Luteinizing Hormone and Gonadal Steroid Levels During the Menstrual Cycle of Orangutans

Scrum luteinizing hormone (LH), progesterone. 17β-estradiol, and testosterone were measured during a single cycle each of five female orangutans, and urinary LH was measured in four of those cycles. Midcycle peaks in LH and luteal phase elevations in progesterone (5.7–13.8 ng/ml) suggested that the cycles were ovulatory. 17β-Estradiol was elevated at midcycle (163–318 pg/ml) and during the luteal phase (56–136 pg/ml) and testosterone was also elevated at midcycle (143–580 pg/ml). These hormone patterns in the orangutans closely resemble those for chimpanzees, gorillas, and human females.     

Sex hormone levels in the brain of d-aspartate-treated rats

d-Aspartate (d-Asp) is an endogenous amino acid present in the central nervous system and endocrine glands of various animal taxa. d-Asp is implicated in neurotransmission, physiology of learning, and memory processes. In gonads, it plays a crucial role in sex hormone synthesis. We have investigated the effects of chronic (30 days d-Asp drinking solution) and acute (i.p. injection of 2 μmol/g bw d-Asp) treatments on sex steroid synthesis in rat brain. Furthermore, to verify the direct effect of d-Asp on neurosteroidogenic enzyme activities, brain homogenates were incubated with different substrates (cholesterol, progesterone, or testosterone) with or without the addition of d-Asp. Enzyme activities were measured by evaluating the in vitro conversion rate of (i) cholesterol to progesterone, testosterone, and 17β-estradiol, (ii) progesterone to testosterone and 17β-estradiol, (iii) testosterone to 17β-estradiol. We found that d-Asp oral administration produced an increase of approximately 40% in progesterone, 110% in testosterone, and 35% in 17β-estradiol. Similarly, the results of the acute experiment showed that at 30 min after d-Asp treatment, the progesterone, testosterone, and 17β-estradiol levels increased by 29–35%, and at 8 h they further increased by a 100% increment. In vitro experiments demonstrate that the addition of d-Asp to brain homogenate + substrate induces a significant increase in progesterone, testosterone and 17β-estradiol suggesting that the amino acid upregulates the local activity of steroidogenic enzymes.     

Hepatic and plasma sex differences in saturated and monounsaturated fatty acids are associated with differences in expression of elongase 6, but not stearoyl-CoA desaturase in Sprague–Dawley rats

Monounsaturated fatty acids (MUFA) have been viewed as either beneficial or neutral with respect to health; however, recent evidence suggests that MUFA may be associated with obesity and cardiovascular disease. Sex differences in MUFA composition have been reported in both rats and humans, but the basis for this sexual dimorphism is unknown. In the current study, enzymes involved in MUFA biosynthesis are examined in rat and cell culture models. Male and female rats were maintained on an AIN-93G diet prior to killing at 14 weeks of age after an overnight fast. Concentrations of 16:0 (2,757 ± 616 vs. 3,515 ± 196 μg fatty acid/g liver in males), 18:1n-7 (293 ± 66 vs. 527 ± 49 μg/g) and 18:1n-9 (390 ± 80 vs. 546 ± 47 μg/g) were lower, and concentrations of 18:0 (5,943 ± 1,429 vs. 3,987 ± 325 μg/g) were higher in phospholipids in livers from female rats compared with males. Hepatic elongase 6 mRNA and protein were 5.9- and 2.0-fold higher, respectively, in females compared with males. Stearoyl-CoA desaturase expression did not differ. Specific hormonal effects were examined in HepG2 cells cultured with varying concentrations of 17β-estradiol, progesterone and testosterone (0, 10, 30 and 100 nM) for 72 h. Progesterone and 17β-estradiol treatments increased, while testosterone decreased, elongase 6 protein. Sex differences in MUFA composition were associated with increased expression of hepatic elongase 6 in females relative to male rats, which appears to be mediated by sex hormones based on observations of hormonal treatments of HepG2 cells.     

Seasonal reproductive cycle of the Galápagos tortoise (Geochelone nigra) in captivity

The reproductive physiology of nine Galápagos tortoises (Geochelone nigra) was studied from February 1988 to May 1989. The study encompassed the annual reproductive cycle to include complete mating and nesting sequences. Male (n = 4) and female (n = 5) seasonal reproductive changes were determined throughout the study with endocrine analysis and ultrasonographic examinations. Males displayed a prenuptial rise in serum testosterone (x― ±SE = 6.62 ± 0.92 ng/ml in August) during which gonadal maturation and spermatogenesis are thought to occur. The male reproductive cycle appears consistent with the prenuptial spermatogenic pattern exhibited by other tropical turtles. In the females, testosterone rose during the mating period (x― ± SE = 499.3 ± 124.6 pg/ml in October) prior to ovulation and is probably related to receptivity in the females. Progesterone was more variable, but also peaked during the mating period (x― ± SE = 1,017.2 ± 220.6 pg/ml in October) and appears related to ovulation. Estradiol rose several months prior to mating (x― ± SE = 75.5 ± 11.9 pg/ml in July) and was correlated with increased serum calcium levels. This increase in estradiol is thought to stimulate vitellogenesis several months prior to mating. Nesting occurred from November 1988 to April 1989, during which six clutches were laid. Clutch size ranged from eight to 17 eggs. Both male and female Galápagos tortoises display seasonal physiological changes that function to regulate annual reproductive patterns. Zoo Biol 17:505–517, 1998. © 1998 Wiley-Liss, Inc.     

Changes in ovarian follicles and in vitro sex hormone release in the lizard Podarcis sicula sicula

An in vitro superfusion method was used to test sex hormone release from different kinds of ovarian follicle (growing follicles, postovulatory follicles, and atretic follicles) in the lizard Podarcis sicula sicula. Sex hormone output changes with the stage of follicle evolution and sexual cycle. Previtellogenetic follicles prevail in early-spring quiescent ovaries and secrete mainly progesterone, which is probably utilized at that phase to delay ovarian resumption. In the active ovary, progesterone output from previtellogenetic follicles decreases, whereas vitellogenetic follicles produce a significant amount of 17β-estradiol, which is necessary for sustaining vitellogenin synthesis by the liver and oviduct growth. As follicles become ripe, progesterone production is resumed, and it increases in young postovulatory follicles. This is in line with the functions assigned to the hormone at that phase of the sexual cycle, i.e., the induction of oocyte maturation and the regulation of egg retention in the oviduct. Postovulatory follicles can also synthetize 17β-estradiol. After oviposition, this hormone, which is secreted by the old postovulatory follicles, can reinitiate vitellogenin synthesis, allowing the development of a new oocyte set. Our data confirm that active, although ephemeral, corpora lutea are also formed in oviparous species. A limited contribution to ovarian sex steroid production derives also from atretic follicles, at least at the early stages of the breeding cycle. © 1993 Wiley-Liss, Inc.     

Effects of different methods and times of 17β-estradiol treatment on the feminization success in the narrow-clawed crayfish Astacus leptodactylus (Eschscholtz, 1823)

Sex differentiation is a profitable technique in crayfish aquaculture. Most of the studies have focused on sex differentiation in crayfish by ablation or implantation of androgenic glands. There is no research on sex differentiation using hormones in crayfish. In the present study, the effects of 17β-estradiol (E2) injections (10^?7 mol/crayfish) to females and baths (50 μg 17β-estradiol/L) to pleopodal eggs and stage1, 2, and 3 juveniles on the feminization of freshwater crayfish, Astacus leptodactylus were investigated. Results showed that E2 injection to females, bath to pleopodal eggs and bath to stage 1, 2, and 3 juveniles increased feminization rate significantly (p < 0.05) in comparison to the control in A. leptodactylus. Best feminization rate (male to female, 0.25:1) was observed after hormonal injection to the females combined with application of both for their both pleopodal eggs and stage 1, 2, and 3 juveniles. In conclusion, it is possible to obtain 75% females A. leptodactylus by E2 injection to females and bath to pleopodal eggs and stage 1, 2, and 3 juveniles. However, future studies are needed to investigate the mechanism of E2 in crayfish feminization and the sexual development of juveniles obtained from feminization.     

Altered Cerebrospinal Fluid Concentrations of TGFβ1 in Patients with Drug-Resistant Epilepsy

Transforming growth factor beta (TGFβ) signaling participates in pathogenesis of epilepsy. TGFβ1, as a transmitter of TGFβ signaling, might be a useful marker for predicting the prognosis of patients with epilepsy. The present study aimed to measure TGFβ1 level in the cerebrospinal fluid (CSF) of patients with drug-resistant epilepsy and non-resistant epilepsy. A total of 43 patients with epilepsy were recruited, 28 were non-resistant epilepsy subgroup, 15 drug-resistant epilepsy subgroup. 11 patients with intracranial infection and 11 individuals with primary headache were used as controls. The concentration of CSF and serum TGFβ1 was measured by enzyme-linked immunosorbent assay. The concentration of CSF-TGFβ1 was 209.26 ± 81.07 pg/ml in the drug-resistant epilepsy subgroup, 121.80 ± 40.32 pg/ml in the non-resistant epilepsy subgroup, 552.17 ± 456.20 pg/ml in intracranial infection control, 133.80 ± 68.55 pg/ml in headache control, respectively. TGFβ1 level was significantly increased in the drug-resistant epilepsy subgroup compared to the non-resistant epilepsy subgroup. TGFβ1 level in intracranial infection control was higher than that in the non-resistant epilepsy subgroup. There was no statistically difference of CSF-TGFβ1 between the non-resistant epilepsy subgroup and headache controls, between the resistant epilepsy subgroup and intracranial infection controls. TGFβ levels are increased in the CSF of patients with drug-resistant epilepsy. High CSF-TGFβ1 levels may be a potential screening biomarker of antiepileptic drug resistance in patients with epilepsy.     

Plasma concentrations of testosterone,androstenedione, progesterone,oestradiol-17β, LH and FSH during the preovulatory period in the ewe

Seven mature ewes were synchronized to oestrus by two injections of 125 μg Cloprostenol given 9 days apart. Blood samples, collected for 72 h at 4-h intervals beginning 16 h after the second Cloprostenol injection, were assayed for testosterone, androstenedione, progesterone, oestradiol-17β, LH and FSH. For the testosterone measurements, two radioimmunoassays, using two different antisera, were validated and used. A typical pattern of release was observed for progesterone, oestradiol-17β, LH and FSH, with a preovulatory gonadotrophin peak recorded 16.1 ± 2.1 h after the observed oestrous behaviour. In two of the experimental animals, an extra oestradiol peak was recorded before the usual preovulatory rise. The changes in the concentrations of testosterone and androstenedione during the same period were not synchronous. The levels of the two androgens fluctuated considerably with occasional peaks of 150–250 pg/ml and even 900–1400 pg/ml. Although a tendency towards an increase in the levels of both androgens was observed during the period of oestrous behaviour, the individual variations were significant.     

Ultrastructural studies of the effect of steroid hormones on pars recta secretions in Bufo arenarum

In amphibians, eggs are released from the ovaries into the coelomic cavity after hormonal stimulation, while related preparatory events occur in the oviducts. We have reported an association between the biological activity of the pars recta (PR), the female reproductive cycle, and ultrastructural modifications of PR epithelium induced by steroid hormones in Bufo arenarum. This article describes (1) the electron microscopic features of PR epithelium and its secretions after ovariectomy; and (2) the effect of either 17β-estradiol, 5α-dihydrotestosterone, progesterone, or a combination of progesterone plus 17β-estradiol on PR epithelium and secretions in ovariectomized animals. Our results indicate that treatment solely with 5α-dihydrotestosterone, 17β-estradiol or progesterone is ineffective in counteracting the effect of ovariectomy, although some effect was noted. The PR secretions of ovariectomized control and ovariectomized animals stimulated with any one of the steroid hormones analyzed, are composed of flocculent material and membranous vesicles. By contrast, treatment of ovariectomized animals with a combination of 17β-estradiol and progesterone, restores the appearance of the pars recta epithelium to that of the nonovariectomized control animals. Progesterone, in the presence of 17β-estradiol, appears to be responsible for triggering the release of secretory granules into the PR lumen. J. Morphol. 231:1–10, 1997. © 1997 Wiley-Liss, Inc.     

Steroidogenic capabilities of the early mouse embryo

Preimplantation embryos from ICR albino mice were used to determine progesterone and estradiol-17β production during incubation in BMOC-2. Following culture of 40 embryos/culture at either the morula, early blastocyst or late blastocyst stages, progesterone and estradiol-17β contents were 192±27 and 82±22 pg, 289±50 and 147±46 pg and 157±28 and 88±23 pg, respectively, for incubated samples and 306±68 and 89±40 pg, 404±63 and 125±44 pg, and 241±54 and 86±39 pg, respectively for control samples. Although, there were significant stage of development and treatments effects (P<0.05) for progesterone, production of this steroid was not evident. These data suggest that the early preimplantation mouse embryo does not produce progesterone or estradiol-17β in a defined culture system.     

Analysis of the reproductive cycle of female wild marble trout <Emphasis Type="Italic">Salmo marmoratus</Emphasis> in a prealpine brook of the Soča River basin (Northeast Italy)

The reproductive cycle of female wild marble trout Salmo marmoratus was studied in a prealpine watercourse (Northeast Italy). Gonadosomatic index, oocyte growth and plasma levels of 17β-oestradiol and testosterone were bimonthly measured during one year to obtain a detailed dataset and to gain useful tools for the identification of the reproductive stage without impact for the species. Monitored features showed significant variations during the study period: gonadosomatic index and oocyte size increased slightly but significantly during the first part of the cycle (from February to June), while steroid levels remained quite constant; for all parameters, major increases were highlighted between August and the spawning season (which occurred from the middle of November to the middle of December). Ranges and trends observed for gonadosomatic index (from 0.87 ± 0.41% to 10.91 ± 3.37%) and oocyte diameter (from 0.692 ± 0.031 mm to 4.624 ± 0.208 mm) were generally in agreement with literature regarding salmonids, while plasma levels of 17β-oestradiol (from 0.214 ± 0.015 ng ml^?1 to 78.090 ± 23.882 ng ml^?1) and testosterone (from 0.327 ± 0.086 ng ml^?1 to 71.800 ± 29.406 ng ml^?1) showed wider ranges. A strong non-linear relationship was found between oocyte size and 17β-oestradiol plasma concentration (r ² = 0.890) and especially between oocyte size and testosterone plasma concentration (r ² = 0.947). This last relationship could likely be used to obtain information relative to the gonadal development, especially in the case of an endangered species like Salmo marmoratus, which needs non-invasive tools for management.     

Serum chorionic gonadotropin,progesterone, and estradiol-17β levels during pregnancy in the common marmoset,Callithrix jacchus

The serum levels of chorionic gonadotropin (LH/CG), progesterone, and estradiol-17β were measured during pregnancy in the common marmoset. The gestation period in five females was 144±1.5 (141–145) days. The LH/CG level increased from the early stage of pregnancy, reached a maximum of 10–17 ng/ml at 50 to 70 days and decreased to under 40 pg/ml at about 100 days. The progesterone level maintained the same value as that at the luteal phase of 20–40 ng/ml until 90 days of pregnancy, when the serum LH/CG was declining, thereafter increased abruptly, reached a maximum of 140–210 ng/ml at 110–130 days and fell to a low level of under 0.4 ng/ml at 5–10 days before parturition. The estradiol-17β was less than 2 ng/ml until 90 days of pregnancy, thereafter increased abruptly and maintained a high level of 40–135 ng/ml until just before parturition. The 3β-hydroxysteroid dehydrogenase activity in the placenta of the common marmoset was 40 times higher than that in the fetal adrenal, while in the Japanese monkey the former was only about one 40th of the latter. The time course of the serum progesterone and estradiol-17β during pregnancy and the role of the placenta which synthesized and secreted these hormones in the common marmoset showed a similarity to those of humans and anthropoid apes rather than those ofMacaca species. The common marmoset represents a valuable animal model for investigating the feto-placental unit in humans.     

Serum 17β-estradiol and progesterone associated with mating behavior during early pregnancy in female rhesus monkeys

The phenomenon of postconception mating behavior was examined in a social group of rhesus monkeys living in an outdoor compound. Periodic blood samples and daily vaginal swabs were obtained from nine females beginning several weeks prior to conception and continuing through 6 weeks of pregnancy to permit an assessment of ovarian hormonal events associated with mating during early pregnancy. Each of the females showed a discrete period of copulatory activity during the periovulatory period which ceased within several days after the 17β-estradiol (E₂) ovulatory peak. In agreement with earlier reports, only a percentage of subjects (44%) exhibited a period of postconception mating, with copulatory activity beginning 19.8 (± 1.9) days following the E₂ peak and continuing for 9.5 (± 1.3 days). Implantation bleeding was detected in all of the subjects with the onset 19.5 (± 0.68) days after the E₂ peak. The interval between the E₂ peak and the onset of implantation bleeding was similar for all females. However, the duration of implantation bleeding was significantly shorter in females who exhibited postconception mating. The females who displayed postconception copulatory activity had significantly lower mean serum progesterone concentrations (2.33 ± 0.24 ng/ml vs. 3.64 ± 0.37 ng/ml) during the period associated with implantation bleeding and copulatory behavior. Although both groups had elevated concentrations of serum E₂ during this period, levels in the females who displayed postconception mating were significantly lower (173.8 ± 19.2 pg/ml vs 223.9 ± 28.8 pg/ml). These data demonstrate that the occurrence of postconception mating behavior in this environment is associated with a distinct pattern of ovarian hormonal events, and analysis suggests that differences in steroid concentrations probably account for the observed differences in implantation bleeding and copulatory behavior during pregnancy.     

Melatonin Effects on Steroid Production by Rainbow Trout Ovarian Follicles In Vitro: Influence of Stage of Follicle Maturation

Rainbow trout ovarian follicles at four different stages of maturation (very early vitellogenesis, early vitellogenesis, peak vitellogenesis, and pre-ovulatory) were incubated either in Cortland's medium alone, or medium containing melatonin at one of five concentrations (1 × 10^-10, 1 × 10^-8, 1 × 10^-6, 1 × 10^-4 or 1 × 10^-2M) to assess the direct actions of melatonin on basal (non-gonadotrophin stimulated) secretion of 17β-estradiol and testosterone. Testosterone secretion by peak vitellogenic phase follicles was significantly (p &lt; 0.01) reduced by melatonin at 1 × 10^-4 or 1 × 10^-2 M, but there were no other significant effects of melatonin on T secretion. There were no significant effects of melatonin at concentrations of 1 × 10^-10 or 1 × 10^-8 M on 17β-estradiol secretion for any stage of follicular maturation, although for follicles at the peak vitellogenesis stage, melatonin at 1 × 10^-6 M had a significant (p &lt; 0.05) stimulatory effect compared with the controls. Melatonin also stimulated 17β-estradiol secretion by very early vitellogenic stage follicles (1 × 10^-2 M concentration; p &lt; 0.05). At concentrations of 1 × 10^-4 and 1 × 10^-2 M, melatonin significantly (p &lt; 0.01) inhibited 17β-estradiol secretion of peak vitellogenic and preovulatory stage follicles. The findings suggest a stimulatory action of melatonin on steroidogenesis of early stage ovarian follicles, a shift to an inhibitory action of the higher concentrations of melatonin in later stages of development, but with a bimodal action of melatonin (related to hormone concentration) being present during the time of maximum follicular growth.     

Testosterone dehydrogenase activity in koala liver: characterisation of cofactor and steroid substrate differences

We have studied the hepatic microsomal 17β-hydroxysteroid dehydrogenase (17β-HSD) capacity of koala (Phascolarctos cinereus) and tammar wallaby (Macropus eugenii). A detailed comparison of the activity in hepatic fractions from koala and rat was made. Hepatic microsomal NADP-supported 17β-HSD activity was significantly higher in koala (11.64±3.35 nmoles/mg protein/min), (mean±S.D.) than in tammar wallaby liver (1.52±0.79 nmoles/mg protein/min). However, when NAD was utilised as cofactor the activity was similar in both marsupial species (2.83±2.03 nmoles/mg protein/min, koala; 0.70±0.71 nmoles/mg protein/min, tammar wallaby). Data for rat indicated a cofactor preference for NAD rather than NADP (17.94±6.40 nmoles/mg protein/min, NAD; 2.18±1.04 nmoles/mg protein/min, NADP). Michaelis–Menten parameters for the kinetics of 17β-HSD testosterone oxidation by NADP and NAD were determined in the koala. The Km for testosterone was of the order of 10.0–24.0 μM (n=6) irrespective of the cofactor used, whilst the Km for NADP was 0.28–0.43 μM (n=2) and for NAD was 13.9–18.5 μM (n=2). 17β-estradiol was found to be an inhibitor of both NAD- and NADP- supported 17β-HSD activity. These findings indicate that NADP-mediated, but not NAD-mediated testosterone dehydrogenation is a major pathway of steroid biotransformation in koala liver; the reaction is less extensive in fractions from wallaby, human and rat. Such species-related differences in cofactor preference may contribute along with species differences in gene expression to observed rates of 17β-HSD activity in mammals.     

Simultaneous radioimmunoassay of testosterone and dihydrotestosterone

A radioimmunoassay, which simultaneously measures both testosterone (T) and dihydrotestosterone (DHT) in the same serum sample, is presented. Celite column chromatography is employed to separate T from DHT, and these two steroids from other potentially cross-reacting and interfering steroids. The normal values for men, women in the follicular phase, women in the luteal phase, ovariectomized and adrenal ectomized women, post-menopausal women and ovariectomized women for T are 5, 140 ± 1190 pg/ml, 307 ± 97 pg/ml, 285 ± 46 pg/ml, undetectable (<5 pg/ml), 262 ±47 pg/ml and 199 ±44 pg/ml; and for DHT 470 ± 165 pg/ml, 160 ±45 pg/ml, 147 ±44 pg/ml, undetectable (<5 pg/ml), 168 ± 27 pg/ml, 94 ± 15 pg/ml. The maximum sensitivity of the method was 10 pg/ml for T and 14.3 pg/ml for DHT when 1 ml was extracted. The blank in most assays was undetectable, but rarely exceeded 10 pg.     

17β-Estradiol Downregulated the Expression of TASK-1 Channels in Mouse Neuroblastoma N2A Cells

TASK channels, an acid-sensitive subgroup of two pore domain K⁺ (K2P) channels family, were widely expressed in a variety of neural tissues, and exhibited potent functions such as the regulation of membrane potential. The steroid hormone estrogen was able to interact with K⁺ channels, including voltage-gated K⁺ (Kv) and large conductance Ca²⁺-activated (BK) K⁺ channels, in different types of cells like cardiac myocytes and neurons. However, it is unclear about the effects of estrogen on TASK channels. In the present study, the expressions of two members of acid-sensitive TASK channels, TASK-1 and TASK-2, were detected in mouse neuroblastoma N2A cells by RT-PCR. Extracellular acidification (pH 6.4) weakly but statistically significantly inhibited the outward background current by 22.9 % at a holding potential of 0 mV, which inactive voltage-gated K⁺ currents, suggesting that there existed the functional TASK channels in the membrane of N2A cells. Although these currents were not altered by the acute application of 100 nM 17β-estradiol, incubation with 10 nM 17β-estradiol for 48 h reduced the mRNA level of TASK-1 channels by 40.4 % without any effect on TASK-2 channels. The proliferation rates of N2A cells were also increased by treatment with 10 nM 17β-estradiol for 48 h. These data implied that N2A cells expressed functional TASK channels and chronic exposure to 17β-estradiol downregulated the expression of TASK-1 channels and improved cell proliferation. The effect of 17β-estradiol on TASK-1 channels might be an alternative mechanism for the neuroprotective action of 17β-estradiol.     

17β-Estradiol Inhibits Outward Voltage-Gated K+ Currents in Human Osteoblast-Like MG63 Cells

Previous studies have shown that 17β-estradiol has a pivotal function by blocking voltage-gated K⁺ (Kv) channels in several different types of cells such as cardiac myocytes and neurons. Outward Kv currents can also be measured in osteoblasts, although little is known about the effects of 17β-estradiol on these currents. In human osteoblast-like MG63 cells, we found that 17β-estradiol inhibits peak and end Kv currents, with IC₅₀ values of 480 and 325 nM, respectively. To elucidate the mechanism of inhibition, the kinetics of Kv currents were investigated. The half-maximum activation potential (V _1/2) was 1.3 mV and was shifted left to ?4.4 mV after application of 500 nM 17β-estradiol. For steady-state inactivation, the V _1/2 was –55.0 mV and weakly shifted left to –58.2 mV. To identify the molecular basis of outward Kv currents in MG63 cells, we performed RT-PCR analyses. The expression of Kv2.1 channels appeared to dominate over that of other Kv channels in MG63 cells. In COS-7 cells with heterologously expressed Kv2.1 channels, 17β-estradiol also inhibits macroscopic currents of Kv2.1. Our data indicate that 17β-estradiol inhibits Kv currents in human osteoblast-like MG63 cells and that Kv2.1 is a potential molecular correlate of outward Kv currents in these cells.     

Involvement of steroid hormones on in vitro maturation of pig oocytes

The purpose of this study was to determine if the addition of steroid hormones into the culture medium could influence the in vitro maturation of pig oocytes. The cumulus-oocyte complexes (COCs). collected from follicles of 2-5 mm diameter, were matured in steroid-free medium supplemented with various concentrations of estradiol-17beta (0-3000 ng/ml), progesterone (0-5000 ng/ml) and testosterone (0-300 ng/ml). The COCs were cultured for 42 h, then fertilized in vitro. We analyzed nuclear and cytoplasmic maturation with lacmoid stain 20 h after in vitro insemination. We observed no significant effect (P > 0.05) on the percentage of oocytes completing nuclear or cytoplasmic maturation or the number of sperm penetrating each oocyte for any concentration of progesterone, estradiol-17beta or testosterone. Similarly, adding a combination of those hormones to the medium did not significantly (P > 0.05) affect any of the criteria. In order to determine if there was a possible secretion of steroids during maturation, we added COCs, denuded oocytes and stripped cumulus cells to drops of a steroid-free medium and cultured them for 42 h, after which we analyzed the medium, before and after culture, for the presence of progesterone, estradiol-17beta and testosterone by radioimmunoassay (RIA) analysis. COCs, as well as cumulus cells alone, secreted similar amounts of estradiol (43.3 and 37.5 pg/ml, respectively) and progesterone (4.24 and 4.79 ng/ml, respectively) into the maturation medium. A small amount of estradiol (28.8 pg/ml) was also detected when oocytes were cultured alone. These results indicate that no steroids need to be added to the maturation medium of pig oocytes and that the COCs secrete steroids during maturation. It is possible that the amounts produced by the COCs fulfill any requirement for steroids if these steroids are required for either nuclear or cytoplasmic oocyte maturation.     

Simultaneous radioimmunoassay of testosterone,dihydrotestosterone, 5α-androstane-3α, 17β-diol and 5α-androstane-3β, 17β-diol in the plasma of adult male rats

A single thin layer chromatography and three antibodies were used for the specific radioimmunoassay of four androgens in pooled rat plasma (Sprague-Dawley adult males). The following values were found (pg/ml ± SD). Testosterone : 3, 138 ± 173; dihydrotestosterone : 374 ± 20; 5α-androstane-3α 17β-diol : 284 ± 24; 5α-androstane-3β, 17β-diol : 223 ± 11.