Effects of oral parenteral nutrition solution on the morphology and mechanical resistance of the small bowel in rats

The objective of this study was to investigate the effect of an elemental diet (ED) on the strength and on the morphology of the small bowel. Male Wistar rats were randomized to two groups to receive during 14 days either standard laboratory rat chow (N=16) or ED (N=16) containing total parenteral nutrition (TPN) solution. After this period they were killed and necropsied. The small bowel was measured and weighted with and without the contents. Bursting pressure (BP) was taken from the jejunum and ileum and histological sections of these two portions was performed to register the crypt depth (CD), vilus height (VH) and wall width (WW). All animals significantly gain weight. The bowel of animals fed with TPN solution had significantly less weight when compared with the controls either with (9.9 ± 1.9g x 7.8 ± 1.5g, p<0.05) or without (8.3 ± 1.3g x 6.5 ± 0.8g; p<0.05) the luminal contents. BP was lower in animals receiving TPN solution compared with controls in both studied segments but the difference only reached significance at the ileum (287 ± 60 x 234 ± 46 mm of Hg; p<0.05). VH, CD and WW were significantly shorter at the ileum in TPN-fed animals when compared to controls (p<0.05). This contrast was also seen at the jejunum though without significant difference. The small bowel looses mass and become less resistant when rats are fed with elemental diet though the nutritional state is maintained. The loss of mass appeared to be not only at the mucosa layer but through all the bowel wall. This occurs predominantly at the terminal part of the small bowel. Foram submetidos a ração padrão de laboratório 16 ratos e outros 16 receberam nutrição parenteral total (NPT) por via oral, durante 14 dias. Os animais de ambos os grupos ganharam peso, sem diferença estatistica. Na necrópsia retirava-se o segmento intestinal a partir do piloro até a valva ileocecal. Não houve diferença no comprimeto do intestino delgado em ambos os grupos. Porém, o intestino dos animais alimentados com NTP apresentaram diminuiçao significante de peso comparado com o grupo controle, independentemente da presença ou não de conteúdo. A resistência intestinal era menor no grupo NTP comparado ao controle, sendo mais significante no íleo. A altura dos vilos, a profundidade das criptas e a extensão da parede eram significantemente menores no íleo no grupo NTP comparado ao controle. Este achado foi observado também no jejuno, mas sem diferença significante. Conclui-se que nos ratos alimentados com NTP o intestino delgado perde massa e torna-se menos resistente, principalmente no íleo,apesar da manutenção do estado nutricional. A perda de massa aparece não apenas na mucosa mas em toda a parede intestinal