E. Zambrano

Recent studies demonstrate long‐term programming of function of specific organ systems resulting from suboptimal environments during fetal life and development up to weaning. Nutrient restriction during pregnancy and lactation impairs overall fetal growth and development. We determined the effects of maternal protein restriction (MPR; 50% normal protein intake) during fetal development and/or lactation in rats on the function and ageing of the reproductive system of female progeny. Rats were fed either a control 20% casein diet (C) or a restricted diet (R) of 10% casein during pregnancy. After delivery mothers received either C or R diet until weaning to provide four groups, CC, RR, CR and RC. We report data on female offspring only. After weaning pups were fed the C diet. MPR increased maternal progesterone, corticosterone, oestradiol and testosterone concentrations at 19 days gestation. Reproductive and somatic phenotype was altered as pup birth weight was decreased, and ano‐genital distance was increased by MPR. Pup corticosterone was decreased at 2 days postnatal (PN) life. Vaginal opening and timing of the first oestrus were delayed in RR and CR and these differences were not related to body weight. At 21 days PN oestradiol in RR and CR and progesterone in RR were reduced; at 70 days PN luteinizing hormone (LH) in all restricted groups was reduced in dioestrus while follicle stimulating hormone (FSH) was unchanged. Cycle length increased between 140 days and 1 year in RR and CR but remained unchanged in CC, providing evidence of premature ageing of reproductive function. Fertility rates declined over the same period in the three experimental groups but not CC. MPR in one of the two experimental periods, either pregnancy or lactation, resulted in decreased pup survival compared with CC and RR. These data show that MPR results in delayed sexual maturation and premature ageing of reproductive function.

Extensive epidemiological and experimental evidence indicates that a sub‐optimal environment during fetal and neonatal development in both humans and animals may programme offspring susceptibility to later development of chronic diseases including obesity and diabetes that are the result of altered carbohydrate metabolism. We determined the effects of protein restriction during pregnancy and/or lactation on growth, serum leptin, and glucose and insulin responses to a glucose tolerance test in male and female offspring at 110 days postnatal life. We fed Wistar rats a normal control 20% casein diet (C) or a restricted diet (R) of 10% casein during pregnancy. Female but not male R pups weighed less than C at birth. After delivery, mothers received the C or R diet during lactation to provide four offspring groups: CC (first letter maternal pregnancy diet and second maternal lactation diet), RR, CR and RC. All offspring were fed ad libitum with C diet after weaning. Relative food intake correlated inversely with weight. Offspring serum leptin correlated with body weight and relative, but not absolute, food intake in both male and female pups. Serum leptin was reduced in RR female pups compared with CC and increased in RC males compared with CC at 110 days of age. Offspring underwent a glucose tolerance test (GTT) at 110 days postnatal life. Female RR and CR offspring showed a lower insulin to glucose ratio than CC. At 110 days of age male RR and CR also showed some evidence of increased insulin sensitivity. Male but not female RC offspring showed evidence of insulin resistance compared with CC. Cholesterol was similar and triglycerides (TG) higher in male compared with female CC. Cholesterol and TG were higher in males than females in RR, CR and RC (P < 0.05). Cholesterol and TG did not differ between groups in females. Cholesterol and TG were elevated in RC compared with CC males. Nutrient restriction in lactation increased relative whole protein and decreased whole lipid in both males and females. RC females showed decreased relative levels of protein and increased fat. We conclude that maternal protein restriction during either pregnancy and/or lactation alters postnatal growth, appetitive behaviour, leptin physiology, TG and cholesterol concentrations and modifies glucose metabolism and insulin resistance in a sex‐ and time window of exposure‐specific manner.

Compelling epidemiological and experimental evidence indicates that a suboptimal environment during fetal and neonatal development in both humans and animals may programme offspring susceptibility to later development of several chronic diseases including obesity and diabetes in which altered carbohydrate metabolism plays a central role. One of the most interesting and significant features of developmental programming is the evidence from several studies that the adverse consequences of altered intrauterine environments can be passed transgenerationally from mother (F₀) to daughter (F₁) to second generation offspring (F₂). We determined whether when F₀ female rats are exposed to protein restriction during pregnancy and/or lactation their F₁ female pups deliver F₂ offspring with in vivo evidence of altered glucose and insulin metabolism. We fed F₀ virgin Wistar rats a normal control 20% casein diet (C) or a protein restricted isocaloric diet (R) containing 10% casein during pregnancy. F₁ female R pups weighed less than C at birth. After delivery, mothers received C or R diet during lactation to provide four F₁ offspring groups CC (first letter pregnancy diet and second lactation diet), RR, CR and RC. All F₁ female offspring were fed ad libitum with C diet after weaning and during their first pregnancy and lactation. As they grew female offspring (F₁) of RR and CR mothers exhibited low body weight and food intake with increased sensitivity to insulin during a glucose tolerance test at 110 days of postnatal life. Male F₂ CR offspring showed evidence of insulin resistance. In contrast RC F₂ females showed evidence of insulin resistance. Sex differences were also observed in F₂ offspring in resting glucose and insulin and insulin: glucose ratios. These sex differences also showed differences specific to stage of development time window. We conclude that maternal protein restriction adversely affects glucose and insulin metabolism of male and female F₂ offspring in a manner specific to sex and developmental time window during their mother's (the F₁) fetal and neonatal development.

Nutrient restriction during pregnancy and lactation impairs growth and development. Recent studies demonstrate long‐term programming of function of specific organ systems resulting from suboptimal environments during fetal life and development up to weaning. We determined effects of maternal protein restriction (50% control protein intake) during fetal development and/or lactation in rats on the reproductive system of male progeny. Rats were fed either a control 20% casein diet (C) or a restricted diet (R) of 10% casein during pregnancy. After delivery mothers received either C or R diet until weaning to provide four groups: CC, RR, CR and RC. We report findings in male offspring only. Maternal protein restriction increased maternal serum corticosterone, oestradiol and testosterone (T) concentrations at 19 days gestation. Pup birth weight was unchanged but ano‐genital distance was increased by maternal protein restriction (P < 0.05). Testicular descent was delayed 4.4 days in RR, 2.1 days in CR and 2.2 days in RC and was not related to body weight. Body weight and testis weight were reduced in RR and CR groups at all ages with the exception of CR testis weight at 270 days postnatal age (PN). At 70 days PN luteinizing hormone and T concentrations were reduced in RR, CR and RC. mRNA for P450 side chain cleavage (P450scc) was reduced in RR and CR at 21 days PN but was unchanged at 70 days PN. Fertility rate was reduced at 270 days PN in RC and sperm count in RR and RC. We conclude that maternal protein delays sexual maturation in male rats and that some effects only emerge in later life.