1. Investigación

Pieces of lumbar adipose tissue from 19-day pregnant rats and their virgin controls were incubated in the presence of albumin, glucose, U- 14C-glycerol, and either bovine insulin (200 µU/ml) or adrenaline (2.6 µM). The rate of glycerol release in the medium was augmented in both fed and 48-hour fasted pregnant rats. Insulin reduced this parameter in tissues from pregnant rats but not from controls. Adrenaline enhanced it in all groups, especially in tissues from fed pregnant rats. The rates of CO2 , fatty acids and glyceride glycerol formation from glycerol were higher and the effect of insulin was greater in pregnant than in control rats when fed. Fasting produced a decrease in all these parameters, the effect being greater in pregnant than in control rats. The augmented sensitivity of adipose tissue from the mother allows for a rapid switch from the anabolic to the catabolic state according to the necessities of the fetus.

Lumbar fat pad oieces taken from fed and 48 h starved 19-day pregnant rats and virgin controls were incubated for different times with [u-14cJ glycerol, albumin and glucose. The glycerol conversion rates to either co2 , saponified lipids and glyceride glycerol were higher in the pregnant rat tissue than in the controls. Starvation produces a greater decline in these parameters in pregnant rat tissue than in controls. The lipolysis rate was elevated in pregnant rat tissue. The augmented glycerol utilization by adipose tissue in the mother would contribute to the net deposition of fat, despite augmented lipolysis. In the starved state the enhanced lipolvsis of the mother is potenciated by a decreased reutilization of glycerol, allowing a maximal net mobilization of the fat stores.