INACTIVATION OF THE ADIPOKINETIC PROPERTY OF ADRENOCORTICOTROPIN, BETA-MELANOCYTE-STIMULATING HORMONE, VASOPRESSIN AND PITUITARY FRACTION H BY TISSUES OF THE RAT AND RABBIT

Lipid mobilization in pigs selected for leanness or fatness

Lipid mobilization was investigated in pigs selected for high and low backfat thickness for four generations. Both epinephrine and pituitary lipid mobilizing factors (LMF) induced in vitro lipolysis in pig fat. The release of non-esterified fatty acids (NEFA) from fat pads sampled from the group selected for thin backfat, the control group, and the group selected for thick backfat differed significantly, the means being 1·16 ± 0·18, 0·83 ± 0·06 and 0·40 ± 0·04 μmol/100 mg per 3 hr respectively.

The inhibition by pig serum from the same groups of an LMF- induced adipokinesis in rabbits also differed significantly. The mean NEFA concentrations were, in the same sequence, 5·05 ± 0·15, 3·35 ± 0·27 and 1·29 ± 0·11 milliequiv/litre respectively. A difference in feeding level of about 20% between 25 and 90 kg live weight did not influence lipid mobilization in vitro.

The serum inhibition method may be a useful aid to early selection for leanness, since it appears that the method may be used for pigs 5 to 6 weeks old.

Effects of caloric restriction and exercise on B-endorphin, ACTH and cortisol circulating levels in obesity

B-Endorphin (B-Ep), ACTH and cortisol circulating levels, before and after a two months therapy with a hypocaloric diet and an increase in physical exercise, were measured by RIA in 17 obese female subjects. After therapy, the body weight excess fell from 56.6 +/- 22.2% to 38.6 +/- 22.1% (p less than 0.01). Plasma levels of B-Ep decreased from 18.3 +/- 12.5 fmol/ml to 6.4 +/- 3.5 fmol/ml (p less than 0.01); those of ACTH from 46.8 +/- 22.8 pg/ml to 31.2 +/- 11.6 pg/ml (p less than 0.01); and those of cortisol from 15.9 +/- 4.6 micrograms% to 10.3 +/- 2.5 micrograms% (p less than 0.01). The reduction of the elevated plasma B-Ep levels found in obese subjects is related principally to the diet therapy. Thus, as shown in experimental animals, excessive feeding results in an increased hypothalamic-pituitary secretion of B-Ep.