ABSTRACT

The formation of new capillaries, both in extraembryonic membranes and in the maternal endometrium, is an essential prerequisite for appropriate feto-maternal relationships throughout pregnancy. At present there is no indication of the nature of the uterine angiogenic stimulus. In-vitro, degradation products of hyaluronic acid, following its catalysis by hyaluronidase, have been shown to have angiogenic properties. In the current study, levels of hyaluronic acid in endometrial tissues and of hyaluronidase and hyaluronic acid in uterine flushings were measured during the oestrous cycle and early pregnancy.

The concentration of both hyaluronic acid and hyaluronidase in uterine flushings followed the growth and regression of the corpus luteum, in that basal levels detected on days 0 and 6 increased to peak concentrations on days 12 and 15. By day 18, levels of both hyaluronidase and hyaluronic acid had decreased in cyclic gilts, but remained increased in pregnant pigs. Tissue concentrations of hyaluronic acid were not affected by pregnancy or by the day of the oestrous cycle. In a subsequent experiment, four groups of gilts were ovariectomized on day 4 and thereafter received daily injections of corn oil, progesterone, oestrogen or a combination of oestrogen and progesterone. Hyaluronidase was undetectable in uterine flushings collected on day 15 from corn oil-and oestrogen-treated gilts, but present in similar amounts in uterine flushings from gilts treated with progesterone and progesterone plus oestrogen. Similarly, uterine fluid concentrations of hyaluronic acid were increased in progesterone- and progesterone plus oestrogen-treated gilts, but not in corn oil-or oestrogen-treated pigs. Tissue concentrations of hyaluronic acid were unaffected by steroid treatment.

These results indicate that progesterone stimulates secretion of hyaluronidase and hyaluronic acid; both substances believed to be associated with the presence of an angiogenic factor in the pig uterus, but there was no evidence of a synergistic interaction between progesterone and oestrogen.

Journal of Endocrinology (1990) 125, 15–19

ABSTRACT

This paper describes the effect of oestradiol-17β implants on unbound cytosolic and nuclear oestrogen receptors in the uterus and anterior pituitary gland of ovariectomized adult rats. Rats were ovariectomized and implanted 1 week later with oil or oestradiol-17β oil solution in silicone elastomer capsules. In the latter animals the capsules either remained in situ until decapitation (subgroup 1) or were removed 48 h after implantation (subgroup 2). Implants of oestradiol-17β caused a significant depletion in both forms of oestrogen receptor in the uterus and anterior pituitary gland of rats in subgroup 1. In subgroup 2, however, there was an almost complete return to control concentrations of uterine cytosolic receptors and anterior pituitary cytosolic and nuclear receptors. Concentrations of uterine nuclear oestrogen receptors showed only a partial recovery.

These data suggest that both forms of oestrogen receptor constitute an integrated population of oestrogen receptors, without dependence on intracellular location, and that in the presence of oestradiol these receptors are bound more quickly than they are synthesized. The results also indicate the existence of a dynamic equilibrium of unbound receptors between the cytosolic and nuclear compartments for both target organs, but show that in the absence of oestradiol this equilibrium is restored in the anterior pituitary sooner than in the uterus.

J. Endocr. (1987) 115, 205–210

ABSTRACT

Oestrogen induces a migration of eosinophil leukocytes to the uterus where, it is suggested, these cells mediate several responses to hormone stimulation. To investigate the mechanism of the recognition of the uterus by the eosinophils, the present study describes the effect of a blockade of the rat reticulo-endothelial system with colloidal carbon on oestrogen-induced uterine eosinophilia, and other responses to oestrogen stimulation that, it has been suggested, are mediated by eosinophils.

In the absence of oestrogen colloidal carbon induced an increase in the number of eosinophils in mesometrium but not in endometrium with myometrium, and a slight oedematous reaction in deep endometrium. Colloidal carbon abolished the oestrogen-induced increase in the number of eosinophils in endometrium with myometrium and drastically decreased the oestrogen-induced increase in uterine wet weight and the endometrial oedematous responses 6 h after the administration of oestrogen.

The present results agree with the hypothesis that most uterine water imbibition is mediated by eosinophils and suggest a possible mechanism for the interaction of colloidal carbon with eosinophil migration to the uterus.

J. Endocr. (1986) 109, 89–95

Uteroglobin is a predominant protein in the rabbit uterus, where it is induced by progesterone, and occurs also in the lung, where its level is constitutive. A recombinant plasmid containing uteroglobin complementary DNA (cDNA) has been constructed previously from partially purified uteroglobin mRNA. In this study, the cloned uteroglobin cDNA has been used as a probe to determine the cellular content of uteroglobin mRNA at different times in early pregnancy in both rabbit uterus and lung. By RNA-excess hybridization to poly A-enriched RNA and to total nucleic acid extracts an increase in steady-state uteroglobin mRNA level was detected, from approximately 250 molecules/uterine epithelial cell in non-pregnant rabbits to approximately 6800 molecules/cell on day 4 of pregnancy, after which the levels declined progressively up to day 8. The pulmonary level of uteroglobin mRNA was about 400 molecules/cell and did not change significantly with day of pregnancy. The major factor in regulating the production of uteroglobin in the uterus of pregnant rabbits is the accumulation and subsequent depletion of its mRNA.

SUMMARY

Observations are recorded on 65-day guinea-pig foetuses removed from twenty-nine experimental animals in which impregnation was limited to one horn of the uterus by transection of the other horn, and from twenty-nine unoperated control animals. The data are used to show that:

(1) As litter size increases, mean foetal weight and length decrease and total litter weight increases.

(2) Mean foetal weight and length decrease as the number of foetuses in the same horn increases, and as the number of foetuses in the other horn increases.

(3) In litters of less than four, association between rate of foetal growth and litter size is independent of distribution of foetuses between the two horns. In litters of four or more there is evidence of a local effect determined by the contiguity of foetuses within the same horn.

These observations suggest that the influence of litter size on rate of foetal growth is due partly to a local effect, determined by the number of foetuses within the same horn of the uterus, and partly to a general effect, determined by the total number of foetuses in the uterus, and independent of their distribution between the horns.

As the number of foetuses in one horn increases, mean number of foetuses in the other horn decreases. This result appears to be determined by a negative correlation between numbers of ova released from the two ovaries. It cannot be ascribed to differences in the proportion of corpora lutea represented by foetuses on the two sides.

ABSTRACT

ICI 182,780 is a potent specific pure antioestrogen which may offer advantages in breast cancer treatment compared with partial agonists like tamoxifen. To characterize further the potency and efficacy of ICI 182,780, its effects on the uterus of ovariectomized, oestrogen-treated monkeys (Macaca nemestrina) have been measured using magnetic resonance imaging (MRI). Quantitative MRI allows accurate non-invasive repetitive measurements of endometrial and myometrial volume following hormonal treatments, using each animal as its own control. Single i.m. injections of a long-acting oil-based formulation of ICI 182,780 sustained blockade of oestradiol action on the monkey uterus in a dose-dependent manner for 3–6 weeks. Repeated injections of 4 mg ICI 182,780/kg at 4-weekly intervals provided increasingly effective blockade of uterine proliferation. In a short-acting formulation, ICI 182,780 also completely blocked the trophic action of oestradiol, administered concurrently, in ovariectomized monkeys. Similarly, ICI 182,780 caused involution of the uterus stimulated by prior treatment with oestradiol. The rate and extent of uterine involution in monkeys treated with ICI 182,780 was similar to that seen following oestrogen withdrawal. These studies demonstrate that ICI 182,780 is a fully effective pure antioestrogen in a primate.

Journal of Endocrinology (1992) 135, 239–247

SUMMARY

The spontaneous motility of the intact uterus of spayed oestrogenized rabbits under sodium pentobarbitone anaesthesia has been recorded. Both uteri of each animal behaved similarly, and contractions often appeared to be synchronous. Small changes of load affected the amplitude of contractions, but did not alter uterine responsiveness to neurohypophysial or adrenomedullary hormones. Mid-thoracic section of the spinal cord obliterated spontaneous motility of the uterus; spinal anaesthesia did not. Spontaneous motility persisted for as long as 7 hr after decerebration and removal of the pituitary gland.

The threshold dose of oxytocin for activating the oestrogenized uterus was the same as that for the lactating mammary gland, i.e. 1–5 mu. Doses up to 50 mu. usually gave an increase in frequency and amplitude of contractions. In the same dose range vasopressin either had little effect or inhibited spontaneous uterine motility, although milk ejection was stimulated. Slow infusion of oxytocin at rates of 1·5–48 mu./min produced graded increases in the rate and depth of uterine contractions and, at the same time, in similarly treated, lactating animals, rhythmic milk-ejection responses which at the higher rates of infusion merged to give a tetanic (plateau) type of milk ejection.

Adrenaline or noradrenaline in doses of 1–5 μg produced diphasic uterine responses, initial contractions being followed by inhibition of spontaneous motility. They also inhibited the uterine, as well as the milk-ejection response to oxytocin injected 10–30 sec later. The inhibitory effect of adrenaline on both organs was about twice that of noradrenaline.

The above-mentioned responses to adrenaline and oxytocin could also be elicited by electrical stimulation of the hypothalamus. Stimuli in the dorsal, lateral, perifornical and posterior hypothalamic areas produced effects equivalent to those of 1–5 μg adrenaline on both the uterus and mammary gland. These responses were abolished by mid-thoracic section of the spinal cord or by spinal anaesthesia. In such preparations responses typical of those produced by oxytocin were seen in both organs after stimulation of the paraventricular nuclei, supraoptic nuclei and the hypothalamo-hypophysial nerve pathways of the tuber cinereum and neural stalk.

Dilatation of the vagina (or rectum) gave rise to a uterine response similar to that resulting from adrenaline or noradrenaline. The response was abolished by spinal anaesthesia, but not by mid-thoracic spinal section or decerebration. The same stimuli also produced 'bearing down' contractions of the abdominal muscles. Contractions of the uterus could also be elicited by mechanical stimuli, in the absence of functional spinal connexions.

Abstract

Uterine natriuretic peptides may be involved in the alterations that occur in the uterus during the estrous cycle through its role in hydromineral balance. The following studies were performed to determine whether uterine natriuretic peptides and receptors follow a cyclic pattern during the estrous cycle. The results obtained show that atrial natriuretic peptide (ANP) content in rat uterine tissue was low in proestrus (8·5 ± 2·6 pg/g) and significantly increased (P<0·001) in estrus (71·5 ± 16·6 pg/g), metestrus (82·6 ± 19·7 pg/g) and diestrus (91·0 ± 19·4 pg/g), whereas plasma ANP was not altered during the cycle. Similarly, measurement of uterine ANP mRNA by reverse transcribed polymerase chain reaction (RT-PCR) indicated lowest levels of ANP mRNA at proestrus. Measurement of C-type natriuretic peptide (CNP) by a specific and sensitive radioimmunoassay revealed that uterine CNP also varies with the estrous cycle. Uterine CNP was low in diestrus (143·2 ± 22·4 pg/mg protein) as compared with proestrus, estrus and metestrus (305·3 ± 51·5, 267·5 ± 44·9, 291 ± 41·2 pg/mg protein respectively, P<0·05). Autoradiography performed on uterine tissue slices localized natriuretic peptide receptors to myometrial smooth muscle layers and to endometrial uterine glands. High binding of ¹²⁵I-ANP was observed in proestrus and estrus with 60–75% decreases during metestrus and diestrus. Binding of ¹²⁵I-tyr⁰CNP to uterine slices was also high during proestrus, but declined by 35% at estrus, metestrus and diestrus. The alterations in the receptors were also observed at the level of synthesis. RT-PCR detection of guanylyl cyclase A (GC-A) receptor mRNA and guanylyl cyclase B (GC-B) mRNA showed high signals at proestrus but 4- and 2-fold reductions respectively at metestrus and diestrus. In conclusion, variations in uterine ANP and CNP and their receptors during the rat estrous cycle imply the involvement of the natriuretic peptides in uterine hydromineral balance and myometrial motor activity.

Journal of Endocrinology (1997) 153, 345–355

ABSTRACT

To investigate the effects of adrenal hormones on oestrogen activity in the uterus, ovariectomized ewes were either adrenalectomized, administered glucocorticoid-like preparations (CORT), or remained as controls. The adrenalectomized ewes were maintained with a corticoid-replacement therapy and monitored daily for plasma glucose and Na⁺/K⁺ concentrations. Blood samples were collected from all ewes at 15-min intervals for 4 h and assayed for LH and FSH. The adrenalectomized ewes were killed 9 days after adrenalectomy, while the CORT ewes were killed after 3 weeks of drug therapy. The control ewes were killed simultaneously with the CORT ewes. Uterine tissues were homogenized and the numbers of oestradiol receptors and tissue concentrations of oestradiol-17β were measured. The adrenalectomized ewes had significantly higher concentrations of cytosolic oestrogen receptors in the uterus than did the control ewes, which had significantly higher concentrations than the CORT ewes (0·95±0·06, 0·76 ± 0·02 and 0·60±0·02 (s.e.m.) μmol/kg protein respectively). The concentrations of oestradiol-17β measured in uterine tissues were significantly lower in adrenalectomized and CORT ewes than in control ewes (37·4±5·5, 61·7±25·7 and 135·5 ± 12·8 pmol/kg respectively). There were no significant differences between any groups in the peripheral concentrations of LH or FSH. These results indicate that the adrenal gland affects the concentrations of both oestrogen and its receptor in the uterus of ovariectomized ewes, probably by different mechanisms. These effects are not mediated by gonadotrophins.

J. Endocr. (1988) 118, 375–380

SUMMARY

The 105000 g supernatant fraction (soluble proteins) of homogenates of human uterine tissue, essentially myometrium, and peripheral blood serum, were assayed for progesterone- and cortisol-binding activity by batchwise use of Sephadex G-25 in test tubes (not gel filtration) under equilibrium conditions; the results were expressed empirically as the reciprocal of the protein concentration, 1/P, at 50% steroid binding. The steroid-binding activity of the uterine soluble proteins was due apparently to a single component closely resembling corticosteroid-binding globulin (CBG) with respect to equilibrium association constants, steroid ligand specificity, and elution behaviour on hydroxylapatite chromatography and Sephadex G-100 filtration. Therefore, the mean 1/P values for steroid-binding activity were converted to the apparent CBG content (nmol/g total soluble protein). Comparison of the mean ratio (about 0·2) of the respective total binding activity, uterus (g): serum (ml), with the mean ratio (0·03) of the total iron content, uterus:serum, indicated that the high CBG content of the uterus could not be attributed to retention of blood; the apparent CBG levels in skeletal muscle (pectoral) were very low. The mean values for the apparent CBG content of uterine soluble protein were almost as high as those for the CBG content of serum protein; the mean value for the apparent CBG content of uterine soluble protein was slightly higher for pregnant women (mostly in early pregnancy) than that for non-pregnant women with various gynaecological complications. On polyacrylamide gel electrophoresis, soluble protein from the uterus resembled that of serum in the areas corresponding to serum albumin and transferrin; the electrophoretic patterns were distinctly different, however, in the area between the origin and the transferrin band.

It is suggested that CBG may accumulate in interstitial fluid of the myometrium, thereby regulating the local concentration of bound and unbound progesterone and cortisol, and influencing hormone action on the respective target cells, muscle and fibroblast. A more extensive study of levels of progesterone- and cortisol-binding activity in serum was carried out also. It was concluded that the progesterone-binding activity of human serum, as in the case of human myometrium, is due largely to CBG.