Estradiol Dipropionate Treatment Research Articles

Effect of exogenous oestrogen treatment frequency on induction of artificial lactation in pseudopregnant sows.

In this study, we examined whether the frequency of exogenous oestrogen treatment affects the induction of artificial lactation and milk production. Furthermore, we analysed changes in milk components obtained from artificially lactating sows. Pseudopregnant induced by treatment with 30 mg of estradiol dipropionate (EDP) on Day 10 (Day 0 = the last day of estrus) were divided into three groups: those administered 5 mg of EDP once on Day 39 (n = 5), twice on Days 32 and 39 (n = 5) and three times on Days 25, 32 and 39 (n = 6). All animals were treated with prostaglandin F2α (PGF2α) on Day 46 for induced lactation. Artificial lactation was induced in 66.7%-80.0% of sows, and the EDP treatment frequency before PGF2α administration had no significant effect on either the induction rate of artificial lactation or the milk yield during the experimental period. The milk composition (levels of crude protein, crude fat, crude ash, lactose and immunoglobulin) did not differ among the groups. In conclusion, the number of EDP treatments prior to PGF2α administration had no effect on either the efficiency of artificial lactation induction or milk production.

Regulation of maternal behavior, social isolation responses, and postpartum estrus by steroid hormones and vaginocervical stimulation in sheep

Periparturient ewes display several activities in addition to maternal behavior per se. They isolate themselves from the flock and, contrary to other mammals, do not show postpartum estrus. We investigated the possibility of a common hormonal control of maternal behavior, prepartum social isolation responses, and absence of postpartum estrus. We quantified responses to flockmate separation and incidence of sexual receptivity at several reproductive stages in intact ewes (Experiment 1). Responses to social isolation were lowest in preparturient ewes and at pregnancy day 149, intermediate at pregnancy day 147 and highest at day 136 and in non-pregnant ewes (P < 0.05 between the 3 levels). In a second experiment, we quantified the same parameters and maternal behavior in 1) ovariectomized ewes receiving medroxyprogesterone acetate only (ovxMPA); 2) ovariectomized ewes receiving MPA + estradiol benzoate (ovxSHORT); 3) intact ewes receiving a longer MPA + estradiol dipropionate treatment, before and after vaginocervical stimulation (VCS). Before VCS no steroid treatments decreased social isolation responses and maternal behavior was scarce or absent. Following VCS and interaction with lamb, maternal responses in the ovxSHORT group increased while social isolation responses decreased. Sexual receptivity occurred in non-pregnant ewes and in ovxSHORT group. Conclusion: some hormonal treatments +VCS can effectively induce maternal behavior and reduce social isolation responses. Long-term progestin treatment can inhibit postpartum estrus.

Artificial lactation by exogenous hormone treatment in non-pregnant sows.

This study aimed to determine if lactation can be induced by exogenous hormonal treatment in non-pregnant sows. In experiment 1, pseudopregnant animals were divided into four groups and given: 1) 5 mg of estradiol dipropionate (EDP) 5 days before (n = 4), 2) 5 mg of EDP 10 days before (n = 3), 3) 10 mg of EDP 5 days before (n = 3) or 4) 10 mg of EDP 10 days (n = 3) before PGF2α treatment. Artificial lactation was induced in seven pseudopregnant sows (53.8%) by exogenous hormonal treatment. There was no significant effect of either an increased EDP dosage or interval from the EDP treatment to PGF2α treatment on the induction rate of artificial lactation. In experiment 2, milk samples were collected from artificial lactating and natural lactating sows (n = 6). IgG and IgA levels in the milk collected from both groups were significantly associated with time during the experimental period. Milk IgG levels 24 h after PGF2α treatment in artificial lactating sows were higher than those in the colostrum of lactating sows. In experiment 3, hormonal profiles in pseudopregnant sows with (n = 3) or without (n = 3) EDP treatment were determined. There was a significant difference in estradiol-17β levels on days 8, 7 and 5 before PGF2α treatment between groups. Progesterone and prolactin concentrations did not differ between groups. The present study revealed for the first time that lactation could be induced by exogenous hormonal treatment in non-pregnant sows and that the milk collected from these sows contained high immunoglobulin levels.

Changes of growth hormone-releasing hormone and somatostatin neurons in the rat hypothalamus induced by genistein: a stereological study

Objectives: Genistein is a plant-derived estrogenic isoflavone commonly found in dietary and therapeutic supplements, due to its potential health benefits. Growth hormone-releasing hormone (GHRH) and somatostatin (SS) are neurosecretory peptides synthesized in neurons of the hypothalamus and regulate the growth hormone secretion. Early reports indicate that estrogens have highly involved in the regulation of GHRH and SS secretions. Since little is known about the potential effects of genistein on GHRH and SS neurons, we exposed rats to genistein.Methods: Genistein were administered to adult rats in dose of 30 mg/kg, for 3 weeks. The estradiol-dipropionate treatment was used as the adequate controls to genistein. Using applied stereology on histological sections of hypothalamus, we obtained the quantitative information on arcuate (Arc) and periventricular (Pe) nucleus volume and volume density of GHRH neurons and SS neurons. Image analyses were used to obtain GHRH and SS contents in the median eminence (ME).Results: Administration of estradiol-dipropionate caused the increase of Arc and Pe nucleus volume, SS neuron volume density, GHRH and SS staining intensity in the ME, when compared with control. Genistein treatment increased: Arc nucleus volume and the volume density of GHRH neurons (by 26%) and SS neurons (1.5 fold), accompanied by higher GHRH and SS staining intensity in the ME, when compared to the orhidectomized group.Discussion: These results suggest that genistein has a significant effect on hypothalamic region, involved in the regulation of somatotropic system function, and could contribute to the understanding of genistein as substance that alter the hormonal balance.

Estrus synchronization in microminipig using estradiol dipropionate and prostaglandin F2α.

The induction of pseudopregnancy by the exogenous administration of estradiol dipropionate (EDP) was investigated in cyclic Microminipigs (MMpigs) and the effects of exogenous administration of prostaglandin (PG) F2α on estrus exhibition were assessed in pseudopregnant MMpigs. In experiment 1, ovariectomized MMpigs were given a single intramuscular injection of 0.5, 1.5, or 2.5 mg of EDP. The estradiol-17β level at each of these doses was significantly higher 1 to 3 days after EDP administration than on the day of the injection. In experiment 2, animals were given 1.5 mg of EDP once at 9 to 12 days after the end of estrus (D0) and then no (1.5 mg × 1 group), one (D0 and D4; 1.5 mg × 2 group), or two (D0, D4 and D7; 1.5 mg × 3 group) additional treatments. The pseudopregnancy rate was significantly higher in the 1.5 mg × 3 than in the 1.5 mg × 1 group. In experiment 3, PGF2α was administered twice between 26 and 28 days after EDP treatment to five pseudopregnant gilts with a 24-h interval between the two injections. Estrus after PGF2α treatment and LH surge were observed in 100% and 80% pseudopregnant MMpigs, respectively. The interval from the day of the first PGF2α treatment to the onset of estrus was 6.5 ± 0.2 days. These results indicate that multiple EDP treatments are required for induction of pseudopregnancy in MMpigs and estrus exhibition can be controlled in MMpigs by treatment with EDP and PGF2α.

Immunohistomorphometric Characteristics Of Pituitary GH Cells In Infant And Peripubertal Female Rats After Treatment With Estradiol Or Human Chorionic Gonadotropin

AbstractThe effects of estradiol-dipropionate (EDP) or human chorionic gonadotropin (hCG) on immunohistomorphometric characteristics of pituitary GH cells in infant and peripubertal female rats were investigated. The first group of females received five injections of EDP (0.25 mg/kg b.w.) during the neonatal period of life, and was further divided into two subgroups which were sacrificed at the infantile period (17th day) or at the peripubertal period (38th day). The second group received two doses of hCG (50 IU/kg b.w.) on the 15th and 16th day of life in the first subgroup, and on the 36th and 37th days of life in the second subgroup, while they were sacrificed 24 h after the last treatment, respectively. The control females were injected with an equivalent volume of the vehicle and sacrificed according to the appropriate schedules as the hormone treated rats. EDP treatment decreased GH cell volume density in infant and peripubertal females, by 38% and 76% (p&lt;0.05) respectively, in comparison with the controls. The number of GH cells per mm2 in infantile and peripubertal period was decreased in EDP treated animals by 26% and 53% (p&lt;0.05) respectively, compared to the controls. Also, upon EDP treatment in both periods, GH cells were diminished in size and less intensely immunolabelled than in the control groups. The morphometric parameters in animals treated with hCG were insignificantly changed in both analyzed periods, in comparison with the controls. Unlike hCG, EDP manifested clear inhibitory effects on the immunohistomorphometric characteristics of GH cells in examined female rats.

The effects of sex steroids on thyroid C cells and trabecular bone structure in the rat model of male osteoporosis

Androgen deficiency is one of the major factors leading to the development of osteoporosis in men. Since calcitonin (CT) is a potent antiresorptive agent, in the present study we investigated the effects of androgen deficiency and subsequent testosterone and estradiol treatment on CT-producing thyroid C cells, skeletal and hormonal changes in middle-aged orchidectomized (Orx) rats. Fifteen-month-old male Wistar rats were either Orx or sham-operated (SO). One group of Orx rats received 5mg kg(-1) b.w. testosterone propionate (TP) subcutaneously, while another group was injected with 0.06mg kg(-1) b.w. estradiol dipropionate (EDP) once a day for 3weeks. A peroxidase-antiperoxidase method was applied for localization of CT in the C cells. The studies included ultrastructural microscopic observation of these cells. The metaphyseal region of the proximal tibia was measured histomorphometrically using an imagej public domain image processing program. TP or EDP treatment significantly increased C cell volume (Vc), volume densities (Vv) and serum CT concentration compared with the Orx animals. Administration of both TP and EDP significantly enhanced cancellous bone area (B.Ar), trabecular thickness (Tb.Th) and trabecular number (Tb.N) and reduced trabecular separation (Tb.Sp). Serum osteocalcin (OC) and urinary Ca concentrations were significantly lower after these treatments in comparison with Orx rats. These data suggest that testosterone and estradiol treatment in Orx middle-aged rats affect calcitonin-producing thyroid C cells, which may contribute to the bone protective effects of sex hormones in the rat model of male osteoporosis.

Reproductive Hormone Profiles in Sows on Estrus Synchronization using Estradiol Dipropionate and Prostaglandin F&lt;sub&gt;2α&lt;/sub&gt;-Analogue and the Reproductive Performance in Female Pigs on Commercial Farms

Changes in ovarian structures and hormonal profiles in estradiol dipropionate (EDP)-induced pseudopregnant sows following PGF2α-analogue (PGF2α-A) administration and practicality of the estrus synchronization protocol using EDP and PGF2α-A on estrus expression and reproductive performance in commercial conditions were investigated. Pseudopregnancy was defined as absence of estrus maintained for at least 20 days after EDP treatment in this study. When 4 pseudopregnant sows induced by 20 mg EDP were treated with PGF2α-A as 0.175 mg cloprostenol twice at a 24-hr interval between 20 and 28 days after EDP treatment, plasma progesterone concentrations rapidly decreased after treatment. The luteinizing hormone surge and ovulation were detected in all sows. The number of ovulated follicles was 17.3 ± 1.1 (SEM). On commercial farms, 94.2% of 52 gilts and 95.2% of 21 sows received EDP became pseudopregnant. When these pseudopregnant females (48 gilts and 20 sows) were treated with PGF2α-A as described above, estrus was detected in all females at 6.1 ± 0.3 days for gilts and 5.5 ± 0.2 days for sows after the first PGF2α-A treatment. There were no significant differences in farrowing rate (85.0 - 100%), average total litter size (10.0 - 11.4), average born alive litter size (9.4 - 10.3) and average piglet birth weight (1.56 - 1.71 kg) between PGF2α-A treated pseudopregnant female pigs that were inseminated during synchronized estrus and females inseminated during spontaneous estrus. This study indicates that estrus synchronization programs using EDP and PGF2α-A are available as practical and convenient procedures for commercial pig farms.

An efficient protocol for inducing pseudopregnancy using estradiol dipropionate and follicular development associated with changes in reproductive hormones after prostaglandin F2alpha treatment in pseudopregnant sows

BackgroundUtilization of estrus synchronization program in livestock industry would provide greater options for reproductive management in herd. To develop a convenient method for estrus synchronization in pigs, we determined the effective protocol using estradiol dipropionate (EDP) for the establishment of pseudopregnancy and investigated follicular development during the estrus synchronization with prostaglandin F2alpha (PGF2alpha) in association with reproductive hormone profiles in pseudopregnant sows.MethodsIn Experiment 1, the effective dose (0, 10, 20, or 30 mg) and timing (5, 8, 11 or 13 days after ovulation) of a single administration of EDP in cyclic pigs for the induction of pseudopregnancy were investigated. In Experiment 2, four pseudopregnant sows were treated with PGF2alpha twice at a 24-h interval between 24 and 28 days after EDP treatment. The changes in plasma concentrations of reproductive hormones were analyzed by time-resolved fluoroimmunoassay. Follicular development and ovulation following PGF2alpha administration were monitored by transrectal ultrasonography.ResultsHigh efficiency (greater than 80%) of pseudopregnancy was achieved with a single treatment with 20 mg of EDP at 8 and 11 days after ovulation (equivalent to 9-13 days after the onset of estrus). Plasma estradiol-17beta concentrations in pseudopregnant sows were significantly higher between 12 h and 7 days than before EDP treatment. Total inhibin concentrations significantly decreased following EDP treatment and remained low for 14 days. The number of small follicles was increased from 6.3 +/- 2.6 at PGF2alpha treatment to 22.8 +/- 4.8 at 3 days later; this was associated with increased plasma concentrations of inhibin. Onset of estrus was detectable in all sows on 5.3 +/- 0.3 days after PGF2alpha treatment and the number of ovulated follicles was 15.5 +/- 1.4 detected at 7.6 +/- 0.2 days after the treatment.ConclusionsThis study has defined the effective dose and timing of EDP treatment for inducing pseudopregnancy in cyclic pigs. Our results also indicated that EDP caused a lowering of inhibin concentrations during pseudopregnancy and small numbers of follicles from 20 to 28 days after EDP. In contrast, EDP-induced pseudopregnancy appears to have no adverse effect on follicular development and subsequent ovulation following PGF2alpha administration.

Chronic Estradiol Exposure Modulates Thyroid Structure and Decreases T4 and T3 Serum Levels in Middle-Aged Female Rats

Objectives: In human medicine, estrogen is applied in prevention and treatment of health problems associated with the menopause. The aim of this study was to examine the effects of chronic estradiol dipropionate (EDP) treatment on thyroid gland structure and function in middle-aged female rats. Methods: At 14 months of age, Wistar rats received 0.625 mg EDP/kg b.w./day intraperitoneally for 2 weeks. The peripheral and central zones of the thyroid were stereologically analyzed and the following morphometric parameters determined: volume density of follicles, follicular epithelium, interstitium and colloid, epithelial height and the index of activation rate. Serum levels of TSH, T₄ and T₃ were determined by ELISA. Results: EDP treatment led to significant decreases in volume densities of follicles and follicular epithelium, epithelial height and index of activation rate (by 11%, p < 0.05; 23%, p < 0.005; 11%, p < 0.05 and 21%, p < 0.05, respectively) in comparison to control values. Hyperplasia of thyroid follicular cells was noticed in 25% of EDP-treated animals. Serum levels of T₄ and T₃ were decreased (by 33%, p < 0.005 and 28%, p < 0.001, respectively), but TSH concentration was not significantly different from that of the controls. Conclusion: Chronic estradiol treatment significantly decreased volume density and height of centrally located follicular epithelium, follicular activation index and serum level of total thyroid hormones in middle-aged rats.

Effect of ovariectomy and estrogen supplementation on brain acetylcholinesterase activity and passive-avoidance learning in rats

The effect of ovariectomy and estrogen treatment on the brain acetylcholinesterase activity and cognition in rats was investigated in this study. Ovariectomized and nonovariectomized rats were treated subcutaneously with estradiol dipropionate for 8 d. In the single-trial, passive-avoidance test all the groups showed significant learning and retention of memory as evident by the increase in transfer latency time in trial 2 as compared with trial 1. No-transfer response was significantly increased in the estradiol-dipropionate-treated ovariectomized (80%) and nonovariectomized (60%) group as compared with the ovariectomized (30%) group. Specific activity of acetylcholinesterase was assayed spectrophotometrically in salt-soluble and detergent-soluble fractions of various brain areas: frontal cortex, cerebral cortex, striatum, hippocampus and hypothalamus, thalamus, pons, medulla, and cerebellum. The effect of ovariectomy and estradiol dipropionate was varied in both fractions of these brain areas. Estradiol dipropionate treatment could restore the acetylcholinesterase activity to the control level only in the detergent-soluble fraction of hypothalamus and salt-soluble fraction of hypothalamus, thalamus, and medulla in ovariectomized rats. The results indicate that ovariectomy alters acetylcholinesterase activity in the brain areas but not in a uniform manner and affects only qualitative aspects of cognitive function, which could be improved by estrogen supplementation.

Effect of estradiol dipropionate on protein synthesis in oocytes and ovary of the sea urchin Strongylocentrotus intermedius at different stages of the reproductive cycle

We studied protein synthesis in the oocytes and ovary of the sea urchin Strongylocentrotus intermedius at different stages of the reproductive cycle after treatment with estradiol dipropionate. During the early development of oocytes and active gametogenesis, this estrogen induced the incorporation of 3H-leucine in the oocytes. The changes in synthetic activity of cells were accompanied by an elevated efficient incorporation of free amino acid in proteins due to its increased pool, increased tissue permeability for precursors, and increased rate of protein synthesis. Before spawning, estradiol dipropionate did not cause any changes in protein synthesis. After estradiol dipropionate treatment, the inhibitors of protein synthesis, puromycin and actinomycin D, decreased the intensity of 3H-leucine incorporation in the oocytes and protein synthesis in the ovary. The involvement of estradiol dipropionate in the regulation of protein synthesis in the sea urchin gonad is discussed.

Alterations of myoepithelial cells in the rat mammary gland during pregnancy, lactation and involution, and after estradiol treatment.

Hormone-induced alterations of myoepithelial cells in the mammary gland have not been fully investigated. The aim of the present study was to examine whether myoepithelial cells are altered in response to hormonal conditions. The immunohistochemical findings of smooth muscle actin for myoepithelial cells were studied during pregnancy, lactation and involution, and after estradiol dipropionate (ED) treatment (50, 500, 1000 microg/kg per week for 1-4 weeks) using a total of 71 Wistar female rats. Myoepithelial cells showed a stratified appearance around ducts during pregnancy, extended cytoplasmic processes with wider distance during lactation, and vacuolated cytoplasm after weaning. ED treatment (50-1000 microg/kg per week) for 1 week increased myoepithelial cells to a variable degree, achieving a level similar to that in pregnancy, but ED treatment for 4 weeks reduced them as the dose elevated. The present study showed that the myoepithelial cells became hyperplastic or hypertrophic by low-dose ED treatment within the physiological range, while weaning pups, and excess high-dose ED treatment beyond the physiological range or prolonged ED treatment induced reduction of the myoepithelial cells. Results indicate that myoepithelial cells themselves are also altered by hormonal conditions coordinating the mammary gland development.