Efeito da restrição alimentar materna durante a prenhez e lactação nos neurônios MCH e CART da área hipotalâmica lateral (LHA)
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Data
2019-02-28
Autores
Machado, Carla de Moraes [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A associação do baixo peso ao nascer com alto risco de doenças como obesidade, diabete tipo 2 e doenças cardiovasculares na vida adulta levaram à hipótese da “Origem Desenvolvimentista da Saúde e Doença” (DOHaD). Nessa hipótese, Programação se refere às adaptações executadas pelo organismo frente a insultos ocorridos durante seu desenvolvimento, gerando efeitos permanentes ou não na estrutura e função de órgãos. A nutrição materna durante o desenvolvimento do indivíduo é considerada um importante indutor de Programação, visto que a deficiência de nutrientes, durante a prenhez e a lactação, provoca alterações significativas no peso corpóreo, no balanço energético, na ingestão alimentar e na expressão de neuropeptídeos. O hormônio concentrador de melanina (MCH) e o transcrito regulado pela cocaína e anfetamina (CART) são neuropeptídeos expressos na área hipotalâmica lateral (LHA), que participam da regulação do balanço energético e do comportamento alimentar, nos quais o MCH desempenha papel orexígeno e o CART, anorexígeno. Nosso objetivo foi analisar o número e a distribuição de neurônios MCH e CART e sua ultraestrutura na LHA de ratos cujas mães foram submetidas à restrição alimentar durante a prenhez e lactação. Fêmeas prenhes Wistar foram separadas em dois grupos experimentais: grupo controle (GC), dieta padrão ad libitum, e grupo restrição calórica (GR), dieta de 50% de restrição em relação ao grupo controle durante os períodos de prenhez e lactação. Foram avaliados o número de animais de cada prole e o peso no DPN 1. Os filhotes machos, provenientes dos grupos restrição (GR) e controle (GC), foram divididos em cinco subgrupos etários (n=8) de 21, 28, 50, 90 e 540 dias. Foram avaliados o peso e comprimento corpóreo de cada animal, sua ingestão alimentar após o desmame, e os níveis sanguíneos de glicose, insulina e leptina, além dos testes de tolerância oral à glicose e à insulina nos animais de 540 dias. Os encéfalos foram processados para análise do número e da distribuição dos neurônios MCH e CART na área hipotalâmica lateral, segundo protocolos de imuno-histoquímica (n=5) e microscopia eletrônica de transmissão (n=3). O mapeamento e a estimativa do número de neurônios MCH e CART na LHA foram realizados, respectivamente, por reconstrução tridimensional e estereologia. A ultraestrutura dos neurônios MCH e CART foi analisada qualitativamente por MET. Nossos dados indicaram que a restrição alimentar materna provocou diminuição permanente no peso e comprimento corporais, no peso encefálico e das gorduras visceral e retroperitoneal. Não foram observadas modificações no metabolismo de glicose e na eficiência alimentar do GR, embora a ingestão alimentar relativa desses animais tenha sido superior ao GC. Não foram observadas alterações nos níveis séricos de leptina, porém os animais do GR apresentaram diminuição dos níveis de insulina no DPN 21. Aos 540 dias de idade, o GR apresentou uma diminuição do número de neurônios CART na LHA. Não houve diferenças no número de neurônios MCH entre os grupos, mas a área e o volume da LHA foi menor no GR em 21, 50 e 90 dias. Modificações na distribuição dos neurônios CART na LHA foram observadas no DPN 540, com diminuição do número de células na região perifornicial e nas secções mais caudais da LHA. Nenhuma alteração ultraestrutural foi observada no GR, tanto nos neurônios CART quanto nos MCH. Concluimos que a restrição alimentar materna durante a prenhez e lactação modificou a estrutura corporal dos descendentes e seu comportamento alimentar. Além disso, diminuiu o número de neurônios CART da LHA, alterando sua distribuição, sem alterações nos neurônios MCH, que não foram refletidas na ultraestrutura.
The association between lower birth weight and an increased risk of obesity, diabetes type 2 and cardiovascular diseases in adult life led to Developmantal Origins of Health and Disease (DOHaD) hypothesis. In this hypothesis, programming is related to the adjustments performed by the organism to insults occurring at key stages of their development, which may lead to long-lasting effects in the organs structure and function. Maternal nutrition during critical periods of individual development is considered an important Programming inductor, since the nutrient deficiency during pregnancy and lactation causes significant changes in body weight, energy balance, food intake and neuropeptides expression. The melanin-concentrating hormone (MCH) and the cocaine- and amphetamine-regulated transcript (CART) are neuropeptides expressed in the lateral hypothalamic area (LHA) that are involved in the regulation of energy balance and feeding behavior in which MCH plays an orexigenic role and CART an anorexigenic one. Thus, our aim was to analyze the number and the distribution of MCH and CART and the ultrastructure of these neurons in the LHA of rats whose mothers were subjected to food restriction during pregnancy and lactation. After pregnancy confirmation, female Wistar rats were divided in two groups: control group (CG), ad libitum standard diet, and caloric restriction group (RG), 50% diet restriction compared to the control group during pregnancy and lactation. After birth, the number of pups and their body weight in postnatal day (PND) 1 were evaluated. The male pups from both groups were divided into five age subgroups (n = 8): PND 21, 28, 50, 90 and 540. Body weight and nasoanal distance of each animal, their weekly food intake after weaning and glycemia, leptin and insulin serum concentrations were evaluated. An oral glucose tolerance test and insulin tolerance test were also executed in PND 540. Brains were processed for analysis of MCH and CART number and distribution in the LHA, according to immunohistochemistry protocols (n=5) and transmission electron microscopy (n=3). The mapping and estimate of MCH and CART neurons in the LHA were performed using three-dimensional reconstruction and stereological study. The ultrastructure of MCH and CART neurons was analyzed by transmission electron microscopy. Our data indicated that caloric restriction during pregnancy and lactation decreased body weight, body length, brain weight and visceral and retroperitoneal adipose tissues throughout life. No differences were observed in the glucose metabolism and in RG food efficiency, although the relative food intake was increased in RG. There were no differences in the leptin concentration; however RG has showed lower insulin concentration in PDN 21. Stereological data have shown a decreased number of CART neurons in the LHA of RG540. There were no differences in the number of MCH neurons among groups, however the LHA area and volume were smaller in RG in PND 21, 50 and 90. Modifications were observed in the distribution of CART neurons in RG540, with lower number of neurons on perifornicial region and caudal sections of LHA. No ultrastructural alterations in CART and MCH neurons were caused by caloric restriction during pregnancy and lactation. In conclusion, maternal food restriction during pregnancy and lactation changed biometric parameters in the offspring and their food intake. Furthermore, there was a decrease in CART neurons in LHA and changes in its distribution, with no effects on MCH neurons and on both neuropeptides ultrastructure.
The association between lower birth weight and an increased risk of obesity, diabetes type 2 and cardiovascular diseases in adult life led to Developmantal Origins of Health and Disease (DOHaD) hypothesis. In this hypothesis, programming is related to the adjustments performed by the organism to insults occurring at key stages of their development, which may lead to long-lasting effects in the organs structure and function. Maternal nutrition during critical periods of individual development is considered an important Programming inductor, since the nutrient deficiency during pregnancy and lactation causes significant changes in body weight, energy balance, food intake and neuropeptides expression. The melanin-concentrating hormone (MCH) and the cocaine- and amphetamine-regulated transcript (CART) are neuropeptides expressed in the lateral hypothalamic area (LHA) that are involved in the regulation of energy balance and feeding behavior in which MCH plays an orexigenic role and CART an anorexigenic one. Thus, our aim was to analyze the number and the distribution of MCH and CART and the ultrastructure of these neurons in the LHA of rats whose mothers were subjected to food restriction during pregnancy and lactation. After pregnancy confirmation, female Wistar rats were divided in two groups: control group (CG), ad libitum standard diet, and caloric restriction group (RG), 50% diet restriction compared to the control group during pregnancy and lactation. After birth, the number of pups and their body weight in postnatal day (PND) 1 were evaluated. The male pups from both groups were divided into five age subgroups (n = 8): PND 21, 28, 50, 90 and 540. Body weight and nasoanal distance of each animal, their weekly food intake after weaning and glycemia, leptin and insulin serum concentrations were evaluated. An oral glucose tolerance test and insulin tolerance test were also executed in PND 540. Brains were processed for analysis of MCH and CART number and distribution in the LHA, according to immunohistochemistry protocols (n=5) and transmission electron microscopy (n=3). The mapping and estimate of MCH and CART neurons in the LHA were performed using three-dimensional reconstruction and stereological study. The ultrastructure of MCH and CART neurons was analyzed by transmission electron microscopy. Our data indicated that caloric restriction during pregnancy and lactation decreased body weight, body length, brain weight and visceral and retroperitoneal adipose tissues throughout life. No differences were observed in the glucose metabolism and in RG food efficiency, although the relative food intake was increased in RG. There were no differences in the leptin concentration; however RG has showed lower insulin concentration in PDN 21. Stereological data have shown a decreased number of CART neurons in the LHA of RG540. There were no differences in the number of MCH neurons among groups, however the LHA area and volume were smaller in RG in PND 21, 50 and 90. Modifications were observed in the distribution of CART neurons in RG540, with lower number of neurons on perifornicial region and caudal sections of LHA. No ultrastructural alterations in CART and MCH neurons were caused by caloric restriction during pregnancy and lactation. In conclusion, maternal food restriction during pregnancy and lactation changed biometric parameters in the offspring and their food intake. Furthermore, there was a decrease in CART neurons in LHA and changes in its distribution, with no effects on MCH neurons and on both neuropeptides ultrastructure.
Descrição
Palavras-chave
rato Wistar, microscopia eletrônica de transmissão, restrição alimentar materna, hipotálamo, neuropeptídeos, prenhez, lactação, Wistar rat, transmission electron microscopy, maternal food restriction, hypothalamus, neuropeptides, pregnancy, lactation