Hormonal imprinting and damages caused by fetal steroid treatment. Influence of fetal treatment with pregnancy-protecting steroids (allylestrenol, diethylstilbestrol) on the effect of gonadotropin administered to cockerels perinatally and at the age of six weeks.

Single fetal (9th day) treatment with either diethylstilbestrol (DES) or allylestrenol (AE) caused a considerable decrease, both at the age of five days and six weeks, in the weight of the testicles and the diameter of the seminiferous cords, while the ratio of spermatogonia to primary spermatocytes increased. When measured either at the age of five days or six weeks, gonadotropin treatment [a combination of follicle stimulating hormone (FSH) and luteinizing hormone (LH)], administered twice daily for three days after the hatching, led to an increase in the above-mentioned parameter and to a shift in the cell ratio towards the control value. However, the absolute value of the controls treated with FSH-LH was by far not reached. The effect of perinatal treatment could be detected even in adulthood, namely, at the age of five days the response capability was relatively weak in the cockerels treated with DES and AE, while high responsiveness was observed at the age of six weeks. In some cases the relative value of the increment exceeded even that of the control; however in absolute term it was well below the control. On the basis of these experiments it might be concluded that hormonal imprinting evoked by FSH-LH treatment also occurs in the gonad damaged by DES and AE. The setting in of imprinting ameliorates the damages caused by DES and AE and increases the response capability of the cells.

Effect of embryonic and/or neonatal diethylstilbestrol and allylestrenol treatment on postnatal development of the chick testis.

The synthetic steroid diethylstilbestrol (DES) and the steroid-like allylestrenol (AE) have been used for years in human medicine for the protection of pregnancy. The hazards to the fetus of gestational DES treatment are well established [2, 17, 18]. Knowledge of a similar effect of AE is still fragmentary. Therefore, further studies are required of the after-effects of embryonic and perinatal AE exposure. In our earlier experiments with polypeptide hormones [4, 5, 6] we have observed that perinatal age is a critical period in the maturation of hormone receptors. In this period the presence of hormone induces the development of its specific receptors. The phenomenon is termed hormonal imprinting [4, 5, 6]. During its maturation the receptor is flexible and the presence of non-specific hormones capable of binding to it may alter its normal development Accordingly, even a single hormone injection in the perinatal period may alter the hormone-sensitivity of the target organ.

Changes of free histones in chick testicular and ovarian cells after embryonic and/or neonatal treatment with diethylstilbestrol (DES) or allyloestrenol (AE).

DES and AE when injected into the yolk sac of chick embryos on the 9th day of incubation decreased the neonatal weight of the testis and the PMB-reaction of spermatogonia whereas they increased the neonatal weight and granulosa cell PMB-reaction of the ovary. In the ovary, embryonic treatment increased the efficiency of post-hatching hormone treatments.

Free histones in the cells of the rat uterus after neonatal treatment with diethylstilbestrol or allylestrenol.

Neonatal diethylstilbestrol and allylestrenol treatments resulted in a prompt release of free histones that could be demonstrated histochemically by the phosphomolybdic-acid-benzidine reaction. This effect could not be observed in the uterus of 6-10-week old rats but reappeared between 11-14 weeks in the myometrium and uterine epithelium without any repeated treatment. This may be due to the increased production of endogenous steroids. The finding suggest caution when applying steroids to pregnants and neonates.

Late effects of embryonic allylestrenol treatment in chicken.

Allylestrenol when applied to chick embryos on the 9th day of incubation or on the 9th day of incubation and at hatching brought about a severe purulent inflammation of the oviduct at 6 weeks of age in 50% of the animals. Treatment at hatching only had no effect whatsoever. The findings suggest that allylestrenol must be applied with caution during pregnancy.

Influence of prenatal steroid exposure on neonatal gonadotropin imprinting. Effect of single and combined hormone treatments on the chicken ovary.

Chicken embryos treated with DES or AE at the 9th day of incubation showed postnatally an increase in ovarian mass, parenchymal zone thickness, follicle diameter and granulosa cell count. Perinatal gonadotropin treatment had a similar effect on these parameters in the control birds not receiving pretreatment, but had no influence on them in the birds pretreated with steroid. The tested ovarian parameters of the DES- and AE-pretreated birds still differed from the control at 6 weeks of age. Neonatal gonadotropin exposure induced imprinting in the birds not pretreated with steroid, to judge from an increased response (indicated by changed values of the tested parameters) to gonadotropin reexposure in adulthood. Similar, but considerably slighter changes were also shown by the steroid pretreated birds. It follows that in the birds prenatally exposed to AE or DES, supervening perinatal exposure to gonadotropin did not elicit greater changes than the prenatal exposure itself.

Effect of prenatal and/or neonatal diethylstilbestrol (DES) or allylestrenol (AE) treatment on the postnatal development of the chicken ovary.

Chickens treated with allylestrenol or diethylstilbestrol in the egg on 9th day of incubation, or one day after hatching, or on both occasions, equally showed histomorphological indications of a distinct ovarian activation at 5 days of age, which was most pronounced in the twice-treated birds. A single steroid exposure at one day of age accounted for inhibition of ovarian activity at 6 weeks, presumably owing to a long-term effect on the hypothalamo-hypophyseal system, which begins to function from the 12th day of incubation.

The damaging effect of diethylstilboestrol and allyloestrenol in the chick embryo.

After diethylstilboestrol (DES) but in particular after allyloestrenol (AE) treatment, an increased mortality of chick embryos was observed. After DES-treatment a glandular-cystic hyperplasia of the oviduct, persistence and hypertrophy of the right ovary, and pseudohermaphroditism occurred. AE caused rectal and ureteral disorders. Although there are principal differences in sexual differentiation between mammals and birds, our results suggest that the use of AE for the protection of human pregnancies requires caution.