Fatty acids inhibit adrenocorticotropin-induced adrenal steroidogenesis.

Unsaturated long chain fatty acids modulate hormone secretion from a variety of endocrine glands, including the adrenal cortex. Oleic acid and linoleic acid have been shown to stimulate production of glucocorticoids in the absence of adrenocorticotropic hormone, but at a high concentration appeared to inhibit the action of this hormone. In the present study, the concentration dependence of the inhibitory actions of these two fatty acids was tested in collagenase-dispersed rat adrenal fasciculata cells, and the effects of both lipids on cAMP production were also determined. Adrenocorticotropic hormone stimulated steroid production from isolated cells approximately ten-fold above unstimulated cells. Oleic and linoleic acid significantly inhibited the response to this hormone by 44% and 54%, respectively. The half-maximally effective inhibitory concentration of both lipids was between 75-100 microM. A maximal concentration of adrenocorticotropic hormone increased cAMP secretion 138-fold above unstimulated cells. Oleic and linoleic acids inhibited the increase in cAMP secretion by 47% and 33%, respectively. It is concluded that pathophysiological concentrations of unsaturated fatty acids inhibit the action of adrenocorticotropic hormone on the adrenal gland, and that the mechanism of action of the lipids may be partly via inhibition of cAMP production.

Zinc absorption, mineral balance, and blood lipids in women consuming controlled lactoovovegetarian and omnivorous diets for 8 wk.

Zinc absorption, mineral balance, and blood lipid concentrations were measured in 21 women aged 33 +/- 7 y (range: 20-42 y) consuming controlled lactoovovegetarian and nonvegetarian diets for 8 wk each in a crossover design. The lactoovovegetarian and nonvegetarian diets, respectively, provided (by analysis) 973 and 995 mg Ca, 1.8 and 1.3 mg Cu, 367 and 260 mg Mg, 5.9 and 2.5 mg Mn, 1457 and 1667 mg P, 9.1 and 11.1 mg Zn, and (by calculation) 40 and 16 g dietary fiber, 2.5 and 0.8 mmol phytic acid, molar ratios of phytate to Zn of 14 and 5, and millimolar ratios of (phytate x Ca) to Zn of 344 and 111. Dietary zinc absorption was measured by extrinsic isotopic labeling and whole-body counting. Plasma cholesterol, cholesterol fractions, and lipoproteins were reduced 7-12% with the lactoovovegetarian diet, consistent with predictions based on dietary cholesterol and fat. Blood pressure was unaffected. Calcium, copper, magnesium, and phosphorus balances were not different between diets; manganese balance tended to be greater with the lactoovovegetarian diet (P < 0.07). The lactoovovegetarian diet was associated with a 21% reduction in absorptive efficiency that, together with a 14% reduction in dietary zinc, reduced the amount of zinc absorbed by 35% (2.4 compared with 3.7 mg/d) and reduced plasma zinc by 5% within the normal range. Zinc balance was maintained with both diets. Although there is a greater risk of zinc deficiency in persons consuming lactoovovegetarian compared with omnivorous diets, with inclusion of whole grains and legumes zinc requirements can be met and zinc balance maintained.