Identification of Ecdysteroid Sinapate Esters with COX-2 Inhibitory Effects from Fibraurea recisa Using Molecular Networking and MS2LDA.

The roots of Fibraurea recisa are recognized as a rich source of protoberberine and aporphine alkaloids, but the non-alkaloidal metabolites in this plant are underexplored. The present study investigated the chemical composition of the plant roots using untargeted metabolomics-based molecular networking and MS2LDA motif annotation, revealing the presence of a characteristic fragment motif related to several sinapoyl-functionalized metabolites. Guided by the targeted motif, two new sinapic acid-ecdysteroid hybrids, named 3-O-sinapoyl makisterone A (1) and 2-O-sinapoyl makisterone A (2), were isolated. The structures of these compounds, including their absolute configuration, were elucidated by HR-ESIQTOFMS, MS2 fragmentation, NMR spectroscopy, and chemical degradation coupled with optical rotation measurements. Although neither compound inhibited nitric oxide (NO) production or inducible nitric oxide synthase (iNOS) protein expression on lipopolysaccharide-induced RAW 264 cells, 2 significantly suppressed cyclooxygenase 2 (COX-2) protein expression at 1-30 µM. Additionally, decreased expression of COX-2 protein was barely observed after treatment with methyl sinapate or makisterone A, the steroid skeleton of 1 and 2. These results indicated that the presence of the sinapoyl moiety at C-2 on the C28-ecdysteroid skeleton played a key role in the selectivity for the suppression of the COX-2 protein expression.

Eriodictyol and thymonin act as GPR35 agonists.

Although herbs and spices have been used in traditional medicine for more than a century owing to their health benefits, the associated underlying mechanism is still not clear. Since the G protein-coupled receptor 35 (GPR35) has been linked to exert various antioxidant and anti-inflammatory effects, we screened 19 different herbs and spices for possible GPR35 agonist(s) to understand the GPR35-dependent functions of herbs and spices. Among the screened extracts, the ethyl acetate extract of thyme exhibited a remarkable GPR35 agonistic activity. Activity-guided separations allowed us to identify 2 polyphenolic phytochemicals, eriodictyol and thymonin, acting as GPR35 agonists. Both eriodictyol and thymonin showed a potent and specific agonist activity toward GPR35 with half maximal effective concentration values of 5.48 and 8.41 µm, respectively. These findings indicate that these phytochemicals may have beneficial health effects upon GPR35 activation.

Garcinoic Acids and a Benzophenone Derivative from the Seeds of Garcinia kola and Their Antibacterial Activities against Oral Bacterial Pathogenic Organisms.

In this study, three new garcinoic acid dimers, δ,δ-bigarcinoic acid (1), δ,δ-bi-O-garcinoic acid (2), and γ,δ-bi-O-garcinoic acid (3), and a new benzophenone derivative, (8E)-4-geranyl-3,5-dihydroxybenzophenone (4), as well as seven known compounds (5-11) were isolated from the seeds of Garcinia kola. The structures of the new compounds were elucidated using MALDI-TOF-MS and spectroscopic data, including 1D and 2D NMR and electronic circular dichroism spectra. All of the isolated compounds were evaluated for their antimicrobial activity against two oral pathogens, Porphyromonas gingivalis and Streptococcus sobrinus. Among them, 4 and δ-garcinoic acid (6) exhibited antimicrobial activity against both of these microorganisms (MICs of 31.3-62.5 µM for P. gingivalis and 15.6-31.3 µM for S. sobrinus). These results indicate that some chemical constituents in G. kola seeds have potential application in the prevention of oral diseases.

Identification of vanilloid compounds in grains of paradise and their effects on sympathetic nerve activity.

BACKGROUND: Grains of paradise (GP) is the seed of Aframomum melegueta, which is widely distributed throughout West Africa and has been used as a spice and a folk remedy for a long time. Anti-obesity effect of GP intake was demonstrated in a previous report. Aim of the present study was to isolate some compounds in GP and clarify the anti-obesity mechanism. RESULTS: Ten vanilloid compounds were isolated. Among them, 1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-ol and 1-(4'-hydroxy-3'-methoxyphenyl)-3-octen-5-one were determined as novel compounds and 6-gingerol, 6-paradol and 6-shogaol were identified as the major constituents in GP extract. Moreover, the extract and 6-gingerol, which is one of the principal components of GP extract, were orally administered to rats to investigate the effect on sympathetic nerve activity (SNA) in brown adipose tissue (BAT). The injection of GP extract and 6-gingerol decreased BAT-SNA, whereas capsaicin, which is a major component of chili pepper, activates the sympathetic nervous system. CONCLUSION: This study suggested that GP extract and 6-gingerol were largely unrelated to the anti-obesity effect by the activation of interscapular BAT-SNA and had a different anti-obesity mechanism to capsaicin. © 2018 Society of Chemical Industry.

Percutaneous fixation of avulsion fracture at the plantar lateral base of the first metatarsal using ZipTight Fixation System: A case report.

Isolated avulsion fracture of the peroneus longus tendon insertion at the base of the first metatarsal without injury of the tarsometatarsal joint is very rare. Similar to most avulsion fractures, this type of injury is caused by strong tension exerted by the peroneus longus tendon. The mechanism leading to this lesion and treatment options are not clearly defined. Several surgical techniques have been advocated for this fracture, including excision of an avulsion fragment and open reduction for internal fixation through the medial aspect of the foot or minimal plantar incision. We have described a method of percutaneous fixing of the avulsion fracture at the plantar lateral base of the first metatarsal using the ZipTight Fixation System (Zimmer Biomet Warsaw, Indiana, USA), which offers the advantage of allowing a rigid fixation and minimal invasive surgical technique for a small fragment.

Cesium Uptake by Rice Roots Largely Depends Upon a Single Gene, HAK1, Which Encodes a Potassium Transporter.

Incidents at the Fukushima and Chernobyl nuclear power stations have resulted in widespread environmental contamination by radioactive nuclides. Among them, 137cesium has a 30 year half-life, and its persistence in soil raises serious food security issues. It is therefore important to prevent plants, especially crop plants, from absorbing radiocesium. In Arabidopsis thaliana, cesium ions are transported into root cells by several different potassium transporters such as high-affinity K+ transporter 5 (AtHAK5). Therefore, the cesium uptake pathway is thought to be highly redundant, making it difficult to develop plants with low cesium uptake. Here, we isolated rice mutants with low cesium uptake and reveal that the Oryza sativa potassium transporter OsHAK1, which is expressed on the surfaces of roots, is the main route of cesium influx into rice plants, especially in low potassium conditions. During hydroponic cultivation with low to normal potassium concentrations (0-206 µM: the normal potassium level in soil), cesium influx in OsHAK1-knockout lines was no greater than one-eighth that in the wild type. In field experiments, knockout lines of O. sativa HAK1 (OsHAK1) showed dramatically reduced cesium concentrations in grains and shoots, but their potassium uptake was not greatly affected and their grain yields were similar to that of the wild type. Our results demonstrate that, in rice roots, potassium transport systems other than OsHAK1 make little or no contribution to cesium uptake. These results show that low cesium uptake rice lines can be developed for cultivation in radiocesium-contaminated areas.

Investigation of optimal display size for viewing T1-weighted MR images of the brain using a digital contrast-detail phantom.

We clarified the relationship between the display size of MRI images and observer performance using a digital contrast-detail (d-CD) phantom. The d-CD phantom was developed using Microsoft Visual Basic 2010 Express. It had a 512 × 512 matrix in size and a total of 100 holes, whose diameter increased stepwise from 4 to 40 pixels with a 4-pixel interval in the vertical direction; the contrast varied stepwise in the horizontal direction. The digital driving level (DDL) of the back-ground, the width of the DDL, and the contrast were adjustable. These parameters were determined on the basis of the actual T1-weighted magnetic resonance (MR) images of the brain. In this study, the DDL, width, and contrast were set to 85, 20, and 1, respectively. The observer performance study was performed for three different display sizes (30 cm × 30 cm as the enlarged size, 16 cm × 16 cm as the original size, and 10 cm × 10 cm as the reduced size) using a 2-megapixel color liquid crystal display monitor, and it was analyzed using Friedman and Wilcoxon statistical tests. The observer performances for the original display (p < 0.01) and the reduced display sizes (p < 0.01) were superior to that observed for the enlarged size, whereas there was no significant difference between the original display and reduced display sizes (p = 0.31). Evaluation with the digital phantom simulating MR imaging also revealed that the original and reduced display sizes were superior to the enlarged display size in observer performance. The d-CD phantom enables a short-term evaluation of observer performance and is useful in analyzing relation-ship between display size and observer performance.

Application of glutathione to roots selectively inhibits cadmium transport from roots to shoots in oilseed rape.

Glutathione is a tripeptide involved in various aspects of plant metabolism. This study investigated the effects of the reduced form of glutathione (GSH) applied to specific organs (source leaves, sink leaves, and roots) on cadmium (Cd) distribution and behaviour in the roots of oilseed rape plants (Brassica napus) cultured hydroponically. The translocation ratio of Cd from roots to shoots was significantly lower in plants that had root treatment of GSH than in control plants. GSH applied to roots reduced the Cd concentration in the symplast sap of root cells and inhibited root-to-shoot Cd translocation via xylem vessels significantly. GSH applied to roots also activated Cd efflux from root cells to the hydroponic solution. Inhibition of root-to-shoot translocation of Cd was visualized, and the activation of Cd efflux from root cells was also shown by using a positron-emitting tracer imaging system (PETIS). This study investigated a similar inhibitory effect on root-to-shoot translocation of Cd by the oxidized form of glutathione, GSSG. Inhibition of Cd accumulation by GSH was abolished by a low-temperature treatment. Root cells of plants exposed to GSH in the root zone had less Cd available for xylem loading by actively excluding Cd from the roots. Consequently, root-to-shoot translocation of Cd was suppressed and Cd accumulation in the shoot decreased.

Molecular networking-based lipid profiling and multi-omics approaches reveal new contributions of functional vanilloids to gut microbiota and lipometabolism changes.

Obesity is now recognized as an epidemic, requiring rapid intervention. We previously demonstrated that vanilloids from the African spice known as Grains of Paradise (GOP) exhibit strong anti-obesity effects. Here, the molecular mechanism behind the obesity prevention property of the GOP extract was investigated by employing molecular networking-based lipid profiling and 16S rRNA sequencing. Administration of either GOP extract or two of its components, 6-paradol and 6-gingerol, reversed the unbalanced gut microbiota composition induced by a high-fat diet (HFD) with a decrease in Firmicutes / Bacteroidetes ratio and increase in genera Bifidobacterium and Akkermansia. Moreover, GOP extract ameliorated abnormal fatty acid metabolism in gut bacteria. Furthermore, lipid molecular networking revealed differences in lipid composition, such as triglycerides and bile acids, in the feces. These results suggest that 6-paradol and 6-gingerol can restore an unhealthy gut environment and prevent lipid absorption, a possible consequence of the reconstruction of the gut microbiota.

A study of elevated interleukin-8 (CXCL8) and detection of leukocyte migration inhibitory activity in patients allergic to beta-lactam antibiotics.

BACKGROUND: The leukocyte migration test (LMT) is effective in identifying the causative drug in drug allergies. Both leukocyte migration activating activity (LMAA) and leukocyte migration inhibitory activity (LMIA) are involved in the development of drug allergies. However, no cytokines associated with LMIA have been identified to date. Because CXCL8 played an important role in neutrophil infiltration and activation, we performed the LMT and measured CXCL8 levels in patients with hypersensitivity to beta-lactam antibiotics (beta-lactams) and antipyretic analgesics (APAs) and investigated the pathogenic mechanism of hypersensitivity to these drugs. METHODS: The LMT was performed according to an improved version of the agarose plate method and CXCL8 levels in the reacted solution that had been stored as described were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. RESULTS: Migration index (MI) values for the LMT were 77.7 ± 11.7 for patients with hypersensitivity to beta-lactams and 83.6 ± 1.9 for those with hypersensitivity to APAs. The CXCL8 concentrations were significantly higher in patients after beta-lactams administration (175.9 ± 71.2 ng/mL) than those without beta-lactams administration (48.3 ± 34.9 ng/mL). The CXCL8 concentrations were significantly lower in patients after APAs administration (41.7 ± 24.3 ng/mL) than those without APAs administration (63.1 ± 30.2 ng/mL). CONCLUSIONS: Increased CXCL8 levels produced by beta-lactams administration were accompanied by LMIA. CXCL8 may be involved in LMIA and play a role in beta-lactam allergies. In contrast, the LMIA detected in patients with allergies to APAs may be a cytokine or chemokine other than CXCL8.

6-Paradol Acts as a Potential Anti-obesity Vanilloid from Grains of Paradise.

SCOPE: Grains of Paradise (GOP), the seeds of Aframomum melegueta, has anti-obesity effects. However, the mechanisms underlying the effects remain unclear. METHODS AND RESULTS: This study sets up to study the anti-obesity impact and homeostatic effects of 6-paradol, a major vanilloid found in GOP, and investigates the physiological outputs and the lipometabolism-related gene in fat and liver in high-fat-induced obese mice with a comparison with structurally similar vanilloids (6-gingerol and 6-shogaol). The vanilloids are synthesized in adequate quantities for performing animal experiments and orally administered to 6-week-old male mice over 2 weeks. This study found that 6-paradol decreased body weight gain and visceral and subcutaneous fats in 2 weeks, whereas 6-gingerol and 6-shogaol have no effect. Additionally, 6-paradol suppresses the hepatic cholesterol and triglyceride and significantly decreases the gene expression related to fatty acid synthesis, lipid transportation, and adipocyte differentiation in both liver and adipose tissue. Moreover, phosphorylation of AMP-activated protein kinase (AMPK) that greatly contributes to lipometabolism is promoted by 6-gingerol but not 6-paradol. CONCLUSION: These results suggest that 6-paradol regulates several obesity-related genes in an AMPK-independent manner. Therefore, it could be the principal active vanilloid in GOP giving it anti-obesity properties with a different mechanism.

Elucidation of Novel cis-Regulatory Elements and Promoter Structures Involved in Iron Excess Response Mechanisms in Rice Using a Bioinformatics Approach.

Iron (Fe) excess is a major constraint on crop production in flooded acidic soils, particularly in rice cultivation. Under Fe excess, plants activate a complex mechanism and network regulating Fe exclusion by roots and isolation in various tissues. In rice, the transcription factors and cis-regulatory elements (CREs) that regulate Fe excess response mechanisms remain largely elusive. We previously reported comprehensive microarray analyses of several rice tissues in response to various levels of Fe excess stress. In this study, we further explored novel CREs and promoter structures in rice using bioinformatics approaches with this microarray data. We first performed network analyses to predict Fe excess-related CREs through the categorization of the gene expression patterns of Fe excess-responsive transcriptional regulons, and found four major expression clusters: Fe storage type, Fe chelator type, Fe uptake type, and WRKY and other co-expression type. Next, we explored CREs within these four clusters of gene expression types using a machine-learning method called microarray-associated motif analyzer (MAMA), which we previously established. Through a comprehensive bioinformatics approach, we identified a total of 560 CRE candidates extracted by MAMA analyses and 42 important conserved sequences of CREs directly related to the Fe excess response in various rice tissues. We explored several novel cis-elements as candidate Fe excess CREs including GCWGCWGC, CGACACGC, and Myb binding-like motifs. Based on the presence or absence of candidate CREs using MAMA and known PLACE CREs, we found that the Boruta-XGBoost model explained expression patterns with high accuracy of about 83%. Enriched sequences of both novel MAMA CREs and known PLACE CREs led to high accuracy expression patterns. We also found new roles of known CREs in the Fe excess response, including the DCEp2 motif, IDEF1-, Zinc Finger-, WRKY-, Myb-, AP2/ERF-, MADS- box-, bZIP and bHLH- binding sequence-containing motifs among Fe excess-responsive genes. In addition, we built a molecular model and promoter structures regulating Fe excess-responsive genes based on new finding CREs. Together, our findings about Fe excess-related CREs and conserved sequences will provide a comprehensive resource for discovery of genes and transcription factors involved in Fe excess-responsive pathways, clarification of the Fe excess response mechanism in rice, and future application of the promoter sequences to produce genotypes tolerant of Fe excess.

Isolation of novel types of Arabidopsis mutants with altered reactions to cadmium: cadmium-gradient agar plates are an effective screen for the heavy metal-related mutants.

We are interested in elucidating the molecular mechanisms underlying plant reactions to the toxic heavy metal cadmium (Cd). To this end, we devised a new screening strategy using agar plates with a gradient of Cd concentrations, termed Cd-gradient agar plates (CGAPs), to isolate Arabidopsis mutants that displayed altered reactions to the metal. Arabidopsis M(2) seeds, derived from ethyl methanesulfonate (EMS) treated seeds, were germinated on the CGAPs such that the primary root of each seedling elongated against increasing concentrations of Cd on the surface of the plate. Under these conditions, the lengths of the primary roots reliably demonstrated the degree of Cd tolerance of individual seedlings. The use of CGAPs also allowed close observation of the root reaction of each seedling to Cd without causing lethal damage. The screen identified three mutant lines, MRC-32, MRC-22 and MRC-26, which showed distinctly different characteristics. MRC-32 plants exhibited enhanced tolerance to Cd and contained Cd at higher concentrations than wild-type (WT) plants treated with the heavy metal. The whole root system of MRC-22 plants showed a Cd-phobic response. MRC-26 plants accumulated less Cd in their aboveground tissues than WT plants, suggesting that they were defective in transporting the heavy metal from roots to aboveground tissues. We also determined the likely chromosomal location of each mutation.

Identification of a responsible promoter region and a key transcription factor, CCAAT/enhancer-binding protein epsilon, for up-regulation of PHGPx in HL60 cells stimulated with TNF alpha.

In the present study we investigated promoter regions of the PHGPx [phospholipid hydroperoxide GPx (glutathione peroxidase)] gene and transcription factors involved in TNFalpha (tumour necrosis factor alpha)-induced up-regulation of PHGPx in non-differentiated HL60 cells. Non-differentiated HL60 cells displayed up-regulation of non-mitochondrial and mitochondrial PHGPx mRNA in response to TNFalpha stimulation. The promoter activity was up-regulated by TNFalpha stimulation in cells transfected with a luciferase reporter vector encoding the region from -282 to -123 of the human PHGPx gene compared with the non-stimulated control. The up-regulated promoter activity was effectively abrogated by a mutation in the C/EBP (CCAAT/enhancer-binding protein)-binding sequence in this region. ChIP (chromatin immunoprecipitation) assays demonstrated that C/EBPepsilon bound to the -247 to -34 region in HL60 cells, but C/EBPalpha, beta, gamma and delta did not. The binding of C/EBPepsilon to the promoter region was increased in HL60 cells stimulated with TNFalpha compared with that of the non-stimulated control. An increased binding of nuclear protein to the C/EBP-binding sequence was observed by EMSA (electrophoretic mobility-shift assay) in cells stimulated with TNFalpha, and it was inhibited by pre-treatment with an anti-C/EBPepsilon antibody, but not with other antibodies. The C/EBPepsilon mRNA was expressed in PMNs (polymorphonuclear cells), non-differentiated HL60 cells and neutrophil-like differentiated HL60 cells displaying TNFalpha-induced up-regulation of PHGPx mRNA, but not in macrophage-like differentiated HL60 cells, HEK-293 cells (human embryonic kidney-293 cells) and other cell lines exhibiting no up-regulation. The up-regulation of PHGPx mRNA, however, was detected in HEK-293 cells overexpressing C/EBPepsilon as a result of TNFalpha stimulation. These results indicate that C/EBPepsilon is a critical transcription factor in TNFalpha-induced up-regulation of PHGPx expression.

Palladium-Catalyzed Reductive Conversion of Acyl Fluorides via Ligand-Controlled Decarbonylation.

Ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides were developed using a Pd(OAc)2/Et3SiH combination. When tricyclohexylphosphine (PCy3) was used as the ligand, aldehydes were obtained as simple reductive conversion products. The use of 1,2-bis(dicyclohexylphosphino)ethane (Cy2P(CH2)2PCy2, DCPE) as the ligand, however, favored the formation of hydrocarbons, which are decarbonylative reduction products.

Melanogenesis inhibitory activity of components from Salam leaf (Syzygium polyanthum) extract.

In order to identify a novel whitening agent, the methanol extract of S. polyanthum leaf was focused on by the screening test using nine Indonesian medicinal plants for the inhibition of melanogenesis and tyrosinase activity in B16 melanoma cells. Three novel compounds [(1) 1-(2,3,5-trihydroxy-4-methylphenyl)hexane-1-one, (2) 1-(2,3,5-trihydroxy methylphenyl)octane-1-one, and (3) (4E)-1-(2,3,5-trihydroxy-4-methylphenyl)decan-1-one and one known compound [(4) 1-(2,3,5-trihydroxy-4-methylphenyl)decan-1-one were isolated from the methanol extract. Our study demonstrated that S. polyanthum leaf methanol extract at 25-200 µg/mL decreased extracellular melanin formation ca. 20-80%, with high cell viability. Compounds 1-4 were found to be active in melanogenesis and tyrosinase inhibition. Compound 3 was the most active against tyrosinase activity (83.98 µM), particularly when L-tyrosine was the substrate. Compounds 1-4 significantly diminished extracellular melanin formation in B16 melanoma cells (> 80%), with high cell viability. Thus, our study suggested that compounds 1-4 isolated from the methanol extract of S. polyanthum leaf play important roles in decreasing extracellular melanogenesis and inhibiting tyrosinase.

Investigation of post-weaning changes in immunological parameters in male rats.

Normal post-weaning changes in immunological parameters were investigated in male Crl:CD(SD) rats (n=7) for matching of ages with children (referential data). The animals received a single intravenous administration of keyhole limpet hemocyanin (KLH) 3mg/kg on day 1 and were euthanized on day 7 at 5, 7, 9, and 11 weeks of age. Furthermore, to investigate age-dependent differences in susceptibility to cyclophosphamide immunotoxicity, the animals were given oral cyclophosphamide 5mg/kgday from days 1 to 8 and intravenous KLH on day 3, and were euthanized on day 9 at the above ages. As a result, the post-weaning development pattern of a continuous increase until 9 weeks of age, followed by a mild decrease at 11 weeks of age, was commonly observed in white blood cell counts and all of its differential counts in peripheral blood, spleen weight, and total cell, CD3+, CD4+, CD8+ and CD45RA+ cell counts in the spleen. This pattern is similar to the development pattern of peripheral blood cell counts in infants, which mostly peaks at 6-12 months of age. Cyclophosphamide decreased almost all of peripheral blood cell counts and lymphocyte subset counts in the thymus and spleen at all ages, to similar degrees. However, decreases in serum anti-KLH IgM and IgG levels were greatest at 9 weeks of age. In conclusion, 9 (immunization at 8) weeks of age in rats was shown to be the most susceptible timing for cyclophosphamide immunotoxicity, likely corresponding to 6-12 months of age in infants.

Enhanced alcohol-drinking behavior associated with active ghrelinergic and serotoninergic neurons in the lateral hypothalamus and amygdala.

Central ghrelin is required for the rewarding properties of drug abuse. We investigated whether alcohol affects ghrelinergic, dopaminergic, and serotoninergic neurons and growth hormone secretagogue receptor 1A (GHS-R1A) levels in the reward system of the brain. Alcohol-naïve C57BL/6J mice received 2g/kg ethanol (EtOH) intraperitoneally (i.p.). Plasma ghrelin levels decreased between 1 and 4h. We investigated the effects of EtOH administration on plasma ghrelin levels in two different animal models at 1, 3, and 10months of age. Plasma ghrelin levels decreased following the EtOH treatment in 1- and 3-month-old short-term (1-day) alcohol vapor-exposed (STA) mice. In contrast, EtOH administration increased plasma ghrelin levels in 1- and 3-month-old long-term (20-day) alcohol vapor-exposed (LTA) mice. In vivo ghrelin release in the lateral hypothalamus (LH) increased in STA and LTA mice after the i.p. administration of EtOH. EtOH increased in vivo dopamine (DA), but not serotonin (5-HT) release in the LH of STA mice, and increased in vivo DA and 5-HT release in the LH of LTA mice. GHS-R1A mRNA expression and GHS-R1A protein levels in the LH were increased in LTA mice. The number of GHS-R1A-immunoreactive cells was greater in the LH and amygdala of LTA mice. These results support the neurobiological correlation between the development of drinking behavior and activation of ghrelinergic and serotonergic neurons in the LH. The activation of ghrelinergic systems in the amygdala may also induce an increase in 5-HT release in the LH during long-term alcohol intake.

In vivo brain microdialysis studies on the striatal dopamine and serotonin release in zitter mutant rats.

In the present study, using in vivo brain microdialysis, we investigated the basal extracellular dopamine (DA) and serotonin (5-HT) release in the caudal striatum (cSTR) of young (4-6 months old) and aged (10-12 months old) zitter mutant rats. The basal extracellular levels of DA release in both young and aged zitter rats were significantly lower than that of age-matched Sprague-Dawley (SD) rats, whereas only aged zitter rats showed a significant difference in the basal 5-HT release. Dopaminergic neurons were more vulnerable than serotonergic neurons in the cSTR of zitter mutant rats during aging. Perfusion of 60 mM potassium (K+) enhanced the extracellular levels of cSTR DA in the young zitter rats and the extracellular levels of both DA and 5-HT in the cSTR of the aged zitter rats. The firing rate of K+-stimulated monoamine release in the cSTR was significantly higher in the zitter rats than in the age-matched SD rats. These findings suggest that there are innate quantitative differences in the releasable pool and the availability of monoamines in the cSTR of zitter mutant rats.