Shu-ichi Ueno

The human serotonin transporter gene linked polymorphism (5-HTTLPR) shows ten novel allelic variants

The serotonin transporter (5-HTT) gene is a promising candidate for introducing the heritability of interindividual variation in personality and the genetic susceptibility for various psychiatric diseases. Transcription of the gene is modulated by a common polymorphism in its upstream regulatory region (5-HTT gene-linked polymorphic region: 5-HTTLPR). The 5-HTTLPR consists of variation of the repetitive sequence containing GC-rich, 20-23-bp-long repeat elements. A deletion/insertion in the 5-HTTLPR was first reported to create a short (S) allele and a long (L) allele (14- and 16-repeats, respectively). Three other kinds of alleles (18-, 19- and 20-repeats) in addition to the S and L alleles in 5-HTTLPR have been reported. In the present study, we examined the 5-HTTLPR polymorphism in detail and identified ten novel sequence variants, concluding that the alleles reported as S and L are divided into four and six kinds of allelic variant, respectively. Subsequently, we developed a method for genotyping. The total number of alleles (14-A, 14-B, 14-C, 14-D, 15, 16-A, 16-B, 16-C, 16-D, 16-E, 16-F, 19, 20 and 22) in the 5-HTTLPR was 14 in our populations (Japanese: n = 131; Caucasian: n = 74) in the present study. In addition, a significant ethnic difference between Japanese and Caucasian populations was observed for distributions of alleles and genotypes (P < 0.0001 and P < 0.0001, respectively). Our results suggest that the analyses of the 5-httlpr should be revised by genotyping with a more complete subdivision of alleles.

A Hydrophilic Peptide Comprising 18 Amino Acid Residues of the Prosaposin Sequence Has Neurotrophic Activity In Vitro and In Vivo

Abstract: Prosaposin, a 517‐amino‐acid glycoprotein, not only acts as the precursor of saposin A, B, C, and D but also possesses neurotrophic activity to rescue hippocampal CA1 neurons from ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Recently, the trophic activity of prosaposin on human neuroblastoma cells has been shown to reside in the NH2‐terminal hydrophilic sequence (LIDNNRTEEILY) of the human saposin C. Here we show that prosaposin, saposin C, and a peptide comprising the 18‐amino‐acid sequence (18‐mer peptide; LSELIINNATEELLIKGL) located in the NH2‐terminal hydrophilic sequence of the rat saposin C‐domain promoted survival and neurite outgrowth of cultured rat hippocampal neurons in a dose‐dependent manner. Moreover, infusion for 7 days of the 18‐mer peptide into the lateral ventricle of gerbils, starting either 2 h before or immediately after 3 min of forebrain ischemia, protected ischemia‐induced learning disability and hippocampal CA1 neuronal loss. Thus, we ascribe the in vitro and in vivo trophic actions of prosaposin on hippocampal neurons to the linear 18‐mer sequence and raise the possibility that this peptide can be used as an agent for the treatment of forebrain ischemic damage.

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism in schizophrenia is associated with age at onset and symptoms

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor that promotes several functions of neurons and modulates neurotransmissions. It has been reported that there are alterations of BDNF levels in schizophrenic brains and that BDNF gene expressional changes would be responsible for the etiology of schizophrenia. Recent studies have shown that a variation of BDNF gene (Val66Met polymorphism) affects the function of neurons, and is associated with several neurological and psychiatrical disorders. We investigated the relationship between BDNF Val66Met polymorphism and the onset age as well as levels of clinical symptoms in 159 of chronic schizophrenia in-patients diagnosed by DSM-IV. The mean onset ages were 27.5+/-9.5 for BDNF Val/Val, 25.5+/-7.4 for BDNF Val/Met and 22.9+/-6.0 for BDNF Met/Met and this polymorphism was significantly associated with age at onset (P=0.023). The mean Brief Psychiatric Rating Scale scores (BPRS) were significantly different among those three groups (P=0.003). No significant differences were demonstrated comparing the BDNF genotype distributions of positive and negative family history (P=0.21). Our investigation indicates that the BDNF gene Val66Met polymorphism is related to the onset age of schizophrenia and the levels of clinical symptoms that remain after long-term antipsychotic treatment.

Prosaposin Facilitates Sciatic Nerve Regeneration In Vivo

Abstract: Prosaposin, a multifunctional protein, is the precursor of saposins, which activate sphingolipid hydrolases. In addition to acting as a precursor for saposins, prosaposin has been shown to rescue hippocampal CA1 neurons from lethal ischemic damage in vivo and to promote neurite extension of neuroblastoma cells in vitro. Here we show that prosaposin, when added to a collagen‐filled nerve guide after sciatic nerve transection in guinea pigs, increased dramatically the number of regenerating nerve fibers within the guide. To identify the target neurons of prosaposin during peripheral nerve regeneration, we determined the degree of atrophy and chromatolysis of neurons in the spinal anterior horn and dorsal root ganglia on the prosaposin‐treated and untreated side. The effect of prosaposin on large spinal neurons and small neurons of the dorsal root ganglion was more conspicuous. Subsequent immunohistochemistry demonstrated that the atrophy of cholinergic large neurons in the anterior horn is prevented to significant extent by prosaposin treatment. These findings suggest that prosaposin promotes peripheral nerve regeneration by acting on α‐motor neurons in the anterior horn and on small sensory neurons in the dorsal root ganglion. The present study raises the possibility of using prosaposin as a tool for the treatment of peripheral nerve injuries.

Gene expression and association analysis of vascular endothelial growth factor in major depressive disorder.

Vascular endothelial growth factor (VEGF) has been implicated in neuronal survival, neuroprotection, regeneration, growth, differentiation, and axonal outgrowth, which are known to be involved in the pathophysiology of major depressive disorder (MDD). Recently, the VEGF mRNA expression in the peripheral leukocytes from Alzheimers disease or cardiovascular disease was reported to be changed. We hypothesized that the expression of the VEGF mRNA in the peripheral leukocytes may be a good candidate for the biological marker for MDD. Thirty two patients with MDD and age- and sex-matched control subjects were included in this expression study. The VEGF mRNA levels in the peripheral leukocytes from drug-naive MDD patients were significantly higher than those from the control subjects and the magnitude of the decrease of VEGF mRNA after 8-week treatment significantly correlated with clinical improvement. Then, we genotyped two single nucleotide polymorphic markers of VEGF gene, which were reported to be associated with amyotrophic lateral sclerosis and Alzheimers disease, in patients with MDD and control subjects (n=154, each). We did not find any significant association between these markers and MDD or its clinical subtypes. Our investigation indicates that the higher expression levels of VEGF mRNA in the peripheral leukocytes are associated with the depressive state and their recovery after treatment may be associated with the clinical improvement.

The Val66Met polymorphism of the brain‐derived neurotrophic factor gene is associated with psychotic feature and suicidal behavior in Japanese major depressive patients

Recent researches have suggested that brain‐derived neurotrophic factor (BDNF) may be implicated in the pathophysiology of mood disorder. This study examined the association between the BDNF Val66Met polymorphism and major depressive disorder (MDD) in a Japanese population. We genotyped the BDNF Val66Met polymorphism in 154 major depressive patients and 154 age‐ and sex‐matched control subjects. The genotypic distributions and allele frequencies were similar among the patients and control subjects. When the relationships of the polymorphism with several clinical variables (i.e., age, sex, age of onset, number of episode, presence of psychotic features, suicidal behavior, and family history) were examined, the dose of Met allele had significant effects on psychotic feature and suicidal behavior and family history. These results suggest that the BDNF Val66Met polymorphism is not related to the development of MDD but related to clinical features of MDD in a Japanese population.

Activation of the prefrontal cortex during the Trail-Making Test detected with multichannel near-infrared spectroscopy

Abstract  The Trail‐Making Test (TMT) is a neuropsychological test for evaluating executive function, and the TMT Part B reflects more complex cognitive processes including cognitive set shifting. The prefrontal cortex (PFC) is thought to be involved in these cognitive processes. The purpose of the present paper was to investigate PFC activation during performance of the TMT Part A and Part B using multichannel near‐infrared spectroscopy (NIRS). Subjects were 41 healthy right‐handed volunteers. The hemodynamic changes in the PFC during the TMT were measured on a 22‐channel NIRS machine. The subjects had a greater increase of oxygenated hemoglobin ([oxyHb]) during the TMT Part B than during Part A in the PFC. Twenty‐seven out of the 41 subjects had a bilateral increase of [oxyHb] in the PFC during Part B according to laterality index. NIRS detected activation in the PFC during the performance of the TMT Part B and this PFC activation may reflect executive functions including cognitive set shifting involved in the TMT Part B.

Serotonin transporter mRNA expression in peripheral leukocytes of patients with major depression before and after treatment with paroxetine

Serotonin transporter (5HTT) is thought to be involved in the pathophysiology of major depression and the target of antidepressants. We hypothesized that 5HTT mRNA levels in peripheral leukocytes may be associated with depressive states and the therapeutic response to antidepressant treatments. Fifteen patients with major depression and age-, sex-matched control subjects were studied. 5HTT mRNA levels were determined with quantitative real-time PCR method. 5HTT mRNA levels in leukocytes were significantly higher in depressive patients at baseline (before medication) than in control subjects. 5HTT mRNA levels were decreased significantly after 8 weeks of paroxetine medication compared with those at baseline. Our investigation suggested that the increased expression of 5HTT mRNA in peripheral leukocytes may be related with the pathophysiology of depression and its reduction after treatment may reflect the adaptive change induced by the antidepressant.

Polymorphisms of the human homologue of the Drosophila white gene are associated with mood and panic disorders.

The Drosophila white gene is a member of the ATP-binding cassette (ABC) transporter superfamily and is involved in the cellular uptake of tryptophan. Its human homologue gene (hW) has been mapped to chromosome 21q22.3. Tryptophan is the precursor for the neurotransmitter serotonin, which has been implicated in the regulation of mood and anxiety. The locus 21q22.3 has also been reported to be associated with mood disorders. The 3′-untranslated region (3′-UTR) in the hW gene has been shown to contain a polymorphic poly(T) region. We have identified a new polymorphism G2457A in the 3′-UTR in the present study. We examined the relationship between these polymorphisms and mood and panic disorders, and a significant association between the poly(T) polymorphisms and mood disorders was detected (P = 0.039 (allele frequency)). Associations were found between the polymorphisms and mood (poly(T) polymorphism: P = 0.047 (allele frequency), G2457A: P = 0.040 (allele frequency), P = 0.044 (genotype frequency)) and panic disorders (G2457A: P = 0.026 (allele frequency), P = 0.011 (genotype frequency)) in males, but not in females. These findings suggest that the hW gene may be an important gene in the control of mood and anxiety as well as one of the genetic factors related to mood disorders and panic disorder in males. The statistical significance of the association remains relatively low and larger materials facilitating further dissection of the clinical phenotype will be needed to confirm and independently validate this finding and to evaluate its significance.

A gene-targeted mouse model for chorea-acanthocytosis

Chorea‐acanthocytosis (CHAC) is a hereditary neurodegenerative disorder with autosomal recessive transmission, in which selective degeneration of striatum has been reported in brain pathology. Clinically, CHAC shows Huntingtons disease‐like neuropsychiatric symptoms and red blood cell acanthocytosis. Recently, we identified the gene, CHAC, encoding a novel protein, chorein, in which a deletion mutation was found in Japanese families with CHAC. In the present study, we have identified the mouse CHAC cDNA sequence and the exon–intron structures of the gene and produced a CHAC model mouse introducing no. 60–61 exon deletion corresponding to a human disease mutation by a gene‐targeting technique. The mice began to show acanthocytosis and motor disturbance in old age. In behavioral observations, locomotor activity was significantly decreased and the contact time at social interaction test was decreased significantly in the model mice. In the brain pathology, many apoptotic cells were observed in the striatum of the mutant mice. In neurochemical determinations, the dopamine metabolite, homovanillic acid, concentration decreased significantly in the portion including the midbrain of the mutant mice. These findings are consistent with the human results reported elsewhere and indicate that the CHAC model mice showed a mild phenotype with late adult onset. The CHAC model mouse therefore provides a good model system to study the human disease.