Efeito da restrição proteica na vida intrauterina e neonatal sobre a morfologia das ilhotas pancreáticas e a homeostase glicêmica de ratas adultas lactantes

Abstract

In the early lactation the increased pancreatic β-cell mass seen during pregnancy is reversed at expense to high apoptosis and low proliferation. We evaluate whether early life protein restriction compromises the islet morphology and glucose homeostasis during lactation in control-fed non-lactating (CNP) and lactating (CL) or proteinrestricted non-lactating (LPNL) and lactating (LPL) rats from foetal to adult life as well as in protein-restricted rats that recovered after weaning (RL and RNL). Protein restriction during intrauterine life did not reduce the body weight at birth, but reduced both blood glucose and insulin concentration. At the end of the suckling period the body weight and blood glucose concentration were lower in low protein rats than in control rats. After nutritional recovery the body weight of recovered rats was higher than low protein rats, but lower in relation to control rats. Independent of the lactation, recovered rats exhibited higher islet, -cell and-cell masses than low-protein rats and similar to the control rats. At 5th day of lactation the Ki67-labelled cell frequency and of cleaved caspase-3-labelled cells did not differ among groups. However, PDX-1/DAPI colocalization was lower in recovered groups than control groups and similar to lowprotein groups, regardless the lactation. The frequency of PI-positive endocrine cells as well as the area under glucose curve during glucose tolerance test was similar in recovered and control groups and both were higher in relation to low-protein groups. Lactating groups exhibited lower frequency of PI-positive endocrine cells than nonlactating groups, independent of the nutritional status. At 14th of lactation, basal glucose was higher in lactating groups compared to non-lactating, but insulinemia did not differ between groups. After challenge with glucose, the area under the glycemic curve was smaller in lactating groups than in non-lactating ones. This variable did not differ between the recovered and control groups and both were smaller compared to the groups submitted to protein restriction. Thus, early life protein restriction did not compromise the islet morphology in the early lactation or the glucose homeostasis in the later lactation