Radioautographic analysis of 6,7-3H estradiol-17beta uptake in rat uterus following extraction of endogenous estrogens

Elevated serum levels in human pregnancy of a molecule immunochemically similar to eosinophil granule major basic protein

We have shown that serum levels of a molecule immunochemically similar to eosinophil granule major basic protein (MBP) are elevated in pregnant women throughout gestation. MBP levels increase during gestation and plateau at approximately 7,500 ng/ml by the 20th wk (greater than 10-fold above normal). Levels return to normal after delivery, with a T1/2 of 13.7 d. The MBP in pregnancy serum is remarkably similar to the eosinophil granule MBP in that: (a) pregnancy MBP fully inhibits the binding of radiolabeled MBP standard in a double antibody radioimmunoassay; (b) this inhibition reaction is specific for human MBP because pregnancy serum produces no inhibition of the binding of radiolabeled guinea pig MBP in the guinea pig MBP radioimmunoassay; (c) in a two-site immunoradiometric assay for MBP, slopes of dose-response curves for pregnancy serum, purified MBP, and serum from a patient with hypereosinophilic syndrome are identical, and maximal binding is comparable; (d) reduction and alkylation of pregnancy sera increases measured MBP 100-fold, as previously shown for eosinophil granule MBP in serum; and (e) the MBP in pregnancy serum demonstrates the same pattern of heat lability as has been previously reported for MBP. Four observations have raised the possibility that the eosinophil is not the source of the MBP in pregnancy serum: (a) no correlation between serum MBP level and peripheral blood eosinophil count exists in pregnant women, in contrast to previous studies of patients with eosinophilia; (b) levels of three other eosinophil-associated proteins are normal or low in pregnancy sera, whereas the serum levels of these proteins are elevated in patients with eosinophilia; (c) the slopes of dose-response curves for pregnancy sera and MBP standards differ in the double antibody radioimmunoassay; and (d) the molecule in pregnancy serum elutes from Sephadex G-50 columns at the void volume, while eosinophil granule MBP and the MBP in serum of patients with eosinophilia elute at a volume consistent with the previously established molecular weight of 9,300. These findings suggest that the MBP in pregnancy serum is derived from a source other than the eosinophil.

Theophylline-estrogen interaction in the rat uterus: role of the ovary

Uterine edema induced by 0.1 microgram/100 g body wt of estradiol further increases in the presence of theophylline. Theophylline alone or in the presence of 0.001, 0.01, 0.1, and 1 microgram/100 g body wt of estradiol increases uterine RNA and protein content 6 h after its administration, as compared with the same doses of estradiol alone. Both phenomena disappear in the ovariectomized immature rat, suggesting that theophylline potentiates the action of gonadotropins, increasing the synthesis of endogenous ovarian estrogens by the immature ovary. Theophylline decreases the number of eosinophils in the blood and concurrently decreases estrogen-induced uterine eosinophilia at doses of 0.01, 0.1, 1, 10, and 30 micrograms/100 g body wt of estradiol. Estrogen binding by uterine eosinophils in vitro increases in the presence of theophylline. This effect of theophylline could also explain the increase in vivo in estrogen-induced uterine edema.

Estrogen action in the male

Estrogen administration induces a migration of eosinophil leukocytes to ductus deferens.

In vitro binding of 3H-estradiol to eosinophil and neutrophil granulocytes in various tissues (normal and neoplastic) of newborn and adult rats

In vitro uptake and binding of tritiated estradiol to the specific granules of eosinophil granulocytes has been observed by ultrastructural radioautography in various tissues of the rat (liver and spleen of newborn, small intestine and bone marrow of adult animals). Binding of 3H-estradiol to granules present in the cytoplasm of neutrophil granulocytes has also been observed in bone marrow and in a cholangioma produced by chemical carcinogenesis. Neither type of granulocyte bound 3H-testosterone.

New concepts on the action of oestrogens in the uterus and the role of the eosinophil receptor system

Two receptor systems for oestrogens have been demonstrated in the uterus: the cytosol-nuclear receptor system and the eosinophil receptor system. It has been proposed that the cytosol-nuclear receptor system mediates the genomic response to oestrogens in the uterus, while the eosinophil receptor system is thought to mediate the uterine edema and other early oestrogenic responses in the uterus. Cortisol is known to decrease drastically the number of eosinophils in the blood and therefore to limit their availability for migration to the uterus. The present results show that cortisol also drastically reduces both the oestrogen-induced uterine eosinophilia and the uterine wet weight responses, but does not interfere with the oestrogen-induced uterine RNA and protein increases. Oestradiol-17 beta has a higher affinity than oestriol for the cytosol-nuclear receptors and is now found to be the more potent oestrogen in inducing the genomic activation in the uterus. Estriol has a higher affinity than oestradiol-17 beta for the eosinophil receptors, and therefore, oestriol is the stronger oestrogen in inducing those oestrogenic effects which are mediated by the eosinophil receptor system. We conclude that the eosinophil receptor system for oestrogens is a new system, independent of Jensen's cytosol-nuclear receptor system, and this eosinophil receptor system is involved in the mechanism of oestrogen action in the uterus.

Dynamics of eosinophils in the uterus after oestrogen administration

To investigase the role of the eosinophil leukocytes in the early oestrogenic responses in the uterus, the kinetics of oestrogen-induced uterine eosinophilia and other parameters of oestrogen stimulation were studied at very early times. Uterine eosinophils increase as early as 5 min after an intravenous injection of oestradiol to immature rats, much earlier than several other changes in the early parameters of oestrogen stimulation. Large number of uterine eosinophils are found attached to the wall of small uterine blood vessels at early times. To elucidate the mechanisms involved in the specific attraction of eosinophils to the uterus in the presence of oestrogens, the in vivo localisation of oestrogens in the rat uterus at early times was studied using a radioautographic technique. Oestrogen receptors were found in the surface of eosinophils and in the wall of small uterine blood vessels. This simultaneous presence of both oestrogen receptors is proposed to explain the specific attachment of eosinophils to uterine blood vessels in the presence of oestrogens, which is the initial step toward eosinophil penetration into the uterus.

Effects of cortisol on uterine eosinophilia and other oestrogenic responses

The effects of cortisol on several oestrogenic responses of the rat uterus were measured. Whether injected i.v., simultaneously with oestradiol-17 beta, or i.p,, 12 h before the oestradiol, cortisol had no effects on the oestrogen-induced increases in uterine glycogen, protein and DNA contents. In contrast, cortisol inhibited both uterine eosinophilia and the increase of wet weight. Both responses show the same higher sensitivity to i.v. injection than to i.p. injection of cortisol. Inhibition of both responses by cortisol follows identical dose-response curves. These data support our hypothesis that the water-imbibition effect of oestrogen i- mediated by uterine eosinophilia and is thus related to the eosinophil receptor system.