• Nuclear Medicine and Molecular Imaging
• /
• v.41 no.2
• /
• pp.118-131
• /
• 2007

Neurotransmitter imaging with radiopharmaceuticals plays major role for understanding of neurological and psychiatric disorders such as Parkinson's disease and depression. Radiopharmaceuticals for neurotransmitter imaging can be divided to dopamine transporter imaging radiopharmaceuticals and serotonin trnasporter imaging radiopharmaceuticals. Many kinds of new dopamine transporter imaging radiopharmcaeuticals has a tropane ring and they showed different biological properties according to the substituted functional group on tropane ring. After the first clinical trials with $[^{123}I]{\beta}-CIT$, alkyl chain substituent introduced to tropane ring amine to decrease time for imaging acquisition and to increase selectivity. From these results, $[^{123}I]PE2I$, [18F]FE-CNT, $[^{123}I]FP-CIT$ and $[^{18}F]FP-CIT$ were developed and they showed high uptake on the dopamine transporter rich regions and fast peak uptake equilibrium time within 4 hours after injection. $[^{11}C]McN$ 5652 was developed for serotonin trnasporter imaging but this compound showed slow kinetics and high background radioactivity. To overcome these problems, new diarylsulfide backbone derivatives such as ADAM, ODAM, AFM, and DASB were developed. In these candidates, $[^{11}C]AFM$ and $[^{11}C]DASB$ showed high binding affinity to serotonin transporter and fast in vivo kinetics. This paper gives an overview of current status on dopamine and serotonin transporter imaging radiopharmaceuitcals and the development of new lead compounds as potential radiopharmaceuticals by medicinal chemistry.

• Korean Journal of Biological Psychiatry
• /
• v.25 no.1
• /
• pp.16-20
• /
• 2018

Objectives Psychological resilience is the ability to cope with stress. The genetic background behind psychological resilience is not much known. The serotonin transporter and dopamine transporter are implicated in stress related psychology and emotional processing. The aim of this study is to investigate a possible genetic role of functional polymorphisms of serotonin and dopamine transporters for psychological resilience. Methods A total of 951 healthy adult subjects were included. Psychological resilience was measured using Connor-Davidson Resilience Scale (CD-RISC). Genotyping was performed for serotonin transporter gene(SERT) promoter variable number tandem repeat (VNTR) and dopamine transporter gene(DAT1) 3'-untranslated region (UTR) VNTR. Genetic association analysis was conducted between genotypes and the CD-RISC score. Results No genetic association was observed for SERT promoter VNTR or DAT1 3'-UTR VNTR with CD-RISC score. No genetic interaction between SERT promoter VNTR and DAT1 3'-UTR VNTR with CD-RISC score was detected. Conclusions Either serotonin or dopamine transporter did not seem to play a significant role for psychological resilience in this sample.

• Korean Journal of Biological Psychiatry
• /
• v.9 no.1
• /
• pp.34-41
• /
• 2002

Background:Since serotonin neurotrasnmission plays an important role in the pathophysiology of depression, the drug that acts on serotonin transporter can be an effective antidepressant. The aim of this study was to investigate the relationship between serotonin transporter polymorphisms(5-HTTLPR) and the long-term effect of the antidepressant treatment. Method:The 175 depressive patients, who met DSM-IV criteria for major depressive disorder or dysthymic disorder were enrolled into three year study. The genotypes of the patients were investigated by polymerase chain reaction of genomic DNA with promoter regions of the serotonin transporter gene. The patients were assessed by the Clinical Global Impression Scale, at the 1st visit, 8th week, 16th week, 1st year, 2nd and 3rd year after the antidepressant treatment. Result:The genotypes of 138 patients were investigated and 128 of them finished this 1st year study and 107 remained in the study after 2-year treatment, and, 97 completed this 3-year study. The therapeutic response of each subset was not different at 8th, 16th week, but the subset with homozygote(l/l) of long variant showed a better antidepressant therapeutic response than heterozygote(l/s). The heterozygote(l/s) showed a better response than the subset with homozygote(s/s) of short variant at 1st, 2nd and 3rd year after the antidepressant treatment in CGI-global improvement score. Conclusion:This result shows that the serotonin transporter polymorphism may be related to the long-term effect of antidepressant treatment and there may be also ethnic difference.

• Korean Journal of Biological Psychiatry
• /
• v.8 no.2
• /
• pp.220-225
• /
• 2001

As numbers of serotonin's function are so many, studies of serotonin are numerous nowadays. In the beginning, concentration of metabolites such as 5-HIAA was a key issue, but recent studies have been challenged for serotonin receptor genes and their relation to mood disoder. Serotonin transporter(5-HTT) gene is a strong candidate gene of mood disoder for following reason. Serotonin transporter is a key protein in the serotonin pathway as it regulate the concentration of serotonin in the synaptic clept and essential pathophysiology of depression is dysregulation of 5-HTT so that all antidepressants have effect of 5-HTT antagonist. The decrease of 5-HTT in the platelet and in brain of the depressive patients is much consistent results in the studies of the pathophysiology of mood disorder till now. By this, we will be able to develop simple and easy marker for diagnosis, type, and treatment monitoring of depression. Many psychiatrists have sought the independent genes in relation to depression or schizophrenia. Obviously, the hereditary vulnerability contributes to etiology of mood disorders, but it is difficult to discriminate the independent genes because of many environmental factors. Moreover, in the hereditarily complex diseases such as mood disorder, the only vulnerability of gene can not sufficiently explain the etiology. In the future, to exclude the role of the gene-environmental interaction, the methods such as gene transfer can be considered. In the opposite direction, by using the gene destruction method, the role of target genes can be examined. As yet the concept of the gene expression, neural plasticity, neurogenesis and etc, is the elementary stage. The development of this field will help to establish the treatment strategy of chronic and refractory mood disorders.

• Korean Journal of Biological Psychiatry
• /
• v.18 no.4
• /
• pp.176-180
• /
• 2011

Depressive disorders have strong genetic components. However, conventional linkage and association studies have not yielded definitive results. These might be due to the absence of objective diagnostic tests, the complex nature of human behavior or the incomplete penetrance of psychiatric traits. Imaging genetics explores the influences of genetic variation on the brain function or structure. This technique could provide a more sensitive assessment than traditional behavioral measures in psychiatric studies. Imaging genetics is a relatively new field of psychiatric researches, and may improve our understanding on neurobiology of psychiatric disorders. In this review, current understanding in neurobiology of depressive disorders, especially imaging genetic studies on serotonin transporter will be discussed.

• Biomolecules & Therapeutics
• /
• v.20 no.6
• /
• pp.506-512
• /
• 2012

Although pruritus is the critical symptom of atopic dermatitis that profoundly affect the patients' quality of life, controlling and management of prurirtus still remains as unmet needs mainly due to the distinctive multifactorial pathogenesis of pruritus in atopic dermatitis. Based on the distinct feature of atopic dermatitis that psychological state of patients substantially influence on the intensity of pruritus, various psychotropic drugs have been used in clinic to relieve pruritus of atopic dermatitis patients. Only several psychotropic drugs were reported to show real antipruritic effects in atopic dermatitis patients including naltrexone, doxepin, trimipramine, bupropion, tandospirone, paroxetine and fluvoxamine. However, the precise mechanisms of antipruritic effect of these psychotropic drugs are still unclear. In human skin, serotonin receptors and serotonin transporter protein are expressed on skin cells such as keratinocytes, melanocytes, dermal fibroblasts, mast cells, T cells, natural killer cells, langerhans cells, and sensory nerve endings. It is noteworthy that serotonergic drugs, as well as serotonin itself, showed immune-modulating effect. Fenfluramine, fluoxetine and 2, 5-dimethoxy-4-iodoamphetamine significantly decreased lymphocyte proliferation. It is still questionable whether these serotonergic drugs exert the immunosuppressive effects via serotonin receptor or serotonin transporter. All these clinical and experimental reports suggest the possibility that antipruritic effects of selective serotonin reuptake inhibitors in atopic dermatitis patients might be at least partly due to their suppressive effect on T cells. Further studies should be conducted to elucidate the precise mechanism of neuroimmunological interaction in pruritus of atopic dermatitis.

• Journal of Life Science
• /
• v.20 no.10
• /
• pp.1451-1457
• /
• 2010

Serotonin (5-hydroxytryptamine, 5-HT) is an important mediator of cell-cell signaling in neuronal systems. The serotonin transporter (SERT) on the plasma membrane controls the extracellular 5-HT level by reuptake of released 5-HT from the synaptic cleft, but the underlying regulation mechanism is unclear. Here, we used the yeast two-hybrid system to identify the specific binding protein(s) that interacts with the carboxyl (C)-terminal region of SERT and found a specific interaction with protein kinase C-$\varepsilon$ (PKC-$\varepsilon$), a PKC isotype that is characterized as a calcium-independent and phorbol ester/diacylglycerol-sensitive serine/threonine kinase. PKC-$\varepsilon$ bound to the tail region of SERT but not to other members of the $Na^+/Cl^-$ dependent SLC6 gene family in the yeast two-hybrid assay. The C-terminal region of PKC-$\varepsilon$ is essential for interaction with SERT. In addition, these proteins showed specific interactions in the glutathione S-transferase (GST) pull-down assay. PKC-$\varepsilon$ phosphorylated the peptide of the SERT amino (N)-terminus in vitro. These results suggest that the phosphorylation of SERT by PKC-$\varepsilon$ may regulate SERT activity in plasma membrane.

• Korean Journal of Biological Psychiatry
• /
• v.19 no.2
• /
• pp.106-113
• /
• 2012

Objectives : The purpose of this study is to investigate the relationship between the triallelic serotonin transporter gene and stressful life events to determine their effect on depression with alcohol dependence. Methods : Ninety-five hospitalized patients with alcohol dependence (73 male, 22 female) were enrolled in this study. Thirty-two (33.7%) of the total patients were diagnosed with major depressive disorder and dysthymic disorder by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV. The characteristics of stress were evaluated using the stressful life events scale, and depressive symptoms were assessed using the depression scale (Beck Depression Inventory, BDI). Alcoholism with depression (n = 32) and alcoholism without depression (n = 63) were genotyped for the triallelic serotonin transporter gene ($L_A$ : higher expressing allele, $L_G$/S : lower expressing allele). Results : There was no significant difference in the allele frequency between the depression group and the non-depression group (${\chi}^2$ = 0.345, p = 0.619). $L_G$/S alleles had more comorbid depression in the higher score of stressful life events scale [Mental-Haenszel (MH)-${\chi}^2$ = 4.477, p = 0.034]. But there was no significant difference in the comorbidity according to the scores from the stressful life event scale in the $L_A$ alleles (MH-${\chi}^2$ = 0.741, p = 0.399). In the results, alcohol-dependent individuals with $L_G$/S alleles had more comorbid depression than those with $L_A$ alleles when they had experienced severe stressful life events (MH-odds ratio = 2.699, p = 0.028). Conclusions : These results suggest that there is no direct relationship between triallelic serotonin transporter gene and depression in the alcohol dependent patients. But alcohol dependent individuals with the lower expressing alleles of the serotonin transporter gene were more susceptible to depression than those with the higher expressing alleles in response to stressful life events.

• Korean Journal of Biological Psychiatry
• /
• v.17 no.2
• /
• pp.65-69
• /
• 2010

Gene-environment interactions are important in pathogenesis of suicide or suicidal behavior. Twin and adoption studies and family studies show that genetic factors play a critical role in suicide or suicidal behavior. Given the strong association between serotonergic neurotransmission and suicide, recent molecular genetic studies have focused on polymorphisms of serotonin genes, especially on serotonin transporter and tryptophan hydroxylase genes. Some studies have revealed a significant interaction between s allele of the serotonin transporter gene and the risk of suicide attempt associated with childhood trauma. In addition, the polymorphism of brain-derived neurotrophic factor gene also may influence the effect of childhood trauma in relation to the risk of attempting suicide. Future studies should explore genetic and environmental factors in suicide or suicidal behavior and examine for gene and environment interaction.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.10
• /
• pp.1439-1444
• /
• 2002

6-Nitroquipazine has higher binding affinity for SERT than other selective serotonin reuptake inhibitors. We have prepared 6-nitroquipazine based rhenium complexes which would lead to the development of potential SPECT imaging agents with $^{99m}Tc$ for 5-HT transporter.