Dietary protein restriction stress in the domestic chicken (Gallus gallus domesticus) induces remodeling of adrenal steroidogenic tissue that supports hyperfunction

The stress of dietary protein restriction in the immature domestic turkey ( Mekagris gallopavo) induces adrenal steroidogenic hypofunction that is asso ciated with an alteration in the proportion of density-dependent subpopulat ions of steroidogenic cells within the adrenal gland. In contrast, when imp osed on immature chickens, this nutritional stressor induces long-term enha ncement of adrenal steroidogenic function. However, whether this alteration in function is accompanied by a remodeling of chicken adrenal steroidogeni c tissue as in the turkey is not known. To address this question, immature cockerels (2 weeks old) were fed established isocaloric synthetic diets con taining either 20% (control) or 8% (restriction) soy protein for 4 weeks. A drenal glands were processed for the isolation of defined, density-separabl e, adrenal steroidogenic cell subpopulations: three low-density adrenal ste roidogenic cell subpopulations [LDAC-1 (rho = 1.0285-1.0430 g/ml), LDAC-2 ( rho = 1.0430-1.0485 g/ml), and LDAC-3 (rho = 1.0485-1.0500 g/ml)] and one h igh-density subpopulation [HDAC (rho = 1.0510-1.0840 g/ml)]. The steroidoge nic function of these cell subpopulations was assessed. Protein restriction consistently, but differentially, enhanced maximal ACTH-induced corticoste rone production by the subpopulations: values of LDAC-1, -2, and -3 and HDA C from protein restricted birds were, respectively, 116, 43, 33, and 20% gr eater than those of corresponding cell subpopulations from control birds. H owever, it had contrasting influences on maximal ACTH-induced aldosterone p roduction by the cell subpopulations. Whereas the value of LDAC-1 from prot ein-restricted birds was 70% greater than that from control birds, the valu es for LDAC-2 and -3 were not different from those of the control, and the value for HDAC was 22% less than that of the control. Protein restriction a lso altered the cell subpopulation composition of the adrenal gland: compar ed to control, it increased the proportion of LDAC-1 by 46% and decreased t he proportion of LDAC-3 and HDAC by 34 and 20%, respectively. Thus, dietary protein restriction increased the proportion of cells (i.e., LDAC-1) havin g the greatest enhancement in corticosteroid production. This pattern of re modeling of chicken adrenal steroidogenic tissue in response to dietary pro tein restriction contrasts sharply with the pattern that occurs in another galliform species, the domestic turkey. (C) 2000 Academic Press.