Efeitos do tratamento com neuropeptídeo Y em um modelo de vulnerabilidade ao Transtorno de Estresse Pós-Traumático induzido pela privação materna
Data
2023-01-18
Autores
Silva, Nathalia Novaes Duarte da [UNIFESP]
Orientadores
Suchecki, Deborah [UNIFESP]
Tipo
Trabalho de conclusão de curso de graduação
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O Transtorno de Estresse Pós-Traumático (TEPT) é caracterizado por alterações comportamentais e neurobiológicas ocasionadas por um evento traumático. Sintomas de ansiedade e depressão e uma resposta fisiológica desregulada de cortisol são observados nos pacientes com este transtorno. As adversidades na infância, como perda de cuidados parentais, podem aumentar a vulnerabilidade para o desencadeamento de TEPT. Ademais, as concentrações de neuropeptídeo Y (NPY), considerado um importante fator de resiliência ao estresse, estão reduzidas em pacientes com TEPT. Entretanto, é difícil estabelecer relações de causa e consequência em estudos transversais com seres humanos e modelos animais podem auxiliar a estabelecer se a redução do NPY é um biomarcador de vulnerabilidade ao transtorno ou consequência do evento traumático. Em um estudo anterior, mostramos que a privação materna por 24 h no dia pós-natal (DPN) 3 (PM3), um modelo de negligência extrema, induz comportamentos do tipo ansioso e depressivo e redução da imunorreatividade do NPY na amígdala e hipocampo dorsal. Portanto, o objetivo deste trabalho foi testar a efetividade do tratamento preventivo com NPY, administrado logo após um evento traumático, em ratos machos e fêmeas adultos submetidos à PM3. Este tratamento foi comparado ao tratamento com veículo e Diazepam (DZP), um ansiolítico clássico que não é eficiente para tratar TEPT. O projeto foi realizado em dois experimentos: Experimento 1: Escolha de melhor dose para o tratamento com NPY. Ratos Wistar machos foram submetidos ao trauma por imersão em água (Underwater trauma – UWT) no DPN 63 e tratados com veículo (água destilada) ou NPY nas doses de 60 µg/kg ou 75 µg/kg, por 3 dias consecutivos, via intraperitoneal (i.p). Trinta dias depois, os animais foram avaliados em um teste de auto-cuidado e um teste de ansiedade (labirinto em cruz elevado – LCE). Experimento 2: Efeitos do tratamento farmacológico com NPY ou DZP em comportamentos do tipo-TEPT. Ninhadas de ratos Wistar machos e fêmeas foram distribuídos nos grupos controle (CTL) e PM3. No dia 74, as ninhadas foram designadas NPY ou DZP; 1 macho e 1 fêmea (par) foram treinados a nadar por 1 min por 6 dias (UWT-) e três pares nadaram por 5 dias e no 6º dia foram submergidos por 45 s. Nas ninhadas DZP, após o trauma, um par recebeu veículo e dois pares, DZP (2 mg/kg de peso) por 3 dias consecutivos. Nas ninhadas NPY utilizamos o mesmo delineamento, mas o tratamento foi com NPY 75 µg/kg. Trinta dias depois do trauma, todos os animais, exceto os não-testados (NT) foram avaliados como no Experimento 1. Os resultados do Experimento 1 mostraram que NPY 60 µg/kg teve efeito ansiogênico, embora não tenha se detectado diferença estatística entre os grupos. Os resultados preliminares do Experimento 2 mostraram que, independente do grupo, as fêmeas expressam mais comportamentos de auto-cuidado. No LCE, as fêmeas ambularam mais e permaneceram mais tempo nos braços abertos do que machos. O tratamento com Diazepam ou NPY teve efeito ansiolítico em alguns parâmetros do LCE. Esses resultados mostram que ambos os tratamentos parecem ter efeito benéfico em comportamentos de ansiedade pós-trauma.
Posttraumatic Stress Disorder (PTSD) is characterized by behavioural and neurobiological changes caused by a traumatic event. Anxiety and depression symptoms and altered physiological cortisol response are observed in patients with this disorder. Childhood adversities, such as loss of parental care, may increase vulnerability to developing PTSD. Furthermore, neuropeptide Y (NPY) concentration, considered an important resilience factor to stress, is reduced in PTSD patients. Nevertheless, it’s difficult to stablish cause-consequence relationships in cross-sectional studies in humans, and animal models might help determine if NPY reduction is a biomarker for vulnerability to the disorder or a consequence of the trauma. In a previous study, we showed that 24-hour maternal deprivation on postnatal day (PND) 3 (DEP3), a model of extreme negligence, induces anxiety and depressive-like behaviours and a decrease of immunoreactivity of NPY in the amygdala and dorsal hippocampus. Therefore, the aim of this project was to test effectiveness of a preventive treatment with NPY, administered after a traumatic event, in male and female adult rats exposed to DEP3. This treatment was compared to treatment with a vehicle and Diazepam (DZP), a classic anxiolytic that is not effective in managing PTSD. Two experiments were executed: Experiment 1: Choosing the best dose for NPY treatment. Male Wistar rats were exposed to Underwater trauma (UWT) on PND 63 and treated with vehicle (distilled water) or NPY (in a 60 µg/kg or 75 µg/kg dosage), on three consecutive days, by intraperitoneal injection (i.p.). Thirty days later, animals were evaluated in a self-care test and an anxiety test (elevated plus maze – EPM). Experiment 2: Effects of NPY or DZP treatment in PTSD-like behaviours. Litters of male and female Wistar rats were distributed in control (CTL) and PM3 groups. On PND 74, litters were designated to NPY or DZP conditions; one male and one female (pair) were trained to swim for 1 min for 6 days (UWT-) and three pairs swam for 5 days and on the 6th, day were submerged for 45 s. On DZP litters, after the trauma, a pair was treated with vehicle and two pairs, DZP (2 mg/kg) for 3 consecutive days. On NPY litters, the same experimental design was used, but animals were treated with a dose of NPY 75 µg/kg. Thirty days after the trauma, all animals, except the ones in the non-tested (NT) group were evaluated as in Experiment 1. Experiment 1 results showed NPY 60 µg/kg had an anxiogenic effect, although no statistical significance has been detected. Preliminary results from Experiment 2 showed that, independently from the group, female rats expressed more self-care behaviours. On the EPM, female rats ambulated more and spent more time in the open arms than male counterparts. These results show that both treatments seem to have a beneficial effect in anxiety behaviours post-trauma.
Posttraumatic Stress Disorder (PTSD) is characterized by behavioural and neurobiological changes caused by a traumatic event. Anxiety and depression symptoms and altered physiological cortisol response are observed in patients with this disorder. Childhood adversities, such as loss of parental care, may increase vulnerability to developing PTSD. Furthermore, neuropeptide Y (NPY) concentration, considered an important resilience factor to stress, is reduced in PTSD patients. Nevertheless, it’s difficult to stablish cause-consequence relationships in cross-sectional studies in humans, and animal models might help determine if NPY reduction is a biomarker for vulnerability to the disorder or a consequence of the trauma. In a previous study, we showed that 24-hour maternal deprivation on postnatal day (PND) 3 (DEP3), a model of extreme negligence, induces anxiety and depressive-like behaviours and a decrease of immunoreactivity of NPY in the amygdala and dorsal hippocampus. Therefore, the aim of this project was to test effectiveness of a preventive treatment with NPY, administered after a traumatic event, in male and female adult rats exposed to DEP3. This treatment was compared to treatment with a vehicle and Diazepam (DZP), a classic anxiolytic that is not effective in managing PTSD. Two experiments were executed: Experiment 1: Choosing the best dose for NPY treatment. Male Wistar rats were exposed to Underwater trauma (UWT) on PND 63 and treated with vehicle (distilled water) or NPY (in a 60 µg/kg or 75 µg/kg dosage), on three consecutive days, by intraperitoneal injection (i.p.). Thirty days later, animals were evaluated in a self-care test and an anxiety test (elevated plus maze – EPM). Experiment 2: Effects of NPY or DZP treatment in PTSD-like behaviours. Litters of male and female Wistar rats were distributed in control (CTL) and PM3 groups. On PND 74, litters were designated to NPY or DZP conditions; one male and one female (pair) were trained to swim for 1 min for 6 days (UWT-) and three pairs swam for 5 days and on the 6th, day were submerged for 45 s. On DZP litters, after the trauma, a pair was treated with vehicle and two pairs, DZP (2 mg/kg) for 3 consecutive days. On NPY litters, the same experimental design was used, but animals were treated with a dose of NPY 75 µg/kg. Thirty days after the trauma, all animals, except the ones in the non-tested (NT) group were evaluated as in Experiment 1. Experiment 1 results showed NPY 60 µg/kg had an anxiogenic effect, although no statistical significance has been detected. Preliminary results from Experiment 2 showed that, independently from the group, female rats expressed more self-care behaviours. On the EPM, female rats ambulated more and spent more time in the open arms than male counterparts. These results show that both treatments seem to have a beneficial effect in anxiety behaviours post-trauma.
Descrição
Citação
SILVA, N. N. D. Efeitos do tratamento com neuropeptídeo Y em um modelo de vulnerabilidade ao Transtorno de Estresse Pós-Traumático induzido pela privação materna. São Paulo, 2023. 57 f. Trabalho de Conclusão de Curso (Graduação em Biomedicina) – Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, 2023.