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Dive into the research topics where Ayaka Takakura is active.

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Featured researches published by Ayaka Takakura.


Neurotoxicology | 2016

Ethanol and acetaldehyde differentially alter extracellular dopamine and serotonin in Aldh2-knockout mouse dorsal striatum: A reverse microdialysis study.

Mostofa Jamal; Kiyoshi Ameno; Takanori Miki; Naoko Tanaka; Asuka Ito; Junichiro Ono; Ayaka Takakura; Mitsuru Kumihashi; Hiroshi Kinoshita

Dopamine (DA) and serotonin (5-HT) seem to be involved in several of the effects of ethanol (EtOH). Acetaldehyde (AcH), especially in the brain, induces effects that mimic those of EtOH. The purpose of this study was to investigate the effects of local perfusion of EtOH and AcH on extracellular DA and 5-HT in the dorsal striatum of Aldh2-knockout (Aldh2-KO) and wild-type (WT) mice. Aldh2-KO mice were used as a model of aldehyde dehydrogenase 2 deficiency in humans to examine the effects of AcH. Mice were perfused with Ringers solution (control), EtOH (100, 200, or 500mM) and AcH (100, 200, or 500μM) into the dorsal striatum. Dialysate samples were collected every 5min, and then analyzed with HPLC coupled to an ECD. We found that local perfusion with 500mM EtOH increased extracellular levels of DA (p<0.05) in both Aldh2-KO and WT mice, while 5-HT levels remain unchanged. EtOH at a dose of 200mM also increased DA in WT mice, but this was limited to a 30-40-min time-point. In contrast, perfusion with 200 and 500μM AcH decreased both DA and 5-HT (p<0.05) in Aldh2-KO mice, but this decrease was not found in WT mice at any AcH dose, indicating an effect of AcH on DA and 5-HT levels. There were no genotype effects on the basal levels of DA and 5-HT. These results indicate that high EtOH can stimulate DA, whereas high AcH can depress both DA and 5-HT in the dorsal striatum of mice.


Legal Medicine | 2015

Detection of chlorine and bromine in free liquid from the sphenoid sinus as an indicator of seawater drowning

Naoko Tanaka; Hiroshi Kinoshita; Mostofa Jamal; Ayaka Takakura; Mitsuru Kumihashi; Kunihiko Tsutsui; Kiyoshi Ameno

We have investigated the usefulness of elemental analysis by energy-dispersive X-ray spectroscopy (EDX) in the examination of free liquid from the sphenoid sinus of drowning victims. We detected both chlorine and bromine in liquid taken from the sphenoid sinus of seawater drowning victims. Because these elements were below the quantification limit in freshwater cases, we could easily distinguish seawater from freshwater drowning cases. Detection of these elements from the liquid in the sphenoid sinuses of drowning victims may be useful as a supportive measure for seawater drowning.


Legal Medicine | 2016

Distinction between entrance and exit wounds by energy dispersive X-ray fluorescence spectrometry

Naoko Tanaka; Hiroshi Kinoshita; Ayaka Takakura; Mostofa Jamal; Asuka Ito; Mitsuru Kumihashi; Kunihiko Tsutsui; Shoji Kimura; Kiyoshi Ameno

We investigated gunshot wounds in two autopsy cases using energy dispersive X-ray spectrometry (EDX). Lead and copper were detected in the entrance wound of one case and lead, antimony, and copper were detected in that of the other case. In the exit wounds of both cases, lead, antimony, and copper were below detection limits. These findings indicate that the detection of metallic elements, such as lead, antimony, and copper, which are found in bullets, may be useful for differentiating entrance from exit wounds using EDX.


Journal of the Neurological Sciences | 2015

Aldehyde dehydrogenase 2 deficiency increases resting-state glutamate and expression of the GluN1 subunit of N-methyl-D-aspartate receptor in the frontal cortex of mice

Mostofa Jamal; Junichiro Ono; Kiyoshi Ameno; Gotaro Shirakami; Naoko Tanaka; Ayaka Takakura; Hiroshi Kinoshita

Our previous study showed that Aldh2-knockout (Aldh2-KO) mice, an animal model of inactive aldehyde dehydrogenase 2 (ALDH2), have better spatial memory when compared with wild-type (WT) mice. Given that the neurotransmitter glutamate has been associated with learning and memory, the goal of the present study was to investigate whether the strain-dependent difference in spatial memory was associated with changes in glutamate transmitter levels or receptor function in the frontal cortex of Aldh2-KO and WT mice. Thus, we first measured extracellular glutamate levels in free-moving mice using microdialysis. Second, we studied protein expression of the N-methyl-D-aspartate (NMDA) receptor (GluN1) subunit and the α-amino-3-hydroxy-5 methylisoxazole-4-propionic acid (AMPA) receptor (GluA1) subunit in lipid raft fractions using Western blot (WB). The samples were collected for WB, and lipid rafts were prepared from the insoluble fraction of homogenate tissue. Protein concentration was measured in the whole cell lysate (WCL) and in five separate lipid raft fractions. Cholesterol was also measured in all fractions 1-5. The microdialysis study revealed that basal glutamate concentration in the dialysates was approximately three-fold (0.27 ± 0.12 μM) higher in Aldh2-KO mice than in WT (0.10 ± 0.03 μM) mice. We also found an increase in the expression of GluN1 in Aldh2-KO mice compared with WT mice, both in the WCL and fraction 5, but GluA1 levels were unchanged as measured by WB. Our novel findings provide the first evidence for the role of ALDH2 in glutamate release and GluN1 protein expression in the frontal cortex. The observed strain differences in glutamate levels and GluN1 expression may suggest that enhanced glutamatergic function facilitates improved spatial memory in Aldh2-KO mice and such observation deserves further investigation.


Neuroscience Letters | 2018

Acetaldehyde administration induces salsolinol formation in vivo in the dorsal striatum of Aldh2-knockout and C57BL/6N mice

Asuka Ito; Mostofa Jamal; Kiyoshi Ameno; Naoko Tanaka; Ayaka Takakura; Toshihiro Kawamoto; Kyoko Kitagawa; Keiichi I. Nakayama; Akiko Matsumoto; Takanori Miki; Hiroshi Kinoshita

Acetaldehyde (AcH) and salsolinol play important roles in the central effects of ethanol. This study aimed to investigate the effect of administration of AcH on dopamine (DA), DA-derived salsolinol and serotonin (5-HT) levels in the dorsal striatum of Aldh2-knockout (Aldh2-KO) and C57BL/6 N (WT) mice. Animals were treated with AcH (50, 100 and 200 mg/kg) intraperitoneally and dialysate levels of DA, 5-HT and salsolinol were determined using in vivo microdialysis coupled with HPLC-ECD. Salsolinol was first detected at 20 min after AcH administration, and reached its peak concentration (WT mice: 0.29 ± 0.22 pg/μl; Aldh2-KO mice: 0.63 ± 0.17 pg/μl) at 25 min in the 200 mg/kg AcH group, before decreasing rapidly and reaching zero at approximately 55-80 min. Treatment with 100 and 200 mg/kg AcH increased levels of salsolinol in both WT and Aldh2-KO mice, with 200 mg/kg AcH inducing a higher level of salsolinol in Aldh2-KO mice than in WT mice. Treatment with 50 mg/kg AcH produced a small increase in salsolinol levels in Aldh2-KO mice, whereas no elevation of salsolinol was detected in WT mice. The increase in salsolinol formation was found to occur a dose-dependent manner in both genotypes. Administration of AcH and the subsequent changes in salsolinol concentrations did not change DA or 5-HT levels in either genotype. Our study suggests that AcH dose-dependently increases the formation of salsolinol in the dorsal striatum of mice, which provides further support for the role of AcH in salsolinol formation in the animal brain.


Legal Medicine | 2018

Comparison of histological findings and the results of energy-dispersive X-ray spectrometry analysis in experimental electrical injury

Naoko Tanaka; Ayaka Takakura; Mostofa Jamal; Asuka Ito; Mitsuru Kumihashi; Kunihiko Tsutsui; Kiyoshi Ameno; Hiroshi Kinoshita

The findings of histological examination and the results of energy-dispersive X-ray spectrometry (EDX) analysis were compared to identify skin metallization in experimental electrical injury. Rats were divided into three experimental groups (n = 5, each group): control, current exposure for five seconds, and current exposure for ten seconds. A relatively high peak of copper, which was used as an electrical conductor, was detected in formalin-fixed skin samples of the two current exposure groups by EDX. There was a significant increase of the specific X-ray intensity in the two current exposure groups compared to the control group. On histological examination, epidermal nuclear elongation was observed in all samples of the two current exposure groups. However, deposition of metal was observed in two samples of each current exposure group. Metallization is an important finding for the diagnosis of electrocution. The present results suggest that EDX analysis is useful for the proof of metallization in electrocution, even where it is not identified on morphological examination.


Drug and Chemical Toxicology | 2018

Perfusion with carbon monoxide does not affect extracellular glutamate in dialysates of the hippocampus of freely moving mice

Asuka Ito; Mostofa Jamal; Kiyoshi Ameno; Naoko Tanaka; Ayaka Takakura; Takanori Miki; Hiroshi Kinoshita

Abstract Carbon monoxide (CO) produces several neurological effects, including cognitive, mood, and behavioral disturbance. Glutamate is thought to play a particularly important role in learning and memory. Thus, the present study was aimed at investigating the local effect of CO on the glutamate level in the hippocampus of mice using in vivo reverse microdialysis. Mice were perfused with Ringer’s solution (control) or CO (60–125 μM) in Ringer’s solution into the hippocampus via microdialysis probe. Dialysate samples were collected every 20 min, and then analyzed with high-performance liquid chromatography coupled to an electrochemical detector. The result revealed that the perfusion with CO had no significant effect on glutamate levels (p = 0.316) as compared to the control group. This finding does not support a local CO rise as the cause of the increased glutamate level in the hippocampus of mice.


Brain Research | 2018

COA-Cl induces dopamine release and tyrosine hydroxylase phosphorylation: In vivo reverse microdialysis and in vitro analysis

Mostofa Jamal; Ikuko Tsukamoto; Maki Takata; Asuka Ito; Naoko Tanaka; Takanori Miki; Ayaka Takakura; Kiyoshi Ameno; Yasuo Kubota; Ryoji Konishi; Hiroshi Kinoshita

We found that local perfusion of COA-Cl (0.1, 0.4, or 1.0 mM) into the dorsal striatum of living mice produced a significant and dose-dependent increase in extracellular DA levels, with the highest dose of 1.0 mM COA-Cl producing an approximately 5-fold increase in DA. Consistent with in vivo findings, 0.1 and 0.2 mM COA-Cl significantly and dose-dependently enhanced DA release 3.0 to 5.0-fold in PC12 cells, an in vitro model of DA-responsive neurons. Interestingly, the increase in striatal DA levels by COA-Cl in vivo was similar in magnitude to that observed in PC12 cells. Treatment with 0.1 mM COA-Cl significantly increased both Ser31 and Ser40 phosphorylation of tyrosine hydroxylase (TH) in PC12 cells, and Ser40 phosphorylation in iCell neurons, without altering total TH protein levels. Further, we examined whether COA-Cl could stimulate neurite outgrowth in PC12 cells and iCell neurons and found that COA-Cl significantly induced neurite outgrowth in both cell lines. Our results provide the first evidence that COA-Cl can stimulate dose-dependent DA release and activation of TH phosphorylation, suggesting that COA-Cl may be a promising therapeutic candidate for the treatment of neurological dysfunction associated with low DA.


Romanian Journal of Legal Medicine | 2017

Application of energy-dispersive X-ray fluorescence spectrometry (EDX) in forensics – titanium, silicon and magnesium in the stomach contents as good indicators for ingestion of pharmaceutical tablets

Naoko Tanaka; Ayaka Takakura; Mitsuru Kumihashi; Mostofa Jamal; Asuka Ito; Shoji Kimura; Kunihiko Tsutsui; Kiyoshi Ameno; Hiroshi Kinoshita

We present a case of drug overdose in which energy-dispersive X-ray fluorescence spectrometry (EDX) was applied as a screening test. Elemental analysis by EDX identified strong peaks for titanium, silicon and magnesium in the stomach contents that seemed to be derived from pharmaceutical additives in ingested pharmaceutical tablets. Toxicological examination using liquid chromatography-tandem mass spectrometry identified toxic levels of 7-aminonitrazepam, 7-aminoflunitrazepam (metabolites of nitrazepam and flunitrazepam, respectively) and some other drugs in the blood, and also residues in the stomach. We concluded that the cause of death was poisoning due to ingestion of multiple drugs. Our results indicate that the detection of titanium, silicon and magnesium in stomach contents offers a good indicator for ingestion of tablets and that EDX provides useful information for forensic diagnosis.


Neurochemical Research | 2016

Ethanol and Acetaldehyde After Intraperitoneal Administration to Aldh2-Knockout Mice-Reflection in Blood and Brain Levels

Mostofa Jamal; Kiyoshi Ameno; Naoko Tanaka; Asuka Ito; Ayaka Takakura; Mitsuru Kumihashi; Hiroshi Kinoshita

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