Efeitos da doxiciclina relacionados à inibição das metaloproteinases em modelo de pré-eclâmpsia induzida por l-name em ratas
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Data
2018-12-05
Autores
Nascimento, Regina Aparecida do
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Universidade Estadual Paulista (Unesp)
Resumo
O óxido nítrico (NO) é um gás produzido principalmente por células endoteliais, e durante a época gestacional, contribui para evitar aumento exacerbado da resistência vascular sistêmica (RVS), uma vez que, durante esse período, aumenta-se o volume sanguíneo e a frequência cardíaca. Quando, há disfunções endoteliais, reduz-se a biodisponibilidade de NO, provocando vasoconstrição e esta, por sua vez, consequentemente aumenta atividade das MMPs. Essa queda do NO e aumento das MMPs culminam em desordens hipertensivas gestacionais. Segundo estudos anteriores realizados em modelos de hipertensão em machos a doxiciclina, um antibiótico derivado das tetraciclinas, diminuiu a pressão arterial sistólica devido a sua capacidade de inibir a atividade das MMPs. No entanto, há escassez de trabalhos que desenvolveram estudos sobre os efeitos da doxicicilina em modelos animais de hipertensão gestacional. Por esse motivo, investigamos os efeitos da doxiciclina na inibição das MMPs na hipertensão gestacional, induzida pelo Nω-nitro-L-arginina-metil éster (LNAME) em ratas. Para tanto, realizamos zimografia para avaliar a atividade da MMP-2 e -9 na placenta, no útero e na aorta torácica. Ainda avaliamos a pressão arterial sistólica, o desenvolvimento feto-placentário e os metabólitos do NO. Também foi avaliada a capacidade antioxidante plasmática, os níveis plasmáticos de soluble fms-like tyrosine kinase-1 (sFlt-1) e o fator de crescimento placentário (PLGF). Nossos dados mostram que o tratamento com LNAME aumentou a pressão arterial e diminuiu a prole destes animais. Por outro lado, a doxiciclina preveniu a hipertensão gestacional induzida por L-NAME sem afetar a prole. Observou-se também uma diminuição da biodisponibilidade de NO em ratas hipertensas. O tratamento com doxiciclina atenuou o aumento da atividade da MMP-2 e -9, provocados pela hipertensão induzida por L-NAME. Concomitantemente, a doxiciclina restaurou o equilíbrio angiogênico por meio do aumento dos níveis de PLGF e redução dos níveis de sFlt-1. A doxiciclina também aumentou a capacidade antioxidante do plasma nas ratas hipertensas. Por causa disso, compreendemos que o aumento da atividade da MMP-2 e -9 deveu-se a uma redução do NO, causada pelo tratamento com L-NAME. Cabe ressaltar que o aumento da ativação de MMPs e o desequilíbrio angiogênico causados pelo modelo de hipertensão gestacional induzido por L-NAME estão associados ao aumento da pressão arterial sistólica, enquanto a doxiciclina restabeleceu todos esses parâmetros. Visto a importância do NO durante a gestação saudável, quanto durante a gestação hipertensiva devido a sua diminuição, realizamos um segundo estudo, em que avaliamos a atividade de MMP-2 e -9 em três diferentes períodos gestacionais: inicial (Early), intermediário (Mid) e tardio (Late). Nesse segundo estudo, observamos que a pressão arterial sistólica apresentou-se elevada nos três períodos gestacionais propostos, evidenciando-se principalmente nos dois últimos períodos (intermediário e tardio) em ratas hipertensas. Paralelamente, nesse mesmo grupo de animais, os níveis de NO plasmático apresentaram-se insuficientes, principalmente nos períodos gestacionais intermediário e tardio, em que há uma maior demanda de NO. Além disso, os parâmetros feto-placentários foram comprometidos em ratas hipertensas. Os níveis plasmáticos de malondialdeído e a atividade da MMP-2 e -9 apresentaram aumentos ao longo dos períodos gestacionais previamente adotados em ratas hipertensas. Em suma, os dados apresentados tanto no primeiro quanto no segundo estudo sugerem que o processo gestacional por si requer uma maior biodisponibilidade de NO e atuação do NO na modulação da atividade das MMPs ao longo da gestação, sendo essa demanda maior nos períodos finais da gestação.
Nitric oxide (NO) is a gas produced mainly by endothelial cells, and during the gestational period contributes to avoid an exacerbated increase in systemic vascular resistance (SVR), since during this period, there is a rise in blood volume and heart rate. When there are endothelial dysfunctions, the bioavailability of NO is reduced, causing vasoconstriction and this, in turn, consequently increases the activity of MMPs. This decrease in NO and increase in MMPs culminates in gestational hypertensive disorders. According to previous studies in non-gestational hypertension models, doxycycline, an antibiotic derived from tetracyclines, lowered systolic blood pressure due to its ability to inhibit MMP activity. However, there is a shortage of works that have developed studies on the effects of doxycycline in animal models of gestational hypertension. For this reason, we investigated the effects of doxycycline on the inhibition of MMPs in gestational hypertension, induced by Nω-nitro-L-arginine-methyl ester (L-NAME) in rats. We performed a zymography to evaluate the activity of MMP-2 and -9 in the placenta, uterus and thoracic aorta. We also evaluated systolic blood pressure, fetalplacental development and NO metabolites. Plasma antioxidant capacity, plasma levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PLGF) were also evaluated. Our data shows that the treatment with L-NAME increased blood pressure and decreased the offspring of these animals. On the other hand, doxycycline prevented LNAME-induced gestational hypertension and the reduction of offspring. A decrease in NO bioavailability in hypertensive rats was also observed. Treatment with doxycycline attenuated the increased activity of MMP-2 and -9, caused by L-NAME-induced hypertension. Concomitantly, doxycycline restored the angiogenic balance by increasing PLGF levels and reducing levels of sFlt-1. Doxycycline also increased plasma antioxidant capacity in hypertensive rats. For this reason, we understand that the increased activity of MMP-2 and -9 was due to a reduction of NO caused by the treatment with L-NAME. It should be noted that the increase in MMP activation and angiogenic imbalance caused by the L-NAME-induced gestational hypertension model are associated with increased systolic blood pressure, while doxycycline reestablished all of these parameters. Considering the importance of NO during a healthy gestation and during a hypertensive pregnancy due to its decrease, we performed a second study, in which we evaluated the activity of MMP-2 and -9 in three different gestational periods: initial, intermediate and late. In this second study, we observed that systolic blood pressure was elevated in the three proposed gestational periods, evidencing mainly in the last two periods (intermediate and late) in hypertensive rats. At the same time, in this same group of animals, plasma NO levels were insufficient, especially in the intermediate and late gestational periods, where there is a greater demand for NO. In addition, the fetal-placental parameters were compromised in hypertensive rats. Plasma levels of malondialdehyde and MMP-2 and -9 activity increased gradually over the gestational periods previously adopted in hypertensive rats. In summary, the data presented in both the first and second studies suggests that the gestational process itself requires a greater bioavailability of NO, and NO action in the modulation of the MMP activity during pregnancy, being this demand is greater in the final periods of gestation.
Nitric oxide (NO) is a gas produced mainly by endothelial cells, and during the gestational period contributes to avoid an exacerbated increase in systemic vascular resistance (SVR), since during this period, there is a rise in blood volume and heart rate. When there are endothelial dysfunctions, the bioavailability of NO is reduced, causing vasoconstriction and this, in turn, consequently increases the activity of MMPs. This decrease in NO and increase in MMPs culminates in gestational hypertensive disorders. According to previous studies in non-gestational hypertension models, doxycycline, an antibiotic derived from tetracyclines, lowered systolic blood pressure due to its ability to inhibit MMP activity. However, there is a shortage of works that have developed studies on the effects of doxycycline in animal models of gestational hypertension. For this reason, we investigated the effects of doxycycline on the inhibition of MMPs in gestational hypertension, induced by Nω-nitro-L-arginine-methyl ester (L-NAME) in rats. We performed a zymography to evaluate the activity of MMP-2 and -9 in the placenta, uterus and thoracic aorta. We also evaluated systolic blood pressure, fetalplacental development and NO metabolites. Plasma antioxidant capacity, plasma levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PLGF) were also evaluated. Our data shows that the treatment with L-NAME increased blood pressure and decreased the offspring of these animals. On the other hand, doxycycline prevented LNAME-induced gestational hypertension and the reduction of offspring. A decrease in NO bioavailability in hypertensive rats was also observed. Treatment with doxycycline attenuated the increased activity of MMP-2 and -9, caused by L-NAME-induced hypertension. Concomitantly, doxycycline restored the angiogenic balance by increasing PLGF levels and reducing levels of sFlt-1. Doxycycline also increased plasma antioxidant capacity in hypertensive rats. For this reason, we understand that the increased activity of MMP-2 and -9 was due to a reduction of NO caused by the treatment with L-NAME. It should be noted that the increase in MMP activation and angiogenic imbalance caused by the L-NAME-induced gestational hypertension model are associated with increased systolic blood pressure, while doxycycline reestablished all of these parameters. Considering the importance of NO during a healthy gestation and during a hypertensive pregnancy due to its decrease, we performed a second study, in which we evaluated the activity of MMP-2 and -9 in three different gestational periods: initial, intermediate and late. In this second study, we observed that systolic blood pressure was elevated in the three proposed gestational periods, evidencing mainly in the last two periods (intermediate and late) in hypertensive rats. At the same time, in this same group of animals, plasma NO levels were insufficient, especially in the intermediate and late gestational periods, where there is a greater demand for NO. In addition, the fetal-placental parameters were compromised in hypertensive rats. Plasma levels of malondialdehyde and MMP-2 and -9 activity increased gradually over the gestational periods previously adopted in hypertensive rats. In summary, the data presented in both the first and second studies suggests that the gestational process itself requires a greater bioavailability of NO, and NO action in the modulation of the MMP activity during pregnancy, being this demand is greater in the final periods of gestation.
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Palavras-chave
Hipertensão gestacional, Doxiciclina, Metaloproteinases, Óxido nítrico, Ratas, Gestational hypertension, Doxycycline, Metalloproteinases, Nitric oxide, Rats