Helen Weber

Ontogenic corticosteroidogenesis of the domestic fowl: response of isolated adrenocortical cells.

Ontogenic adrenocortical function of the domestic was investigated using adrenocortical cells isolated from embryonic chicks (18, 19, 20, and 21 days old) and male and female posthatch birds (1 day, 1 week, and 3 weeks old). Production of the predominant corticosteroids secreted by the chicken adrenal gland, corticosterone, cortisol, and aldosterone, was measured by radioimmunoassay after 2-hr incubation of cells with or without steroidogenic agents. Approaching hatch, basal and maximal ACTH-(1-24) (ACTH)-induced corticosteroid production increased steadily and peaked around 1 day posthatch (5-18 times and 3-9 times, respectively, the production values at 18 days embryonic life). Thereafter, corticosteroid production values decreased steadily to 3 weeks posthatch. Corticosterone predominated over the ages studied: Maximal ACTH-induced corticosterone production averaged 52 and 115 times the production values of aldosterone and Cortisol, respectively. In addition, maximal ACTH-induced aldosterone production was roughly 2.2 times greater than Cortisol production over the ages studied except for a short-lived, disproportionately greater aldosterone production at 1 day posthatch. In addition to perihatch and age-related differences in cellular corticosteroid production, there were also differences in cellular sensitivity to steroidogenic agents as indicated by the differences in half-maximal steroidogenic concentration values (ED50 values) of the steroidogenic agents. Sensitivity to ACTH increased 2.7 times from Day 18 of embryonic life to 1 day posthatch and then decreased steadily to 3 weeks posthatch. In addition, sensitivity to 8-bromo-cAMP (8-Br-cAMP) increased abruptly at 1 day posthatch (nearly 3 times) but then remained constant thereafter. However, a consistent change in cellular sensitivity to 25-hydroxycholesterol was not observed until 3 weeks posthatch (an increase in sensitivity of 3 times that at Day 18 of embryonic life). These data of cellular sensitivity suggest that there were distinct developmental and maturational alterations in the cellular loci at which ACTH, 8-Br-cAMP, and 25-hydroxycholesterol acted. Thus, during the transition from embryonic to postembryonic life of the domestic fowl, there are alterations in adrenocortical cell steroidogenic capacity and in the function of some cellular loci comprising the corticosteroidogenic pathway.

Genetic-dependent alterations in adrenal stress response and adrenocortical cell function of the domestic fowl (Gallus domesticus).

Strain-dependent differences in adrenocortical function were investigated in male White Leghorn domestic fowl. Adrenocortical function of Cornell K strain (K) (genetic control), autosomal dwarf strain (ADW), and sex-linked recessive dwarf strain (SLD) was evaluated in vivo by measuring plasma corticosterone and in vitro by measuring acute (2 hr) corticosterone production by enriched adrenocortical cell populations. Regardless of strain, there was an age-dependent decrease (27-57%) in plasma corticosterone from 1 to 12 weeks of age. However, there was a tendency for plasma corticosterone values of ADW and SLD to be, respectively, greater and less than that of K. In addition, at 12 weeks of age, plasma corticosterone responses of ADW and SLD to transient heat stress (50°C, 30 min) were, respectively, 22.8% greater and 15.9% less than that of K. Strain differences in adrenal weight and relative adrenal weight (mg% body wt) were also apparent. At 12 weeks of age, adrenal weights of ADW and SLD were, respectively, 33 and 42% less than that of K, whereas relative adrenal weights were, respectively, 27.6% greater and 22.4% less than that of K. In addition there were strain-dependent differences in adrenocortical function at the cellular level. Although there were no consistent strain differences in basal and maximal corticosterone production by cells, there were strain differences in cellular sensitivity to ACTH and pregnenolone. On an equal cell concentration basis, the half-maximal steroidogenic concentrations (ED50 values or effective doses for 50% maximal effect) of ACTH for ADW and SLD adrenocortical cells were, respectively, 0.23 and 2.07 times the ED50 value for K cells. In addition, the ED50 value of pregnenolone for ADW cells was 0.46 times that for K and SLD cells. Since ED50 values are a measure of cellular sensitivity (the greater the ED50 value the lesser the cellular sensitivity), the order of sensitivity to ACTH was ADW > K > SLD and the order of sensitivity to pregnenolone was ADW > K = SLD.

Adrenocortical Function of the Domestic Fowl: Effects of Orchiectomy and Androgen Replacement

Abstract The effect of orchiectomy and androgen replacement on cockerel adrenocortical function was investigated. Orchiectomized cockerels (2 weeks old) were implanted with Silastic tubing containing various amounts of one of the following steroids: cholesterol, testosterone (T), androstenedione (A4), and 5α-dihydrotestosterone (DHT). Birds were administered additional implants, containing doses of steroids equivalent to those of the initial implants, at 4 and 8 weeks of treatment (i.e., 6 and 10 weeks of age). Sham-operated cockerels administered empty implants served as intact controls for comparison of data. Animals were killed after 10 weeks of treatment (12 weeks old). Trunk plasma corticosterone (B) and plasma T, and B production by collagenase-isolated adrenocortical cells incubated briefly (2 hr) with or without steroidogenic agents were measured by radioimmunoassay. Orchiectomy with implantation of the inert sterol, cholesterol (hereafter referred to as orchiectomy), did not alter plasma B concentrations and did not affect basal cellular B production or cellular B production induced by a maximal steroidogenic concentration of ACTH or that maximally supported by 25-hydroxycholesterol. However, orchiectomy did lower maximal 8-bromo-cyclic AMP-induced B production by 30%. Low-implant doses of A4 (1-cm implant) and T (0.3-cm implant), that maintained comb growth, lowered plasma B concentrations by 24–42%, whereas a high-implant dose of T (3-cm implant) and all implant doses of DHT had no effect on plasma B concentrations. Thus, androgen replacement had different effects on plasma B depending on the type of androgen and the implant dose. In contrast, androgen replacement consistently suppressed basal and maximal ACTH-induced cellular B production regardless of the type of androgen. Furthermore, the degree of suppression was dose-dependent. These results suggest that the differential effect of androgen replacement on plasma B concentrations was due to differences in the clearance of circulating B and/or differences in blood volume. In addition, the present study suggests that in the absence of the testes, androgens are suppressants of adrenocortical cell function in the domestic fowl.

Effect of 3,3′-lminodiproprionitrile (IDPN) on Corticosteroidogenesis of Isolated Adrenocortical Cells

Abstract The neurotoxic agent, 3,3′-iminodiproprionitrile (IDPN), is a disrupter of neurofilament- and intermediate filament-organelle association. In the present study, the effect of IDPN on corticosteroidogenesis was investigated using isolated rat (having few intermediate filaments) and domestic fowl (having abundant intermediate filaments) adrenocortical cells. Cells were incubated with or without steroidogenic agents and precursors and with or without various concentrations of IDPN for 2 hr. IDPN had similar inhibitory potencies (as indicated by the half-maximal inhibitor concentrations (ID50 values)) with both rat and domestic fowl cells despite their grossly different intermediate filament content. However, the average ID50 values of IDPN varied with the different steroidogenic agents and precursors used. The average IDPN ID50 values for maximal ACTH- and 8-bromo-cyclic AMP (8-Br-cAMP)-induced corticosterone production were equivalent (49.7 and 45.7 mM, respectively). However, the IDPN ID50 values for maximal ACTH-induced cAMP production, maximal 25-hydroxycholesterol- and pregnenolone-supported corticosterone production, and maximal ACTH- and 8-Br-cAMP-induced protein synthesis varied from 3.7 to 5.4 times the average ID50 values for maximal ACTH- and 8-Br-cAMP-induced corticosterone production. Thus, the inhibitory action of IDPN was not closely linked to the inhibition of ACTH-transmembrane signaling via cAMP, protein synthesis, and steroidogenic enzyme activity. The data suggest that IDPN inhibited corticosteroidogenesis at a step after cAMP but before cholesterol side-chain cleavage and that the inhibition was not dependent on the presence of intermediate filaments.

Adrenocortical function in deoxycorticosterone acetate (DOCA)-hypertensive Yucatan miniature swine

Abstract function was assessed in six normal and six chronic (>12 weeks), DOCA-hypertensive Yucatan miniature swine; mean arterial pressures were 115.3 ± 11.7 and 163.6 ± 27.2 mm Hg, respectively (mean ± SEM). Adrenocortical function was evaluated in vivo by measuring changes in plasma cortisol and aldosterone in response to exogenous ACTH (0.25 mg, iv), and in vitro by measuring the responses of collagenase-isolated adrenocortical cells to ACTH and angiotensin II. Corticoids were measured by specific radioimmunoassay. Basal plasma cortisol values of conscious DOCA-hypertensive swine were approximately 53% of the values of normotensive swine (P 0.05). However, ACTH induced a 419% increase in plasma cortisol values in DOCA-hypertensive swine compared to a 261% increase in the normotensive swine (P 0.05). These differences between the two groups were not altered by anesthesia. There were no significant differences in ACTH-induced changes in plasma aldosterone between the normotensive and DOCA-hypertensive swine. Experiments in vitro showed that the corticoid secretory responses of adrenocortical cells from DOCA-hypertensive animals were 6 times more sensitive to ACTH and 3.2 times more sensitive to angiotensin II than those of cells from normotensive swine. Thus, despite the possibility of adrenocortical insufficiency due to suppressed plasma renin activity and the negative feedback of DOCA on the hypothalamic-hypophyseal-adrenal axis, adrenocortical function of DOCA-hypertensive swine was hyperre-sponsive to trophic hormones. Results from this study suggest that the DOCA-hypertensive swine may be a valuable model in elucidating the relationship between hypertension and adrenocortical function and in investigating nonclassical control of the adrenal cortex, that is, control exerted during the hypertensive state that exists apart from or in addition to that exerted by ACTH and angiotensin II.