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ABSTRACT

Using tritiated-thymidine incorporation as a measure of cell growth, interleukin-1β stimulated the growth of bovine zona fasciculata/reticularis adrenocortical cells after 72h in primary culture. Within the range of 10–1000pg/ml, interleukin-1β produced over 40% of angiotensin II-stimulated [³H]thymidine incorporation (P<0.005 compared with basal for 10pg/ml and 1000pg/ml; P<0.05 for 100pg/ml; two-tailed unpaired Student's t-test). Interleukin-1β did not directly stimulate cortisol secretion.

By stimulating adrenocortical growth, the increase in interleukin-1 during fever provides a potential mechanism for chronically raising glucocorticoid output. This study is the first demonstration of a long-term effect involving interleukin-1β on the adrenal cortex.

ABSTRACT

The effects of angiotensin II (AII), acetylcholine and vasopressin on the intracellular concentration of Ca²⁺ have been little studied in adrenocortical cells from the zona fasciculata/reticularis (ZFR).

Primary cultures of bovine ZFR cells maintained in suspension culture for 72 h produce cortisol in response to AII (0·1 μm), acetylcholine (0·1 mm) and vasopressin (1 μm). This response is accompanied by a breakdown of membrane phosphoinositides from [³H]inositol-prelabelled cells.

Using cells loaded with the Ca²⁺ indicator fura-2, the intracellular concentration of Ca²⁺ was measured in response to increasing doses of all three agonists and found to increase in a graded fashion in each case. The basal intracellular concentration of Ca²⁺ was 75±3 nm (mean±s.e.m., n=52), rising to a maximum 1·82±0·14-fold (n=6) for AII (0·1 μm), 1·35±0·05-fold (n=7) for acetylcholine (0·1 mm) and 1·27±0·10-fold (n=6) for vasopressin (1 μm).

In the case of AII and acetylcholine, agonists were added sequentially in medium of normal extracellular Ca²⁺ concentration (1·2 mm) or in medium in which the Ca²⁺ concentration was buffered to approximate to the intracellular concentration of Ca²⁺ (75–100 nm). Evidence was thereby obtained that both AII and acetylcholine mobilize a common intracellular pool of Ca²⁺.

Our findings suggest that these three agonists, all of which stimulate phospholipase C, increase intracellular Ca²⁺ through a mechanism which depends, at least in part, on the release of Ca²⁺ from a common intracellular pool.

ABSTRACT

Cells isolated from the zona fasciculata/reticularis (ZFR) of the bovine adrenal cortex and maintained in culture were found to secrete cortisol in response to vasopressin stimulation. The increased cortisol secretion was dose dependent, with a threshold response at 1 nm and a maximal response (1·68-fold over basal) at 0·1 μm. In cells cultured in the presence of [³H]inositol (to prelabel the membrane phosphoinositide pool), stimulation with vasopressin in the presence of LiCl (10 mm) resulted in a similar dose-dependent increase in labelling of the phosphoinositol fraction, with a maximal response (1·45-fold over basal) at 10 nm. The increased labelling of the phosphoinositol fraction was independent of extracellular Ca²⁺ as it was not abolished in medium with [Ca²⁺ ] buffered to intracellular resting levels. This suggests that vasopressin stimulation results in the activation of a phosphoinositidase C. It is probable that cortisol secretion by bovine ZFR cells in response to vasopressin is dependent upon activation of this Ca²⁺-independent phosphoinositidase C. However, the small magnitude of the cortisol secretory response makes it unlikely that vasopressin is a primary regulator of cortisol secretion in vivo.

ABSTRACT

Sodium nitroprusside spontaneously breaks down in solution to produce the vasodilator nitric oxide. In many cell types, this stimulates the cytosolic form of the enzyme guanylate cyclase, resulting in the elevation of cyclic GMP (cGMP). We have investigated the effect of sodium nitroprusside on the generation of cGMP in primary human thyrocytes and the SV40-transfected human thyroid cell line SGHTL-189. A dose-dependent increase in cGMP was obtained and the maximum response was observed with concentrations above 10 μm sodium nitroprusside in both cell types. Methylene blue (50 μm) had no significant effect on basal cGMP production but inhibited the effect of sodium nitroprusside at all concentrations tested, thus demonstrating that the effect was due to nitric oxide. Sodium nitroprusside had no effect on cyclic AMP (cAMP) production in these cells. TSH at 100 and 1000 μU/ml significantly stimulated the production of cAMP, but not that of cGMP, in primary human thyrocytes. Sodium nitroprusside had no significant effect on basal or TSH-stimulated triiodothyronine secretion in primary human thyrocytes. Forskolin (10 μm) significantly stimulated cAMP production in both primary thyrocytes and SGHTL-189 cells. Although forskolin had no significant effect on basal cGMP production, sodium nitroprusside-stimulated cGMP production was significantly reduced by forskolin. However, this inhibitory effect was not related to the production of cAMP.

ABSTRACT

The presence of mRNA for epidermal growth factor (EGF) and transforming growth factor-α (TGFα) was demonstrated in small fragments of human endometrium and decidua by use of the technique of reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers. The presence of mRNA encoding EGF and TGFα has not been shown in human endometrium previously. Other studies using conventional techniques, such as Northern blot or in-situ hybridization, showed the presence in low copy number of EGF but not TGFα in murine endometrium. Messenger RNA for EGF was not present in peripheral leukocytes or platelets, suggesting an endometrial source for the message. Messenger RNA for TGFα was found in these blood components, thus preventing confirmation of the source of TGFα mRNA.