RESUMO
There are conflicting data from human studies regarding the ability of exogenous glucocorticoids to stimulate maturation of the small intestine. The discrepancies may relate to differences in hormone doses and age administered. To explore this general concept, we have used a mouse model to determine intestinal responsiveness to dexamethasone (DEX) at various times during development. We first showed that trehalase mRNA is a sensitive marker of intestinal maturation in the mouse; being undetectable (by Northern blotting) in the prenatal period, expressed at low levels during the first 2 postnatal weeks and then displaying a marked increase in the 3rd postnatal week. DEX was unable to elicit detectable trehalase mRNA in fetal mice, but caused significant increases in the postnatal period. The use of a range of DEX doses (0.0125-2.5 nmol/g BW per day) established that there is no change in sensitivity between the 1st and 2nd postnatal weeks, but there is a significant increase in maximal responsiveness of trehalase mRNA to the hormone. Similar results were obtained when sucrase-isomaltase mRNA was assayed in the same animals. Thus, in this rodent model, there appears to be at least three phases in the DEX responsiveness of the developing intestine: an early phase (prenatal) when DEX is unable to elicit intestinal maturation; then a phase (first postnatal week) of modest responsiveness; then a transition to increased responsiveness. These findings point to the need for careful attention to dose and age in analyses of glucocorticoid effects in human infants.
Assuntos
Dexametasona/farmacologia , Glucocorticoides/farmacologia , Intestino Delgado/efeitos dos fármacos , Intestino Delgado/embriologia , Animais , Animais Recém-Nascidos , Feminino , Maturidade dos Órgãos Fetais/efeitos dos fármacos , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Humanos , Intestino Delgado/enzimologia , Intestino Delgado/crescimento & desenvolvimento , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Complexo Sacarase-Isomaltase/genética , Trealase/genéticaRESUMO
Patients with ARC and AIDS develop a variety of symptoms that significantly affect their nutritional status. Podiatrists, although not directly involved with the intricacies of the nutritional management of people with AIDS, should be aware of the effect of the virus on the human body. Investigators are predicting that almost 100% of the estimated 12 million HIV-positive persons in the world will develop AIDS. By giving people with AIDS nutritional education, not only may there be a beneficial response in respect to treatment but it may enhance an individual's quality of life and positive self-image.
