Biomedical subjects

Kazuhiko Nakayama

Publications and source records attributed to Kazuhiko Nakayama.

11 recordsLinked to original sources

PubMed2005

[Psychophysiological evaluations of clinical efficacy in outpatients: Morita therapy for psychophysiological insomnia].

The clinical efficacy of Morita therapy on outpatients with psychophysiological insomnia (PPI) was evaluated psychophysiologically. The subjects, 13 outpatients (mean age: 47. 6 +/-17.7, male/female: 6/7), were diagnosed with PPI at the International Classifications of Sleep Disorders. For each patient the examinations were performed consecutively during, one week of pre-treatment (PRE) and post-treatment (POST; 2.0 +/- 1.1 months), using objective (wrist actigraphy) and subjective (sleep log) measurements. The results were as follows. (1) Subjectively, total sleep time increased and sleep latency shortened significantly at POST compared with PRE. (2) Objectively, the numbers of times of waking decreased, sleep efficiency increased and mean activity in sleep decreased significantly at POST compared with PRE. (3) Dissociations between subjective and objective evaluations about awakening time, total sleep time and sleep latency at PRE improved significantly at POST. From the above-mentioned results, it was suggested that the lack of dissociations between subjective and objective evaluations at POST showed psychophysiologically the reconstruction of sleep a preventing association and breaking free from the entrapment of insomnia. This finding suggested that Morita therapy on outpatients with PPI was effective in helping subjects accept their insomnia and lied a constructive life.

Adult↗

PubMed2004

Mirtazapine increases dopamine release in prefrontal cortex by 5-HT1A receptor activation.

Mirtazapine has a low affinity for 5-HT(1A) receptors but shows 5-HT(1A)-agonistic-like effects in behavioral pharmacology test. However, there is to date no clear evidence that mirtazapine enhances 5-HT(1A) neurotransmission. The object of the present study was to assess the effects of mirtazapine on dialysate levels of dopamine and 5-HT in the medial frontal cortex of freely moving rats and to determine whether this drug could modulate 5-HT(1A) neurotransmission. In vivo microdialysis was used to study the effects of mirtazapine on extracellular dopamine and 5-HT levels, and the effect of the 5-HT(1A) antagonist WAY100,356 on extracellular dopamine level increased by mirtazapine in the rat prefrontal cortex. Mirtazapine (4-16 mg/kg, i.p.) produced a dose-dependent increase in extracellular dopamine levels in the medial prefrontal cortex (mPFC) of freely moving rats without modifying those of 5-HT. In the presence of the selective 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazineyl]ethyl]-N-(pyridinyl)-cyclohexane-carboxamide (WAY100,635; 0.3 mg/kg; i.p.), the influence of mirtazapine on cortical levels of dopamine was markedly attenuated. These results indicate that mirtazapine induces the enhancement of the output of cortical dopamine mediated via blockade of alpha(2)-adrenergic receptors and facilitation of post-synaptic 5-HT(1A) function.

Animals↗

PubMed2004

Low dopamine d(2) receptor binding in subregions of the thalamus in schizophrenia.

OBJECTIVE: Several structural and functional brain imaging studies have pointed to a disturbance of thalamic subnuclei in patients with schizophrenia. The dopamine hypothesis of schizophrenia has, however, not been thoroughly examined in terms of this complex structure, which has connections with most brain regions of central interest in schizophrenia research. The aim of the present study was to examine dopamine D(2) receptor binding in subregions of the thalamus in patients with schizophrenia. METHOD: The authors used positron emission tomography and the radioligand [(11)C]FLB457 to examine dopamine D(2) receptor binding in thalamic subregions of 10 drug-naive patients with schizophrenia. Binding potential was calculated by the reference tissue method and used as an index for dopamine D(2) receptor binding. Comparisons were made with 19 healthy subjects. Subregions of interest were defined on individual magnetic resonance images using a percentage-based operational approach. Clinical symptoms were rated by using the Brief Psychiatric Rating Scale (BPRS). RESULTS: The [(11)C]FLB457 binding potential was lower in the central medial and posterior subregions of the thalamus in patients with schizophrenia. At a functional level, there was a significant negative correlation between binding potential and BPRS positive symptom scores. CONCLUSIONS: The subregions with low D(2) receptor binding comprise primarily the dorsomedial nucleus and pulvinar, two important components in circuitries previously suggested in the pathophysiology of schizophrenia. Aberrant dopaminergic neurotransmission in thalamic subregions might be a mechanism underlying positive symptoms in schizophrenia.

Adult↗

PubMed2003

Possible alteration of tryptophan metabolism following repeated administration of sertraline in the rat brain.

The levels of tryptophan and the serotonin (5-HT) turnover were examined in various brain regions of rats after single or repeated treatment with the selective 5-HT uptake inhibitor, sertraline. A single administration of sertraline (10mg/kg, i.p.) increased tryptophan and 5-HT levels in all the brain regions investigated. The levels of 5-hydroxyindolacetic acid (5-HIAA) decreased in various brain regions. The 5-HIAA/5-HT ratio as turnover index was significantly decreased by a single administration of sertraline in all the brain regions investigated. Daily treatment with sertraline (10mg/kg) for 21 days did not affect tryptophan and 5-HT levels in various brain regions 1h after last injection. The 5-HT turnover was not changed in any of the brain regions investigated by a repeated administration of sertraline. In conclusion, the data show that the increase in tryptophan levels and the decrease in 5-HT turnover in rat brain are attenuated by repeated treatment of sertraline.

Animals↗

PubMed2003

[A clinical study of emergent anxiety in neuroleptic-naïve, first-episode schizophrenia patients following treatment with risperidone].

Risperidone (RIS) alone was administered to patients with neuroleptic-naïve, first-episode schizophrenia who visited the outpatient clinic of the Department of Psychiatry, Jikei University School of Medicine Hospital between April 1998 and December 2001, and the effectiveness of the drug in alleviating anxiety symptoms was prospectively examined. The study population comprised 42 patients (24 males and 18 females). Their mean age at first visit was 26.0 +/- 6.5 years, DUP (Duration of Untreated Psychosis) was 41.1 +/- 60.0 weeks, and the mean total BPRS (Brief Psychiatric Rating Scale) score at first visit was 60.5 +/- 8.5 points. The rating "effective" (a total BPRS score improvement at week 8 of 50% or more) was given to 32 out of the 42 patients (76.2%). Among these 32 patients, a 25% improvement in the PANSS (Positive and Negative Syndrome Scale) positive scale was achieved at 1. 53 +/- 0.72 weeks and a 50% improvement at 2.93 +/- 2.10 weeks, suggesting early onset of the effects of RIS. The present study focused on the anxiety complained of by some of the patients in whom treatment was rated as effective (increase of 2 points in anxiety BPRS score), dividing these patients into an anxiety group and a non-anxiety group. The anxiety group comprised 17 patients (53.1%). The anxiety observed during the course of treatment with RIS tended to develop early after the disappearance of positive symptoms. A comparison of demographic factors and GAF between the two groups revealed a significant difference in mean age at first visit, DUP and GAF score, the anxiety group tending to be younger, to have shorter DUP and to have social dysfunction compared to the non-anxiety group. Although it cannot be concluded that these anxiety symptoms are characteristic of risperidone, the effect of chemotherapy with other atypical antipsychotic drugs remains as an interesting theme for future investigation.

Adult↗

PubMed2003

[Aphonia].

Explore the source record for details and available documents.

Aphonia↗

PubMed2003

[Case of prolonged recovery from serotonin syndrome caused by paroxetine].

We report a case of serotonin syndrome in a patient being treated with paroxetine for depression. Despite prompt discontinuation of medication, his serotonin syndrome continued for 10 days before full consciousness was restored. The patient was a 48-year-old male with chief complaints of hypobulia and suicidal thoughts. He consulted as a psychiatric outpatient, and oral paroxetine 20 mg/day, etizolam 1.0 mg/day, and brotizolam 0.25 mg/day were immediately started. Upsurge of feeling and disinhibition state were noted the following day, then on treatment day 6 his condition deteriorated to substupor state and he was admitted for further treatment. On admission, change of mental condition (consciousness disturbance), perspiration, hyperreflexia, myoclonus and tremor were seen, and serotonin syndrome caused by paroxetine was suspected. Paroxetine was thus discontinued, and under intravenous drip his condition gradually improved. However, it was not until the 10th hospital day that he became fully alert. In examinations, no infectious, metabolic or organic diseases were detected. The patient's condition often improves with in 24 hours of discontinuation of the causative medication in serotonin syndrome. Symptoms continued for 10 days in this patient, however, perhaps because paroxetine was administered for 6 days before discontinuation. In addition, interaction with other medications may have occurred. Therefore, when serotonin syndrome is suspected, prompt discontinuation of the suspected causative medication, followed by close monitoring of the pharmacokinetics is warranted.

Amoxapine↗

PubMed2002

Serotonin transporter binding in patients with mood disorders: a PET study with [11C](+)McN5652.

BACKGROUND: Several lines of studies have suggested the involvement of serotonin transporter (5-HTT) in the pathophysiology of mood disorders. The aim of this study was to examine whether 5-HTT binding was altered in patients with mood disorders using positron emission tomography (PET). METHODS: Thirteen antidepressant-naive or -free patients with mood disorders and 21 age-matched healthy control subjects participated in this study. The patients consisted of 7 with major depressive disorder (MDD) and 6 with bipolar disorder (BD). Positron emission tomography scans were performed using a selective ligand for 5-HTT, [11C](+)McN5652. The uptake was quantified in the thalamus and midbrain by graphical method with reference tissue, and binding potential (BP) was used for the index of 5-HTT binding. RESULTS: Binding potential in the thalamus was significantly increased in patients with mood disorders as compared to control subjects, whereas BP in the midbrain did not differ between the groups. Subgroup comparison showed that MDD patients had significantly higher BP in the thalamus compared to control subjects. Binding potential of the thalamus was higher by approximately 22% in the combined patients and 23% in MDD patients relative to control subjects. CONCLUSIONS: These findings may suggest the possibility of altered 5-HTT in patients with mood disorders. Functional abnormality in the thalamus may be involved in the pathophysiology of mood disorders.

Adult↗

PubMed2002

Decreased dopamine D2 receptor binding in the anterior cingulate cortex in schizophrenia.

BACKGROUND: The clinical efficacy of dopamine D2 receptor antagonism on the psychotic symptoms of schizophrenia has been widely demonstrated. However, most in vivo imaging studies have not been able to detect significant changes in striatal D2 receptors in schizophrenia. On the other hand, a number of studies have reported abnormalities in the cerebral cortex of schizophrenia. The aim of this study was to examine the extrastriatal D2 receptors of patients with schizophrenia. METHODS: Eleven drug-naive male patients with schizophrenia were examined with positron emission tomography using carbon 11-labeled FLB 457. Symptoms were assessed using the Brief Psychiatric Rating Scale. Eighteen healthy controls were used for comparison. Region-of-interest analysis was performed using the reference tissue method, and binding potential (BP) was used for the index of dopamine D2 receptor binding. RESULTS: The BP value was significantly lower, by about 12.5%, in the anterior cingulate cortex in drug-naive patients with schizophrenia than in healthy controls. A significant negative correlation was observed between BP in the anterior cingulate cortex and the positive symptom score on Brief Psychiatric Rating Scale. CONCLUSIONS: The lower BP values indicate fewer D2 receptors in the anterior cingulate cortex in patients with schizophrenia. Alterations in D2 receptor function in the extrastriatal region may underlie the positive symptoms of schizophrenia.

Adult↗

PubMed2002

Diurnal rhythm in extracellular levels of 5-hydroxyindoleacetic acid in the medial prefrontal cortex of freely moving rats: an in vivo microdialysis study.

The cerebral monoaminergic nervous system was monitored for its diurnal changes to find whether these can be used as neurochemical indices for emotional states. Freely moving rats that were not anesthetized were used: by employing an in vivo microdialysis technique, the levels of extracellular monoamine metabolites were measured. Under an alternating 12 h light and dark (LD) cycle and subsequent constant light (LL) condition, the extracellular 5-hydroxyindoleacetic acid (5-HIAA) level was significantly higher in the dark phase than in the light phase in the medial prefrontal cortex (mPFC). However, the 5-HIAA levels in the light and dark phases in the striatum or hippocampus did not significantly differ. The homovanillic acid (HVA) level was significantly higher in the dark phase than in the light phase in the mPFC and striatum. These findings indicate that the extracellular 5-HIAA level in the mPFC has site-specific circadian rhythmicity. Furthermore, considering the relationship among diurnal rhythm, emotional disturbance and the mPFC, the site-specific diurnal rhythmicity of 5-HIAA in the mPFC may be a useful index in neurochemical studies on emotional states, such as seen in affective disorders and psychiatric diseases.

Animals↗

PubMed2001

Effect of paroxetine on extracellular serotonin and dopamine levels in the prefrontal cortex.

Abstract. Paroxetine, a selective serotonin (5-HT) reuptake inhibitor, increased extracellular 5-HT and dopamine levels, as determined by microdialysis, in the medial prefrontal cortex (mPFC) of freely moving rats. There was a difference in the time course of the maximum response between the 5-HT and dopamine levels after paroxetine administration. The extracellular dopamine concentration reached its maximum 20 min after the peak effect of 5-HT had appeared. The paroxetine-induced increase in extracellular dopamine concentration, but not 5-HT concentration, was inhibited by the 5-HT(3)-receptor antagonist granisetron. These results suggest that the increase in extracellular dopamine concentration in the mPFC elicited by paroxetine is the result of stimulation of 5-HT(3) receptors by the extracellular accumulation of 5-HT in the mPFC.

Animals↗