Dissertation (Ph.D.)--University of South Florida, 2008. / Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xv, 190 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

The serious nature of MDD has intensified the need to identify and elucidate new neurobiological targets for antidepressant drug action. Depression presents with evidence for degenerative pathology that relates to disturbances in excitatory glutamatergic pathways, particularly the N-methyl-D-aspartate (NMDA) receptormediated release of the pleiotropic molecule, nitric oxide (NO), and cyclic guanosine monophosphate (cGMP). The contribution of the glutamate-NO/cGMP pathway may realize great importance as a fundamental substrate underlying the pathophysiology of major depression. In the next generation of antidepressant drugs, the nitric oxide pathway could playa dynamic role in addressing urgent therapeutic needs. In this study, we have used a genetic model of depression, the Flinders Sensitive Line (FSL) rat, to investigate the surrogate markers of the NO/cGMP pathway. The aim was to determine whether the depressive-like behaviour of the hypercholinergic FSL rat is accompanied by altered activation of the NO/cGMP pathway. To this end, the extent to which the FSL and Flinders Resistant Line (FRL) rats differ neurochemically with regard to basal hippocampal and frontal cortical NOS-activity, as well as nitric oxide (NO) and cGMP accumulation, were determined. Additionally, select behavioural assessments were performed to confirm the anxiogenic phenotype of the FSL strain. For neurochemical determinations a sensitive fluorometric reversed phase highperformance liquid chromatographic (HPLC) assay was developed to analyze total nitrite and nitrate in brain tissue. Nitrate was enzymatically converted to nitrite before derivatization with 2,3-diaminonaphthalene (DAN). The stable and highly fluorescent product, 2,3-naphthotriazole (NAT), was quantified. Secondly, the quantity of the amino acid L-citrulline was measured by HPLC with electrochemical detection after o-phthalaldehyde (OPA) derivatization. L-citrulline formation was used as an index for nNOS activity. Finally, a direct, competitive enzyme immunoassay kit was used to determine the downstream activity of the NO-pathway in brain tissue. FSL rats were compared to FRL rats with respect to sensitivity to serotonin 5-HT1A . receptor-mediated hypothermia under our lab-conditions. The Open Field Test (OFT) behavioural assessment was performed to compare FSL with FRL groups under baseline conditions according to their level of inherent anxiety. The parameters used to measure anxiety were number of line crosses (locomotor activity), time spent in middle blocks and social interaction time between pairs of rats. As an additional behavioural assessment, the Forced Swim Test (FST) was performed to assess behavioural restraint measured as time of immobility. Basal cGMP levels in the frontal cortex were found to be significantly less in FSL than in FRL rats, whereas the levels in the hippocampus did not differ significantly. No other significant differences with respect to NO and nNOS activity were apparent in either of the brain areas. The hypothermia test confirmed a significantly greater decrease in temperature in the FSL rat than the FRL rat. The FST did not confirm any differences in immobility time between the two rat strains. In the OFT, FSL rat groups exhibited behaviour that indicated significantly more anxiety than FRL rats. Under basal conditions, FSL rats do not present with significant changes in markers of the NO cascade in the hippocampus and frontal cortex compared to FRL controls, including NOS activity as well as NO accumUlation. However, cGMP levels were found to be significantly lower in the frontal cortex of FSL rats versus FRL rats, although not in the hippocampus. Since the FSL rat is known to be hypercholinergic, these data support an interaction between the NO/cGMP pathway and the cholinergIc system in the frontal cortex but not hippocampus of FSL animals. The mechanisms and implications of such a mutual involvement need further clarification. Further, this anatomical differentiation may have important implications for understanding the role of NO in the depressive-like behaviour of the FSL rat and, indeed, may reveal more on the neurobiology and treatment of depression. Through the performed behavioural assessments, the FSL and FRL rats were successfully separated with respect to their anxiety phenotype as well as their heightened response to serotonergic challenge, thus confirming a contribution of both the serotonergic and cholinergic systems to the depressogenic nature of these animals. As concluding remark can be said that under normal basal conditions markers of the NO/cGMP signalling cascade are not altered in FSL vs FRL rats, although cGMP levels are reduced in the frontal cortex of FSL rats, supportive of an NO-independent mechanism of cGMP regulation, possibly involving ACh. / Thesis (M.Sc. (Pharmacology)--North-West University, Potchefstroom Campus, 2009.

The serious nature of MDD has intensified the need to identify and elucidate new neurobiological targets for antidepressant drug action. Depression presents with evidence for degenerative pathology that relates to disturbances in excitatory glutamatergic pathways, particularly the N-methyl-D-aspartate (NMDA) receptormediated release of the pleiotropic molecule, nitric oxide (NO), and cyclic guanosine monophosphate (cGMP). The contribution of the glutamate-NO/cGMP pathway may realize great importance as a fundamental substrate underlying the pathophysiology of major depression. In the next generation of antidepressant drugs, the nitric oxide pathway could playa dynamic role in addressing urgent therapeutic needs. In this study, we have used a genetic model of depression, the Flinders Sensitive Line (FSL) rat, to investigate the surrogate markers of the NO/cGMP pathway. The aim was to determine whether the depressive-like behaviour of the hypercholinergic FSL rat is accompanied by altered activation of the NO/cGMP pathway. To this end, the extent to which the FSL and Flinders Resistant Line (FRL) rats differ neurochemically with regard to basal hippocampal and frontal cortical NOS-activity, as well as nitric oxide (NO) and cGMP accumulation, were determined. Additionally, select behavioural assessments were performed to confirm the anxiogenic phenotype of the FSL strain. For neurochemical determinations a sensitive fluorometric reversed phase highperformance liquid chromatographic (HPLC) assay was developed to analyze total nitrite and nitrate in brain tissue. Nitrate was enzymatically converted to nitrite before derivatization with 2,3-diaminonaphthalene (DAN). The stable and highly fluorescent product, 2,3-naphthotriazole (NAT), was quantified. Secondly, the quantity of the amino acid L-citrulline was measured by HPLC with electrochemical detection after o-phthalaldehyde (OPA) derivatization. L-citrulline formation was used as an index for nNOS activity. Finally, a direct, competitive enzyme immunoassay kit was used to determine the downstream activity of the NO-pathway in brain tissue. FSL rats were compared to FRL rats with respect to sensitivity to serotonin 5-HT1A . receptor-mediated hypothermia under our lab-conditions. The Open Field Test (OFT) behavioural assessment was performed to compare FSL with FRL groups under baseline conditions according to their level of inherent anxiety. The parameters used to measure anxiety were number of line crosses (locomotor activity), time spent in middle blocks and social interaction time between pairs of rats. As an additional behavioural assessment, the Forced Swim Test (FST) was performed to assess behavioural restraint measured as time of immobility. Basal cGMP levels in the frontal cortex were found to be significantly less in FSL than in FRL rats, whereas the levels in the hippocampus did not differ significantly. No other significant differences with respect to NO and nNOS activity were apparent in either of the brain areas. The hypothermia test confirmed a significantly greater decrease in temperature in the FSL rat than the FRL rat. The FST did not confirm any differences in immobility time between the two rat strains. In the OFT, FSL rat groups exhibited behaviour that indicated significantly more anxiety than FRL rats. Under basal conditions, FSL rats do not present with significant changes in markers of the NO cascade in the hippocampus and frontal cortex compared to FRL controls, including NOS activity as well as NO accumUlation. However, cGMP levels were found to be significantly lower in the frontal cortex of FSL rats versus FRL rats, although not in the hippocampus. Since the FSL rat is known to be hypercholinergic, these data support an interaction between the NO/cGMP pathway and the cholinergIc system in the frontal cortex but not hippocampus of FSL animals. The mechanisms and implications of such a mutual involvement need further clarification. Further, this anatomical differentiation may have important implications for understanding the role of NO in the depressive-like behaviour of the FSL rat and, indeed, may reveal more on the neurobiology and treatment of depression. Through the performed behavioural assessments, the FSL and FRL rats were successfully separated with respect to their anxiety phenotype as well as their heightened response to serotonergic challenge, thus confirming a contribution of both the serotonergic and cholinergic systems to the depressogenic nature of these animals. As concluding remark can be said that under normal basal conditions markers of the NO/cGMP signalling cascade are not altered in FSL vs FRL rats, although cGMP levels are reduced in the frontal cortex of FSL rats, supportive of an NO-independent mechanism of cGMP regulation, possibly involving ACh. / Thesis (M.Sc. (Pharmacology)--North-West University, Potchefstroom Campus, 2009.

Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 4 uppsatser.

Dissertation (Ph.D.)--University of South Florida, 2005. / Includes vita. Includes bibliographical references (leaves 179-187). Also available online.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 217-246.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiv, 197 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Aug 16.

Orientador: Licio Augusto Velloso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-06T23:35:52Z (GMT). No. of bitstreams: 1 Moraes_JulianaContin_M.pdf: 1484102 bytes, checksum: 31482341aabc46ac3c7f655aead3fbd6 (MD5) Previous issue date: 2006 / Resumo: Durante as últimas décadas tem se observado um aumento surpreendente na prevalência de obesidade e diabetes mellitus em populações de várias regiões do mundo, inclusive no Brasil. Diversos estudos epidemiológicos apontam o consumo de dietas ricas em lípides como um dos mais importantes fatores de risco para o desenvolvimento dessas patologias. Em recente trabalho em nosso laboratório, foi demonstrado que a oferta de uma dieta rica em lípides leva a uma maior expressão hipotalâmica de proteínas participantes de respostas pró-inflamatórias como TNF-a, IL-2, IL-6 e IL-ß. A citocina TNFa, agindo no hipotálamo, modula a ingestão alimentar e o gasto energético através de mecanismos incompletamente elucidados. Neste trabalho exploramos a hipótese de que, para modular a sinalização anorexigênica induzida por insulina no hipotálamo, o TNFa deve requerer a síntese de óxido nítrico. O TNFa ativa sinalização intracelular canónica no hipotálamo, com pico na concentração de 10-8 M. Esse efeito é acompanhado pela indução da expressão das formas neuronal e induzível da enzima NOS, em ambos os casos com pico em 10-12 M. Em adição, TNFa estimula a atividade catalítica de NOS. O pré-tratamento com TNFa em baixa dose (10-12 M) inibe a sinalização anorexigênica insulino-dependente. Esse efeito é abolido em camundongos iNOS mas não em camundongos nNOS knockout. Portanto, o efeito inibitório exercido pela baixa dose de TNFa sob a inibição da ingestão alimentar induzida por insulina depende, pelo menos em parte, da expressão de iNOS. Embora nNOS hipotalâmica seja induzida por TNFa, esta não participa da modulação TNFa-dependente dos sinais anorexigênicos da insulina. / Abstract: Obesity has reached epidemic proportion in several regions of the world. General changes in life-style, including consumption of fat-rich food, are amongst the most important factors leading to an unprecedented increase in the prevalence of this disease. In a recently work on our laboratory, we showed that high fat feeding (hyperlipidic diet) induced the expression of several pro-inflammatory cytokines and inflammatory responsive proteins in hypothalamus, like TNFa, IL-2, IL-6 e IL-lß. The cytokine TNFa, acting on the hypothalamus, modulates food intake and energy expenditure through mechanisms incompletely elucidated. Here, we explored the hypothesis that, to modulate insulin-induced anorexigenic signaling in hypothalamus, TNF-a would require the synthesis of NO. TNF-a activates canonical intracellular signaling in hypothalamus, peaking at 10-8 M. This is accompanied by the induction of expression of the inducible and neuronal forms of NOS, in both cases peaking at 10-12 M. In addition TNF-a stimulates NOS catalytic activity. The pre-treatment with TNF-a at low dose (10-12 M) inhibits insulin-dependent anorexigenic signaling. This effect is abolished in iNOS but not in Nnos knockout mice. Thus, the inhibitory effect exerted by low dose TNF-a upon the insulin-induced inhibition of food intake depends, at least in part, on the expression of iNOS. Although hypothalamic nNOS is induced by TNF-a it does not participate on TNF-a-dependent modulation of the insulin anorexigenic signals. / Mestrado / Ciencias Basicas / Mestre em Clinica Medica