Ultrastructural analysis of nigrostriatal dopaminergic terminals in a knockin mouse model of DYT1 dystonia

DYT1 dystonia is associated with decreased striatal dopamine release. In this study, we examined the possibility that ultrastructural changes of nigrostriatal dopamine terminals could contribute to this neurochemical imbalance using a serial block face/scanning electron microscope (SBF/SEM) and three-dimensional reconstruction to analyse striatal tyrosine hydroxylase-immunoreactive (TH-IR) terminals and their synapses in a DYT1(ΔE) knockin (DYT1-KI) mouse model of DYT1 dystonia. Furthermore, to study possible changes in vesicle packaging capacity of dopamine, we used transmission electron microscopy to assess the synaptic vesicle size in striatal dopamine terminals. Quantitative comparative analysis of 80 fully reconstructed TH-IR terminals in the WT and DYT1-KI mice indicate (1) no significant difference in the volume of TH-IR terminals; (2) no major change in the proportion of axo-spinous versus axo-dendritic synapses; (3) no significant change in the post-synaptic density (PSD) area of axo-dendritic synapses, while the PSDs of axo-spinous synapses were significantly smaller in DYT1-KI mice; (4) no significant change in the contact area between TH-IR terminals and dendritic shafts or spines, while the ratio of PSD area/contact area decreased significantly for both axo-dendritic and axo-spinous synapses in DYT1-KI mice; (5) no significant difference in the mitochondria volume; and (6) no significant difference in the synaptic vesicle area between the two groups. Altogether, these findings suggest that abnormal morphometric changes of nigrostriatal dopamine terminals and their post-synaptic targets are unlikely to be a major source of reduced striatal dopamine release in DYT1 dystonia.

Corticostriatal Suppression of Appetitive Pavlovian Conditioned Responding

The capacity to suppress learned responses is essential for animals to adapt in dynamic environments. Extinction is a process by which animals learn to suppress conditioned responding when an expected outcome is omitted. The infralimbic (IL) cortex to nucleus accumbens shell (NAcS) neural circuit is implicated in suppressing conditioned responding after extinction, especially in the context of operant cocaine-seeking behavior. However, the role of the IL-to-NAcS neural circuit in the extinction of responding to appetitive Pavlovian cues is unknown, and the psychological mechanisms involved in response suppression following extinction are unclear. We trained male Long Evans rats to associate a 10 s auditory conditioned stimulus (CS; 14 trials per session) with a sucrose unconditioned stimulus (US; 0.2 ml per CS) in a specific context, and then following extinction in a different context, precipitated a renewal of CS responding by presenting the CS alone in the original Pavlovian conditioning context. Unilateral, optogenetic stimulation of the IL-to-NAcS circuit selectively during CS trials suppressed renewal. In a separate experiment, IL-to-NAcS stimulation suppressed CS responding regardless of prior extinction and impaired extinction retrieval. Finally, IL-to-NAcS stimulation during the CS did not suppress the acquisition of Pavlovian conditioning but was required for the subsequent expression of CS responding. These results are consistent with multiple studies showing that the IL-to-NAcS neural circuit is involved in the suppression of operant cocaine-seeking, extending these findings to appetitive Pavlovian cues. The suppression of appetitive Pavlovian responding following IL-to-NAcS circuit stimulation, however, does not appear to be an extinction-dependent process.SIGNIFICANCE STATEMENT Extinction is a form of inhibitory learning through which animals learn to suppress conditioned responding in the face of nonreinforcement. We investigated the role of the IL cortex inputs to the NAcS in the extinction of responding to appetitive Pavlovian cues and the psychological mechanisms involved in response suppression following extinction. Using in vivo optogenetics, we found that stimulating the IL-to-NAcS neural circuit suppressed context-induced renewal of conditioned responding after extinction. In a separate experiment, stimulating the IL-to-NAcS circuit suppressed conditioned responding in an extinction-independent manner. These findings can be used by future research aimed at understanding how corticostriatal circuits contribute to behavioral flexibility and mental disorders that involve the suppression of learned behaviors.

A Pilot Study of Changes in the Level of Catecholamines and the Activity of α-2-Macroglobulin in the Tear Fluid of Patients with Parkinson's Disease and Parkinsonian Mice

Development of differential and early (preclinical) diagnostics of Parkinson’s disease (PD) is among the priorities in neuroscience. We searched for changes in the level of catecholamines and α-2-macroglobulin activity in the tear fluid (TF) in PD patients at an early clinical stage. It was shown that TF in patients is characterized by an increased level of noradrenaline mainly on the ipsilateral side of pronounced motor symptoms (72%, p = 0.049), a decreased level of adrenaline on both sides (ipsilateral—53%, p = 0.004; contralateral—42%, p = 0.02), and an increased α-2-macroglobulin activity on both sides (ipsilateral—53%, p = 0.03; contralateral—56%, p = 0.037) compared to controls. These changes are considered as potential biomarkers for differential diagnosis. Similar changes in the TF were found in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice when modeling clinical and preclinical stages of PD. These data show the adequacy of models to the pathogenesis of PD along the selected metabolic pathways, and also suggest that the found TF changes can be considered as potential biomarkers for preclinical diagnosis of PD. In Parkinsonian mice, the level of catecholamines also changes in the lacrimal glands, which makes it possible to consider them as one of the sources of catecholamines in the TF.

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.

Strength of resting state functional connectivity and local GABA concentrations predict oral reading of real and pseudo-words

Reading is a learned activity that engages multiple cognitive systems. In a cohort of typical and struggling adult readers we show evidence that successful oral reading of real words is related to gamma-amino-butyric acid (GABA) concentration in the higher-order language system, whereas reading of unfamiliar pseudo-words is not related to GABA in this system. We also demonstrate the capability of resting state functional connectivity (rsFC) combined with GABA measures to predict single real word compared to pseudo-word reading performance. Results show that the strength of rsFC between left fusiform gyrus (L-FG) and higher-order language systems predicts oral reading behavior of real words, irrespective of the local concentration of GABA. On the other hand, pseudo-words, which require grapheme-to-phoneme conversion, are not predicted by the connection between L-FG and higher-order language system. This suggests that L-FG may have a multi-functional role: lexical processing of real words and grapheme-to-phoneme processing of pseudo-words. Additionally, rsFC between L-FG, pre-motor, and putamen areas are positively related to the oral reading of both real and pseudo-words, suggesting that text may be converted into a phoneme sequence for speech initiation and production regardless of whether the stimulus is a real word or pseudo-word. In summary, from a systems neuroscience perspective, we show that: (i) strong rsFC between higher order visual, language, and pre-motor areas can predict and differentiate efficient oral reading of real and pseudo-words. (ii) GABA measures, along with rsFC, help to further differentiate the neural pathways for previously learned real words versus unfamiliar pseudo-words.

Neuroprotection of Fasting Mimicking Diet on MPTP-Induced Parkinson's Disease Mice via Gut Microbiota and Metabolites

Parkinson's disease (PD) is strongly associated with life style, especially dietary habits, which have gained attention as disease modifiers. Here, we report a fasting mimicking diet (FMD), fasting 3 days followed by 4 days of refeeding for three 1-week cycles, which accelerated the retention of motor function and attenuated the loss of dopaminergic neurons in the substantia nigra in 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced PD mice. Levels of brain-derived neurotrophic factor (BDNF), known to promote the survival of dopaminergic neurons, were increased in PD mice after FMD, suggesting an involvement of BDNF in FMD-mediated neuroprotection. Furthermore, FMD decreased the number of glial cells as well as the release of TNF-α and IL-1β in PD mice, showing that FMD also inhibited neuro-inflammation. 16S and 18S rRNA sequencing of fecal microbiota showed that FMD treatment modulated the shifts in gut microbiota composition, including higher abundance of Firmicutes, Tenericutes, and Opisthokonta and lower abundance of Proteobacteria at the phylum level in PD mice. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry revealed that FMD modulated the MPTP-induced lower propionic acid and isobutyric acid, and higher butyric acid and valeric acid and other metabolites. Transplantation of fecal microbiota, from normal mice with FMD treatment to antibiotic-pretreated PD mice increased dopamine levels in the recipient PD mice, suggesting that gut microbiota contributed to the neuroprotection of FMD for PD. These findings demonstrate that FMD can be a new means of preventing and treating PD through promoting a favorable gut microbiota composition and metabolites.

Kami-shoyo-san ameliorates sociability deficits in ovariectomized mice, a putative female model of autism spectrum disorder, via facilitating dopamine D1 and GABAA receptor functions

ETHNOPHARMACOLOGICAL RELEVANCE

Kami-shoyo-san (KSS) is a Kampo formula used clinically for menopause-related symptoms in Japan. However, the effect of KSS on autism spectrum disorder (ASD), a developmental disorder with a higher prevalence in males than in females, has not been reported yet.

AIM OF THE STUDY

It is accepted generally that dysfunction in the GABAergic system is associated with pathogenesis of ASD. In our previous study, a decrease in brain allopregnanolone (ALLO), a positive allosteric GABA_A receptor modulator, induced ASD-like symptoms such as impaired sociability-related performance and increased repetitive self-grooming behavior in male mice, and that KSS ameliorated these behavioral abnormalities via GABA_A receptor- and dopamine D₁ receptor-mediated mechanisms. In this study, to better understand a gender difference in the prevalence of ASD, we examined whether dissection of ovary (OVX), a major organ secreting progesterone in females, causes ASD-like behaviors in a manner dependent on brain ALLO levels, and if so, how KSS affects the behaviors.

MATERIALS AND METHODS

Six-week-old ICR female mice received ovariectomy, and KSS (74 mg/kg and 222 mg/kg, p.o.) were treated before 1 h starting each behavioral test. The sociability, social anxiety-like behavior, and self-grooming behavior were analyzed by the resident-intruder test, mirror chamber test, and open field test, respectively. After finishing the behavioral experiment, the ALLO content in the brain was measured by ELISA. Furthermore, we examined the effects of OVX on the neuro-signaling pathways in the prefrontal cortex and striatum by Western blotting.

RESULTS

The results revealed that OVX induced sociability deficits and social anxiety-related behaviors, but not repetitive self-grooming behavior, and that these behavioral changes were accompanied not only by a decrease of brain ALLO levels, but also by impairment of CREB- and CaMKIIα-mediated neuro-signaling in the prefrontal cortex. Moreover, the administration of KSS had no effect on the brain ALLO level, but significantly ameliorated the OVX-induced behavioral and neurochemical changes via facilitation of GABA_A receptor and dopamine D₁ receptor-mediated neurotransmission.

CONCLUSIONS

These findings suggest that a decrease in gonadal hormone-derived ALLO plays a major role in ASD-like behaviors in female mice and that KSS is beneficial for the treatment of ASD in females.

On-line regeneration of electrochemical biosensor for in vivo repetitive measurements of striatum Cu2+ under global cerebral ischemia/reperfusion events

The detection of Cu²⁺ ion, one of the metal ions substantial in cerebral physiology, is critical in studying brain activities and understanding brain functions. However, repetitive measurements of Cu²⁺ in the progress of physiological and pathological events is still challenging, because lack of the platform for repetitive on-line detection-regeneration cycle. Herein we report the design of a regenerated electrochemical biosensor combined with the in vivo microdialysis system. In this biosensor, hyperbranched polyethyleneimine (hPEI) acts as a regenerated recognition unit for Cu²⁺. Just by a simple rinse of ethylenediaminetetraacetic acid (EDTA) disodium salt, the Cu²⁺ and Cu⁺ ions on the biosensor interface were chelated with EDTA disodium salt, thus achieving the regeneration of the biosensor. In addition, 6-(ferrocenyl)hexanethiol (FcHT) serves as the inner reference moiety to elevate the sensing accuracy over regeneration cycles. As a result, this ratiometric electrochemical biosensor not only revealed high sensitivity and selectivity, but also exhibited excellent stability during multiple regeneration processing. This biosensor was capable of determining Cu²⁺ with a linear range between 0.05 and 12 μM and low detection limit (LOD) of 13 nM. Then, the platform has been successfully applied in repetitive Cu²⁺ analysis in rat brain under global cerebral ischemia/reperfusion events. The combination of results from 7 rats indicates global cerebral ischemia caused an obvious increase of the Cu²⁺ level, while reperfusion brought this level back to normal.

Perinatal Exposure to Arsenic in Drinking Water Alters Glutamatergic Neurotransmission in the Striatum of C57BL/6 Mice

Although exposure to arsenic (As) induces developmental neurotoxicity, there is a lack of data regarding its specific effects on glutamatergic neurotransmission in offspring from dams exposed to As during gestation and lactation. In this study, the body weight, glutamate content, and expression of vesicular glutamate transporter 2 (VGLUT2) and metabotropic glutamate receptors mGluR2 and mGluR3 was examined in the striatum of offspring following treatment of the dams with As (10 or 100 mg/L NaAsO₂ in drinking water). At postnatal day 21, body weight was decreased significantly, whereas the glutamate content in the striatum of offspring in the 100-mg/L As group were not significantly different from those in the control group. Although mGluR3 expression was not significantly different, VGLUT2 and mGluR2 expression was significantly lower in the striatum of offspring of As-exposed dams. These data indicate that altered glutamatergic neurotransmission may contribute to As-induced developmental neurotoxic effects.

Tracking tonic dopamine levels in vivo using multiple cyclic square wave voltammetry

For over two decades, fast-scan cyclic voltammetry (FSCV) has served as a reliable analytical method for monitoring dopamine release in near real-time in vivo. However, contemporary FSCV techniques have been limited to measure only rapid (on the order of seconds, i.e. phasic) changes in dopamine release evoked by either electrical stimulation or elicited by presentation of behaviorally salient stimuli, and not slower changes in the tonic extracellular levels of dopamine (i.e. basal concentrations). This is because FSCV is inherently a differential method that requires subtraction of prestimulation tonic levels of dopamine to measure phasic changes relative to a zeroed baseline. Here, we describe the development and application of a novel voltammetric technique, multiple cyclic square wave voltammetry (M-CSWV), for analytical quantification of tonic dopamine concentrations in vivo with relatively high temporal resolution (10 s). M-CSWV enriches the electrochemical information by generating two dimensional voltammograms which enable high sensitivity (limit of detection, 0.17 nM) and selectivity against ascorbic acid, and 3,4-dihydroxyphenylacetic acid (DOPAC), including changes in pH. Using M-CSWV, a tonic dopamine concentration of 120 ± 18 nM (n = 7 rats, ± SEM) was determined in the striatum of urethane anethetized rats. Pharmacological treatments to elevate dopamine by selectively inhibiting dopamine reuptake and to reduce DOPAC by inhibition of monoamine oxidase supported the selective detection of dopamine in vivo. Overall, M-CSWV offers a novel voltammetric technique to quantify levels and monitor changes in tonic dopamine concentrations in the brain to further our understanding of the role of dopamine in normal behavior and neuropsychiatric disorders.

Radial Glial Lineage Progression and Differential Intermediate Progenitor Amplification Underlie Striatal Compartments and Circuit Organization

The circuitry of the striatum is characterized by two organizational plans: the division into striosome and matrix compartments, thought to mediate evaluation and action, and the direct and indirect pathways, thought to promote or suppress behavior. The developmental origins of these organizations and their developmental relationships are unknown, leaving a conceptual gap in understanding the cortico-basal ganglia system. Through genetic fate mapping, we demonstrate that striosome-matrix compartmentalization arises from a lineage program embedded in lateral ganglionic eminence radial glial progenitors mediating neurogenesis through two distinct types of intermediate progenitors (IPs). The early phase of this program produces striosomal spiny projection neurons (SPNs) through fate-restricted apical IPs (aIPSs) with limited capacity; the late phase produces matrix SPNs through fate-restricted basal IPs (bIPMs) with expanded capacity. Notably, direct and indirect pathway SPNs arise within both aIPS and bIPM pools, suggesting that striosome-matrix architecture is the fundamental organizational plan of basal ganglia circuitry.

Intranasal Administration of chitosan-Coated Nanostructured Lipid Carriers Loaded with GDNF Improves Behavioral and Histological Recovery in a Partial Lesion Model of Parkinson's Disease

Parkinson's disease (PD) is the second most frequent neurodegenerative disorder, but current therapies are only symptomatic. A promising alternative to address the neurodegenerative process is the use of neurotrophic factors, such as the glial cell-derived neurotrophic factor (GDNF). However, its clinical use has been limited due to its short half-life and rapid degradation after in vivo administration, in addition to difficulties in crossing the blood-brain barrier (BBB). This barrier is a limiting factor in brain drug development, making the future progression of neurotherapeutics difficult. In the past few years, intranasal drug delivery has appeared as an alternative non-invasive administration route to bypass the BBB and target drugs directly to the CNS. Thus, the aim of this work was to study the in vivo neuroprotective effect of intranasally administered GDNF, encapsulated in chitosan-coated nanostructured lipid carrier (CS-NLC-GDNF), in a 6-OHDA partially lesioned rat model. The developed CS-NLC-GDNF showed a particle size of approximately 130 nm and high encapsulation efficiency. The in vitro study in PC-12 cells demonstrated the ability of the encapsulated GDNF to protect these cells against 6-OHDA toxin. After two weeks of daily intranasal administration of treatments, the administration of CS-NLC-GDNF achieved a behavioral improvement in rats, as well as a significant improvement in both the density of TH+ fibres in the striatum and the TH+ neuronal density in the SN. Thus, it can be concluded that the nose-to-brain delivery of CS-NLC-GDNF could be a promising therapy for the treatment of PD.

Encapsulated PC 12 Cell Transplants into Hemiparkinsonian Monkeys: A Behavioral, Neuroanatomical, and Neurochemical Analysis

Four cynomolgus monkeys were trained on a hand reaching task and then rendered hemiparkinsonian with an intracarotid injection of n-methyl 4 phenyl 1,2,3,6, tetrahydropyridine (MPTP). Performance on this task with the limb contralateral to the MPTP injection was significantly impaired following the lesion. Three monkeys received implants of polymer-encapsulated containing PC12 cells into the caudate nucleus and putamen. One monkey received identical implants of empty capsules and served as a control. After a transient improvement, limb use in the control monkey dissipated and returned to post-MPTP disability. Two of the three PC12 cell grafted monkeys recovered performance on the hand reach task to near normal levels for up to 6.5 mo posttransplantation. Capsules retrieved from the monkeys who recovered limb function postimplantation contained numerous viable PC12 cells that continued to release levodopa, basal dopamine, and potassium evoked dopamine. In contrast, capsules retrieved from the PC12 cell-grafted monkey which did not recover limb use on the hand reach task contained few cells which secreted negligible or undetectable levels of levodopa and dopamine. Interestingly, functional disability was not reinstated following removal of the capsules. Neuroanatomical and neurochemical evaluation of the grafted striatum did not reveal a host-derived sprouting response of catecholaminergic or indolaminergic fibers. These data indicate that xenografts of PC12 cells can survive for up to 6.5 mo in nonimmunosuppressed monkeys when immunoisolated via polymer encapsulation. Moreover, these cells continue to secrete high levels of levodopa and dopamine and induce recovery of motor function in parkinsonian nonhuman primates.

The Age of Striatum Determines the Pattern and Extent of Dopaminergic Innervation: a Nigrostriatal Double Graft Study

In animal models of Parkinson's disease, transplanted fetal mesencephalic dopaminergic neurons can innervate the dopamine-depleted host brain, but it is unclear why large portions of the host striatum are left uninnervated. During normal development, the dopaminergic innervation first occurs in the form of a dense patchy pattern in the striatum, followed by a widespread nerve fiber network. Using intraocular double grafts we have investigated dopaminergic growth patterns initiated when ventral mesencephalic grafts innervate striatal targets. The fetal lateral ganglionic eminence was implanted into the anterior eye chamber. After maturation in oculo, fetal ventral mesencephalon was implanted and placed in contact with the first graft. In other animals the two pieces of tissue were implanted simultaneously. Tyrosine hydroxylase (TH) immunohistochemistry revealed a pattern of dense TH-positive patches throughout the total volume of the striatal grafts in simultaneously transplanted cografts, while a widespread, less dense, pattern was found when mature striatal transplants were innervated by fetal dopaminergic grafts. To investigate which type or types of growth patterns that developed after grafting to striatum in situ of an adult host, fetal ventral mesencephalic tissue was implanted into the lateral ventricle adjacent to the dopamine-lesioned striatum. After maturation of the mesencephalic graft, the fetal lateral ganglionic eminence was implanted into the reinnervated part of the host striatum. TH immunohistochemistry revealed a few nerve fibers within the striatal graft and the growth pattern was of the widespread type. In conclusion, grafted dopaminergic neurons preferably innervate mature striatum with a widespread sparse nerve fiber network, while the innervation of the immature striatum occurs in the form of dense patches. Furthermore, when the patchy pattern is formed, the total volume of the striatal target is innervated while growth of the widespread type terminates prior to reaching distal striatal parts. Thus, the growth pattern seems essential to the final volume that is innervated. Once the widespread growth pattern is initiated, the presence of immature striatum does not change the dopaminergic growth pattern.

High sensitivity HPLC method for analysis of in vivo extracellular GABA using optimized fluorescence parameters for o-phthalaldehyde (OPA)/sulfite derivatives

Reversed-phase HPLC with derivatization using o-phthalaldehyde (OPA) and sulfite allows electrochemical detection of γ-aminobutyric acid (GABA) in microdialysis samples. However, OPA/sulfite derivatives have been reported to produce lower fluorescent yield than OPA derivatives using organic thiols as the nucleophile. To overcome this limitation we examined excitation and emission spectra, reaction time, pH, and concentration of reagents in the derivatization solution. Optimal detection parameters were determined as λex=220nm and λem=385nm for maximal fluorescence. The derivatization reaction occurred immediately and the product was stable up to 24 h [corrected]. A pH of 10.4 for the borate buffer used in the derivatization solution was significantly better than lower pH. Increasing the amount of sulfite combined with diluting the derivatization solution in borate buffer resulted in complete separation of the GABA peak from contaminants without any loss in signal. Controlling the temperature of the detector at 15°C significantly improved sensitivity with a detection limit of approximately 1nM. To validate this assay, we performed microdialysis in the dorsal striatum and ventral tegmental area (VTA) of adult Long Evans rats. GABA concentrations in dialysates were determined using external standards and standard additions, in order to further confirm interfering peaks were not present in biological samples. Within the dorsal striatum (n=4), basal GABA concentrations were 12.9±2.2 and 14.5±2.2nM (external and additions, respectively). Respective basal GABA concentrations in the VTA (n=3) were 4.6±1.1 and 5.1±0.6nM. Thus, we have developed a novel, sensitive fluorescence method to determine GABA in microdialysates using HPLC of an OPA/sulfite derivative.

Specific behavioral and cellular adaptations induced by chronic morphine are reduced by dietary omega-3 polyunsaturated fatty acids

Opiates, one of the oldest known drugs, are the benchmark for treating pain. Regular opioid exposure also induces euphoria making these compounds addictive and often misused, as shown by the current epidemic of opioid abuse and overdose mortalities. In addition to the effect of opioids on their cognate receptors and signaling cascades, these compounds also induce multiple adaptations at cellular and behavioral levels. As omega-3 polyunsaturated fatty acids (n-3 PUFAs) play a ubiquitous role in behavioral and cellular processes, we proposed that supplemental n-3 PUFAs, enriched in docosahexanoic acid (DHA), could offset these adaptations following chronic opioid exposure. We used an 8 week regimen of n-3 PUFA supplementation followed by 8 days of morphine in the presence of this diet. We first assessed the effect of morphine in different behavioral measures and found that morphine increased anxiety and reduced wheel-running behavior. These effects were reduced by dietary n-3 PUFAs without affecting morphine-induced analgesia or hyperlocomotion, known effects of this opiate acting at mu opioid receptors. At the cellular level we found that morphine reduced striatal DHA content and that this was reversed by supplemental n-3 PUFAs. Chronic morphine also increased glutamatergic plasticity and the proportion of Grin2B-NMDARs in striatal projection neurons. This effect was similarly reversed by supplemental n-3 PUFAs. Gene analysis showed that supplemental PUFAs offset the effect of morphine on genes found in neurons of the dopamine receptor 2 (D2)-enriched indirect pathway but not of genes found in dopamine receptor 1(D1)-enriched direct-pathway neurons. Analysis of the D2 striatal connectome by a retrogradely transported pseudorabies virus showed that n-3 PUFA supplementation reversed the effect of chronic morphine on the innervation of D2 neurons by the dorsomedial prefontal and piriform cortices. Together these changes outline specific behavioral and cellular effects of morphine that can be reduced or reversed by dietary n-3 PUFAs.

Enhanced dopamine detection sensitivity by PEDOT/graphene oxide coating on in vivo carbon fiber electrodes

Dopamine (DA) is a monoamine neurotransmitter responsible for regulating a variety of vital life functions. In vivo detection of DA poses a challenge due to the low concentration and high speed of physiological signaling. Fast scan cyclic voltammetry at carbon fiber microelectrodes (CFEs) is an effective method to monitor real-time in vivo DA signaling, however the sensitivity is somewhat limited. Electrodeposition of poly(3,4-ethylene dioxythiophene) (PEDOT)/graphene oxide (GO) onto the CFE surface is shown to increase the sensitivity and lower the limit of detection for DA compared to bare CFEs. Thicker PEDOT/GO coatings demonstrate higher sensitivities for DA, but display the negative drawback of slow adsorption and electron transfer kinetics. The moderate thickness resulting from 25 s electrodeposition of PEDOT/GO produces the optimal electrode, exhibiting an 880% increase in sensitivity, a 50% decrease in limit of detection and minimally altered electrode kinetics. PEDOT/GO coated electrodes rapidly and robustly detect DA, both in solution and in the rat dorsal striatum. This increase in DA sensitivity is likely due to increasing the electrode surface area with a PEDOT/GO coating and improved adsorption of DA's oxidation product (DA-o-quinone). Increasing DA sensitivity without compromising electrode kinetics is expected to significantly improve our understanding of the DA function in vivo.

Proteomic Analysis of the Effect of Korean Red Ginseng in the Striatum of a Parkinson's Disease Mouse Model

Recent studies have shown that Korean Red Ginseng (KRG) suppresses dopaminergic neuronal death in the brain of a Parkinson's disease (PD) mouse model, but the mechanism is still elusive. Using a 2-dimensional electrophoresis technique, we investigated whether KRG can restore the changes in protein expressions in the striatum (ST) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-injected mice. Male C57BL/6 mice (9 weeks old) were injected with 20 mg/kg MPTP intraperitoneally four times at 2-h intervals. KRG (100 mg/kg) was orally administered once a day for 3 days from one hour after the first MPTP injection. Two hours after the third KRG administration a pole test was performed to evaluate motor function, after which the brains were immediately harvested. Survival of dopaminergic neurons in the nigrostriatal pathway and protein expression in the ST were measured by immunohistochemistry and 2-dimensional electrophoresis. KRG suppressed MPTP-induced behavioral dysfunction and neuronal death in the nigrostriatal pathway. Moreover, 30 proteins changed by MPTP and KRG in the ST were identified and shown to be related to glycolysis/gluconeogenesis and neurodegenerative diseases including Alzheimer's disease and PD. KRG has neuroprotective effects against MPTP toxicity and alleviates protein expression profiles related to enhancing energy metabolism in the ST of MPTP-treated mice.

Aggregated single-walled carbon nanotubes attenuate the behavioural and neurochemical effects of methamphetamine in mice

Methamphetamine (METH) abuse is a serious social and health problem worldwide. At present, there are no effective medications to treat METH addiction. Here, we report that aggregated single-walled carbon nanotubes (aSWNTs) significantly inhibited METH self-administration, METH-induced conditioned place preference and METH- or cue-induced relapse to drug-seeking behaviour in mice. The use of aSWNTs alone did not significantly alter the mesolimbic dopamine system, whereas pretreatment with aSWNTs attenuated METH-induced increases in extracellular dopamine in the ventral striatum. Electrochemical assays suggest that aSWNTs facilitated dopamine oxidation. In addition, aSWNTs attenuated METH-induced increases in tyrosine hydroxylase or synaptic protein expression. These findings suggest that aSWNTs may have therapeutic effects for treatment of METH addiction by oxidation of METH-enhanced extracellular dopamine in the striatum.

Effects of ethanol withdrawal on the activity of rho-kinase in rat brain

Besides its effect regarding addiction, ethanol also damages the central nervous system when it is used at high doses for a long time. The increase in the activity of Rho/Rho kinase pathway leads to central nervous system pathologies such as cerebral injury and epileptogenesis. The aim of this study was to investigate the contribution of Rho/Rho Kinase pathway to the degenerative and addictive effects of ethanol. For this purpose, we determined the Rho-kinase activity in striatum and hippocampus of rat brain. Wistar rats were treated with ethanol in a special liquid diet for 21 days. An isocaloric liquid diet without ethanol was given to the rats in the control group during the study. At the end of the 21 day ethanol exposure, one group was kept on taking ethanol and another group was withdrawn from ethanol. The rats were decapitated and their brains were taken out. Striatum and hippocampus were isolated. Phospho-moesin protein levels were measured in striatum and hippocampus homogenates using by Western blot analysis. The Rho-kinase (ROCK) activity in the striatum was found to be significantly decreased in ethanol exposed rats. In the hippocampus, there was a significant increase in the ROCK activity in the ethanol group. Our results indicated that ethanol caused some significant changes in Rho/Rho Kinase pathway in rat brain (Fig. 2, Ref. 25).

Detection of lactate in the striatum without contamination of macromolecules by J-difference editing MRS at 7T

Lactate levels are measurable by MRS and are related to neural activity. Therefore, it is of interest to accurately measure lactate levels in the basal ganglia networks. If sufficiently stable, lactate measurements may be used to investigate alterations in dopaminergic signalling in the striatum, facilitating the detection and diagnosis of metabolic deficits. The aim of this study is to provide a J-difference editing MRS technique for the selective editing of lactate only, thus allowing the detection of lactate without contamination of overlapping macromolecules. As a validation procedure, macromolecule nulling was combined with J-difference editing, and this was compared with J-difference editing with a new highly selective editing pulse. The use of a high-field (7T) MR scanner enables the application of editing pulses with very narrow bandwidth, which are selective for lactate. We show that, despite the sensitivity to B0 offsets, the use of a highly selective editing pulse is more efficient for the detection of lactate than the combination of a broad-band editing pulse with macromolecule nulling. Although the signal-to-noise ratio of uncontaminated lactate detection in healthy subjects is relatively low, this article describes the test-retest performance of lactate detection in the striatum when using highly selective J-difference editing MRS at 7 T. The coefficient of variation, σw and intraclass correlation coefficients for within- and between-subject differences of lactate were determined. Lactate levels in the left and right striatum were determined twice in 10 healthy volunteers. Despite the fact that the test-retest performance of lactate detection is moderate with a coefficient of variation of about 20% for lactate, these values can be used for the design of new studies comparing, for example, patient populations with healthy controls.

(-) Epigallocatechin-3-gallate attenuates reserpine-induced orofacial dyskinesia and oxidative stress in rat striatum

Reserpine-induced orofacial dyskinesia (OD) has been used for decades as an animal model for human tardive dyskinesia (TD) because both of them have pathophysiology strongly associated with striatal oxidative stress. Green tea catechins, especially (-) epigallocatechin-3-gallate (EGCG), have potent antioxidative effects and are able to protect against various oxidative injuries. In this study, we examined the potential protective effects of EGCG on reserpine-induced behavioral and neurochemical dysfunction in rats. Reserpine treatment (1mg/kgs.c. one injection every other day, three injections total) induced significant increases (p<0.001) in the frequency of vacuous chewing movement (VCM) and tongue protrusion (TP) as well as the duration of facial twitching (FT). EGCG treatment (100mg/kgi.p. for 11days, starting 7days before the reserpine injections) was able to prevent most of the reserpine-induced OD. Also, EGCG treatment was able to reduce the reserpine-induced lipid peroxidation (LPO) production, and enhances the antioxidation power in the striatum of reserpine-treated rats. The above results indicate that EGCG has a protective role against reserpine-induced OD, probably via its powerful antioxidative properties. Thus, EGCG may possible have a clinically relevant therapeutic effect in preventing, delaying or even treating TD.

Antidepressant-like effects of ferulic acid: involvement of serotonergic and norepinergic systems

Ferulic acid is a polyphenol that has antioxidant, anti-inflammatory and anticancer properties. The present study analyzed the antidepressant-like potential of ferulic acid using two well-validated mouse models of despair test, tail suspension and forced swim tests. The results suggested that ferulic acid treatment at doses of 10, 20, 40 and 80 mg/kg (p.o.) significantly reduced the immobility time in both of these two tests. These doses that affected the depressive-like behaviors did now show any effect on locomotion counts. The further neurochemical assays suggested that ferulic acid increased monoamine neurotransmitter levels in the brain regions that are relative to mood disorders: the hippocampus and frontal cortex. The increased tend to serotonin and norepinephrine was also found in the hypothalamus after higher dose of ferulic acid treatment. The subsequent study suggested that monoamine oxidase A (MAO-A) activity was inhibited in the frontal cortex and hippocampus when treatment with 40 and 80 mg/kg ferulic acid; while MAO-B activity did not change significantly. The current study provides the first lines of evidence that serotonin and norepinephrine, but not dopamine levels were elevated in mouse hippocampus and frontal cortex after ferulic acid treatment. These changes may be attributable to the inhibition of MAO-A activities in the same brain regions.

Subacute manganese exposure in rats is a neurochemical model of early manganese toxicity

Manganese (Mn) is an essential trace element, but excess exposure leads to accumulation in biological tissues, including the brain. Chronically high Mn levels in the brain are neurotoxic and can result in a progressive, irreversible neurological disorder known as manganism. Manganism has signs and symptoms similar to, but distinguishable from idiopathic Parkinson's disease, which include both psychological and motor disturbances. Evidence suggests that Mn exposure impacts neurotransmitter levels in the brain. However, it remains unclear if subacute, low-level Mn exposure resulted in alterations in neurotransmitter systems with concomitant behavioral deficits. The current study used high performance liquid chromatography to quantify neurotransmitter levels in rat striatum (STR), substantia nigra (SN), and hippocampus (HP). Subacute Mn exposure via i.p. injection of 15mg Mn/kg as MnCl2 caused significantly increased dopamine (DA) levels in the STR. The enhancement was accompanied by significantly elevated levels of the DA metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the STR. In addition, levels of HVA were significantly increased in the SN and HP. These data indicate that subacute, low-level Mn exposure disrupts multiple neurotransmitter systems in the rat brain which may be responsible, in part, for observed locomotor deficits.

SorCS2 regulates dopaminergic wiring and is processed into an apoptotic two-chain receptor in peripheral glia

Balancing trophic and apoptotic cues is critical for development and regeneration of neuronal circuits. Here we identify SorCS2 as a proneurotrophin (proNT) receptor, mediating both trophic and apoptotic signals in conjunction with p75(NTR). CNS neurons, but not glia, express SorCS2 as a single-chain protein that is essential for proBDNF-induced growth cone collapse in developing dopaminergic processes. SorCS2- or p75(NTR)-deficient in mice caused reduced dopamine levels and metabolism and dopaminergic hyperinnervation of the frontal cortex. Accordingly, both knockout models displayed a paradoxical behavioral response to amphetamine reminiscent of ADHD. Contrary, in PNS glia, but not in neurons, proteolytic processing produced a two-chain SorCS2 isoform that mediated proNT-dependent Schwann cell apoptosis. Sciatic nerve injury triggered generation of two-chain SorCS2 in p75(NTR)-positive dying Schwann cells, with apoptosis being profoundly attenuated in Sorcs2(-/-) mice. In conclusion, we have demonstrated that two-chain processing of SorCS2 enables neurons and glia to respond differently to proneurotrophins.

Sex differences in the effects of estradiol in the nucleus accumbens and striatum on the response to cocaine: neurochemistry and behavior

BACKGROUND

Females exhibit more rapid escalation of cocaine use and enhanced cocaine-taking behavior as compared to males. While ovarian hormones likely play a role in this increased vulnerability, research has yet to examine the role of estradiol in affecting the behavioral and neurological response to cocaine in a brain region- and sex-specific way.

METHODS

First, we examined stereotypy and locomotor sensitization after repeated cocaine administration (10 mg/kg i.p.) in intact (SHAM) and castrated (CAST) males, and ovariectomized (OVX) females treated with 5 μg estradiol benzoate (EB) or vehicle (OIL). Next, we used in vivo microdialysis to examine the effects of acute EB treatment on cocaine-induced DA in the regions mediating the display of these behaviors (i.e., the dorsolateral striatum, DLS; and the nucleus accumbens, NAc; respectively).

RESULTS

We find that EB enhances sensitization of cocaine-induced stereotypy in OVX females after 12 days of cocaine treatment, and after a 10-day withdrawal. Similarly, the OVX/EB females show enhanced locomotor sensitization compared to the other three groups on the same days. Using in vivo microdialysis to assess the neurochemical response, we find that EB rapidly enhances cocaine-induced DA in DLS dialysate of OVX females but not CAST males, and has no effect in NAc of either sex.

CONCLUSIONS

With these experiments, we show that there are sex differences in the effects of estradiol to preferentially enhance the response to cocaine in the DLS over the NAc in females, which may contribute to the preferential sensitization of stereotypy in females.

AC-186, a selective nonsteroidal estrogen receptor β agonist, shows gender specific neuroprotection in a Parkinson's disease rat model

Drugs that selectively activate estrogen receptor β (ERβ) are potentially safer than the nonselective estrogens currently used in hormonal replacement treatments that activate both ERβ and ERα. The selective ERβ agonist AC-186 was evaluated in a rat model of Parkinson's disease induced through bilateral 6-hydroxydopamine lesions of the substantia nigra. In this model, AC-186 prevented motor, cognitive, and sensorimotor gating deficits and mitigated the loss of dopamine neurons in the substantia nigra, in males, but not in females. Furthermore, in male rats, 17β-estradiol, which activates ERβ and ERα with equal potency, did not show the same neuroprotective benefits as AC-186. Hence, in addition to a beneficial safety profile for use in both males and females, a selective ERβ agonist has a differentiated pharmacological profile compared to 17β-estradiol in males.

Beneficial Effects of a Protein Free, High Carbohydrate Meal on Rat Coping Behavior and Neurotransmitter Levels During Heat Stress

This study examined effects of a single protein-free (PROT-free), high carbohydrate meal (0% protein, 82% carbohydrate) or control meal (20% protein, 62% carbohydrate) on coping behavior and neurotransmitter levels of male Fischer 344 rats. Meals varying in protein/carbohydrate ratio differentially affect transport of neurotransmitter precursors into the brain and alter neurotransmission. The meals were studied in animals exposed to heat stress and normothermic control animals. Coping behavior was assessed using the Porsolt swim test (N = 39). In other rats, dopamine (DA), epinephrine (EPI), norepinephrine (NE) and serotonin in the striatum were assessed using in vivo microdialysis (N = 35). In control-fed rats, heat stress impaired Porsolt performance in comparison to normothermic controls (p <0.05). The PROT-free, high carbohydrate meal protected animals from adverse effects of stress on coping performance as it reduced the effect of heat stress more than 90%. Significant changes in striatal DA and EPI efflux were observed as a consequence of the nutritional manipulation and heat exposure. It is concluded a single PROT-free, high carbohydrate meal improves ability to cope with heat stress and alters neurotransmission. The neurochemical basis for these effects may be a change in DA efflux, although other mechanisms cannot be ruled out.

An interface for sensitive analysis of monoamine neurotransmitters by ion-pair chromatography-electrospray ionization-mass spectrometry with continuous online elimination of ion-pair reagents

A challenge in coupling ion-pair chromatography (IPC) online with electrospray ionization-mass spectrometry (ESI-MS) is that the nonvolatile ion-pair reagent (e.g., alkyl sulfate for amines or tetrabutylammonium for carboxylic acids) in the mobile phase suppresses the ESI-MS signals in the gas phase and their accumulation can clog the MS sampling interface. Consequently, IPC-ESI-MS is conducted either with a volatile ion-pair reagent, which could compromise the analyte separation efficiency, or with a downstream ion-exchange column to rid the ion-pair reagents of the mobile phase. In the latter approach, the limited capacity of ion-exchange columns requires frequent off-line column regeneration, which affects the separation throughput and prohibits long separations from being performed. A dual-valve, dual-ion exchange column interface of IPC-ESI-MS is designed for undisrupted separations and simultaneous column regeneration. Owing to the efficacy in removing the ion-pair reagent, the detection of eluents of monoamine neurotransmitters by an ion trap MS results in the limits of detection of 0.03 μM for dopamine or DA and 0.01 μM for 5-hydroxytryptamine or 5-HT. These values are lower than those obtained with ion trap MS of similar sensitivity when combined with the use of specialized chromatographic columns or sample preconcentration. Excellent reproducibility was attained with repeatedly regenerated ion-exchange columns (RSD = 4-6%) for an extended period of time (RSD < 6% for 6 days). DA and 5-HT in rat straital extracts were analyzed, and our data demonstrate that interferences inherent in the tissues and the ion-pair reagent have been successfully eliminated. This simple interface should be readily amenable to the separation and MS analysis of other types of polar compounds in complex sample media.

Counteraction by nitric oxide synthase inhibitor of neurochemical alterations of dopaminergic system in 6-OHDA-lesioned rats under L-DOPA treatment

Nitric oxide synthase inhibitors reduce L-3, (Del-Bel et al., Cell Mol Neurobiol 25(2):371-392, 2005) 4-dihydroxyphenylalanine (L-DOPA)-induced abnormal motor effects subsequent to depletion of dopaminergic neurons in rodents and non-human primates. The present study used quantitative high-performance liquid chromatography to analyze, for the first time, dopamine metabolism in striatum of rats in order to elucidate the mechanism of action of the nitric oxide synthase inhibitors. Adult male Wistar rats received unilateral microinjection of saline (sham) or 6-hydroxydopamine (6-OHDA-lesioned) in the medial forebrain bundle. Past 3 weeks, rats were treated during 21 days with L-DOPA/benserazide (30 mg/kg/7.5 mg/kg, respectively, daily). On the 22nd day rats received an intraperitoneal (i.p.) injection of either vehicle or 7-nitroindazole, a preferential neuronal nitric oxide synthase inhibitor before L-DOPA. Abnormal involuntary movements and rotarod test were assessed as behavioral correlate of motor responses. Lesion intensity was evaluated through tyrosine hydroxylase immunohystochemical reaction. Dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), and an extent of dopamine striatal tissue levels/dopamine metabolism were measured in the striatum. Lesion with 6-OHDA decreased dopamine, DOPAC, and DOPAC/dopamine ratio in the lesioned striatum. L-DOPA treatment induced abnormal involuntary movements and increased DOPAC/dopamine ratio (nearly five times) in the lesioned striatum. L-DOPA-induced dyskinesia was mitigated by 7-nitroindazole, which also decreased dopamine turnover, dopamine and DOPAC levels. Our results revealed an almost two times increase in dopamine content in the non-lesioned striatum of 6-OHDA-lesioned rats. Reduction of striatal DOPAC/dopamine ratio in dyskinetic rats may suggest an increase in the dopamine availability. Our data confirm contribution of nitrergic transmission in the pathogenesis of L-DOPA-induced dyskinesia with potential utilization of nitric oxide synthase inhibitors for treatment.

Microfabricated sampling probes for in vivo monitoring of neurotransmitters

Microfabricated fluidic systems have emerged as a powerful approach for chemical analysis. Relatively unexplored is the use of microfabrication to create sampling probes. We have developed a sampling probe microfabricated in Si by bulk micromachining and lithography. The probe is 70 μm wide by 85 μm thick by 11 mm long and incorporates two buried channels that are 20 μm in diameter. The tip of the probe has two 20 μm holes where fluid is ejected or collected for sampling. Utility of the probe was demonstrated by sampling from the brain of live rats. For sampling, artificial cerebral spinal fluid was infused in through one channel at 50 nL/min while sample was withdrawn at the same flow rate from the other channel. Analysis of resulting fractions collected every 20 min from the striatum of rats by liquid chromatography with mass spectrometry demonstrated reliable detection of 17 neurotransmitters and metabolites. The small probe dimensions suggest it is less perturbing to tissue and can be used to sample smaller brain nuclei than larger sampling devices, such as microdialysis probes. This sampling probe may have other applications such as sampling from cells in culture. The use of microfabrication may also enable incorporation of electrodes for electrochemical or electrophysiological recording and other channels that enable more complex sample preparation on the device.

Neuronal metabolomics by ion mobility mass spectrometry: cocaine effects on glucose and selected biogenic amine metabolites in the frontal cortex, striatum, and thalamus of the rat

We report results of studies of global and targeted neuronal metabolomes by ambient pressure ion mobility mass spectrometry. The rat frontal cortex, striatum, and thalamus were sampled from control nontreated rats and those treated with acute cocaine or pargyline. Quantitative evaluations were made by standard additions or isotopic dilution. The mass detection limit was ~100 pmol varying with the analyte. Targeted metabolites of dopamine, serotonin, and glucose followed the rank order of distribution expected between the anatomical areas. Data was evaluated by principal component analysis on 764 common metabolites (identified by m/z and reduced mobility). Differences between anatomical areas and treatment groups were observed for 53 % of these metabolites using principal component analysis. Global and targeted metabolic differences were observed between the three anatomical areas with contralateral differences between some areas. Following drug treatments, global and targeted metabolomes were found to shift relative to controls and still maintained anatomical differences. Pargyline reduced 3,4-dihydroxyphenylacetic acid below detection limits, and 5-HIAA varied between anatomical regions. Notable findings were: (1) global metabolomes were different between anatomical areas and were altered by acute cocaine providing a broad but targeted window of discovery for metabolic changes produced by drugs of abuse; (2) quantitative analysis was demonstrated using isotope dilution and standard addition; (3) cocaine changed glucose and biogenic amine metabolism in the anatomical areas tested; and (4) the largest effect of cocaine was on the glycolysis metabolome in the thalamus confirming inferences from previous positron emission tomography studies using 2-deoxyglucose.

Intranasal application of secretin, similarly to intracerebroventricular administration, influences the motor behavior of mice probably through specific receptors

Secretin and its receptors show wide distribution in the central nervous system. It was demonstrated previously that intravenous (i.v.) and intracerebroventricular (i.c.v.) application of secretin influenced the behavior of rat, mouse, and human. In our previous experiment, we used a special animal model, Japanese waltzing mice (JWM). These animals run around without stopping (the ambulation distance is very limited) and they do not bother with their environment. The i.c.v. secretin attenuated this hyperactive repetitive movement. In the present work, the effect of i.c.v. and intranasal (i.n.) application of secretin was compared. We have also looked for the presence of secretin receptors in the brain structures related to motor functions. Two micrograms of i.c.v. secretin improved the horizontal movement of JWM, enhancing the ambulation distance. It was nearly threefold higher in treated than in control animals. The i.n. application of secretin to the left nostril once or twice a day or once for 3 days more effectively enhanced the ambulation distance than i.c.v. administration. When secretin was given twice a day for 3 days it had no effect. Secretin did not improve the explorative behavior (the rearing), of JWM. With the use of in situ hybridization, we have found very dense secretin receptor labeling in the cerebellum. In the primary motor cortex and in the striatum, only a few labeled cells were seen. It was supposed that secretin exerted its effect through specific receptors, mainly present in the cerebellum.

[Effect of single-used borneol and combining it with diazepam on content of neurotransmitter in corpus striatum of rats]

OBJECTIVE

To research the content changes of excitatory neurotransmitter and inhibitory neurotransmitter in corpus striatum of rats after single-used borneol and combining it with diazepam in hope of comprehending the activity of borneol on central nervous system and to observe whether borneol could increase the penetration of other drugs into the brain.

METHOD

The content of four amino acids neurotransmitters in corpus striatum of rats were sampled by brain microdialysis technology at different time after administration and were determined by RP-HPLC which involved pre-column derivation with orthophthaladehyde (OPA), using phosphate gradient elution and fluorescence detection to detect the content of excitatory neurotransmitter aspartate (Asp), glutamate (Glu) and inhibitory neurotransmitter glycine (Gly), gamma-aminobutyric acid (GABA) in standards and samples and carry on statistical analysis.

RESULT

The content of both Gly and GABA in corpus striatum of rats with borneol increased significantly, compared with diazepam group (P < 0.05), while Asp and Glu showed no significant difference.

CONCLUSION

Borneol can improve permeability of diazepam through BBB.

Behavioral and neurophysiological correlates of striatal dopamine depletion: a rodent model of Parkinson's disease

Both limb and cranial motor functions are adversely impacted by Parkinson's disease (PD). While current pharmacological and surgical interventions are effective in alleviating general limb motor symptoms of PD, they have failed to provide significant benefit for cranial motor functions. This suggests that the neuropathologies mediating limb and cranial motor impairments in PD may differ. Animal models provide a mechanism by which the potential neural dysfunctions underlying these different motor impairments may be characterized. Central goals to our laboratory have been to (a) determine the differential responses of cranial motor and limb motor function to striatal dopamine depletion and (b) determine the differential effects of striatal dopamine depletion on the integrity of cranial motor and limb motor neural circuits. This paper details the use of a comprehensive battery of limb and cranial motor behavioral tasks and the application of intracortical microstimulation to assess corticospinal and corticobulbar circuits in a rodent model of PD. Our work suggests that striatal dopamine depletion does differentially affect cranial and limb motor function and corticospinal and corticobulbar circuits. Further, we propose that cranial motor impairments in PD may be mediated by pathology both within and outside nigrostriatal dopamine system.

LEARNING OUTCOMES

Readers will be able to (a) describe a set of motor tests used to assess limb motor and cranial motor function in an animal model of Parkinson's disease, (b) understand the application of intracortical microstimulation to assess corticospinal and corticobulbar circuits, (c) describe the differential effects of dopamine depletion on limb motor and cranial motor function in a rodent model of PD, and (d) understand the potential role of dysfunction outside the nigrostriatal system mediating cranial motor impairments in Parkinson's disease.

Sub-second dopamine detection in human striatum

Fast-scan cyclic voltammetry at carbon fiber microelectrodes allows rapid (sub-second) measurements of dopamine release in behaving animals. Herein, we report the modification of existing technology and demonstrate the feasibility of making sub-second measurements of dopamine release in the caudate nucleus of a human subject during brain surgery. First, we describe the modification of our electrodes that allow for measurements to be made in a human brain. Next, we demonstrate in vitro and in vivo, that our modified electrodes can measure stimulated dopamine release in a rat brain equivalently to previously determined rodent electrodes. Finally, we demonstrate acute measurements of dopamine release in the caudate of a human patient during DBS electrode implantation surgery. The data generated are highly amenable for future work investigating the relationship between dopamine levels and important decision variables in human decision-making tasks.

Synthesis and biological evaluation of 3-alkyl-dihydrotetrabenazine derivatives as vesicular monoamine transporter-2 (VMAT2) ligands

In the search of new probes for in vivo brain imaging of vesicular monoamine transporter type 2 (VMAT2), we have developed an efficient synthesis of a novel series of 3-alkyl-dihydrotetrabenazine (DTBZ) derivatives. The affinity of VMAT2 was evaluated by an in vitro inhibitory binding assay using [(125)I]-iodovinyl-TBZ or [(18)F](+)-FP-DTBZ as radioligands in rat striatal tissue homogenates. New DTBZ derivatives exhibited moderate to good binding affinity to VMAT2. Among these new ligands, compound 4b showed the best affinity for VMAT2 (K(i)=5.98 nM) and may be a useful lead compound for future structure-activity studies.

Biochemical and morphological consequences of human α-synuclein expression in a mouse α-synuclein null background

A consensus about the functions of human wild-type or mutated α-synuclein (αSYN) is lacking. Both forms of αSYN are implicated in Parkinson's disease, whereas the wild-type form is implicated in substance abuse. Interactions with other cellular proteins and organelles may meditate its functions. We developed a series of congenic mouse lines containing various allele doses or combinations of the human wild-type αSYN (hwαSYN) or a doubly mutated (A30P*A53T) αSYN (hm(2) αSYN) in a C57Bl/6J line spontaneously deleted in mouse αSYN (C57BL/6JOla). Both transgenes had a functional role in the nigrostriatal system, demonstrated by significant elevations in striatal catecholamines, metabolites and the enzyme tyrosine hydroxylase compared with null-mice without a transgene. Consequences occurred when the transgenes were expressed at a fraction of the endogenous level. Hemizygous congenic mice did not exhibit any change in the number or size of dopaminergic neurons in the ventral midbrain at 9 months of age. Human αSYN was predominantly located in neuronal cell bodies, neurites, synapses, and in intraneuronal/intraneuritic aggregates. The hm(2) αSYN transgene resulted in more aggregates and dystrophic neurites than did the hw5 transgene. The hwαSYN transgene resulted in higher expression of two striatal proteins, synaptogamin 7 and UCHL1, compared with the levels of the hm(2) αSYN transgene. These observations suggest that mutations in αSYN may impair specific functional domains, leaving others intact. These lines may be useful for exploring interactions between hαSYN and environmental or genetic risk factors in dopamine-related disorders using a mouse model.

Diffusion and clearance of superparamagnetic iron oxide nanoparticles infused into the rat striatum studied by MRI and histochemical techniques

The purpose of the present study was to investigate, by MRI and histochemical techniques, the diffusion and clearance abilities of superparamagnetic iron oxide nanoparticles (SPION) coated with dextran (Dextran-SPION) and gold (Au-SPION) following their local infusions into the rat brain. In separate groups of anesthetized rats, the Dextran-SPION and Au-SPION were infused at concentrations of 0.01, 0.1, 1 and 5 µg Fe/0.5 µl and at the flow rate of 0.5 µl min(-1) into the left and right striata, respectively. Repetitive T2-weighted spin-echo MRI scans were performed at time intervals of 1, 6, 12, 24, 48, 72 h, and one, two and eight weeks after inoculation. Following infusion of Dextran-SPION (0.1 µg and 1 µg Fe), the maximal distribution volume was observed at about 12-24 h after inoculation and two weeks later the Fe signals were undetectable for the lower dose. On the other hand, Au-SPION remained tightly localized in the closest vicinity of the infusion site as revealed by unchanged MRI signal intensities and strong histochemical staining of Fe(2+) and Fe(3+) ions in the corresponding brain slices. Immunohistochemical staining of astrocytic and microglial reactions revealed that there were no marked differences in GFAP, VIM or OX-42 labeling observed between the nanoparticle types, however the astrocytic reaction was more pronounced in rats receiving nanoparticles compared to the control (aCSF-infused) rats. In conclusion, the present data demonstrate that the viral-sized Dextran-SPION were able to diffuse freely through the interstitial space of the brain being progressively cleared out from the infusion site within two weeks. Thus, Dextran-SPION could be beneficially used in MRI-guided diagnostic applications such as in experimental oncology or as labels and carriers for targeted drug delivery, whereas Au-SPION could be used for labeling and tracking the transplanted stem cells in experimental MRI.

Neurogenetics and pharmacology of learning, motivation, and cognition

Many of the individual differences in cognition, motivation, and learning-and the disruption of these processes in neurological conditions-are influenced by genetic factors. We provide an integrative synthesis across human and animal studies, focusing on a recent spate of evidence implicating a role for genes controlling dopaminergic function in frontostriatal circuitry, including COMT, DARPP-32, DAT1, DRD2, and DRD4. These genetic effects are interpreted within theoretical frameworks developed in the context of the broader cognitive and computational neuroscience literature, constrained by data from pharmacological, neuroimaging, electrophysiological, and patient studies. In this framework, genes modulate the efficacy of particular neural computations, and effects of genetic variation are revealed by assays designed to be maximally sensitive to these computations. We discuss the merits and caveats of this approach and outline a number of novel candidate genes of interest for future study.

Direct in vivo measurement of glycine and the neurochemical profile in the rat medulla oblongata

The medulla oblongata (MO) contains a high density of glycinergic synapses and a particularly high concentration of glycine. The aims of this study were to measure directly in vivo the neurochemical profile, including glycine, in MO using a spin-echo-based (1)H MRS sequence at TE = 2.8 ms and to compare it with three other brain regions (cortex, striatum and hippocampus) in the rat. Glycine was quantified in MO at TE = 2.8 ms with a Cramér-Rao lower bound (CRLB) of approximately 5%. As a result of the relatively low level of glycine in the other three regions, the measurement of glycine was performed at TE = 20 ms, which provides a favorable J-modulation of overlapping myo-inositol resonance. The other 14 metabolites composing the neurochemical profile were quantified in vivo in MO with CRLBs below 25%. Absolute concentrations of metabolites in MO, such as glutamate, glutamine, γ-aminobutyrate, taurine and glycine, were in the range of previous in vitro quantifications in tissue extracts. Compared with the other regions, MO had a three-fold higher glycine concentration, and was characterised by reduced (p < 0.001) concentrations of glutamate (-50 ± 4%), glutamine (-54 ± 3%) and taurine (-78 ± 3%). This study suggests that the functional specialisation of distinct brain regions is reflected in the neurochemical profile.

Collection of nanoliter microdialysate fractions in plugs for off-line in vivo chemical monitoring with up to 2 s temporal resolution

An off-line in vivo neurochemical monitoring approach was developed based on collecting nanoliter microdialysate fractions as an array of "plugs" segmented by immiscible oil in a piece of Teflon tubing. The dialysis probe was integrated with the plug generator in a polydimethlysiloxane microfluidic device that could be mounted on the subject. The microfluidic device also allowed derivatization reagents to be added to the plugs for fluorescence detection of analytes. Using the device, 2 nL fractions corresponding to 1-20 ms sampling times depending upon dialysis flow rate, were collected. Because axial dispersion was prevented between them, each plug acted as a discrete sample collection vial and temporal resolution was not lost by mixing or diffusion during transport. In vitro tests of the system revealed that the temporal resolution of the system was as good as 2 s and was limited by mass transport effects within the dialysis probe. After collection of dialysate fractions, they were pumped into a glass microfluidic chip that automatically analyzed the plugs by capillary electrophoresis with laser-induced fluorescence at 50 s intervals. By using a relatively low flow rate during transfer to the chip, the temporal resolution of the samples could be preserved despite the relatively slow analysis time. The system was used to detect rapid dynamics in neuroactive amino acids evoked by microinjecting the glutamate uptake inhibitor l-trans-pyrrolidine-2,4-dicarboxylic acid (PDC) or K(+) into the striatum of anesthetized rats. The resulted showed increases in neurotransmitter efflux that reached a peak in 20 s for PDC and 13 s for K(+).

[Study of extracellular concentration of dopamine and its metabolites in mice striatum by a microdialysis technique at intraperitoneal administration of MPTP]

In this paper a structure of a microdialytic cannula inserted into brain areas just before a microdialysis is described. The cannula used allowed to find out a correspondence of behavioral and biochemical changes in C57BL/6 mice at various time intervals after a single dose administration (20 mg/kg) of the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, without any additional pharmacological actions enhancing an extracellular striatal dopamine concentration. Immediately after 1-methyl-4-phenyl-1.2,3.6-tetrahydropyridine administration an essential disturbance of mice behavior and a significant reduction of the extracellular concentration of dopamine and homovanillic acid were observed in striatum. A week after the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration neither behavior nor the extracellular dopamine and homovanillic acid striatal concentration substantially differed from those of controls. 30 days after the neurotoxin administration there was again an essential disturbance of behavior and the large reduction of dopamine and its metabolite concentration in striatum. There was suggested that a reduction of the dopamine concentration immediately after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injection connected with abnormalities of dopamine synthesis and metabolism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine whereas a reduction of the extracellular striatal dopamine concentration 30 days after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration related to damage of the nigrastriatal dopaminergic system.

Response of aged parkinsonian monkeys to in vivo gene transfer of GDNF

This study assessed the potential for functional and anatomical recovery of the diseased aged primate nigrostriatal system, in response to trophic factor gene transfer. Aged rhesus monkeys received a single intracarotid infusion of MPTP, followed one week later by MRI-guided stereotaxic intrastriatal and intranigral injections of lentiviral vectors encoding for glial derived neurotrophic factor (lenti-GDNF) or beta-galactosidase (lenti-LacZ). Functional analysis revealed that the lenti-GDNF, but not lenti-LacZ treated monkeys displayed behavioral improvements that were associated with increased fluorodopa uptake in the striatum ipsilateral to lenti-GDNF treatment. GDNF ELISA of striatal brain samples confirmed increased GDNF expression in lenti-GDNF treated aged animals that correlated with functional improvements and preserved nigrostriatal dopaminergic markers. Our results indicate that the aged primate brain challenged by MPTP administration has the potential to respond to trophic factor delivery and that the degree of neuroprotection depends on GDNF levels.

In vivo microdialysis studies of striatal level of neurotransmitters after haloperidol and chlorpromazine administration

Therapeutic success of atypical antipsychotics has focused the attention on the role of receptor systems other than dopaminergic system in the pathophysiology of neuroleptics-associated acute (Parkinson's like syndrome) and chronic (tardive dyskinesia) extrapyramidal side effects. This study was planned to investigate changes in striatal levels of norepinephrine, dopamine and serotonin after acute and chronic administration of classical neuroleptics (haloperidol and chlorpromazine). These changes were correlated with behavioural alterations in rats. In vivo microdialysis with HPLC/ECD system revealed that there was a marked decrease in striatal neurotransmitter contents (NE, DA and 5-HT), which was also correlated with severe cataleptic response in rats after acute administration of haloperidol (2 mg/kg) and chlorpromazine (20 mg/kg). Chronic administration of haloperidol (1 mg/kg for 21 days) and chlorpromazine (5 mg/kg for 21 days) resulted in time dependent increase in orofacial hyperkinetic movements. The microdialysis studies also showed a significant decrease in the striatal levels of all the neurotransmitters. The results provide evidence for the involvement of striatal adrenergic and serotonergic systems, besides dopaminergic system in neuroleptic-induced acute and chronic extrapyramidal symptoms.

Striatal dopamine D(2) receptor availability in OCD with and without comorbid social anxiety disorder: preliminary findings

Dopamine D(2) receptor availability in the striatum has been reported to be low in generalized social anxiety disorder (GSAD) and obsessive-compulsive disorder (OCD), but it has not been studied in persons with comorbid OCD and GSAD (OCD+GSAD). D(2) receptor availability was assessed in 7 subjects with OCD+GSAD, 8 with OCD, and 7 matched healthy comparison (HC) subjects, all unmedicated adults. D(2) receptor availability was assessed with single-photon emission computerized tomography (SPECT) to measure binding potential (BP) of the D(2) receptor radiotracer [(123)I] iodobenzamide ([(123)I]IBZM). Mean striatal [(123)I]IBZM BP was significantly lower in the OCD+GSAD group (72.58 mL/g, SD=18.17) than in the HC group (118.41 mL/g, SD=45.40; P=.025). Mean BP in the OCD group (93.08 mL/g, SD=36.90) did not differ significantly from the HC group (P=.247). Trait detachment, as measured by the Detachment subscale of the Karolinska Scales of Personality, was negatively correlated with D(2) availability across all subjects (r(s)= -.55, P=.013). Comorbid GSAD and OCD may be associated with decreased availability of D(2) receptors in the striatum, consistent with prior findings in GSAD. Prior findings of decreased D(2) receptor availability in noncomorbid OCD were not confirmed. Decreased D(2) receptor availability was also associated with trait detachment, supporting prior findings in samples of healthy subjects.

Striatal proteomic analysis suggests that first L-dopa dose equates to chronic exposure

L-3,4-dihydroxypheylalanine (L-dopa)-induced dyskinesia represent a debilitating complication of therapy for Parkinson's disease (PD) that result from a progressive sensitization through repeated L-dopa exposures. The MPTP macaque model was used to study the proteome in dopamine-depleted striatum with and without subsequent acute and chronic L-dopa treatment using two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The present data suggest that the dopamine-depleted striatum is so sensitive to de novo L-dopa treatment that the first ever administration alone would be able (i) to induce rapid post-translational modification-based proteomic changes that are specific to this first exposure and (ii), possibly, lead to irreversible protein level changes that would be not further modified by chronic L-dopa treatment. The apparent equivalence between first and chronic L-dopa administration suggests that priming would be the direct consequence of dopamine loss, the first L-dopa administrations only exacerbating the sensitization process but not inducing it.

MPTP-induced central dopamine depletion exacerbates experimental autoimmune encephalomyelitis (EAE) in C57BL mice

It is obvious that the central nervous system plays a role in the regulation of an immune response. However, the mechanisms of this regulation are poorly understood. The goal of the present study was to examine the role of one of the neurotransmitters - dopamine, in this process. We used experimental autoimmune encephalomyelitis (EAE), an autoimmune disease with its effector phase in the CNS, as a model to study the effect of central dopamine depletion on the development of an immune response. Dopamine depletion was achieved by treatment with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropiridine (MPTP; 40 mg/kg), whereas EAE was elicited by immunization with MOG 35-55 (150 microg) in complete Freund's adjuvant (CFA), supplemented with Mycobacterium tuberculosis. As determined by HPLC, striatal dopamine contents in mice treated with MPTP were significantly lower compared to vehicle-treated controls. Remarkably, striatal depletion of dopamine prior to EAE induction resulted in an earlier onset of the disease and an augmentation of its clinical signs. Moreover, the striatal dopamine-depleted mice demonstrated an increased concentration of IL-1beta and decreased concentration of TGFbeta in the spinal cord, compared to EAE mice. Since MPTP itself does not have any direct effect on immune cells, it strongly suggests that the observed changes in EAE induction and progression after MPTP administration depended on lower dopamine level. Further studies are required to find out the cellular mechanism of the dopamine action.

Echinacoside prevents the striatal extracellular levels of monoamine neurotransmitters from diminution in 6-hydroxydopamine lesion rats

We investigated the effects of echinacoside, a phenylethanoid glycoside isolated and purified from the stems of Cistanche salsa, a Chinese herbal medicine, on the striatal extracellular levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in 6-hydroxydopamine (6-OHDA) lesion rats. Seven days after 6-OHDA was injected into the right striatum of rats, the striatal extracellular levels of DA, DOPAC and HVA fell significantly (P<0.01 vs. vehicle), as demonstrated by the method of cerebral microdialysis and high performance liquid chromatography with electrochemical detection. However, simultaneous treatment with echinacoside (7.0, 3.5mg/kg) attenuated the diminution of them (P<0.01 vs. model). The results implied that echinacoside could protect the striatal dopaminergic neurons from injury induced by 6-OHDA and may be useful in the prevention and treatment of Parkinson's disease (PD).

[The effect of dopaminergic nigrostriatal system on sleep deprivation in rats]

The analysis of the electrophysiological features of sleep-wakefulness cycle in Wistar rats for 9h after a 6h sleep deprivation was carried out. The delay of sleep rebound (since 2.5-3 h after deprivation) was found in the form of moderate increasing of slow-wave sleep and fast-wave sleep phases. According to these sleep-wakefulness cycle changes, a quantitative immunohistochemical study of tyrosine hydroxylase: a key enzyme of dopamine synthesis--and D1 and D2 receptors in nigro-striatal projections has been performed. After sleep, an elevation of D1 receptors immunoreactivity in caudate nucleus and reduction of tyrosine hydroxylase immunoreactivity in compact part of substancia nigra was found. After postdeprivation sleep, a decrease of D1 receptors immunoreactivity and increase of D2 receptors immunoreactivity in caudate nucleus together some increase of tyrosine hydroxilase immunoreactivity in substancia nigra compacta has been observed. These data can testify about active role of dopaminergic nigrostriatal system which provide at the same time with another neurotransmitters of the central nervous system the telencephalo-diencephalic interaction in sleep-wakefulness-sleep cycle.