSG, GPx and GR were assessed in the caudate region of postmortem brains from schizophrenic patients and control subjects (with and without other psychiatric disorders). Significantly lower levels of GSH, GPx, and GR were found in schizophrenic group than in control groups without any psychiatric disorders. Concomitantly, a decreased GSH:GSSG ratio was also found in schizophrenic group. Moreover, both GSSG and GR levels were significantly and inversely correlated to age of schizophrenic patients, but not control subjects. No significant differences were found in any GSH redox measures between control subjects and individuals with other types of psychiatric disorders. There were, however, positive correlations between GSH and GPx, GSH and GR, as well as GPx and GR levels in control subjects without psychiatric disorders. These positive correlations suggest a dynamic state is kept in check during the redox coupling under normal conditions. By contrast, lack of such correlations in schizophrenia point to a disturbance of redox coupling mechanisms in the antioxidant defense system, possibly resulting from a decreased level of GSH as well as age-related decreases of GSSG and GR activities.

Localization of nerve growth factor, neurotrophin-3, and glial cell line-derived neurotrophic factor in nestin-expressing reactive astrocytes in the caudate-putamen of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated C57/Bl mice

To address the hypothesis that reactive astrocytes in the basal ganglia of an animal model of Parkinson's disease serve neurotrophic roles, we studied the expression pattern of neurotrophic factors in the basal ganglia of C57/Bl mice that had been treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce the degeneration of nigral dopamine neurons and parkinsonism. MPTP induced significant neuronal degeneration in the substantia nigra pars compacta as detected with Fluoro-Jade B staining, and this was accompanied by an increase in nestin-expressing astrocytes within the caudate-putamen. The number of nestin-positive reactive astrocytes in the caudate-putamen peaked within 3-5 days following MPTP treatment and then declined progressively toward the basal level by 21 days after treatment. Immunofluorescence and confocal microscopy confirmed coexpression of nestin or Ki-67 (cell proliferation marker) in glial fibrillary acid protein-positive astrocytes in the caudate-putamen. Double immunolabeling further revealed immunoreactivities for nerve growth factor (NGF), neurotrophin-3 (NT3), and glial cell line-derived neurotrophic factor (GDNF) in nestin-positive reactive astrocytes. Semiquantification of data obtained from mice 5 days after MPTP injection indicated that the majority of nestin-expressing cells expressed NGF (92%), NT3 (90%), or GDNF (86%). Our results present novel evidence of neurotrophic features among reactive astrocytes in the dopamine-depleted striatum. These nestin-expressing reactive astrocytes may therefore play neurotrophic roles in neural remodeling of the basal ganglia in Parkinson's disease.

Prolonged exposure of rats to intravenous methamphetamine: behavioral and neurochemical characterization

The translational value of preclinical models of methamphetamine abuse depends in large part on the degree to which the drug regimens used in animals produce methamphetamine exposure patterns similar to those experienced by human methamphetamine abusers. To approximate one common form of methamphetamine abuse, we studied the effects of a schedule of intravenous methamphetamine administration in rats which included 2 weeks of progressively more frequent drug injections (0.125 mg/kg/injection) followed by 40 maintenance days during which animals received 40 daily injections (at 15-min intervals), with the dose gradually increasing (0.125-0.25 mg/kg per injection) every 5-10 days. This treatment produced an emerging behavioral profile characterized by gradually more continuous periods of activation consisting of progressively more intense, focused stereotypy interrupted by episodic bursts of locomotion. We also assessed markers of dopamine neurotransmission (dopamine transporter, vesicular monoamine transporter, and dopamine D1 and D2 receptors) at 15 min and (including dopamine levels) at 6 and 30 days following cessation of methamphetamine treatment. All dopamine components measured in caudate-putamen were significantly reduced at 15 min and 6 days after the final methamphetamine injection. Dopamine D1 and D2 receptors fully recovered after 30 days of drug abstinence, whereas dopamine and the dopamine transporter exhibited significant but incomplete recovery by this time point. In contrast, only the vesicular monoamine transporter exhibited no evidence of recovery over the 30-day withdrawal period. These data are discussed in terms of damage to dopamine terminals and compensatory adjustments in mechanisms maintaining functional dopaminergic transmission.

Neurochemical alterations produced by daily nicotine exposure in periadolescent vs. adult male rats

Chronic treatment with nicotine differentially alters behavior in adolescent rats compared to adult rats. It is not known, however, whether the effects of nicotine on the neurochemical pathways with which it interacts differ in adolescents vs. adults. In the current study, the effects of a 7-day treatment with nicotine on nicotinic, dopaminergic, and serotonergic neurochemistry were examined in the caudate putamen and nucleus accumbens in periadolescent vs. adult male rats. Nicotine treatment increased dopamine transporter densities and decreased serotonin transporter densities in periadolescent rats. There was no change in nicotinic acetylcholine receptor densities or dopamine D1 or D2 receptor densities in nicotine-pretreated periadolescent rats. In adult rats pretreated with nicotine, there was an increase in nicotinic acetylcholine densities, but no change in dopamine transporter, dopamine D1 or D2 receptor, or serotonin transporter densities. Overall, these findings show that periadolescent rats have neurochemical adaptations to nicotine different from adult rats. These alterations may explain, at least in part, the differential behavioral effects of chronic nicotine in adult and adolescent male rats.

Quinolinic acid lesions of the caudate putamen in the rat lead to a local increase of ciliary neurotrophic factor

When applied prior to excitotoxic lesions, ciliary neurotrophic factor (CNTF) has been shown to be neuroprotective. However, data concerning the endogenous CNTF content of the intact rat striatum are rare and have not until now been available for the quinolinic acid (QA)-lesioned striatum. Therefore, we investigated the CNTF content in the QA-lesioned rat striatum for at least 1 month using immunohistochemistry and Western blot analysis. In lesioned striata a neuronal loss was observed by Nissl staining and by a reduction of NeuN-immunoreactive cells, whereas increased glial fibrillary acidic protein immunoreactivity showed a gliotic reaction. With CNTF immunohistochemistry we found that in the QA-lesioned striatum CNTF was increased over time, whereas it was not detectable in intact and sham-lesioned striata. CNTF-immunoreactive cells had the morphology of protoplasmatic astrocytes. Furthermore, quantitative Western blotting demonstrated that the content of CNTF protein from striatal lysates containing 1 mg of whole protein 1 month after QA lesioning (2.76 +/- 1.71 ng) was significantly increased (P < 0.05, U-test) compared with sham-lesioned hemispheres (0.68 +/- 0.25 ng) and intact controls (0.55 +/- 0.25 ng). We conclude that CNTF content is correlated with glial scar formation and suggest that our results may be of relevance to cell grafting strategies for the treatment of Huntington's disease.

Atypical [(3)H]clonidine binding sites in human caudate and platelets on cryostat-cut sections

Pharmacological characterization is described for a human imidazoline binding site (I-site) labeled by [(3)H]clonidine using standard autoradiographic method. Under conditions that mask alpha(2)-adrenergic sites, only a single high affinity site was observed in human caudate and blood platelet sections. Affinity constants (K(i)) were highly correlated between the two tissues (r = 0.90, P = 0.0003). This site is dissimilar to classical I(1) and I(2) sites, even though both tissues possess abundant I(1) and I(2) sites by filtration binding methods. It is suggested that the isotonic buffer conditions inherent to the procedure alter drug affinities to the classical I(1) site.

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.

[Morphochemical characteristic of rat brain structures after exposure to delta-sleep inducing peptide following long-term amphetamine administration]

The aim of this work, that was carried out using Wistar rats, was to characterize the response of neurons of different morphofunctional types to amphetamine administration and to study the possibility of correction of these changes by delta-sleep inducing peptide (DSIP). Single intraperitoneal injection of 60 microg/kg of DSIP following a long term amphetamine administration (2.5 mg/kg for 3 weeks) was shown to result in normalization of brain metabolism, that was disturbed by the drug. The correcting DSIP effect was found in rat brain structures judging by the parameters of the state of proteins in neurons of sensomotor cortex and caudate nucleus and by the activity of enzymes of neurotransmitter metabolism, such as type A and B monoamine oxidases and acetylcholine esterase, that was determined in subfractions of the same brain structures. DSIP modulating effect in phenamine stereotypy supports its role as an adaptogen of intercenter relations in CNS pathology.

Simultaneous gas chromatographic-mass spectrometric determination of dopamine, norsalsolinol and salsolinol enantiomers in brain samples of a large human collective

Using a solid-phase extraction procedure, an enantioselective derivatization and a gas chromatographic-mass spectrometric method, the levels of dopamine (DA) and of the dopamine-derived tetrahydroisoquinoline alkaloids (R)/(S)-salsolinol (SAL) and norsalsolinol (NorSAL) were determined in human brain samples. A complex pre-analytical synthesis of reference substances as well as deuterated internal standards allowed the standardized and reproducible analysis. In this study, to our best knowledge for the first time, the regional distribution of (R)-SAL and (S)-SAL, as well as NorSAL is examined systematically in a large collective of human brain samples obtained by autopsy. The material comprises 91 brains and 8 standardized specimens in each case. Anatomical concentration differences and no ubiquitous occurence were encountered. Significant amounts of (R)-SAL, (S)-SAL and NorSAL were only found in dopamine-rich areas of the basal ganglia, whereas in other regions of the brain no tetrahydroisoquinolines were detected. These findings suggest that the concentration of the substrate dopamine may determine the alkaloid level during in vivo formation. In our opinion, non-enzymatic formation of SAL via the Pictet-Spengler reaction reveals both the SAL enantiomers. An additional enzymatic synthesis of only (R)-SAL could explain the predominant occurrence of this enantiomer. Especially in the nucleus caudatus, the concentrations of DA, SAL and NorSAL decreased significantly with rising age, which may be consistent with apoptotic effects of ageing. Our data can serve as reference for other studies in humans concerning the etiology of alcoholism or other neurodegenerative diseases with the involvement of tetrahydroisoquinolines.

Optimizing primer--probe design for fluorescent PCR

TaqMan, a variation of fluorescent PCR, is a powerful tool for gene expression and polymorphism studies. Here we describe the design and evaluation of 27 new TaqMan primer-probe sets for rat genes that play a key role in neural signaling. These newly designed and synthesized probes were tested and then used for quantification of RNA isolated from rat brain. The usual length of common TaqMan probes is 25 bases or less. In these studies we constructed probes with lengths of 25-39 bases to span exon-exon junctions of nucleic acids to avoid the influence of DNA contamination upon the RNA quantification. The specific sequences at these positions required probes of these lengths to optimize hybridization. We found that the relocation of the quencher from the traditional 3' position to an internal one increases the sensitivity of probe up to 30 fold. Substitution of 6-carboxyfluorescein with Alexa Fluor 488 as fluorophore and TAMRA with non-fluorescent quencher dabcyl was also investigated. We also describe the evaluation of part of a newly designed set of 27 TaqMan primer-probes for the measurement of differences in gene expression levels in samples from the caudate putamen region of rat brain after 'binge' paradigm cocaine administration. Cocaine-induced alterations in expression of c-fos and preprodynorphin mRNAs measured by TaqMan were confirmed by ribonuclease protection assay.

Periadolescent mice show enhanced DeltaFosB upregulation in response to cocaine and amphetamine

Children and adolescents are increasingly exposed to psychostimulants, either illicitly or for the treatment of common neuropsychiatric conditions, such as attention deficit disorder with and without hyperactivity. Despite the widespread use of psychomotor stimulants in younger age groups, little is known regarding the chronic molecular neuroadaptive responses to these agents in the immature brain. Here we demonstrate that, after chronic administration of the psychostimulants cocaine and amphetamine, the transcription factor DeltaFosB is upregulated in the nucleus accumbens of periadolescent mice but not in post-weanling or adult mice. Induction of DeltaFosB also occurs exclusively in the caudate putamen of periadolescent mice after amphetamine administration. These results demonstrate the unique plasticity in the adolescent brain of a critical molecule that regulates psychostimulant action and suggest that these neuroadaptive changes may be involved in the mediation of enhanced addictive tendencies in the adolescent relative to the adult.

Three-dimensional cartography of functional territories in the human striatopallidal complex by using calbindin immunoreactivity

This anatomic study presents an analysis of the distribution of calbindin immunohistochemistry in the human striatopallidal complex. Entire brains were sectioned perpendicularly to the mid-commissural line into 70-microm-thick sections. Every tenth section was immunostained for calbindin. Calbindin labeling exhibited a gradient on the basis of which three different regions were defined: poorly labeled, strongly labeled, and intermediate. Corresponding contours were traced in individual sections and reformatted as three-dimensional structures. The poorly labeled region corresponded to the dorsal part of the striatum and to the central part of the pallidum. The strongly labeled region included the ventral part of the striatum, the subcommissural part of the external pallidum but also the adjacent portion of its suscommissural part, and the anterior pole of the internal pallidum. The intermediate region was located between the poorly and strongly labeled regions. As axonal tracing and immunohistochemical studies in monkeys show a similar pattern, poorly, intermediate, and strongly labeled regions were considered as the sensorimotor, associative, and limbic territories of the human striatopallidal complex, respectively. However, the boundaries between these territories were not sharp but formed gradients of labeling, which suggests overlapping between adjacent territories. Similarly, the ventral boundary of the striatopallidal complex was blurred, suggesting a structural intermingling with the substantia innominata. This three-dimensional partitioning of the human striatopallidal complex could help to define functional targets for high-frequency stimulation with greater accuracy and help to identify new stimulation sites.