Clearing factor lipase and its role in the regulation of triglyceride utilization. Studies on the enzyme in adipose tissue

Developmental and neurobehavioral effects of perinatal exposure to diets with different omega-6:omega-3 ratios in mice

OBJECTIVE

To investigate in mice the effect of diets enriched with soy or sunflower oil with different omega-6:omega-3 ratios on gestation, reproductive success, physical maturation, and the neurobiological development of the pups.

METHODS

Dams were assigned, throughout gestation and lactation, to different groups: a commercial diet (CD), a soy oil-enriched diet (SOD), or a sunflower oil-enriched diet (SFOD). Measurements during gestation were dams' body weights and daily food intakes. Measurements in the offspring were physical parameters (body weight, body length, body mass index, fur appearance, pinna detachment, incisor eruption, eye opening, and puberty onset) and behavioral preweaning tests (surface righting reflex, negative geotaxis, and cliff avoidance).

RESULTS

The SOD and SFOD dams became significantly heavier than the CD dams from gestational days 14 and 19, respectively, to parturition. There were no significant differences in gestational length or food consumption during pregnancy or lactation or in maternal weight during lactation. Diets did not modify litter size, sex ratio, survival index at weaning, or body weight. The SFOD and SOD offspring were significantly shorter than the CD offspring at weaning. The mean offspring physical scores of SOD and SFOD offspring were higher than CD offspring and simple reflexes were earlier in the SOD and SFOD groups. In SFOD offspring, puberty onset was significantly delayed, at postnatal days 26 and 27 in male and female offspring, respectively.

CONCLUSION

This study suggests that the maintenance of an adequate omega-6:omega-3 ratio is necessary for the optimal growth and development of murine offspring. In populations that do not have sufficient provision of polyunsaturated fatty acids in the diet, their consumption would be advisable during gestation and lactation because these improve most neurodevelopmental outcomes included in this study.

Serum cholesterol and lipoprotein concentrations in mothers during and after prolonged exclusive lactation

The effect of exclusive lactation on lipid levels was investigated by evaluating serum concentrations of total and lipoprotein cholesterol, triglyceride (TG), and apoprotein (apo) B in mothers during and after exclusive, prolonged lactation. Serum total cholesterol concentrations were measured at delivery (n = 195), at 2 (n = 165), 6 (n = 119), 9 (n = 74), and 12 months (n = 32) of lactation, and 2 months (n = 27) after ending this exclusive lactation. In a subgroup of 34 mothers, serum levels of very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein 2 (HDL2), HDL3, and LDL apo B were determined at 2, 6, 9, and 12 months of lactation. The mean value of serum total cholesterol concentrations decreased from 6.2 +/- 0.12 (SEM; n = 195) at delivery to 4.8 +/- 0.1 mmol/L (n = 116) at 6 months of exclusive lactation (P < .001). The average decrement in total cholesterol level was 0.80 mmol/L (P < .001) from delivery to 2 months of lactation and 0.55 mmol/L (P < .001) from 2 to 6 months of lactation, and levels were stable thereafter. In the 27 mothers who were exclusively breast-feeding their infants at 9 months of lactation and whose serum cholesterol levels were measured 2 months after the end of lactation, cholesterol levels increased rapidly to 5.7 +/- 0.21 mmol/L (P = .001). In the subgroup of 34 mothers who were examined more closely, the course just described was also true for serum TG, LDL and VLDL cholesterol, and LDL apo B levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Diet, pregnancy, and lactation: effects on adipose tissue, lipoprotein lipase, and fat cell size

Adipose tissue fat cell size and lipoprotein lipase (LPL) activity were determined in the retroperitoneal and subscapular depots of nonpregnant, pregnant, and postpartum rats fed either a standard laboratory diet or a high-fat diet containing 55% fat by weight. High-fat feeding for 20 days increased, in nonpregnant rats, fat cell size and LPL activity two- to threefold in both depots. In pregnant rats at term, fat cell size was increased and LPL activity was depressed in both dietary groups. Twenty days postpartum, both retroperitoneal fat cell size and LPL activity were decreased in proportion to the size of the litter. Rats not allowed to lactate had fat cell sizes and LPL activity that were not significantly different than in nonpregnant controls. Fat cell size and LPL activity in rats nursing four pups were reduced to 77% and 36% of control, respectively. Those nursing a normal-sized litter of eight pups demonstrated a further reduction of fat cell size to 38% and of LPL activity to 2% of nonpregnant control values. High-fat feeding and obesity did not prevent the fat loss and decreased LPL activity associated with lactation; fat cell size was decreased to 61% and LPL activity to 3% of control values. Values for the subscapular depot followed essentially the same pattern as that observed for the retroperitoneal depot. Mammary LPL activity was increased more than tenfold in animals nursing four or eight pups compared with values at term, whereas no activity was detected in rats not allowed to lactate.

Hormonal modulation of adipose tissue lipoprotein lipase may alter food intake in rats

Daily injections of 5 mg progesterone for 3 wk preferentially increased parametrial depot weight and fat cell size in ovarian intact rats. Adipose tissue lipoprotein lipase (LPL) activity was also preferentially increased in the parametrial depot. LPL activity increased at 24 h, whereas food intake did not increase until 36 h after the first injection. Parametrial fat cell size was significantly increased by 84 h and increased further by 3 wk. Daily injections of 2.5 microgram of estradiol for 3 wk decreased fat cell size and LPL activity in the parametrial depot of female rats, whereas in vitro glycerol release was unchanged. Serum triglycerides were increased, but free fatty acids were unaffected. The data suggest that ovarian hormones affected fat cell size in the rat through their modulation of LPL activity. These findings are consistent with the hypothesis that, during progesterone administration, preferential uptake of serum triglycerides into adipose stores decreases the availability of triglyceride-derived energy to the organism stimulating increased food intake.