RAFAEL AUGUSTO TEIXEIRA DE SOUSA
Projetos de Pesquisa
Unidades Organizacionais
LIM/27 - Laboratório de Neurociências, Hospital das Clínicas, Faculdade de Medicina
4 resultados
Resultados de Busca
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- Lithium increases platelet serine-9 phosphorylated GSK-3 beta levels in drug-free bipolar disorder during depressive episodes(2015) SOUSA, Rafael T. de; ZANETTI, Marcus V.; TALIB, Leda L.; SERPA, Mauricio H.; CHAIM, Tiffany M.; CARVALHO, Andre F.; BRUNONI, Andre R.; BUSATTO, Geraldo F.; GATTAZ, Wagner E.; MACHADO-VIEIRA, RodrigoBackground: Glycogen synthase kinase-3 beta (GSK3 beta) is an intracellular enzyme directly implicated in several neural processes relevant to bipolar disorder (BD) pathophysiology. GSK3 beta is also an important target for lithium and antidepressants. When phosphorylated at serine-9, GSK3 beta becomes inactive. Few studies evaluated serine-9 phosphorylated GSK3 beta(phospho-GSK3 beta) levels in BD subjects in vivo and no study has assessed it specifically in bipolar depression. Also, the effect of lithium monotherapy on GSK3 beta has never been studied in humans. Methods: In 27 patients with bipolar depression, total GSK3 beta and phospho-GSK3 beta were assessed in platelets by enzyme immunometric assay. Subjects were evaluated before and after 6 weeks of lithium treatment at therapeutic levels. Healthy subjects (n = 22) were used as a control group. Results: No differences in phospho-GSK3 beta or total GSK3 beta were observed when comparing drug-free BD subjects in depression and healthy controls. Baseline HAM-D scores were not correlated with phospho GSK3 beta and total GSK3 beta levels. From baseline to endpoint, lithium treatment inactivated GSK3 beta by significantly increasing phospho-GSK3 beta levels (p = 0.010). Clinical improvement (baseline HAM-D endpoint HAM-D) negatively correlated with the increase in phospho-GSK3 beta (p = 0.03). Conclusion: The present results show that lithium inactivates platelet GSK3 beta in BD during mood episodes. No direct association with pathophysiology of BD was observed. Further studies are needed to clarify the role of GSK3 beta as a key biomarker in BD and its association with treatment response as well as the relevance of GSK3 beta in other neuropsychiatric disorders and as a new therapeutic target per se.
- Early improvement of psychotic symptoms with lithium monotherapy as a predictor of later response in mania(2012) SOUSA, Rafael T. de; BUSNELLO, Joao V.; FORLENZA, Orestes V.; ZANETTI, Marcus V.; SOEIRO-DE-SOUZA, Marcio G.; BILT, Martinus T. van de; MORENO, Ricardo A.; ZARATE JR., Carlos A.; GATTAZ, Wagner F.; MACHADO-VIEIRA, RodrigoAlthough lithium has been the first line agent in the treatment of bipolar disorder (BD), few studies have evaluated lithium's efficacy in mania with psychosis and its association with later response. Furthermore, given the widespread concern about antipsychotic side effects, answering a question about whether lithium alone can manage to treat both psychotic and non-psychotic mania seems a very relevant one. The present study addresses the antipsychotic efficacy of lithium monotherapy in acute mania and early improvement of psychotic symptoms as a predictor of later response of manic symptoms. Forty-six patients presenting a manic episode (32 with psychotic features and 14 subjects without psychotic features) were treated for 4 weeks with lithium monotherapy and evaluated weekly using the Young Mania Rating Scale (YMRS). Subjects with rapid cycling, substance abuse/dependence, or mixed episodes were excluded. The overall antimanic efficacy of lithium in psychosis vs. non-psychosis groups was evaluated. In addition, early improvement of psychotic symptoms and its prediction of subsequent response (>50% decrease in total YMRS scores) or remission were evaluated. Lithium showed a similar efficacy in both psychosis and non-psychosis mania. Early improvement of psychotic symptoms was associated with clinical response and remission at endpoint.
- Lithium increases nitric oxide levels in subjects with bipolar disorder during depressive episodes(2014) SOUSA, Rafael T. de; ZANETTI, Marcus V.; BUSATTO, Geraldo F.; MOURO, Margaret G.; ZARATE JR., Carlos A.; GATTAZ, Wagner F.; HIGA, Elisa M.; MACHADO-VIEIRA, RodrigoBackground: Altered nitric oxide (NO) signaling has been associated with the pathophysiology of Bipolar Disorder (BD), directly affecting neurotransmitter release and synaptic plasticity cascades. Lithium has shown to regulate NO levels in preclinical models. However, no study has addressed peripheral NO levels in unmedicated BD. Also, lithium's effects on NO levels have not been studied in humans. Methods: Plasma NO was evaluated in subjects with BD I and II during a depressive episode (n = 26). Subjects had a score of >= 18 in the 21-item Hamilton Depression Rating Scale and were followed-up during a 6-week trial with lithium. Plasma NO levels were also compared to matched healthy controls (n = 28). NO was determined by chemiluminescence method. Results: Lithium treatment significantly increased plasma NO levels after 6 weeks of treatment in comparison to baseline levels in bipolar depression (p = 0.016). Baseline NO levels during depressive episodes showed no difference when matching up to healthy controls (p = 0.66). Conclusion: The present findings suggest that lithium upregulates NO signaling in unmedicated BD with short illness duration. Further studies with larger samples are needed to confirm the effects of lithium on NO pathway and its association with synaptic plasticity and therapeutics of BD.
- Oxidative stress in early stage Bipolar Disorder and the association with response to lithium(2014) SOUSA, Rafael T. de; ZARATE JR., Carlos A.; ZANETTI, Marcus V.; COSTA, Alana C.; TALIB, Leda L.; GATTAZ, Wagner F.; MACHADO-VIEIRA, RodrigoBackground: Several studies have described increased oxidative stress (OxS) parameters and imbalance of antioxidant enzymes in Bipolar Disorder (BD) but few is know about the impact of treatment at these targets. However, no study has evaluated OxS parameters in unmedicated early stage BD and their association with lithium treatment in bipolar depression. Methods: Patients with BD I or II (n = 29) in a depressive episode were treated for 6 weeks with lithium. Plasma samples were collected at baseline and endpoint, and were also compared to age-matched controls (n = 28). The thiobarbituric acid reactive substances (TBARS), and the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities were measured. Results: Subjects with BD depression at baseline presented a significant increase in CAT (p = 0.005) and GPx (p < 0.001) levels, with lower SOD/CAT ratio (p = 0.001) and no changes on SOD or TBARS compared to healthy controls. Regarding therapeutics, lithium only induced a decrease in TBARS (p = 0.023) and SOD (p = 0.029) levels, especially in BDII. Finally, TBARS levels were significantly lower at endpoint in lithium responders compared to non-responders (p = 0.018) with no difference in any biomarker regarding remission. Conclusion: The present findings suggest a reactive increase in antioxidant enzymes levels during depressive episodes in early stage BD with minimal prior treatment. Also, decreased lipid peroxidation (TBARS) levels were observed, associated with lithium's clinical efficacy. Overall, these results reinforce the role for altered oxidative stress in the pathophysiology of BD and the presence of antioxidant effects of lithium in the prevention of illness progression and clinical efficacy.