Influência da restrição alimentar de vitamina A sobre o coração de ratas adultas
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Data
2007-12-18
Autores
Gaiolla, Paula Schmidt Azevedo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A deficiência de vitamina A é problema de saúde pública mundial e as principais populações acometidas são crianças e gestantes. Existem 250 milhões de pessoas no mundo com esta deficiência e sua principal causa é a redução da ingestão deste composto. O conceito de deficiência de vitamina A consta da depleção de estoques hepáticos associada à redução do retinol sérico. A deficiência de vitamina A é sabidamente prejudicial à fase embriogênica cardíaca. Após o nascimento, na idade adulta,~ vitamina A exerce papel na manutenção da estrutura e função do coração e su~ suplementação parece ser benéfica como atenuante da remodelação cardíaca. Pouco se sabe, no entanto, sobre a influência da deficiência de vitamina A sobre o coração após o nascimento, já que esta carência não é comum na população adulta, devido ao grande estoque hepático. Existe, entretanto, o transporte de vitamina A, para os tecidos, pela via dos quilomicrons. Esta via é dependente da ingestão vitamínica e não de seus estoques. Sendo assim, é possível que a ingestão inadequada deste composto, cause redução tecidual desta vitamina previamente à depleção dos estoques hepáticos e ao aparecimento da deficiência de vitamina A. Considerando que mais da metade da população brasileira, incluindo adultos, apresenta ingestão de vitamina A inferior a 50% das recomendações, a redução tecidual deste composto passa a ser uma possibilidade ainda não estudada nos tecidos, como o coração. Portanto, formulamos a hipótese que a ingestão inadequada de vitamina A, na ausência de deficiência deste composto, ou seja, com manutenção da retinolemia sé rica e estoques hepáticos, leva à redução vitamínica no tecido cardíaco causando remodelação. Assim, foram estudadas 91 ratas Wistars...
Pregnancy and childhood Vitamin A deficiency is an important public health concern. There are 250 million people around the world with this deficiency. The inadequate ingestion of this nutrient is the most important cause of it. Low serum retinol concentration and liver stores severely depleted are the biochemical findings in vitamin A deficiency. Cardiac embryonic development requires vitamin A. Postnatal heart are also a retinoid target organ, including the remodeling processo In spite of it, there are few studies about vitamin A deficiency at postnatal heélrt. Esterified retinol transported in chylomicron to tissues is reduced in low vitamin A ingestion and can cause target organ deficiency in spite of preserved serum and hepatic vitamin A. The hypothesis of this study is that inadequate vitamin A ingestion, without systemic deficiency of this nutrient, produces low heart levels of vitamin A, resulting in cardiac remodeling. Wistars female rats were studied: 45 at control group and 46 at diet reduced in vitamin A (RvitA) group. Control rats were born from dams fed with AIN-93 diet sufficient in vitamin A, during pregnancy and lactation. RvitA rats were born from dams fed with AIN-93 vitamin A-free diet, during pregnancy and lactation. Liver vitamin A was measured in sixteen newborns of each group. Twenty nine control rats were fed onto the same diet during weaning and post weaning period. Thirty RvitA rats were fed onto vitamin A-free diet during weaning and vitamin A containing 0,18 retinol equivalent (RE)(g of diet post weantng. When the animais were 200-250g, they were subjected to a transthoracic echocardiographic exam and to isolated rat heart study. Blood, liver and heart samples were collected to vitamin A dosage, to oxidative stress evaluation, to energetic metabolism evaluation, and to hypertrophy and fibrosis measurements.
Pregnancy and childhood Vitamin A deficiency is an important public health concern. There are 250 million people around the world with this deficiency. The inadequate ingestion of this nutrient is the most important cause of it. Low serum retinol concentration and liver stores severely depleted are the biochemical findings in vitamin A deficiency. Cardiac embryonic development requires vitamin A. Postnatal heart are also a retinoid target organ, including the remodeling processo In spite of it, there are few studies about vitamin A deficiency at postnatal heélrt. Esterified retinol transported in chylomicron to tissues is reduced in low vitamin A ingestion and can cause target organ deficiency in spite of preserved serum and hepatic vitamin A. The hypothesis of this study is that inadequate vitamin A ingestion, without systemic deficiency of this nutrient, produces low heart levels of vitamin A, resulting in cardiac remodeling. Wistars female rats were studied: 45 at control group and 46 at diet reduced in vitamin A (RvitA) group. Control rats were born from dams fed with AIN-93 diet sufficient in vitamin A, during pregnancy and lactation. RvitA rats were born from dams fed with AIN-93 vitamin A-free diet, during pregnancy and lactation. Liver vitamin A was measured in sixteen newborns of each group. Twenty nine control rats were fed onto the same diet during weaning and post weaning period. Thirty RvitA rats were fed onto vitamin A-free diet during weaning and vitamin A containing 0,18 retinol equivalent (RE)(g of diet post weantng. When the animais were 200-250g, they were subjected to a transthoracic echocardiographic exam and to isolated rat heart study. Blood, liver and heart samples were collected to vitamin A dosage, to oxidative stress evaluation, to energetic metabolism evaluation, and to hypertrophy and fibrosis measurements.
Descrição
Palavras-chave
Coração - Doenças - Estudos experimentais, Vitamina A - Efeitos fisiológicos, Stress oxidativo, Vitamina A - Deficiência, Metabolismo energético, Vitamin A deficiency
Como citar
GAIOLLA, Paula Schmidt Azevedo. Influência da restrição alimentar de vitamina A sobre o coração de ratas adultas. 2007. 87 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, 2007.