1. Investigación

To determine the effect of under-nutrition during suckling in adults, at delivery female Sprague Dawley rats were allowed to lactate litters of either eight (controls) or sixteen pups each (large litter, LL). The amount of milk taken by LL pups was less than the controls and the concentration of triacylglycerols (TG) in the milk of the former was lower. The increase of both body weight and length in LL was lower than in the controls during suckling. At weaning, pups were allowed to eat ad libitum a standard diet and whereas at 20 months female body weight did not differ between LL and control rats, LL males weighed less than controls. Plasma NEPA were lower in male LL than in controls at 10 months, leptin at 10 and 16 months and TG and VLDL-TG at 20 months, with no differences in females. When 20 months old, lumbar and epididymal adipose tissue weights were lower in male LL than in controls, but not in females. The increase in plasma insulin after oral glucose load was lower in LL than in controls, both in males and females at 4 and 16 months, and only in males at 10 months, whereas the change in plasma glucose remained constant between the groups. Results indicate that both the pancreatic [3-cell function and insulin sensitivity and adipose tissue metabolism are independently programmed as a consequence of under-nutrition during suckling, the effect being more manifest for males than for females.

Since during pregnancy the mother switches from an anabolic to a catabolic condition, the present study was addressed to determine the effect of 48 h food deprivation on days 7, 14 and 20 of pregnancy in the rat as compared to age matched virgin controls. Body weight, free of conceptus, decreased with food deprivation more in pregnant than in virgin rats, with fetal weight (day 20) also diminishing with maternal starvation. The decline of plasma glucose with food deprivation was greatest in 20 day pregnant rats. Insulin was highest in fed 14 day pregnant rats, and declined with food deprivation in all the groups, the effect being not significant in 7-day pregnant rats. Food deprivation increased plasma glycerol only in virgin and 20 day pregnant rats. Plasma NEFA and 3-hydroxybutyrate increased with food deprivation in all groups, the effect being highest in 20 day pregnant rats. Food deprivation decreased plasma triacylglycerols in 14 day pregnant rats but increased in 20 day pregnant rats. In 20-day fetuses, plasma levels of glucose, NEFA and triacylglycerols were lower than in their mothers when fed, and food deprivation caused a further decline in plasma glucose, whereas both NEFA and 3-hydroxybutyrate increased. Liver triacylglycerols concentration did not differ among the groups when fed, whereas food deprivation caused an increase in all pregnant rats and fetuses, the effect being highest in 20-day pregnant rats. Lipoprotein lipase (LPL) activity in adipose tissue was lower in 20 day pregnant rats than in any of the other groups when fed, and it decreased in all the groups with food deprivation, whereas in liver it was very low in all groups when fed and increased with food deprivation only in 20 day pregnant rats. A significant increase in liver LPL was found with food deprivation in 20 day fetuses, reaching higher values than their mothers. Thus, the response to food deprivation varies with the time of pregnancy, being lowest at mid pregnancy and greatest at late pregnancy, and although fetuses respond in the same direction as their mothers, they show a specific response in liver LPL activity