Kaori Koike

Alterations of serum levels of brain-derived neurotrophic factor (BDNF) in depressed patients with or without antidepressants

BACKGROUND Because researchers have reported that antidepressants increase the expression of brain-derived neurotrophic factor (BDNF) in the rat hippocampus, we investigated whether serum BDNF levels may be used as a putative biological marker for major depressive disorders (MDD). METHODS We measured serum BDNF in the following three groups: antidepressant-naive patients with MDD (n = 16), antidepressant-treated patients with MDD (n = 17), and normal control subjects (n = 50). Patients were evaluated using the Hamilton Rating Scale for Depression (HAM-D). Serum BDNF was assayed with the sandwich ELISA method. RESULTS We found that serum BDNF was significantly lower in the antidepressant-naive group (mean, 17.6 ng/mL; SD, 9.6) than in the treated (mean, 30.6 ng/mL; SD, 12.3; p =.001) or in the control group (mean, 27.7 ng/mL; SD, 11.4; p =.002). There was a significant negative correlation (r = -.350, z = -2.003, p =.045) between serum BDNF and HAM-D scores in all patients. In a preliminary examination, reduced BDNF values of three drug-naive patients recovered to basal levels after antidepressant treatment. CONCLUSIONS Our study suggests that low BDNF levels may play a pivotal role in the pathophysiology of MDD and that antidepressants may increase BDNF in depressed patients.

Serum brain-derived neurotrophic factor (BDNF) levels in schizophrenia are indistinguishable from controls

Our previous study showed that serum brain-derived neurotrophic factor (BDNF) was significantly decreased in the antidepressant-naive patients with major depressive disorders. However, it was still unclear whether serum BDNF level was altered in drug-naive patients with schizophrenia. Using ELISA, we measured serum BDNF levels in antipsychotic-naive (n=15) and medicated (n=25) patients with schizophrenia, and in age- and sex-matched normal controls (n=40). There were no significant differences in serum BDNF levels among antipsychotic-naive (n=15) and medicated (n=25) patients and normal controls (n=40). Possible factors such as duration of illness, age of onset, Brief Psychiatric Rating Scale scores, and chlorpromazine equivalent dosages of antipsychotics did not reveal any significant correlations with BDNF levels. Our results do not support the view that serum BDNF levels are associated with schizophrenia.

Tropisetron improves deficits in auditory P50 suppression in schizophrenia

Physiological deficits in inhibition of the P50 auditory evoked potential in schizophrenia have been related to diminished expression of alpha7 nicotinic acetylcholine receptors. Diminished P50 inhibition is correlated with neuropsychological deficits in attention, one of the principal neurocognitive disturbances in schizophrenia. Nicotine administration improves P50 inhibition, presumably by achieving additional activation of these diminished receptors, but its toxicity and marked tachyphylaxis make it an ineffective therapeutic. Nicotine also has weak positive effects on several neurocognitive deficits in schizophrenia, which raises the possibility that the alpha7 nicotinic receptor is a clinically relevant therapeutic target that should be addressed by less toxic agents. Tropisetron, a drug already approved for clinical use outside the United States as an anti-emetic, is a partial agonist at alpha7 nicotinic receptors and an antagonist at 5-HT(3) receptors. As an initial proof-of-principle study, we determined that a single administration of tropisetron significantly improves P50 inhibition in schizophrenia. These data are consistent with biological activity at a pathophysiological mechanism in schizophrenia and support further trials of this drug as a possible therapeutic for neurocognitive deficits in schizophrenia.

Effect of antioxidant N-acetyl-l-cysteine on behavioral changes and neurotoxicity in rats after administration of methamphetamine

Several lines of evidence suggest that oxidative stress may play a role in the behavioral changes and neurotoxicity in rats after administration of methamphetamine (MAP). N-acetyl-L-cysteine (NAC) is a precursor of glutathione, and it also exerts as an antioxidant. In this study, we investigated the effects of NAC on the behavioral changes (hyperlocomotion and development of sensitization) and neurotoxicity in male Wistar rats after administration of MAP. Pretreatment with NAC (30, 100 or 300 mg/kg, i.p.) attenuated significantly hyperlocomotion in rats induced by a single administration of MAP (2 mg/kg, i.p.), in a dose-dependent manner. Furthermore, pretreatment with NAC (100 mg/kg, i.p., 15 min before MAP injection, once daily for 5 consecutive days) blocked significantly the development of behavioral sensitization in rats after repeated administration of MAP (2 mg/kg, once daily for 5 consecutive days), whereas the behaviors in rats after repeated administration of NAC plus saline groups were not different from those of control (vehicle plus saline) groups. One week after administration of MAP (7.5 mg/kg x 4, 2-h intervals), levels of dopamine (DA) in rat striatum were significantly decreased as compared with control groups. Pretreatment with NAC (1, 3, 10 or 30 mg/kg, i.p., 30 min before each MAP injection) attenuated significantly the MAP-induced reduction of DA in rat striatum, in a dose-dependent manner. These results suggest that NAC could prevent the behavioral changes (acute hyperlocomotion and development of behavioral sensitization) in rats and neurotoxicity in rat striatum after administration of MAP, and that NAC would be a useful drug for treatment of several symptoms associated with MAP abuse.

Association between the brain-derived neurotrophic factor 196G/A polymorphism and eating disorders.

Several lines of evidence suggest that genetic factors might contribute to the pathogenesis of eating disorders and that brain‐derived neurotrophic factor (BDNF) plays a role in the pathophysiology of eating disorders. To investigate the role of the BDNF gene in the susceptibility to eating disorders, we analyzed the BDNF 196G/A gene polymorphism in female patients with eating disorders and female normal controls. The difference in the genotype frequency between patients (n = 198) and normal controls (n = 222) was statistically significant (P = 0.029). Interestingly, a significant (P = 0.015) difference in the genotype frequency between normal controls and bulimia nervosa patients (n = 101) with binge‐purging type was detected. This study suggests that the BDNF 196G/A gene polymorphism might be associated with a susceptibility to eating disorders.© 2003 Wiley‐Liss, Inc.

Serum brain-derived neurotrophic factor (BDNF) levels in patients with panic disorder: as a biological predictor of response to group cognitive behavioral therapy.

Little is known about biological predictors of treatment response in panic disorder. Our previous studies show that the brain-derived neurotrophic factor (BDNF) may play a role in the pathophysiology of major depressive disorders and eating disorders. Assuming that BDNF may be implicated in the putative common etiologies of depression and anxiety, the authors examined serum BDNF levels of the patients with panic disorder, and its correlation with therapeutic response to group cognitive behavioral therapy (CBT). Group CBT (10 consecutive 1 h weekly sessions) was administered to the patients with panic disorder after consulting the panic outpatient special service. Before treatment, serum concentrations of BDNF and total cholesterol were measured. After treatment, we defined response to therapy as a 40% reduction from baseline on Panic Disorder Severity Scale (PDSS) score as described by [Barlow, D.H., Gorman, J.M., Shear, M.K., Woods, S.W., 2000. Cognitive-behavioral therapy, imipramine, or their combination for panic disorder: A randomized controlled trial. JAMA. 283, 2529-2536]. There were 26 good responders and 16 poor responders. 31 age- and sex-matched healthy normal control subjects were also recruited in this study. The serum BDNF levels of the patients with poor response (25.9 ng/ml [S.D. 8.7]) were significantly lower than those of the patients with good response (33.7 ng/ml [S.D. 7.5]). However, there were no significant differences in both groups of the patients, compared to the normal controls (29.1 ng/ml [S.D. 7.1]). No significant differences of other variables including total cholesterol levels before treatment were detected between good responders and poor responders. These results suggested that BDNF might contribute to therapeutic response of panic disorder. A potential link between an increased risk of secondary depression and BDNF remains to be investigated in the future.

Possible role of d-serine in the pathophysiology of Alzheimer's disease

Several lines of evidence suggest that D-serine may function as an endogenous agonist of the glycine site on the N-methyl-D-aspartate (NMDA) receptor that has been implicated in the pathophysiology of Alzheimers disease (AD). The purpose of the study was to determine whether serum levels of D- and L-serine in patients with AD are altered as compared with normal controls. Serum levels of D- and L-serine in patients of AD and age- and gender-matched normal controls were determined using a high-performance liquid chromatography (HPLC). Serum levels of D-serine in the patients with AD were slightly (z=-1.77, p=0.078) lower than those of normal controls. In contrast, serum levels of L-serine in the patients were slightly (z=-1.73, p=0.083) higher than those of controls. In addition, the percentage (%) of D-serine in the total (L+D) serine in the patients was significantly (z=-2.36, p=0.018) lower than that of controls. The present study suggests that the reduced activity of serine racemase, an enzyme catalyzing the formation of D-serine from L-serine may play a role in the pathophysiology of AD.

No association of the brain-derived neurotrophic factor (BDNF) gene polymorphisms with panic disorder

Several lines of evidence suggest that genetic factors might contribute to susceptibility to panic disorder. Our previous studies show that the brain-derived neurotrophic factor (BDNF) may play a role in the pathophysiology of major depressive disorders and eating disorders. Assuming that BDNF may be implicated in the putative common pathophysiology of depression and anxiety, we analyzed the association of two BDNF gene single nucleotide polymorphisms (SNPs), 132C > T (formerly named C270T) in the noncoding region of exon V and 196G > A (val66met) in the coding region of exon XIIIA, with panic disorder. In this study, 109 patients with panic disorder diagnosed according to the DSM-IV criteria, and 178 control subjects were recruited. There were no significant differences in the frequency of the genotype or allele in these two SNPs between patients and controls [132C > T in exon V: genotype, p = 1.0, allele, p = 0.59; 196G > A (val66met) in exon XIIIA: genotype, p = 0.77, allele, p = 0.78]. Furthermore, no significant associations of agoraphobia with the two SNPs were detected. This study suggests that the BDNF gene polymorphisms are not associated with panic disorder in our Japanese population.

Lack of association between angiotensin I-converting enzyme insertion/deletion gene functional polymorphism and panic disorder in humans.

Family and twin studies have indicated that genes influence susceptibility to panic disorder, but the genes involved remain unknown. The neuropeptide angiotensin II has been found to be involved in anxiety and regulation of respiration which are important in the pathophysiology of panic attacks. Assuming that angiotensins may be candidate genes in panic disorder, we analyzed the association between panic disorder and angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) gene functional polymorphism. We recruited 101 patients with panic disorder diagnosed according to DSM-IV criteria, and 184 control subjects in the study. No significant differences in the frequency of the genotype or allele in the polymorphism between patient and control groups were found (genotype, chi(2)=0.56, d.f.=2, P=0.77; allele, chi(2)=0.074, d.f.=1, P=0.78). This study suggests that the ACE I/D gene polymorphism is not directly associated with panic disorder in our Japanese patient group.

Deficits in auditory P50 inhibition in obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) is considered to involve abnormalities in inhibitory processes including gating systems. Auditory P50 inhibition, which is assessed by using a paired auditory stimulus paradigm to record P50 mid-latency evoked potential, is assumed to reflect sensory gating. In the present study, we investigated auditory P50 inhibition in subjects with OCD, and examined the relationship between P50 and clinical variables or neuropsychological performance. Twenty-six subjects with OCD and 26 age- and sex-matched healthy controls received P50 recording and neuropsychological tests. In the OCD subjects, we also evaluated clinical features including OC symptoms and subtypes of the disorder. P50 T/C ratios were significantly higher in OCD subjects than in control subjects (t=2.9, df=50, p=0.006). Compared to the controls, the OCD subjects performed significantly worse on the Symbol Digit Modalities Test (SDMT) and the Trail Making Test (TMT). There were no correlations between P50 T/C ratios and clinical variables or the results of neuropsychological tests. Our findings suggest that sensory gating deficits may be involved in the pathophysiology of OCD in a different way from clinical symptoms and executive attention dysfunction.