Depression is a major psychological disorder that affects a person's mental and physical abilities. The National Institute of Mental Health (NIMH) classified it as a serious medical illness. It causes huge economic, as well as financial impact on the people, and it is also becoming a major public health issue. Antidepressant drugs are prescribed to mitigate the suffering caused by this disorder. Different generations of antidepressants have been developed with dissimilar mechanisms of action. According to the Center for Disease Control, the usage of antidepressants has skyrocketed by 400 percent increase over 2005- 2008 survey period. This dramatic rise in usage indicates that these are the most prescribed drugs in the US. Even with the FDA mandated "black box" warning of increased suicidal thoughts upon use of selected antidepressants, these drugs are still being used at a higher rate. <br>All classes of antidepressants are plagued by side effects with mainly sexual dysfunction common among them. To avoid the adverse effects, an emphasis is to discover novel structural drug scaffolds that can be further developed as a new generation of antidepressants. The importance of this research is to discover structurally novel antidepressants by performing in silico virtual screening (VS) of chemical databases using the serotonin transporter (SERT). In the absence of a SERT crystal structure, a homology model was developed. The homology model was utilized to develop the first structure-based pharmacophore for the extracellular facing secondary ligand binding pocket. The pharmacophore captured the necessary drug-SERT interaction pattern for SERT inhibitory action. This pharmacophore was employed as one of the filters for VS of candidate ligands. The ten compounds identified were purchased and tested pharmacologically. Out of the ten hits, three structurally novel ligands were identified as lead compounds. Two of these compounds exhibited selectivity towards SERT; the remaining lead compound was selective towards the dopamine transporter and displayed cocaine inhibition. The two SERT selective compounds will provide new opportunities in the development of novel therapeutics to treat depression. <br>For dopamine transporter (DAT), the study was based on recently developed structurally diverse photo probes. In an effort to better understand the binding profile similarities among these different scaffolds, the photo probes were docked into DAT. The finger print analysis of the interaction pattern of docked poses was performed to identify the inhibitor-binding sites. <br>For mitogen activated protein kinase 5 (MEK5), given the lack of structural information, a homology model of MEK5 was developed to guide the rational design of inhibitors. Docking of known MEK5 inhibitors into the homology model was performed to understand the inhibitory interaction profile. Several series of analogues were designed utilizing the generated interaction profile. / Bayer School of Natural and Environmental Sciences / Chemistry and Biochemistry / PhD / Dissertation

A depressão pós-parto (DPP) é um importante problema de saúde pública podendo provocar uma ruptura do vínculo entre a mãe e o bebê e até estar associada com respostas trágicas, como suicídio materno e infanticídio. A DPP é multifatorial e o seu surgimento pode ser favorecido por componentes hormonais, genéticos e ambientais. O ciclo gravídico-puerperal é considerado um período de risco, pois algumas mulheres possuem uma sensibilidade particular as alterações hormonais. O risco de DPP é aumentado em mulheres que possuem histórico de depressão na família, logo, um componente genético determina maior suscetibilidade. Segundo o DMS-IV, existe uma relação entre a sintomatologia depressiva e as alterações na concentração cerebral de neurotransmissores, com destaque para serotonina. O transportador de serotonina (SERT) controla a intensidade e duração da re-captação da serotonina nas sinapses serotonérgicas. Diversos trabalhos associam os polimorfismos do SERT com transtornos mentais, como unipolar, bipolar, depressão e esquizofrenia. Nosso objetivo foi analisar as concentrações salivares de cortisol (CORT), as freqüências alélicas e genotípicas dos polimorfismos 5-HTTVNTR e 5- HTTLPR no gene SLC6A4 entre mulheres que desenvolveram ou não DPP. A amostra foi constituída por 128 mulheres brancas da cidade de Pelotas/RS, triadas em ambulatórios do SUS. A avaliação diagnóstica foi realizada através de entrevista psiquiátrica e diagnóstica usando como instrumento o Beck Depression Inventory entre 30 a 45 dias após o nascimento das crianças. A coleta de material biológico (leucócitos e saliva) foi realizada no turno da manhã, respeitando o período de duas horas de jejum. A região promotora do gene contendo o polimorfismo 5-HTTLPR (inserção/deleção) e a região do segundo íntron contendo o polimorfismo 5- HTTVNTR (repetições em tandem) foram amplificadas através da reação em cadeia da polimerase. A dosagem do CORT foi realizada a partir da saliva por técnica de ELISA utilizando kit específico. A mediana e o intervalo interquartil das concentrações salivares do CORT entre os portadores dos diferentes genótipos foram comparados entre os grupos estudados usando o teste de Kruskal-Wallis e Mann-Whitney. A comparação das freqüências alélicas e genotípicas dos polimorfismos estudados entre as mulheres que apresentarem ou não DPP foram feitas pelo teste do Qui-quadrado com correção de Yates (p£ 0,05). A análise da distribuição das freqüências genotípicas dos polimorfismos 5-HTTLPR e 5- HTTVNTR do SERT permitiu verificar que a população está sob Equilíbrio Hardy– Weinberg. Quando os polimorfismos foram analisados isoladamente, não foi observada associação entre os polimorfismos 5-HTTLPR (p=0,48) e 5-HTTVNTR (p=0,77) e o diagnóstico para DPP. Porém, a análise combinada dos haplótipos dos polimorfismos 5-HTTLPR e 5-HTTVNTR demonstraram que mulheres portadoras do diplótipo L-12/L-12 apresentaram escores menores de sintomas depressivos (mediana: 0,5; intervalo inter-quartil: 0,00-4,00, p=0,04) quando comparadas com mulheres portadoras de outros diplótipos (mediana: 4,0; intervalo inter-quartil: 1,00- 10,00). O polimorfismo 5-HTTVNTR foi associado com as concentrações salivares de CORT (p=0,03), já o polimorfismo 5-HTTLPR não foi associado (p=0,41). Nossos achados são inovadores, visto que até a presente data a associação dos genótipos 5-HTTLPR e 5-HTTVNTR com DPP e concentrações salivares de CORT ainda não haviam sido investigados. / The postpartum depression (PPD) is an important public health problem that may cause a rupture of the bond between the mother and the baby and may even be associated with tragic responses such as maternal suicide and infanticide. The DPP is multifactorial and its appearance can be favored by hormonal components, genetic and environmental factors. The pregnancy and childbirth is considered a risk period, because some women have a particular sensitivity to hormonal changes. The rate of DPP is increased in women who have a record of depression in the family, so a genetic component determines higher susceptibility. According to the DSM-IV, there is a relationship between depressive symptoms and brain concentration changes of neurotransmitters, particularly serotonin. The serotonin transporter (SERT) controls the intensity and duration of re-uptake of serotonin in serotonergic synapses. Several studies linking polymorphisms of SERT with mental disorders such as unipolar, bipolar, depression, and schizophrenia. Our objective was to analyze the concentrations of salivary cortisol (CORT), the allele and genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SLC6A4 gene in women who developed or not DPP. The sample consisted of 128 white women from Pelotas, RS, sorted out from public health clinics. The diagnostic evaluation was conducted through interviews and psychiatric diagnostic instrument as using the Beck Depression Inventory among 30 to 45 days after the birth of children. The collection of biological materials (leukocytes and saliva) was performed in the morning, observing the twohour period of fasting. The promoter region of the gene containing the 5-HTTLPR polymorphism (insertion/deletion) and the region containing the second intron polymorphism 5-HTTVNTR (tandem repeats) were amplified by polymerase chain reaction. The dose of CORT was performed from the saliva by ELISA using the specific kit. The median and interquartile interval of salivary concentrations of CORT among patients of different genotypes were compared between groups using the Kruskal-Wallis and Mann-Whitney. The comparison of allele and genotype frequencies of polymorphisms among women who developed or not DPP were made by chi-square test with Yates correction (p <0.05). The analysis of the distribution of genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SERT showed that the population is under Hardy-Weinberg Equilibrium. When the polymorphisms were analyzed alone, no association was observed between the 5-HTTLPR (p=0.48) and 5-HTTVNTR (p=0.77) polymorphisms and the PPD diagnosis. But, the information from these analyses combined with information regarding the haplotypes of the 5-HTTLPR and 5-HTTVNTR polymorphisms demonstrated that women carriers of diplotype L-12/L-12 have a lower depression symptoms score (median: 0.5; interquartile range: 0.00-4.00; p=0.04) than women with other diplotypes (median: 4.0; inter-quartile range: 1.00-10.00). The 5-HTTVNTR polymorphism was associated with the salivary concentrations of CORT (p=0.03), whereas the 5-HTTLPR polymorphism was not associated (p=0.41). Our findings are innovative since the association of 5- HTTLPR genotypes and 5-HTTVNTR with DPP and salivary concentrations of CORT had not been investigated before.

A depressão pós-parto (DPP) é um importante problema de saúde pública podendo provocar uma ruptura do vínculo entre a mãe e o bebê e até estar associada com respostas trágicas, como suicídio materno e infanticídio. A DPP é multifatorial e o seu surgimento pode ser favorecido por componentes hormonais, genéticos e ambientais. O ciclo gravídico-puerperal é considerado um período de risco, pois algumas mulheres possuem uma sensibilidade particular as alterações hormonais. O risco de DPP é aumentado em mulheres que possuem histórico de depressão na família, logo, um componente genético determina maior suscetibilidade. Segundo o DMS-IV, existe uma relação entre a sintomatologia depressiva e as alterações na concentração cerebral de neurotransmissores, com destaque para serotonina. O transportador de serotonina (SERT) controla a intensidade e duração da re-captação da serotonina nas sinapses serotonérgicas. Diversos trabalhos associam os polimorfismos do SERT com transtornos mentais, como unipolar, bipolar, depressão e esquizofrenia. Nosso objetivo foi analisar as concentrações salivares de cortisol (CORT), as freqüências alélicas e genotípicas dos polimorfismos 5-HTTVNTR e 5- HTTLPR no gene SLC6A4 entre mulheres que desenvolveram ou não DPP. A amostra foi constituída por 128 mulheres brancas da cidade de Pelotas/RS, triadas em ambulatórios do SUS. A avaliação diagnóstica foi realizada através de entrevista psiquiátrica e diagnóstica usando como instrumento o Beck Depression Inventory entre 30 a 45 dias após o nascimento das crianças. A coleta de material biológico (leucócitos e saliva) foi realizada no turno da manhã, respeitando o período de duas horas de jejum. A região promotora do gene contendo o polimorfismo 5-HTTLPR (inserção/deleção) e a região do segundo íntron contendo o polimorfismo 5- HTTVNTR (repetições em tandem) foram amplificadas através da reação em cadeia da polimerase. A dosagem do CORT foi realizada a partir da saliva por técnica de ELISA utilizando kit específico. A mediana e o intervalo interquartil das concentrações salivares do CORT entre os portadores dos diferentes genótipos foram comparados entre os grupos estudados usando o teste de Kruskal-Wallis e Mann-Whitney. A comparação das freqüências alélicas e genotípicas dos polimorfismos estudados entre as mulheres que apresentarem ou não DPP foram feitas pelo teste do Qui-quadrado com correção de Yates (p£ 0,05). A análise da distribuição das freqüências genotípicas dos polimorfismos 5-HTTLPR e 5- HTTVNTR do SERT permitiu verificar que a população está sob Equilíbrio Hardy– Weinberg. Quando os polimorfismos foram analisados isoladamente, não foi observada associação entre os polimorfismos 5-HTTLPR (p=0,48) e 5-HTTVNTR (p=0,77) e o diagnóstico para DPP. Porém, a análise combinada dos haplótipos dos polimorfismos 5-HTTLPR e 5-HTTVNTR demonstraram que mulheres portadoras do diplótipo L-12/L-12 apresentaram escores menores de sintomas depressivos (mediana: 0,5; intervalo inter-quartil: 0,00-4,00, p=0,04) quando comparadas com mulheres portadoras de outros diplótipos (mediana: 4,0; intervalo inter-quartil: 1,00- 10,00). O polimorfismo 5-HTTVNTR foi associado com as concentrações salivares de CORT (p=0,03), já o polimorfismo 5-HTTLPR não foi associado (p=0,41). Nossos achados são inovadores, visto que até a presente data a associação dos genótipos 5-HTTLPR e 5-HTTVNTR com DPP e concentrações salivares de CORT ainda não haviam sido investigados. / The postpartum depression (PPD) is an important public health problem that may cause a rupture of the bond between the mother and the baby and may even be associated with tragic responses such as maternal suicide and infanticide. The DPP is multifactorial and its appearance can be favored by hormonal components, genetic and environmental factors. The pregnancy and childbirth is considered a risk period, because some women have a particular sensitivity to hormonal changes. The rate of DPP is increased in women who have a record of depression in the family, so a genetic component determines higher susceptibility. According to the DSM-IV, there is a relationship between depressive symptoms and brain concentration changes of neurotransmitters, particularly serotonin. The serotonin transporter (SERT) controls the intensity and duration of re-uptake of serotonin in serotonergic synapses. Several studies linking polymorphisms of SERT with mental disorders such as unipolar, bipolar, depression, and schizophrenia. Our objective was to analyze the concentrations of salivary cortisol (CORT), the allele and genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SLC6A4 gene in women who developed or not DPP. The sample consisted of 128 white women from Pelotas, RS, sorted out from public health clinics. The diagnostic evaluation was conducted through interviews and psychiatric diagnostic instrument as using the Beck Depression Inventory among 30 to 45 days after the birth of children. The collection of biological materials (leukocytes and saliva) was performed in the morning, observing the twohour period of fasting. The promoter region of the gene containing the 5-HTTLPR polymorphism (insertion/deletion) and the region containing the second intron polymorphism 5-HTTVNTR (tandem repeats) were amplified by polymerase chain reaction. The dose of CORT was performed from the saliva by ELISA using the specific kit. The median and interquartile interval of salivary concentrations of CORT among patients of different genotypes were compared between groups using the Kruskal-Wallis and Mann-Whitney. The comparison of allele and genotype frequencies of polymorphisms among women who developed or not DPP were made by chi-square test with Yates correction (p <0.05). The analysis of the distribution of genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SERT showed that the population is under Hardy-Weinberg Equilibrium. When the polymorphisms were analyzed alone, no association was observed between the 5-HTTLPR (p=0.48) and 5-HTTVNTR (p=0.77) polymorphisms and the PPD diagnosis. But, the information from these analyses combined with information regarding the haplotypes of the 5-HTTLPR and 5-HTTVNTR polymorphisms demonstrated that women carriers of diplotype L-12/L-12 have a lower depression symptoms score (median: 0.5; interquartile range: 0.00-4.00; p=0.04) than women with other diplotypes (median: 4.0; inter-quartile range: 1.00-10.00). The 5-HTTVNTR polymorphism was associated with the salivary concentrations of CORT (p=0.03), whereas the 5-HTTLPR polymorphism was not associated (p=0.41). Our findings are innovative since the association of 5- HTTLPR genotypes and 5-HTTVNTR with DPP and salivary concentrations of CORT had not been investigated before.

A depressão pós-parto (DPP) é um importante problema de saúde pública podendo provocar uma ruptura do vínculo entre a mãe e o bebê e até estar associada com respostas trágicas, como suicídio materno e infanticídio. A DPP é multifatorial e o seu surgimento pode ser favorecido por componentes hormonais, genéticos e ambientais. O ciclo gravídico-puerperal é considerado um período de risco, pois algumas mulheres possuem uma sensibilidade particular as alterações hormonais. O risco de DPP é aumentado em mulheres que possuem histórico de depressão na família, logo, um componente genético determina maior suscetibilidade. Segundo o DMS-IV, existe uma relação entre a sintomatologia depressiva e as alterações na concentração cerebral de neurotransmissores, com destaque para serotonina. O transportador de serotonina (SERT) controla a intensidade e duração da re-captação da serotonina nas sinapses serotonérgicas. Diversos trabalhos associam os polimorfismos do SERT com transtornos mentais, como unipolar, bipolar, depressão e esquizofrenia. Nosso objetivo foi analisar as concentrações salivares de cortisol (CORT), as freqüências alélicas e genotípicas dos polimorfismos 5-HTTVNTR e 5- HTTLPR no gene SLC6A4 entre mulheres que desenvolveram ou não DPP. A amostra foi constituída por 128 mulheres brancas da cidade de Pelotas/RS, triadas em ambulatórios do SUS. A avaliação diagnóstica foi realizada através de entrevista psiquiátrica e diagnóstica usando como instrumento o Beck Depression Inventory entre 30 a 45 dias após o nascimento das crianças. A coleta de material biológico (leucócitos e saliva) foi realizada no turno da manhã, respeitando o período de duas horas de jejum. A região promotora do gene contendo o polimorfismo 5-HTTLPR (inserção/deleção) e a região do segundo íntron contendo o polimorfismo 5- HTTVNTR (repetições em tandem) foram amplificadas através da reação em cadeia da polimerase. A dosagem do CORT foi realizada a partir da saliva por técnica de ELISA utilizando kit específico. A mediana e o intervalo interquartil das concentrações salivares do CORT entre os portadores dos diferentes genótipos foram comparados entre os grupos estudados usando o teste de Kruskal-Wallis e Mann-Whitney. A comparação das freqüências alélicas e genotípicas dos polimorfismos estudados entre as mulheres que apresentarem ou não DPP foram feitas pelo teste do Qui-quadrado com correção de Yates (p£ 0,05). A análise da distribuição das freqüências genotípicas dos polimorfismos 5-HTTLPR e 5- HTTVNTR do SERT permitiu verificar que a população está sob Equilíbrio Hardy– Weinberg. Quando os polimorfismos foram analisados isoladamente, não foi observada associação entre os polimorfismos 5-HTTLPR (p=0,48) e 5-HTTVNTR (p=0,77) e o diagnóstico para DPP. Porém, a análise combinada dos haplótipos dos polimorfismos 5-HTTLPR e 5-HTTVNTR demonstraram que mulheres portadoras do diplótipo L-12/L-12 apresentaram escores menores de sintomas depressivos (mediana: 0,5; intervalo inter-quartil: 0,00-4,00, p=0,04) quando comparadas com mulheres portadoras de outros diplótipos (mediana: 4,0; intervalo inter-quartil: 1,00- 10,00). O polimorfismo 5-HTTVNTR foi associado com as concentrações salivares de CORT (p=0,03), já o polimorfismo 5-HTTLPR não foi associado (p=0,41). Nossos achados são inovadores, visto que até a presente data a associação dos genótipos 5-HTTLPR e 5-HTTVNTR com DPP e concentrações salivares de CORT ainda não haviam sido investigados. / The postpartum depression (PPD) is an important public health problem that may cause a rupture of the bond between the mother and the baby and may even be associated with tragic responses such as maternal suicide and infanticide. The DPP is multifactorial and its appearance can be favored by hormonal components, genetic and environmental factors. The pregnancy and childbirth is considered a risk period, because some women have a particular sensitivity to hormonal changes. The rate of DPP is increased in women who have a record of depression in the family, so a genetic component determines higher susceptibility. According to the DSM-IV, there is a relationship between depressive symptoms and brain concentration changes of neurotransmitters, particularly serotonin. The serotonin transporter (SERT) controls the intensity and duration of re-uptake of serotonin in serotonergic synapses. Several studies linking polymorphisms of SERT with mental disorders such as unipolar, bipolar, depression, and schizophrenia. Our objective was to analyze the concentrations of salivary cortisol (CORT), the allele and genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SLC6A4 gene in women who developed or not DPP. The sample consisted of 128 white women from Pelotas, RS, sorted out from public health clinics. The diagnostic evaluation was conducted through interviews and psychiatric diagnostic instrument as using the Beck Depression Inventory among 30 to 45 days after the birth of children. The collection of biological materials (leukocytes and saliva) was performed in the morning, observing the twohour period of fasting. The promoter region of the gene containing the 5-HTTLPR polymorphism (insertion/deletion) and the region containing the second intron polymorphism 5-HTTVNTR (tandem repeats) were amplified by polymerase chain reaction. The dose of CORT was performed from the saliva by ELISA using the specific kit. The median and interquartile interval of salivary concentrations of CORT among patients of different genotypes were compared between groups using the Kruskal-Wallis and Mann-Whitney. The comparison of allele and genotype frequencies of polymorphisms among women who developed or not DPP were made by chi-square test with Yates correction (p <0.05). The analysis of the distribution of genotype frequencies of polymorphisms 5-HTTLPR and 5-HTTVNTR SERT showed that the population is under Hardy-Weinberg Equilibrium. When the polymorphisms were analyzed alone, no association was observed between the 5-HTTLPR (p=0.48) and 5-HTTVNTR (p=0.77) polymorphisms and the PPD diagnosis. But, the information from these analyses combined with information regarding the haplotypes of the 5-HTTLPR and 5-HTTVNTR polymorphisms demonstrated that women carriers of diplotype L-12/L-12 have a lower depression symptoms score (median: 0.5; interquartile range: 0.00-4.00; p=0.04) than women with other diplotypes (median: 4.0; inter-quartile range: 1.00-10.00). The 5-HTTVNTR polymorphism was associated with the salivary concentrations of CORT (p=0.03), whereas the 5-HTTLPR polymorphism was not associated (p=0.41). Our findings are innovative since the association of 5- HTTLPR genotypes and 5-HTTVNTR with DPP and salivary concentrations of CORT had not been investigated before.

The serotonergic system is involved in a broad range of functions in both vertebrates and invertebrates and is highly conserved across taxa. Serotonin is an important monoamine acting in the brains of humans and animals, and has large and varying influences on many aspects of an individual’s life. For example, in humans, serotonin modulates feelings of happiness and in fruit flies, higher levels of serotonin increase aggression. In humans, an abnormal serotonergic system can result in health issues, such as depression and obsessive compulsive disorders, for which medications have been developed, including selective serotonin reuptake inhibitors (SSRI). Because the serotonin system has a large influence on human health, understanding how it functions is of great interest to researchers. Using comparative studies to explore differences in the serotonin system across taxa can provide insight into the mechanistic details of the system. To investigate if the serotonin system is comparable between vertebrates and invertebrates, a literature study with particular focus on receptors and proteins involved was performed. In addition, this report takes part in an experimental study investigating the effect of the SSRI fluoxetine in Mediterranean field crickets.  Fluoxetine reduced exploration propensity of crickets, which was reversed, compared to what was anticipated and compared to effects seen in vertebrates. The literature review suggests that serotonin receptors are quite similar, but that proteins differ more when comparing vertebrates and invertebrates. This offers a likely explanation as to why results of studies on these different groups of animals may differ.

The serotonin transporter (SLC6A4) has been a prominent choice in studying multiple neuropsychiatric illnesses. However, underlying molecular mechanisms of the regulatory control of this gene leading to these illnesses remain incomplete. Since this locus is the target of virtually every antidepressant, understanding the molecular mechanisms would benefit the development of effective therapeutic agents. In an attempt to better understand the regulatory control of the human serotonin transporter, a series of investigations were conducted on the 5HTTLPR genotype, DNA methylation and SLC6A4 mRNA expression with respect to childhood sexual abuse and depression. Moreover, since vast majority of studies have only concentrated on the Long (L) and Short (S) polymorphisms, the characteristics of the Extra-Long (XL) allele with respect to transcriptional efficiency was investigated. Finally, due to the increase in gene expression studies, the normalization of gene expression with respect to multiple housekeeping genes was explored. Through this study, we demonstrate significant gene-environmental interaction effects at this locus. The extra-long variant was associated with increased gene transcriptional efficiency. Also, although the best gene expression normalization was achieved with one housekeeping gene, we present a strong explanation on the importance of utilizing more than one housekeeping gene. These results could certainly aid in understanding and treating disorders related to the human serotonin transporter.

Chronic stress and dysfunction of the serotonergic system in the brain have been considered two of the major risks for development of depression. In this study, adult Fischer 344 rats were subjected to a regimen of chronic social defeat (CSD). To mimic stressful conditions, some rats were not exposed to CSD, but instead treated with corticosterone (CORT) in oral solution while maintained in their home cage. Protein levels of the serotonin transporter (SERT) in the dorsal raphe nucleus (DRN), hippocampus, frontal cortex, and amygdala were examined by Western blotting or immunofluorescence staining. The results showed that CSD up-regulated SERT protein levels in the DRN, hippocampus, frontal cortex, and amygdala regions. This up-regulation was abolished or prevented by adrenalectomy, or treatment with antagonists of corticosteroid receptors mifepristone and spironolactone, alone or in combination. Similarly, up-regulated SERT protein levels in these brain regions were also observed in rats treated with oral CORT ingestion, which was analogously prevented by treatment with mifepristone and spironolactone. Furthermore, both CSD- and CORT-induced up-regulation of SERT protein levels in the DRN and three brain regions were attenuated by simultaneous treatment with fluoxetine, an antidepressant that specifically inhibits serotonin reuptake. The results indicate that up-regulation in SERT protein levels in the DRN and forebrain limbic structures caused by CSD regimen was mainly motivated by CORT through corticosteroid receptors. The present findings demonstrate that chronic stress is closely correlated with the serotonergic system by acting on the regulation of the SERT expression in the DRN and its projection regions, which may contribute to the development of depression. Chronic stress and dysfunction of the serotonergic system are etiologically related to depression. In an attempt to explore their interaction, we found that chronic social defeat upregulated expression of serotonin transporter in the DRN and the projection regions, which may induce an alteration of serotonin transformation in the brain. This interaction may account for the development of this disease.

A gene x environment interaction exists in the expression of anxiety for both human and nonhuman primates, such that individuals who are carriers of the (s) allele of the serotonin transporter genotype ( 5-HTT LPR) and exposed to early life stress are more at risk for exhibiting anxiety. The hypothalamic-pituitary-adrenal (HPA) axis has also been implicated in anxiety disorders but the relationship between early life/genotype, HPA activity, and anxiety is not well understood. Further, studies linking the HPA axis to anxiety have relied on "point" samples (blood and salivary cortisol) which reflect moments in time rather than long-term activity. The purpose of this dissertation was three fold: (1) to examine anxious behavior in monkeys with different 5-HTT LPR genotypes and rearing environments across the first two years of life, (2) to compare long-term HPA activity (as measured with hair cortisol) with acute HPA activity (as measured with salivary cortisol) in the same period, and (3) to determine which measure of HPA activity predicts anxiety and/or mediates the rearing/genotype influences on anxious behavior. Infant rhesus monkeys ( Macaca mulatta , N=61) were mother-peer-reared (MPR, n=21), peer-reared (PR, n=20), or surrogate-peer-reared (SPR, n=20) for 8 months, then all relocated into a large social housing situation for the next 18 months. Monkeys were genotyped for 5-HTT LPR and hair and saliva samples were collected for cortisol analysis at months 6, 12, 18, and 24. Behavior was recorded twice per week per subject from 2-24 months and analyzed for the duration of anxiety, social play, and grooming. Regression analysis established predictors of these behaviors. Rearing condition and sex were significant predictors of anxiety across the two years, and HPA activity added significant predictive power in the first six months only. Mediation of the rearing/anxiety relationship by the HPA axis was not evident. Interestingly, hair (but not salivary) cortisol early in life was positively correlated with later anxious behavior. These findings demonstrate the detrimental effects of adverse early life experience on behavioral development and shed light on the interplay between environment, adrenocortical activity, and anxiety. They further demonstrate the usefulness of a long-term measure of HPA activity in predicting later behavior.

No description available.

No description available.