Dissociation between cortisol-induced pycnosis and inhibition of [3H]uridine incorporation in rat thymocytes.

Treatment of rat thymocytes with cortisol induced an inhibition of [3H]uridine incorporation after 30-90 min, an accumulation of pycnotic cells after 90 min, and a decrease in cell viability after several hours. No cortisol-resistant cells could be distinguished, and dose-response curves for a number of glucocorticoids showed a correlation to the saturation of the glucocorticoid receptors. The pycnotic effect of cortisol increased between pH 5.2--7.0 in parallel with a stimulation of the spontaneous development of pycnotic cells. The cortisol-induced accumulation of pycnotic cells and inhibition of [3H]uridine incorporation varied independently as a function of the cell density, and in a glucose-salt medium only the pycnotic effect of cortisol became inhibited. The inhibition of [3H] uridine incorporation is therefore not an integral part of the pycnotic change of the cells. The glucocorticoid sensitivity was found to increase with the age of the animals, before the onset of thymus involution.     

Cortisol metabolism in lymphocytes from cancer-bearing patients

A study was conducted to determine the pattern of cortisol metabolism by lymphocytes obtained from four groups of subjects: 27 male and female patients suffering from various types of malignancy other than malignancy of lymphatic tissues; and 26 healthy male and female controls. Known concentrations of cells were incubated with 1,2-³H-cortisol and the products were isolated by thin-layer and paper chromatography. Three metabolites were found to be produced by lymphocytes from both normal and cancer-bearing patients: 20α-hydroxycortisol, 20β-hydroxycortisol, and tetrahydrocortisol. Cells from the female control group were found to be more active than those from the male controls, while cells from cancer-bearing patients were markedly more active than the normal cells, regardless of sex. It is suggested that this finding of increased metabolism of cortisol by lymphocytes from patients with different types of malignancy other than lymphoma may provide the basis for a new diagnostic aid.     

Progestin receptors in human uterine cytosol

Progestin(norethindrone and norethindrone acetate)-binding protein, exhibiting characteristics similar to uterine progesterone receptor, has been identified in human uterine cytosol. The progestin receptor was characterized by sedimentation coefficient 4.2 S; Stokes radius, 39 Å; frictional ratio 1.29; isoelectric pH 4.6; molecular radius 2.7 nm; and molecualr weight in the range 67 000–74 000. The ammonium-sulfate-precipitated progestin-receptor complex was eluted from a DEAE-cellulose column at 0.18 M KC1. The progestin binding was saturable and stereospecific. The sequential variation in receptor concentration (early proliferative, 3800–4300 sites/cell; late proliferative, 9500–11200 sites/cell; early secretory, 4900–6200 sites/cell; late secretory, 1800–2300 sites/cell) was in conformity for progesterone and the progestins, when concurrently measured. Oral administration of norethindrone significantly reduced the cytoplasmic and nuclear receptor concentration for estradiol and progesterone. A significant observation was that the progestins stabilized the progestin receptor by forming a slowly dissociating complex with a $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～ 110?130}\text{min}$ as compared with the progesteronereceptor complex dissociating with $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～41}\text{min}$. Thus, the uterine progestin receptor recognizes progestins in general, although with a varying degree of affinity, and the altered rate constants could be of putative importance in determining the biological potency of the progestins.     

Effect of 17 beta-estradiol on thyroliberin responsiveness in GH3/B6 rat prolactin cells

GH3/B6 rat prolactin cells were used to analyse at the cellular level the mechanisms by which 17 beta-estradiol (E2) regulates TRH responsiveness of prolactin cells. Before experiments, cells were grown for up to 7 days in 3 different media: normal medium (N) containing 15% horse serum and 2.5% fetal calf serum, CD medium prepared with charcoal-dextran extracted serum and CDE medium supplemented with 4 x 10(-8) M E2. The binding of 3H-TRH (30 min at 37 degrees C) and the TRH-induced percent increase of prolactin release as a function of TRH doses were compared in the 3 conditions. Preculture in E2 enriched medium increased by 50% the number of TRH high-affinity binding sites without modifying their affinity, increased by up to 3 times the percent of the TRH-induced stimulation of prolactin release and improved by one order of magnitude the ED50 of the TRH effect on prolactin release. The presence of HEPES (10 mM) during TRH challenge masked the effect of E2 on the increase in number of binding sites but respected its potentiating effect on prolactin release.     

Androgen-binding proteins in rat epididymis: properties of a cytoplasmic receptor for androgen similar to the androgen receptor in ventral prostate and different from androgen-binding protein (ABP)

The cytoplasmic receptor (CR) in rat epididymal 105,000 $\text{g}$ supernatant was separated from the androgen-binding protein (ABP) by gel electrophoresis following labeling with [1,2,6,7-³H]-testosterone in vivo. ABP disappeared from epididymal supernatants after castration 01 hypophysectomy, while CR remained unchanged. CR was evenly distributed between caput and cauda, while much more ABP was present in caput. Properties of CR in epididymis and prostate were similar and distinctly different from ABP. Binding to CR was destroyed by charcoal treatment (1 mg/mg protein) of supernatant at 0 °C for 6 h, heating at 50 °C for 30 min, or exposure to the sulfhydryl blocking reagent, $\text{p}$-chloromercuriphenylsulfonate (1 mM) at 25 °C for 30 min, while binding to ABP was unaffected. The isoelectric pH of CR (5.8) was higher than that of ABP (4.6). Dissociation of radioactive 5α-dihydrotestosterone (DHT) from CR and nuclear receptors was extremely slow (half-time at 0 °C >2 days), while dissociation from ABP was rapid (half-time at 0 °C ~ 6 min). Cyproterone acetate (250 mg/100g body weight) inhibited binding to CR both in epididymis and ventral prostate but did not affect binding to ABP. Nuclear uptake was inhibited by cyproterone to the same extent as binding to CR, indicating that nuclear uptake and binding are dependent on CR and independent of ABP. The time-course of uptake and binding in epididymal supernatant and nuclear fractions was essentially the same 1 day after bilateral castration when both CR and ABP were present or 8 days after castration when CR alone was present. It is concluded that the cytoplasmic receptor for androgen in rat epididymis has properties very similar to the androgen receptor in ventral prostate but different from ABP.