Increased ovulation rate in gilts treated with dihydrotestosterone

Treatment with testosterone increases ovulation rate in pigs. The present study was conducted to examine the effects of 5alpha-dihydrotestosterone (DHT), a non-aromatizable androgen receptor ligand, on ovulation rate and amounts of androgen receptor and FSH receptor mRNAs in postpubertal gilts. In Expt 1, ovulation rate in response to daily i.m. injections of 0, 6, 60 or 600 microg DHT kg(-1) body weight from day 13 of the oestrous cycle (day 0 = day 1 of oestrus) to the following oestrus increased with each dose of DHT (P < 0.05). The mean increase in number of corpora lutea ranged from approximately three to 17 over the three dosages of DHT. In Expt 2, gilts treated daily with 60 microg DHT kg(-1) body weight during the early follicular phase (from day 13 to day 16), coincident with follicular recruitment, or the late follicular phase (day 17 to oestrus), had higher (P < 0.05) rates of ovulation compared with gilts that received vehicle, and were not different from gilts treated with DHT from day 13 to oestrus. Percentage recovery of day 3 embryos was not altered when gilts were treated from day 13 to day 16 or from day 17 to oestrus; however, treatment of gilts with DHT from day 13 to oestrus decreased recovery of day 3 (Expt 1) or day 11 (Expt 2) conceptuses. Daily administration of 6 microg DHT kg(-1) body weight to gilts from day 13 of the oestrous cycle to the following oestrus (Expt 3) did not affect the relative amounts of androgen receptor mRNA, but increased (P < 0.05) the amounts of FSH receptor mRNA in preovulatory follicles as determined by RT-PCR. The results of these experiments indicate that androgens may regulate ovulation rate in gilts. One of the roles of androgens might be regulation of the amounts of FSH receptor mRNA in ovarian follicles.

Molecular identification of evolutionarily significant units in the Amazon River dolphin Inia sp. (Cetacea: Iniidae)

The Amazon river dolphin, genus Inia, is endemic to the major river basins of northern South America. No previous studies have focused on the genetic structure of this genus. In this work, 96 DNA samples from specimens of this genus were collected in the Orinoco basin (four rivers), the Putumayo River, a tributary of the Colombian Amazon and the Mamoré, and the Tijamuchí and Ipurupuru rivers in theBolivian Amazon. These samples were used to amplify a fragment of 400 bp of the mitochondrial DNA (mtDNA) control region. In addition, 38 of these samples were also used to sequence 600 bp of the mitochondrial cytochrome b gene. The analysis of the population structure subdivision with an analysis of molecular variance (AMOVA) revealed important aspects about the genetic structure of Inia groups fromthese three geographically separate regions. By comparing the control region DNA and cytochrome b sequences, distinct types of nonshared haplotypes were observed. The net genetic divergence of control region sequences was 6.53% between the Orinoco and Bolivian rivers, 5.32% between the Putumayo and Bolivian rivers, and 2.50% between the Orinoco and Putumayo rivers. For the cytochrome b gene, these values were 2.48%, 2.98%, and 0.06%, respectively. The nucleotide sequences were analyzed phylogenetically using several genetic distance matrices and applying neighbor-joining, maximum likelihood, and maximum parsimony procedures. The results support the proposal to subdivide the Inia genus into at least two evolutionarily significant units: one confined to the Bolivian river basin and the other widely distributed across the Amazon and Orinoco basins.

Androgen receptor and follicle-stimulating hormone receptor in the pig ovary during the follicular phase of the estrous cycle

Follicle-stimulating hormone (FSH) is an important regulator of follicular development. Some effects of FSH on ovarian follicles might be enhanced by androgens. The main objectives of the present study were to examine expression of the androgen receptor (AR) and FSH receptor (FSHR) in late developing follicles in pigs. Ovaries were collected from gilts on days 13, 15, 17, and 19 of the estrous cycle (day 0 = first day of estrus, n = 4 gilts/day), a period coincident with the follicular phase. One ovary was processed for immunohistochemistry (IHC) of AR. Samples of surface wall from the largest follicles (4-5 per gilt) were dissected from the other ovary, pooled and processed for determination of AR and FSHR mRNAs using reverse transcription-polymerase chain reaction (RT-PCR). Intense AR immunostaining was present in nuclei of granulosa cells of preantral and antral follicles. AR immunoreactivity was also present in the nuclei of oocytes. Weak staining for AR was observed in cells of the theca interna, ovarian surface epithelium, and in most cells of the ovarian stroma. Relative amounts of immunoreactive AR in granulosa cells of late developing follicles, or small antral follicles (< 2 mm), did not differ between days 13, 15, 17, and 19. However, amounts of AR in granulosa cells of small antral follicles was greater (P < 0.05) than in the largest follicles present in the same ovary. The relative amounts of AR mRNA in tissue from the largest follicles on days 13, 15, 17, and 19 did not differ; however, amounts of FSHR mRNA in the same follicles were not different between days 13, 15, and 17, but decreased (P < 0.05) by day 19. Results indicate that during the follicular phase in gilts, the AR protein is mainly present in granulosa cells. Relative amounts of AR protein in granulosa cells and mRNA in walls of late developing follicles did not significantly change from day 13 to 19; however, amounts of FSHR mRNA decreased in preovulatory follicles by day 19 of the estrous cycle.

Circadian variation of basal plasma prolactin, prolactin response to suckling, and length of amenorrhea in nursing women

The circadian pattern of plasma PRL levels and the PRL response to suckling were examined at various times during the first postpartum year and related to the length of lactational amenorrhea. Ten healthy women whose infants were breast-fed exclusively and who were amenorrheic 3 months postpartum were studied 3, 6, and 9-11 months postpartum. The women and their babies were admitted to a metabolic unit for 48 h. On the second day, blood samples were drawn at 2-h intervals for 26 h starting at 0800 h and also 10 and 30 min after the initiation of six of the nursing episodes. During the three postpartum periods, there was a circadian rhythm of basal plasma PRL concentrations; the peak concentrations occurred between 2400-0600 h. Suckling induced a significant rise in plasma PRL levels at all hours except 0800 h. There was a positive correlation between the duration of the nursing episode and the suckling-induced PRL increase at 30 min. Both the basal plasma PRL levels and the PRL responses to suckling diminished with time after delivery. This trend was less evident at 0400 h and was not fully explained by changes in the nursing pattern. The five women in whom menstrual cycles resumed before day 180 postpartum had lower basal and suckling-induced plasma PRL levels than the women who had amenorrhea for a longer period. This difference was present in the third month, when all women were amenorrheic and fully nursing and when the frequency and duration of nursing episodes and infant growth rates were similar. The results indicate that comparable nursing patterns may be associated with different plasma PRL levels, which are associated with different lengths of lactational amenorrhea. An early difference in the sensitivity of the breast-hypothalamus-pituitary system to suckling may explain the differences in the duration of lactational amenorrhea, which are not dependant on the breastfeeding pattern. The magnitude of the PRL response to suckling may predict the likelihood of recovering ovarian function during lactation.

Effects of administration of human chorionic gonadotropin or progesterone before maternal recognition of pregnancy on blastocyst development and pregnancy in sheep

A series of four experiments with 258 ewes was conducted to determine whether blastocyst size could be altered before normal luteolysis and, if so, how this affected fertility. In Exp. 1 and 2, nonmated and mated ewes, respectively, were treated with hCG (100 IU), progesterone (12 mg), or vehicle on d 11.5 (d 0 = onset of estrus). In Exp. 3 and 4, field trials were conducted to compare the effects of either hCG or progesterone treatment on d 11.5 on subsequent pregnancy rates. In Exp. 1, hCG transiently increased (P < .01) concentrations of progesterone and estradiol in plasma, whereas progesterone treatment increased only plasma progesterone. Neither hCG nor progesterone affected the duration of the estrous cycle. In Exp. 2, d-13 blastocysts were longer (3.5 +/- 1.6 vs .8 +/- .5 cm; Mean +/- SE; P < .05), and concentrations of protein and interferon tau (IFN tau) in uterine flushings were greater (10.7 vs 1.2 micrograms; P < .05) in hCG than in vehicle-treated ewes. Progesterone treatment did not affect blastocyst development. In Exp. 3, pregnancy rates tended to be greater (P < .10) in ewes given hCG than in those given vehicle (44/47; 94% vs 40/48; 83%); however, administration of progesterone in Exp. 4 had no effect on pregnancy rates (P < .14; 41/45; 91% vs 37/46; 80%; control ewes). These results indicate that treatment with hCG on d 11.5 stimulated uterine secretions and conceptus growth sufficiently to influence pregnancy rates.

Contraceptive efficacy of lactational amenorrhea in urban Chilean women

The contraceptive efficacy of breastfeeding was assessed in 236 healthy urban women who were followed at monthly intervals during the first postpartum year. Proportional hazard models were used to evaluate the influence of time postpartum, menstrual status and breastfeeding pattern upon the risk of pregnancy. Time and menstrual status had a highly significant effect on this risk. Those women who remained in amenorrhea had cumulative probabilities of pregnancy of 0.9% and 17% at 6 and 12 months postpartum, respectively. In those who recovered menstrual cycles, the risk rose to 36% and 55% at 6 and 12 months, respectively. Milk supplementation also increased significantly the risk when considered alone but not when time and/or menstrual status were included in the analysis. However, amenorrheic women who introduced bottle feeding, had a higher risk of pregnancy after 6 months postpartum than those who remained fully nursing. The analysis was unable to detect a significant influence of the nursing frequency. The results confirm that lactational amenorrhea is an effective contraceptive during the first six months postpartum. The first postpartum bleeding marks a great increase in the risk of pregnancy. Supplementation also increases the risk, particularly in amenorrheic women.

Interactions of Al(acac)3 with cell membranes and model phospholipid bilayers

Aluminum is a neurotoxic agent; however, little information has been obtained regarding its molecular cytotoxicity and the effects on the stability of biological membranes. This is mainly due to the ill-defined chemical speciation of the metal compounds. For this reason, the present study used aluminum acetylacetonate, (Al(acac)3), a neutral, chemically well-defined, hydrolytically stable and lipophilic compound. To understand the molecular mechanism of its interaction with cell membranes, Al(acac)3 was incubated with human erythrocytes, isolated toad skin and molecular models of biomembranes. The latter consisted of multilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoyphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. The results showed that Al(acac)3 interacted with the erythrocyte membrane modifying its normal discoid morphology to both echinocytic and stomatocytic shapes. This finding indicates that the Al complex was inserted in both the outer and inner layers of the red cell membrane, a conclusion supported by X-ray diffraction analyses of DMPC and DMPE bilayers. Electrophysiological measurements performed on toad skin revealed a significant decrease in the potential difference and short-circuit current responses after application of Al(acac)3, effects interpreted to reflect inhibition of the active transport of ions. Al(acac)3 was active on both surfaces of the skin suggesting that the membrane was permeated by the metal complex. It is concluded that Al(acac)3 both alters the molecular structure of the lipid bilayer, thereby modifying the biophysical properties of the cell membrane, and changes its physiological properties.

Recovery of fertility and outcome of planned pregnancies after the removal of Norplant subdermal implants or Copper-T IUDs

The recovery of fertility after discontinuation of NORPLANT implant use was assessed in ninety women who stated a desire for a new child at the time of removal. Three subjects were lost to follow-up after removal. The cumulative probability of conception in the remaining 87 women was 25, 49, 73 and 86 percent at one, three, six and twelve months after removal, respectively. Nine observations were censored either because of the use of a contraceptive method soon after removal of the implants (n = 7) or separation (n = 2). All other cases were pregnant at the end of two years with exception of three subjects where a male factor for infertility was present. There was no significant correlation between the length of NORPLANT use and the length of the interval from removal to conception. A significantly higher frequency of intervals longer than 6 months was observed among women older than 30 years as compared to younger women. Pathology during pregnancy was cholestasia (n = 5), hypertension (n = 1) and gestational diabetes (n = 1). The outcome was term delivery in 59 cases, premature delivery in 4 cases, and spontaneous abortion in 7 cases. One woman is still pregnant and the outcome is unknown in 4 cases. One premature infant died. A contemporary control group of Copper T users enrolled under the same criteria as NORPLANT implant users provided 44 women who had the device removed to become pregnant. The cumulative probability of pregnancy was 27, 69, 84 and 89 at one, three, six and twelve months and all were pregnant by the end of the second year. Six censored observations occurred because of the use of another contraceptive method after removal (n = 3) or loss to follow-up (n = 3). The outcome of pregnancy was term delivery in 23 cases and abortion in 7 cases. Recovery of fertility occurred at a normal rate after NORPLANT implant removal and the incidence of problems detected in the ensuing pregnancy were within the expected range for Chilean women.

Early difference in the endocrine profile of long and short lactational amenorrhea

The endocrine profiles associated with long and short lactational amenorrhea were assessed in a longitudinal study in which morning blood samples were drawn in 48 women from the first postpartum month until the recovery of ovulation and in a cross-sectional study in which the samples were drawn throughout 24 h at the end of the third postpartum month in 10 fully nursing and amenorrheic women. PRL, LH, FSH, estradiol (E2), progesterone, cortisol, and dehydroepiandrosterone sulfate were measured. In both studies we detected a smaller PRL increase in response to suckling (P less than 0.001) and higher E2 levels (P less than 0.001) in nursing women who ovulated within 6 months postpartum compared to those in women who did not. Such differences were observed early after delivery when all women were fully nursing and amenorrheic. These results suggest some probable sources of variability in the duration of lactational amenorrhea in our population. The greater PRL response to suckling associated with longer amenorrhea may be due to higher sensitivity of the breast-hypothalamus-pituitary system or a stronger suckling stimulus in this group. Differences in plasma E2 levels between longer and shorter periods of amenorrhea may reflect dissimilar endogenous production, intake, or clearance of estrogens.

Estrogen receptor beta in the sheep ovary during the estrous cycle and early pregnancy

Objectives were to sequence and examine the expression of the estrogen receptor beta (ERbeta) in the sheep ovary. The sequence of the ovine ERbeta (oERbeta) was determined using reverse-transcription polymerase chain reaction (RT-PCR) and cloning techniques. The reading frame of oERbeta contained 527 amino acids and exhibited high overall homology with cow (98%), rat (88%), and human (88%) ERbeta. In addition, an oERbeta isoform having a 139-base pair deletion (oERbeta1) was identified. The predicted amino acid sequence of this isoform is lacking the ligand-binding and carboxyl-terminal transactivation domains. The oERbeta protein and mRNA were determined in ovaries obtained from ewes on Days 0 (first day of estrus), 2, 6, and 10 of the estrous cycle and Day 30 of gestation. Immunohistochemistry showed that oERbeta protein was located in granulosa cells, the ovarian surface epithelium, endothelium, and Day 2 corpus luteum (CL). Weak immunostaining for ERbeta was detected in the theca interna. Relative steady-state amounts of oERbeta mRNA in the CL were determined using semiquantitative RT-PCR. Amounts of oERbeta mRNA were greater (P < 0.05) during CL formation (Day 2) than at later stages. The oERbeta to oERbeta1 mRNA ratio was lower (P < 0.05) on Day 2 than on Day 10 or Day 30 due to a decrease in amounts of oERbeta1. Results indicate that the oERbeta is a 527-amino acid protein expressed in specific cells of the ovary. Changes in relative amounts of full-length oERB and a deletion isoform in CL occurred during the estrous cycle, suggesting that these two types of ERbeta might regulate estrogen actions during early CL development in sheep.

Administration of testosterone during the follicular phase increased the number of corpora lutea in gilts

The effects of 0 (vehicle), 1, 10, or 100 mg of testosterone, administered on d 17 and 18 of the estrous cycle (d 0 = 1st d of estrus), on the number of preovulatory follicles on d 19 or the number of corpora lutea (CL) and blastocysts on d 11 of the subsequent cycle were examined in 82 gilts. The mean number of preovulatory follicles increased (P < .01) in a dose-dependent manner. Likewise, gilts that received 1, 10, or 100 mg of testosterone had more (P < .05) CL than gilts treated with vehicle. The mean number of blastocysts increased (P = .06) in gilts receiving 1 mg of testosterone but decreased (P < .05) in gilts treated with 10 mg of testosterone compared with gilts receiving vehicle. Similarly, recovery rates of blastocysts decreased (P < .05) in gilts treated with 10 or 100 mg of testosterone relative to gilts administered 0 or 1 mg of testosterone. Plasma concentrations of testosterone and estradiol increased (P < .05) 2 h following administration of 1 mg of testosterone on d 17 of the estrous cycle. These results indicate that although the 10- and 100-mg dosages of testosterone were detrimental to blastocyst survival, the 1-mg dosage increased synthesis of estradiol and the number of CL and d-11 blastocysts.

Effects of AlCl3 on toad skin, human erythrocytes, and model cell membranes

Aluminum, a very abundant metal, could play a toxic role in several pathological processes, including neurodegeneration. Although the effects of Al(III) on biological membranes have been extensively described, direct information concerning the molecular basis of its biological activity is rather scanty. To examine aluminum challenges on cell membranes, various concentrations of AlCl3 in aqueous solutions were incubated with human erythrocytes, isolated toad skin, and molecular models of biomembranes. The latter consisted of multilayers of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, representing phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane. These specimens were studied by scanning electron microscopy, electrophysiological measurements, and x-ray diffraction. The results indicate that Al(III) in the concentration range of 10-100 microM induced the following structural and functional effects: (i) change in the normal discoid shape of human erythrocytes to echinocytes due to the accumulation of Al(III) ions in the outer moiety of the red cell membrane; (ii) perturbation of dimyristoylphosphatidylcholine, and to a lesser extent of dimyristoylphosphatidylethanolamine bilayers, and (iii) decrease in the short-circuit current and in the potential difference of the isolated toad skin, effects that are in accordance with a time-dependent modulation of ion transport in response to changes in the molecular structure of the lipid bilayer.

Clearance of levonorgestrel from the circulation following removal of NORPLANT subdermal implants

The disappearance of levonorgestrel from plasma after the removal of NORPLANT subdermal implants was studied in 12 women who had been treated from 5.5 to 78 months. The existence of one or two half-lives for the rate of disappearance was assessed. The influence of body weight, body fat and length of treatment upon levonorgestrel clearance was studied through stepwise regression analysis. It was found that the levonorgestrel decay rate after implant removal can be entirely accounted assuming one half-life of 42 +/- 16 h (mean +/- SD; range 13 to 62 h). Stepwise regression analysis showed that levonorgestrel half-life is positively correlated with body weight and not significantly correlated with the length of treatment or body fat. It is concluded that, after long-term administration of levonorgestrel via subdermal implants, the major part of the steroid is cleared from plasma within 96 h and that only trace amounts are detected in the following days.

Mechanism of action of progesterone as contraceptive for lactating women

Progesterone vaginal rings releasing 5-15 mg/day were tested as a contraceptive for lactating women. Progesterone plasma levels achieved ranged from 10 to 20 nmol/L. Pregnancy rates at the end of the year were less than 1% and 39% in treated (n = 210) and untreated (n = 236) nursing women, respectively. Around 70% of treated and 30% of untreated women were amenorrheic at 8 months post partum. The endocrine profile during the first 8 months post partum was assessed in 36 treated and 28 untreated nursing women. Pre- and postsuckling prolactin (PRL) levels were measured at 1600 hr at fortnightly intervals and E2 determinations and ovarian ultrasound were performed twice a week. Prolactin increases in response to suckling and postsuckling PRL levels were higher, E2 levels were lower, and follicular growth was arrested at earlier stages in progesterone-treated than in untreated women. The pattern observed in progesterone-treated women was similar to that in prolonged lactational amenorrhea. This suggests that progesterone increases the sensitivity of the breast-hypothalamic-pituitary system to suckling and reinforces the mechanism of lactational infertility.

Iron affects the structure of cell membrane molecular models

The effects of Fe(3+) and Fe(2+) on molecular models of biomembranes were investigated. These consisted of bilayers of dimyristoylphosphatidylcholine (DMPC) and of dimyristoylphosphatidylethanolamine (DMPE), classes of phospholipids located in the outer and inner moieties of cell membranes, respectively. X-ray studies showed that very low concentrations of Fe(3+) affected DMPC organization and 10(-3)M induced a total loss of its multilamellar periodic stacking. Experiments carried out with Fe(2+) on DMPC showed weaker effects than those induced by Fe(3+) ions. Similar experiments were performed on DMPE bilayers. Fe(3+) from 10(-7)M up to 10(-4)M had practically no effect on DMPE structure. However, 10(-3)M Fe(3+) induced a deep perturbation of the multilamellar structure of DMPE. However, 10(-3)M Fe(2+) had no effect on DMPE organization practically. Differential scanning calorimetry measurements also revealed different effects of Fe(3+) and Fe(2+) on the phase transition and other thermal properties of the examined lipids. In conclusion, the results obtained indicate that iron ions interact with phospholipid bilayers perturbing their structures. These findings are consistent with the observation that iron ions change cell membrane fluidity and, therefore, affect its functions.

Administration of testosterone from day 13 of the estrous cycle to estrus increased the number of corpora lutea and conceptus survival in gilts

The effects of exogenous androgens on the number of corporea lutea (CL) and conceptus survival were examined in crossbred gilts. In Exp. 1, gilts received 1 mg of testosterone per day from d 13 (d = 0 first day of estrus, n = 21) or d 16 until estrus (n = 23). Gilts in the vehicle group received corn oil (n = 20). Gilts were mated and on d 11.5 their concepti and CL were evaluated. In Exp. 2, conceptus survival was examined at the 4- to 8-cell, early blastocyst or hatching blastocyst stages for gilts given vehicle or 1 mg testosterone from d 13 (24 gilts per group). In Exp. 3, gilts received 1 mg of androstenedione (n = 20) or vehicle (n = 18) per day from 13 d to estrus and then were mated and evaluated on d 11.5. Results from Exp. 1 indicated that the number of CL was greater (P < .04) in gilts treated with testosterone from d 13 to estrus than in gilts receiving vehicle (16.4 vs 14.8, respectively). Similarly, the number (P < .01) and recovery rate (P < .04) of blastocysts were greater in gilts treated with testosterone from d 13 to estrus than in gilts treated with testosterone from d 16 to estrus in gilts receiving vehicle (number, 15.3 vs 12.8 or 12.8; recovery rate, 95 vs 87 or 86%, respectively). Gilts treated testosterone or vehicle did not exhibit differences (P > .05) in number of normal concepti at the 4- to 8-cell and hatching stages. However, prior treatment with testosterone delayed conceptus death; gilts treated with testosterone had more (P < .01) normal concepti at the intermediate stage (early blastocyst) than those treated with vehicle (treatment x embryo stage interaction, P < .05). In Exp. 3, androstenedione treatment did not influence (P > .10) the number of CL or the number and recovery rates of d-11.5 blastocysts. Treating gilts with testosterone from d 13 of the estrous cycle to the following estrus increased the number of CL and blastocyst survival, perhaps by improving some, as yet unknown, aspect(s) of oocyte quality.

Distribution and changes in amounts of the androgen receptor in the pig uterus during the estrous cycle, early pregnancy and after treatment with sex steroids

Two experiments were performed to examine the expression of the androgen receptor (AR) gene in the pig uterus. In experiment 1, immunohistochemistry (IHC) was used to determine the distribution of the AR in uterine tIssue of pigs when collected at the first day of estrus (day 0) and the mid-luteal phase (day 12) of the estrous cycle, or early pregnancy (day 12, n=4 gilts per group). In experiment 2, AR immunostaining and AR mRNA in uterine tIssue were compared among ovariectomized gilts (n=4 per group) following treatment for 4 days with daily injections of: (1) progesterone (2 mg/kg bodyweight (BW)), (2) estradiol-17beta (E(2,) 2 micro g/kg BW), (3) E(2) plus progesterone (same dosages as 1 and 2 combined), (4) 5alpha-dihydrotestosterone (DHT, 7 micro g/kg BW), or (5) vehicle (corn oil). Data were analyzed using ANOVA. In experiment 1, nuclear staining for AR in luminal and glandular epithelia was strong and did not differ in intensity between the two locations. Immunostaining of AR in the myometrium was less (P<0.001) intense than in the luminal and glandular epithelia. Nuclei of stromal cells contained AR immunostaining that varied in intensity from strong (mainly in subepithelial stroma) to weak or no staining. Stages of the estrous cycle or early pregnancy did not influence AR immunostaining in the endometrial epithelia and myometrium. In experiment 2, immunostaining of AR in glandular and luminal epithelia and myometrium of ovariectomized gilts treated with vehicle or DHT was less (P<0.05) than in gilts treated with E(2), progesterone, or E(2) plus progesterone. Immunostaining of AR did not differ between ovariectomized gilts treated with vehicle or DHT, or between gilts treated with E(2), progesterone, or E(2) plus progesterone. In both experiments, intensity of AR immunostaining was greater in glandular epithelium located at the adluminal region compared with glandular epithelium located at the basal region of the endometrium. Competitive reverse-transcription PCR (RT-PCR) indicated a stimulatory effect (P<0.01) of E(2) on amounts of AR mRNA in whole endometrium. This increase in AR mRNA after E(2) treatment was not detected when E(2) was combined with progesterone. Endometrial AR mRNA was not influenced by DHT or progesterone relative to vehicle-treated gilts. In conclusion, immunoreactive AR is mainly present in luminal and glandular epithelia of the pig uterus and to a lesser extent in the myometrium, and does not change significantly during the estrous cycle or early pregnancy. Expression of the AR gene in the pig endometrium and myometrium appears to be regulated by E(2) and progesterone.

Effect of the rate of progesterone decline at luteolysis on the ovulatory follicles and subsequent estrous cycle length in ewes

Follicular and interestrous characteristics were examined in 34 ewes after experiencing either a rapid decline in plasma concentrations of progesterone at luteolysis [prostaglandin F2 alpha (PGF2 alpha)-induced] or a slow rate of decline, lasting over 72 h. All ewes were given PGF2 alpha on day 10 (day 0 = estrus). A slow rate of decline was established in 17 ewes by the intravenous infusion of progesterone initially at 72 ml h-1, delivering 4.5 mg progesterone h-1, then decreasing the infusion rate by 1 ml h-1 for the next three days. Seventeen additional ewes, predestined to experience a rapid decline in progesterone, were infused with vehicle. In Experiment 1, after infusion, ewes (6 ewes/group) were necropsied at the onset of estrus and follicle diameter was determined, follicular fluid was aspirated and the remaining follicular wall was microscopically examined to determine the number of granulosa cell layers. In Experiment 2, the interestrous interval, after infusion, was observed in both groups of ewes (11 ewes/group). Ewes experiencing a rapid rate of progesterone decline at luteolysis had no differences in follicle diameter nor follicular concentration of progesterone or estradiol but their ovulatory follicles contained fewer (P < 0.01) granulosa cell layers and the resulting estrous cycle was longer (P < 0.05) than ewes experiencing a slow rate of progesterone decline.

Dihydrotestosterone influenced numbers of healthy follicles and follicular amounts of LH receptor mRNA during the follicular phase of the estrous cycle in gilts

The present experiments were conducted to determine androgenic effects on numbers, health, and amounts of gonadotropin receptor mRNA in late developing follicles of gilts. Gilts (n=5 per group) received daily injections of one of the following treatments on days 13–16 or days 13–18 of the estrous cycle: corn oil, 5α-dihydrotestosterone (DHT, 10 mg), flutamide (1.5 g, an androgen receptor inhibitor), DHT (10 mg) plus flutamide (1.5 g), testosterone (10 mg), and testosterone (10 mg) plus flutamide (1.5 g). Ovarian follicles ≥5 mm in diameter were evaluated on day 17 or 19, 24 h after receiving the last treatment dose. Follicles were classified as healthy (H), moderately atretic (MA), or very atretic (VA). Treatment with DHT increased (P<0.05) the numbers of H follicles relative to control gilts on days 17 and 19. DHT administration from days 13 to 16 diminished (P<0.05) the amounts of LH receptor (LHR) mRNA in H follicles from day 17 (relative amounts: 1.45±0.33 and 2.72±0.33 for DHT- and vehicle-treated gilts respectively). The effects of DHT on numbers of H follicles and LHR mRNA were not observed in gilts receiving DHT plus flutamide. Androgens did not influence numbers of MA, VA, and total follicles, or follicular estradiol-17β concentrations and amounts of FSHR mRNA. Treating gilts with DHT during follicular recruitment and selection did not induce changes in the numbers of total follicles ≥5 mm, but rather increased the numbers of healthy follicles in this follicular population in association with decreased amounts of LHR mRNA.

A longitudinal study on cortisol, prolactin and thyroid hormones in users of Norplant subdermal implants or a copper T device

A longitudinal study was undertaken to assess PRL, cortisol, TSH, T3 and T4 levels in NORPLANT implant users (n = 22) and Copper T users (n = 20). Participants were healthy women with no contraindication for hormonal contraception. Samples were drawn at 0930 to 1000 h twice pretreatment and at month 2, 4, 6, 12, 24 and 36 after insertion. At the second treatment month, a second sample was obtained at 1600 h to assess cortisol diurnal variation. Hormones were measured by RIA. Values for all hormones were similar in Norplant and Copper T users. No significant changes occurred throughout the study period. Elevated PRL levels (greater than 500 mU/1) were found in three women from each group before and during treatment but no clinical evidence of hyperprolactinemia was detected. The results of this study reassure that long-term use of NORPLANT implants do not impair plasma levels of cortisol, prolactin and thyroid hormones.

Effect of time of mating relative to ovulation on morphological diversity of swine blastocysts

The effect of time of mating relative to ovulation on the amount of embryonic diversity was investigated in 37 mature crossbred gilts. Ovulation was induced by injecting proestrous gilts with 1000 IU of hCG. Gilts were naturally mated once at 24-32 (control), 41, or 43 h after hCG injection (n = 10, 9, and 18, respectively). Blastocysts were collected surgically 288 h post-hCG from gilts mated at 24-32 h post-hCG, from those mated at 41 h post-hCG, and from 8 of those mated at 43 h post-hCG. Collection of blastocysts was performed at 295 h in 10 gilts mated at 43 h post-hCG. Blastocysts within the ranges 1.0-4.0, 4.5-7.0, 7.5-10.0, 10.5-15.0, and 15.5-40.0 mm and those > 40.0 mm were classified morphologically as small, medium, and large spheres and as ovoidal, tubular, and filamentous, respectively. Blastocysts were incubated for 6 h to quantify secretion of estradiol-17 beta (estradiol). Morphological diversity (standard deviation of size) did not differ among blastocysts of treatment groups. Delaying the time of mating reduced (p < 0.07) the subsequent size and estradiol secretion of blastocysts. Waiting until 295 h after hCG to evaluate blastocysts of gilts mated at 43 h resulted in blastocysts size and estradiol secretion similar to that of conception of controls. Estradiol secretion by medium and large spherical blastocysts of gilts mated at 43 h post-hCG and evaluated at 288 h was lower (p < 0.05) than that by blastocysts of the same classifications from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Steroidogenic changes and steady state amount of messenger RNA encoding steroidogenic enzymes, gonadotropin receptors and cell-death signalling in the dominant ovarian follicle during estradiol-induced atresia in cattle

Changes in steroidogenic function and associated gene expression were characterized in dominant ovarian follicles (DF) of cattle where follicles were induced to become atretic by systemic administration of estradiol benzoate (EB). In experiment 1, follicular fluid (FF) steroid concentrations in the DF were measured at 12-hourly time points for 48 h in heifers treated with 1 mg EB i.m./500 kg body weight (EB; n=20) as compared with untreated controls (C; n=19). Treatment with EB promoted a transient reduction in circulating FSH, a rapid (12 h) and sustained reduction in FF estradiol, a rapid (12 h) but transient reduction in FF progesterone and a delayed (36 h) increase in FF testosterone concentrations. In experiment 2, whole follicular wall tissue was collected from DF of mature non-lactating cows allocated to a 0 h control group (0 HC: n=7), a 24h control group (24 HC; n=7) or an EB-treated group where tissue was collected 24 h after administration of 1 mg EB i.m./500 kg body weight (EB; n=8). As for experiment 1, EB promoted a transient reduction in circulating FSH, a pronounced reduction in FF estradiol and a smaller but significant reduction in FF progesterone concentrations. Semi-quantitative RT-PCR on follicular wall tissue revealed that the loss in estrogen activity at 24 h after EB was associated with two-fold reduction in aromatase mRNA, with an apparent acceleration in loss of 17alpha-hydroxylase mRNA. Expression of genes for gonadotropin receptors (LHR and FSHR) and a cell-death signalling pathway (Fas antigen and Fas ligand) were unchanged during the initial 24h of EB-induced atresia. These results suggest that EB initiates atresia in dominant ovarian follicles through a rapid suppression of follicular estradiol synthesis, an effect associated with down-regulation of the aromatase gene. A transient suppression in circulating FSH following administration of EB appears to have initiated these events, and it is suggested that subsequent processes involved in atresia follow this loss in estrogenic function.