Estrone Treatment Research Articles

Distinct roles of estrone and estradiol in endothelial colony-forming cells.

Our current understanding of the relationship between estrogen and human endothelial colony-forming cell (hECFC) function is based almost exclusively on studies investigating estradiol action at nuclear estrogen receptors. In the current study the hypothesis was tested that the less potent estrogen receptor agonist, estrone, affects hECFC proliferation, migration, secretion, and tube formation in a way that is unique from that of estradiol. The relationship between the estrogens, estradiol and estrone, is clinically important, particularly in postmenopausal women where estradiol levels wane and estrone becomes the predominant estrogen. Cultured hECFCs from peripheral blood mononuclear cell fractions were treated with concentrations of estradiol and estrone ranging from 1 nM to 1 μM separately and in combination. Following treatment, proliferation, migration, ability to attract other hECFCs (autocrine secretion), and ability to enhance endothelial cell tube formation (tubulogenesis) were tested. Functional assays revealed unique, concentration-dependent physiological effects of estrone and estradiol. Estradiol exposure resulted in increased hECFC proliferation, migration, secretion of chemoattractant, and enhancement of tube formation as expected. As with estradiol, hECFC secretion of chemoattractant increased significantly with each increase in estrone exposure. Estrone treatment produced a biphasic, concentration-dependent relationship with proliferation and tube formation and relatively no effect on hECFC migration at any concentration. The quantitative relationship between the effects of estrone and estradiol and each hECFC function was analyzed. The extent to which estrone was similar in effect to that of estradiol was dependent on both the concentrations of estradiol and estrone and the hECFC function measured. Interestingly, when the two estrogens were present, differing ratios resulted in unique functional responses. hECFCs that were treated with combinations of estrone and estradiol with high estrone to estradiol ratios showed decreased proliferative capacity. Conversely, hECFCs that were treated with combinations that were relatively high in estradiol, showed increased proliferative capacity. Cells that were treated with estrone and estradiol in equal concentrations showed an attenuated proliferative response that was decreased compared to the proliferation that either estrone or estradiol produced when they were present alone. This co-inhibitory relationship, which has not been previously reported, challenges the prevailing understanding of estrone as solely a weak agonist at estrogen receptors. This study provides evidence that estrone signaling is distinct from that of estradiol and that further investigation of estrone's mechanism of action and the biological effect may provide important insight into understanding the dysfunction and decreased number of hECFCs, and the resulting cardiovascular disease risk observed clinically in menopausal women and women undergoing hormone replacement therapy.

The role of sex steroids on cellular events involved in vascular disease

In this work we checked the hypothesis whether estrone, progesterone, and testosterone are able to modulate the interactions between platelets, monocytes, and endothelial cells either under basal or inflammatory conditions. Using adhesion assays we demonstrated that pretreatment of endothelial cells with estrone, progesterone, or testosterone prevented monocytes and platelets adhesion induced by the proinflammatory agent bacterial lipopolysaccharide. The hormones reduced the expression of mRNA of ICAM-1, VCAM-1, and P-selectin, endothelial surface proteins that mediate monocytes and platelets adhesion respectively. Integrins are the main leukocyte proteins that allow firm adhesion. Using flow cytometry we showed that estrone treatment of monocytes reduced CD11b and CD11c expression, either under basal or injury (lipopolysaccharide) conditions. The three steroids inhibited platelet aggregation in a nitric oxide dependent manner. Platelet function was not affected by the steroid treatment. The molecular mechanisms of action exerted by the steroids included the participation of the intracellular signaling pathways PKC, MAPK, and PI3K, which selectively and differentially mediate the stimulation of nitric oxide release. We evidence that estrone, progesterone, and testosterone modulate monocyte and platelet adhesion to endothelial cells, events that play a major role in the initiation and progression of vascular lesions. The steroid action was evidenced under basal or inflammatory conditions. The mechanisms of action exerted by the steroids included stimulation of nitric oxide production and the participation of PKC, MAPK, and PI3K systems.

Continuous estrone treatment impairs spatial memory and does not impact number of basal forebrain cholinergic neurons in the surgically menopausal middle-aged rat

CEE (conjugated equine estrogens) is the most widely prescribed estrogen-only menopausal hormone therapy in the United States, and is comprised of over 50% estrone (E1) sulfate. Following CEE administration, E1 is the principal circulating estrogen. However, the cognitive and neurobiological effects of E1 in a middle-aged rodent model have not yet been evaluated. We assessed cognitive effects of continuous E1 treatment in middle-aged surgically menopausal rats using a maze battery. We also quantified number of choline acetyltransferase-immunoreactive (ChAT-IR) neurons in distinct basal forebrain regions known in earlier studies in to be impacted by the most potent naturally-circulating estrogen in rodents and women, 17β-estradiol (17β-E2), as well as CEE. On the spatial working memory delayed-match-to-sample water maze, the highest E1 dose impaired memory performance during acquisition and after delay challenge. E1 did not impact ChAT-IR neuron number in the medial septum (MS) or horizontal/vertical diagonal bands. In a comparison study, 17β-E2 increased MS ChAT-IR neuron number. Findings indicate that E1 negatively impacts spatial working memory and memory retention, and does not increase ChAT-IR neuron number in basal forebrain, as does 17β-E2. Thus, data from prior studies suggest that 17β-E2 and CEE can enhance cognition and increase number of ChAT-IR basal forebrain neurons, while here we show that E1 does not induce these effects. Findings from preclinical basic science studies can inform the design of specific combinations of estrogens that could be beneficial to the brain and cognition. Accumulating data suggest that E1 is not likely to be among these key beneficial estrogens.

Evaluation of Estrogen Treatment in an Immunodeficient Mouse Endometriosis Model

Background/Aims: Endometriosis is known to be an estrogen-dependent disease. However, only a few studies have analyzed the effect of estrogen treatment in mice xenotransplanted with human endometrium. The objective of this study was to adapt a previously developed heterologous murine model to the study of estrogens and test the impact of estrone treatment on endometriosis development. Methods: Human proliferative endometrium was xenotransplanted into the peritoneal cavity of castrated immunodeficient mice. These mice were treated with estrogens by means of subcutaneous estrone-releasing pellets. The effect of estrone on estradiol level, uterine histology and endometriosis development was evaluated after 21 days. Results: Bioactivity of estrone pellets and their metabolization into estradiol were demonstrated. However, there was no impact on endometriosis development (no difference in lesion number, weight, size or fluorescence). This lack of response was not due to absence of estrogen receptor expression, since strong expression was found in all lesions harvested. Surprisingly, castrated nontreated mice presented with lesions showing high proliferative activity, similar to lesions found in treated mice (around 30%). Conclusion: The high proliferation observed in lesions recovered from ovariectomized nontreated mice questions the utility of using estrogens in heterologous murine models.

Estrogen Levels Do Not Correlate With Improvement in Cognition

To investigate whether an association exists between estradiol and estrone levels and measures of cognitive functioning in women with Alzheimer disease (AD) treated with conjugated equine estrogen (Premarin; Wyeth-Ayerst, Philadelphia, Pa). We studied 120 postmenopausal women who underwent hysterectomy and who had AD treated with Premarin for 1 year. Plasma estradiol and estrone levels were determined at multiple points during the 1-year treatment trial. The change from baseline level at 2 and 12 months was associated with the change score on 7 different assessments of cognitive functioning. At baseline, estradiol levels were low and there were no associations between the estradiol level and the 7 neuropsychological measures. A similar pattern was observed for estrone treatment. During treatment with 0.625 mg/d of Premarin, estradiol levels increased about 4-fold; while receiving 1.25 mg/d of Premarin, estradiol levels increased about 8-fold. A similar pattern was seen with estrone treatment. For both estradiol and estrone levels, there were no significant associations between the change in plasma level and the change in neuropsychological test scores at either 2 or 12 months. Although Premarin elevated estradiol and estrone levels, there was no association between hormone levels and cognitive functioning after either 2 or 12 months of treatment.

Steroid sulfatase inhibitor alters blood pressure and steroid profiles in hypertensive rats

Our hypothesis is that the steroid sulfatase gene ( Sts) may indirectly contribute to the modulation of blood pressure (BP) in rats with genetic hypertension. The steroid sulfatase enzyme (STS) catalyzes the conversion of estrone sulfate, dehydroepiandrosterone sulfate, cholesterol sulfate and glucocorticoid sulfates to their active nonconjugated forms. This causes the elevation of biologically active steroids, such as glucocorticoids, mineralcorticoids as well as testosterone, which may lead to increased BP. The main objective was to examine the effects of a steroid sulfatase inhibitor on blood pressure and steroid levels in rats with hypertensive genetic backgrounds. Three treatment groups, 5–15 weeks of age were used: controls, estrone and STS inhibitor (estrone-3- O-sulfamate), ( n=8 per group). BP was taken weekly by tail cuff, and serum testosterone (T), estrogens (E), and plasma corticosterone (C) levels were measured by radioimmunoassay. BP was significantly reduced by the STS inhibitor in the strains with genetically elevated BP. Also the inhibitor alone significantly reduced plasma corticosterone in all strains compared to estrone treatment with a concomitant as well as significant rise in estrogens and reduction in testosterone and body weight.

Protective effects of estrogen in a rat model of age-related cataracts.

Women have a higher incidence of cataracts, and epidemiologic data suggest that the increased risk may be caused by a lack of estrogen in postmenopausal years. We have examined the effects of estrogen on methylnitrosourea (MNU)-induced cataractogenesis in Sprague-Dawley rats. Animals were ovariectomized, injected with MNU, and treated with estradiol or estrone by a continuous-release, subcutaneous Silastic implant, or they received an empty Silastic implant (no hormone). In the no-hormone group, rats developed opaque lenses approximately 6 months after MNU treatment. By 8 months, 74% (14/19) of the no-hormone rats had evident opacity in one or both eyes by simple gross inspection; 58% (22/38) of the eyes in this group were opaque. Estradiol or estrone treatment reduced the incidence of cataractous eyes to 12% or 25%, respectively. Lenses were examined under a dissecting microscope for light transmission. The lenses of the group treated with no hormone had light transmission of 26% +/- 9.2%, whereas lenses from the estradiol-treated animals had light transmission of 72% +/- 5.8%. Histological examination revealed that the anterior cortices of the opaque lenses were disrupted and showed the hallmark signs of age-related cataracts; in addition, some eyes that appeared clear by macroscopic examination showed the early histologic signs of cataractogenesis. It was demonstrated with reverse transcription-PCR that lens cells express both alpha and beta types of estrogen receptor, suggesting that the protective effects of the hormones may be a direct, receptor-mediated phenomenon. Thus, the MNU-treated, ovariectomized rat serves as a model for age-related cataractogenesis, and observation of a clear protective effect of estrogens in this system supports the implications of epidemiologic data.

The effect of estrone and estradiol treatment on endometrial total protein, uteroferrin, and retinol-binding protein secretion during midpregnancy or midpseudopregnancy in swine.

It has been hypothesized that conceptus estrogens influence endometrial protein secretion during pregnancy in swine. To test this hypothesis, the effect of estrone and estradiol treatment from d 30 to 60 of pregnancy or pseudopregnancy on endometrial protein secretion was investigated. Pregnant (P; n = 16) and pseudopregnant (PP) gilts (n = 18) received either sham treatment or estrone or estradiol implants (5 mg/d release rate; 60 d release) on d 30 of P or PP. Blood samples were collected on d 30, 40, 50, and 60 to measure estrone and estradiol. On d 60, gilts were hysterectomized. For P gilts, endometrium in apposition to one placenta from each uterine horn was collected. For PP gilts, each uterine horn was flushed with 40 mL of leucine-deficient minimal essential medium (MEM), and endometrial tissue was collected from each horn. Endometrial tissues were incubated in MEM in the presence of 50 microCi of [3H]leucine to examine protein secretion. Estrone and estradiol treatments increased both plasma and endometrial concentrations of estrone (P < .01 except endometrium for P gilts) and estradiol (P < .01, respectively). Endometrium from P gilts secreted more nondialyzable macromolecules (NDM), acid phosphatase activity (AP, a measure of uteroferrin), and retinol-binding protein (RBP) in culture than did endometrium from PP gilts. Estrone treatment increased (P < .01) endometrial NDM from P gilts but not that from PP gilts; estradiol had no effect. Both estrone and estradiol increased (P = .069) endometrial secretion of AP of PP but not of P gilts. Endometrial secretion of RBP was not affected by either estrone or estradiol treatment. Neither estrone nor estradiol affected total protein or AP and estrone treatment decreased (P < .05) RBP in uterine flushings from PP gilts. These data indicate that endometrium from P pigs secretes more protein than endometrium from PP pigs but neither estrone nor estradiol completely mimics the effect of pregnancy.

THE ANTIPROLIFERATIVE EFFECT OF LUTEOLIN AGAINST DIETHYLSTILBESTROL-INDUCED CELL-PROLIFERATION IN THE MAMMARY-GLAND OF RAT

We have shown previously that stilbene estrogen or estrone treatment increases proliferative activity and alters cell cycle. In the present study we present evidence that alterations of the proliferative activity and cell cycle kinetics in the epithelial cells of the mammary glands of Noble rats by stilbene estrogen can be significantly blocked by the coadministration with naturally occurring plant flavone, luteolin. Luteolin treatment alone does not have any effect on cell growth, cell proliferation, cell cycle or cell differentiation. Diethylstilbestrol (DES) treatment increased the average number of cells from 3,080 to 8,936 as compared to controls. The average number of cells observed in DES alone treated group was reduced to 3,845 by luteolin cotreatment. The co-treatment with luteolin significantly reversed the effect of DES on the proliferative activity in all structures of mammary gland. An increase in both labeling index and growth fractions by DES exposure was also significantly reversed by co-treatment with luteolin. Cotreatment with luteolin plus DES led to a 64% decrease in the cells in G1 phase (p<0.05), whereas cells in S phase were reduced by 55% (p<0.05) as compared with DES alone. Similarly, the potential doubling time (T-pot) was significantly reduced from 50-55 h as observed in control group to 22-24 h by DES treatment. However. luteolin co-treatment protected the reduction of (T-pot) by DES by increasing the potential doubling time from 22-24 h to 33-38 h. Also, co-treatment with luteolin plus DES prevented the conversion of a small percentage of the gland to Lob 2 and Lob 3 compared to DES treated female rats. Antiproliferative action of luteolin suggests that it may have potential anticarcinogenic effects against estrogen-induced mammary carcinogenesis.

Perturbation of cell cycle kinetics in the mammary gland by stilbene estrogen, diethylstilbestrol (DES).

In the present study we have examined the effect of stilbene estrogen on the proliferative activity, cell cycle kinetics and the differentiation of the mammary gland of female Noble rats. The exposure of animals to stilbene estrogen (diethylstilbestrol) or natural estrogen (estrone) (10 micrograms/24 h) significantly increased proliferation in mammary epithelial cells. Both labeling index and growth fraction were increased by DES or estrone treatment. In addition, both stilbene and natural estrogen exposure altered cell cycle kinetics. Stilbene estrogen exposure to animals increased the conversion of mammary epithelial cells from G0 to G1 and G1 to S-phase cells by 8.3- and 8.5-fold, respectively, compared to that of control. Differentiation measured by the degree of lobular maturation revealed that the conversion of immature structures to mature structures was significantly increased by 2.4-fold in response to DES or estrone exposure compared to that of control. Perturbation of cell cycle is considered as a risk factor for the development of cancer. Changes in proliferation and cell cycle have been shown to lead to genetic instability, ultimately resulting in cell transformation. Our results indicated an increase in labeling index and growth fraction and a perturbation in cell cycle kinetics from DES or estrone exposure. Perturbation of cell cycle in response to stilbene estrogen exposure may produce adverse effects in the mammary glands of the Noble rats.

Estrone-induced cell proliferation and differentiation in the mammary gland of the female Noble rat.

In this study we examined the influence of estrone on proliferation and differentiation in the mammary gland of female Noble rats. Estrone treatment increased proliferation in mammary epithelial cells at days 3 and 7, and peaked by day 11 of estrone exposure. In addition, estrone exposure altered cell cycle kinetics. Animals exposed to estrone for 11 days demonstrated a 9-fold increase in the cells in G1 phase and a 48-fold increase in the cells in S phase, compared to those of controls. Differentiation, measured by the degree of lobular maturation, was significantly increased in the treatment group by day 7 and continued to mature through day 21 post estrone implant. The appearance of the mammary glands in these animals approached the morphology normally found during pregnancy and lactation. In a subset of animals we examined the effects of a concurrent treatment with luteolin, a bioflavonoid which has been shown to inhibit estrone binding to type II estrogen receptors. Luteolin significantly reversed the effects of estrone treatment on both proliferation and differentiation in these animals. Changes in proliferation and cell cycle kinetics have been shown to lead to genetic instability, ultimately resulting in cell transformation. Our results indicated an increase in proliferative cells by > 2-fold and a perturbation in cell cycle kinetics from estrone exposure. These changes may play a role in the induction of estrone-induced mammary cancer in the Noble rat model. In addition, the anti-proliferative action of luteolin suggests that it may play a protective role in estrone-induced mammary carcinogenesis.

Effect of estrone treatment from day 30 to 45 of pregnancy on endometrial protein secretion and uterine capacity

Secretion of proteins by the endometrium of pigs during pregnancy is reported to be influenced by progesterone and estrogen. The effect of estrone treatment from d 30 to 45 of pregnancy on endometrial protein secretion and uterine capacity was tested in unilaterally hysterectomized-ovariectomized (UHO) gilts. Ten intact and 16 UHO crossbred gilts were mated and assigned to the following treatments: 1) intact controls, n = 10; 2) UHO, n = 8; and 3) UHO + estrone (E; two 150-mg implants, 60-d release, implanted on d 30 of gestation), n = 8. Gilts were killed on d 45 of pregnancy. A sample of allantoic fluid was collected from each conceptus. Blood and endometrial tissue samples were collected to evaluate estrone concentrations, and placental and endometrial tissues were incubated to evaluate protein secretion. Estrone treatment increased (P < .01) plasma and endometrial tissue estrone concentrations. Unilateral hysterectomy-ovariectomy decreased (P < .01) fetal survival. No effect of estrone was detected on the number of live fetuses, protein secretion by endometrial tissue in culture, or allantoic fluid protein, acid phosphatase, retinol binding protein, or retinol. Estrone treatment decreased uterine weight (P = .05) and allantoic fluid fructose concentrations (P < .05). After correction for allantoic fluid volume, allantoic fluid protein, retinol, and acid phosphatase activity were decreased (P < .05) in UHO-treated pigs. The UHO treatment did not affect allantoic fluid fructose concentrations. These results indicate that 1) estrone treatment from d 30 to 45 of pregnancy and at the dosage used did not alter endometrial protein secretion or fetal survival, and 2) UHO decreased the amount of endometrial proteins available to conceptuses.

The Role of Steroid Hormones and Decidual Induction in the Regulation of Adenosine Diphosphoribosyl Transferase Activity in Rat Endometrium*

Adenosine diphosphoribosyl transferase (ADPRT) activity was measured in endometrial nuclei isolated on estrus and day 4 from rats ovariectomized on estrus (day 0) and treated on days 0-3 with vehicle, estrone (E), progesterone (P), or E plus P, a treatment that supports a decidual response. Also, measures were made of ADPRT in endometrial nuclei isolated from rats during the estrous cycle, days 1-7 of pseudopregnancy, and days 5-7 of pseudopregnancy after decidual induction on day 4. E treatment produced an increase in ADPRT activity, DNA content, tissue mass, and total protein. P alone did not affect ADPRT activity or DNA content. Enzyme activity and DNA content measured after E plus P treatment were significantly lower than those after estrone treatment and higher than those in vehicle-treated controls. The parallel stimulation of ADPRT activity and DNA synthesis by E supports a role for ADPRT in cellular proliferation. The blockade of E-stimulated ADPRT activity by P is consistent with a previously proposed model of hormonal regulation of rat uterine pyridine nucleotide metabolism. In endometrium from cycling rats, ADPRT activity did not change between metestrus and proestrus, but declined on estrus. After a rise on day 1 of pseudopregnancy, ADPRT activity remained stable through day 5 and declined on day 6. The relatively constant enzyme activity during the cycle and early pseudopregnancy, when hormone levels undergo great changes, may reflect an additional level of control in intact animals not observed in ovariectomized hormone-treated rats. Decidual ADPRT activity declined on day 5, 1 day after uterine trauma, and increased on day 6. This pattern of enzyme activity is consistent with the initial phase of cytodifferentiation, followed by rapid proliferation during early decidualization.

Hormonal regulation of mouse mammary tumor growth

In view of reports that human breast cancer cells secrete growth factors that can replace estradiol in sustaining tumor growth [1], we have investigated whether hormone independent (HI) GR mouse mammary tumors can sustain growth of estrogen-depleted hormone dependent (HD) tumors. HD GR mammary tumor TS1 106 was grafted subcutaneously in the right flank of estrone plus progesterone treated castrated (020 × GR)F 1 mice. After 2 weeks the estrone treatment was stopped and the mice received 50,100 or 150 mg HI GR mammary tumor TS1 104 in the left flank. However, the regression of the HD tumor due to estrone depletion was not prevented or retarded by the HI grafts. In other experiments we investigated integrations of mouse mammary tumor virus (MMTV) proviral DNA in the DNA of GR mammary tumors. We could demonstrate the presence of two cell populations in tumor TS196, both HD but differing in MMTV DNA integration events. Our data indicate that exogenous integrations of MMTV proviruses can take place in mouse mammary tumor DNA without loss of hormone dependency of the tumors. Like in GR/Mtv-2 + mice, mammary tumor transplants differing in MMTV proviral integrations are also observed in 020/Mtv-2 + mice.

Mitochondrial protein phosphorylation and cardiomyopathy in genetically diabetic mice: The effect of estrone treatment

The alpha-subunit of pyruvate dehydrogenase and succinyl-CoA synthetase are phosphorylated after incubation of cardiac mitochondria from genetically diabetic mice with [gamma-32P]ATP. There is significantly increased incorporation of 32P into pyruvate dehydrogenase from diabetic mice when compared to controls. The enhanced rate of pyruvate dehydrogenase phosphorylation correlates well with the previously reported defective oxidative metabolism and decreased activity of this enzyme from diabetic mice. The relationship between abnormal mitochondrial function and development of cardiomyopathy in the diabetic mice has been studied further by in vivo estrone treatment. The results indicate that ultrastructural alterations of myocardium are closely associated with the defective pyruvate oxidation (via phosphorylation of pyruvate dehydrogenase) and both processes can be prevented by 7-12 weeks estrone treatment.

Estrone treatment dissociates primary versus secondary consequences of "diabetes" (db) gene expression in mice

Estrone treatment dissociates primary versus secondary consequences of "diabetes" (db) gene expression in mice

Uptake, receptor and biological response of estrone in the fetal uterus of guinea pig.

In vivo and in situ subcutaneous injection of 30 muCi of 3H-estrone (3H-E1) to guinea pig fetuses was carried out to study the dynamics of the selective uptake and retention of this estrogen in the uterus and other fetal organs. In the fetal uterus an increase in the uptake of radioactivity with time was found which was maximal 1 h after injection of 3H-E1. The analysis of radioactive material showed that in the fetal uterus unmetabolized 3H-E1 accounts for 65-75% of the total radioactivity between 10 and 60 min after the injection and its maximal concentration is 2.5-15 times and 10 times higher than the maximal concentrations found in other fetal organs and fetal plasma, respectively. Significant amounts of 3H-E1 were also present in lung (33-60% of the total radioactivity in this tissue), brain (37-52%) and ovary (18-47%), while an important conversion of 3H-E1 into 3H-estradiol was observed in the kidney (20-26%). Estrogen sulfates, essentially estrone sulfate, represented the greater part of the fetal plasma radioactivity (30-49%). 3H-E1-specific binding sites in the cytosol of the fetal uterus were found with physicochemical characteristics (specifically limited to natural and synthetic estrogens, Kd = 8.1 +/- 1.2 x 10(-10) M (SD), sedimentation coefficient 8S) similar to those of the typical estrogen receptor. The cytosol receptor-3H-E1 complex has a dissociation rate constant (K-1) of 16 +/- 0.7 x 10(-4) s-1 at 25 degrees C. The responsiveness of the fetal uterus to estrone treatment was studied after subcutaneous administration of estrone to pregnant guinea pigs (1 mg/kg/day for 3 consecutive days). Two biological responses were observed: an increase in fetal uterine weight (50-100% in relation to the nontreated animals) and a significant stimulation of progesterone receptor protein (10-16 times higher than in control animals). At the same time, there was a 50-70% decrease in the total estrogen receptor concentration. It is concluded that estrone could be involved in the biological responses to estrogen in the fetal uterus of guinea pig.

Maintenance of unimplanted fertilized ova in spayed rats: effects of cortisone acetate therapy during the period of embryonic diapause.

Rat dams were ovariectomized on day 3 of pregnancy and treated with corn oil (0.25 ml/day), progesterone (4 mg/day), cortisone acetate (2 or 10 mg/day), cortisone acetate (10 mg/day) plus progesterone (4 mg/day) or progesterone (4 mg/day) plus oestrone (1 microgram/day) from days 2 to 8 or 14, followed by 6 to 11 days of treatment with progesterone (4 mg/day) plus oestrone (1 microgram/day). Implantation of ova at the normal time was realized in the animals treated from day 2 with progesterone plus oestrone. Implantation of ova was only realized subsequent to progesterone plus oestrone in the dams treated with progesterone alone, cortisone acetate alone, or progesterone plus cortisone acetate, except for one animal in the latter group. Implantation of ova was not usually realized even after progesterone plus oestrone treatment in the dams treated with corn oil. Even though cortisone acetate maintained unimplanted ova in spayed rats in much the same manner as does progesterone, it was not equivalent to progesterone in efficacy or action.

Silastic implants releasing estrone in the treatment of climacteric complaints

A study on continuous low-dose estrone treatment achieved with two different silastic implants is presented. In the study the estrogen treatment was supplemented with the addition of progestin in three different modes of application. The measurements of plasma estrone and estradiol concentration showed a 3- to 6-fold and a 2- to 3-fold increase, and that of FSH a decrease of 25%. The measurements of plasma estrone gave concentrations of 200–400 pg/ml and plasma estradiol was 70–200 pg/ml with uncovered estrone-releasing implants after 4 wk of treatment. The ratio of plasma levels of estrone/estradiol was around 3. The initial high estrone concentration after implantation could be eliminated by covering the rods with a thin layer of neutral silastic material. Plasma FSH and LH concentrations significantly depressed when the estrone treatment was combined with levonorgestrel-releasing implants. The insertion of estrone-releasing implants alone and in combination with the cyclic treatment with norethindrone perorally, or with a norgestrienone-releasing silastic vaginal ring suppressed only the plasma FSH concentration. The climacteric complaints disappeared in a few days in every patient treated with uncovered estrone-releasing implants. Because it is easy to remove when required, the treatment with estrone-releasing silastic implants can be regarded as being safe for the patients.

Prolactin secreting cells in the hypophysis of the brown spiny mouseMus platythrix (Bennett)

Prolactin secreting cells are identified in thepars distalis of Mus platythrix by conventional methods of light and electron microscopy. Two types of prolactin secreting cells are recognised. These types are estrone-sensitive, mammotrophic type I, and luteotrophic type II, respectively. Histochemical analysis revealed that the cells are rich in RNA, basic proteins, alkaline phosphatase and are resistant to extraction with 0·5% trichloroacetic acid. Quantitative data showed that the prolactin secreting cells increase during pregnancy, lactation and estrone treatment. Estrone at low dose levels caused immense hyperplasia whereas at higher levels there was no corresponding increase in the percentage of type I cells. Ultrastructurally, prolactin secreting cells are characterised by the presence of stacked endoplasmic reticulum, oval or irregular secretory granules. The Golgi apparatus is seen rich in vacuolar system.