Effect of glutamate and somatostatin-14 on basal and cAMP-stimulated steroidogenesis by rainbow trout (Oncorhynchus mykiss) ovarian follicles, in vitro

The effects of glutamate and somatostatin-14 (SRIF) on the in vitro basal and cAMP-stimulated steroid production of mid-vitellogenic rainbow trout (Oncorhynchus mykiss) ovarian follicles were investigated. cAMP-stimulation was achieved by the addition of the adenylyl cyclase activator, forskolin (FS), or a membrane permeate cAMP agonist, 8-bromo-cAMP (BA), to the incubation medium. Testosterone (T) and 17β-estradiol (E₂) secretion was measured using radioimmunoassay. Solid phase extraction (SPE) was used to measure the relative formation of unconjugated and conjugated steroids, and high performance liquid chromatography (HPLC) was used to examine the steroid metabolites formed from the metabolism of a tritium labelled precursor, pregnenolone (P₅). The accumulations of T and E₂ in the medium were suppressed in the presence of the glutamate agonists, N-methyl-d,l-aspartate (NMA) or l-glutamic acid (GA), and by the presence of SRIF. The suppression was evident for both basal and cAMP-stimulated steroidogenesis except for T concentrations of GA treatments following basal steroidogenesis, when there were no treatment effects. No significant effects of treatment on conjugated:unconjugated steroid ratios were found. For all treatments E₂ was the major end product steroid synthesized from P₅, and the steroid profiles were similar except for trace amounts of radiolabelled androgens in the medium following cAMP-stimulated steroidogenesis that were not present following basal steroidogenesis. The findings suggest that glutamate and SRIF reduce end point steroid production, possibly by reducing P₅ production. However, since the inhibitory affect was found for basal and cAMP-stimulated steroidogenesis, the response does not appear to be due to the inhibition of cAMP synthesis.     

In vitro effect of vitellogenin on steroid production by ovarian follicles of greenback flounder Rhombosolea tapirina

Ovarian follicles from vitellogenic greenback flounder (Rhombosolea tapirina) were incubated in L15 medium alone, or containing human chorionic gonadotropin (hCG), dibutyryl cyclic AMP (dbcAMP) or the steroid precursors testosterone (T), 17-hydroxyprogesterone (17P) and androstenedione (A) in the presence of vitellogenin (Vtg) at 0.1-5.0mg mL(-)(1). Medium concentrations of 17beta-estradiol (E(2)) and T were measured by radioimmunoassay. HCG generally stimulated follicular E(2) but not T production, whereas 17P, A and T stimulated production of E(2), T, and E(2) respectively. Treatment of follicles with dbcAMP inhibited follicular E(2) production, but increased follicular T production at high doses. The effect of low concentrations of Vtg on follicular steroid production was variable; however, higher doses of Vtg significantly suppressed basal, hCG-, dbcAMP- and steroid precursor-stimulated follicular E(2) and T production. The results of this study show that high concentrations of Vtg may suppress follicular steroid production by interfering in the steroidogenic pathway. This suggests that Vtg may regulate its own production by limiting the ovarian production of E(2).     

Differential steroid and gonadotropin response by individual tertiary porcine follicles in vitro. Possible physiologic role of atretic follicles

Since atretic follicles contain significant amounts of androgen and/or progesterone in their follicular fluid, we examined whether they also contribute to ovarian steroid secretion. Steroid secretion by atretic porcine follicles and their responsiveness to FSH was assessed by a perifusion system that allows for separate dynamic incubation of whole follicles in vitro. Identically treated nonatretic follicles of comparable size served as a reference group. The extent of granulosal pyknosis, on which the staging of atresia was based, was inversely related to follicular estradiol (E2) secretion and its responsiveness to FSH. Both basal and FSH-stimulated secretion of testosterone (T), androstenedione (A), and progesterone (P) were maintained by follicles in all stages of atresia. Secretion of A by late atretic follicles was greater than that in earlier stages or by nonatretic follicles. Atretic follicles may therefore release comparable or larger amounts of androgen and P into their intraovarian environment than do nonatretic follicles. We examined whether steroids secreted by atretic follicles in vitro could be utilized by nonatretic follicles. A static incubation system was used that allows for simultaneous incubation of a number of individual follicles. When nonatretic follicles were exposed to A, T, or P in physiologic concentrations (10(-7)-10(-5) M), their secretion of E2 increased 2-8-fold. Doses of FSH or LH that stimulated follicular steroid in vitro had no additional stimulatory effect when combined with A or P treatment, respectively. In conclusion, atretic follicles may contribute significantly to intraovarian levels of androgen and P.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of parameters for in vitro culture of isolated ovarian follicles of greenback flounder Rhombosolea tapirina

Isolated ovarian follicles of greenback flounder Rhombosolea tapirina were incubated with a variety of gonadotropins (GtHs) and steroid precursors for periods of up to 42 h, and levels of free and glucuronated testosterone (T) and 17beta-estradiol (E(2)) in the medium, and free T and E(2) from inside follicles were measured by RIA. Short incubations (6 h) generated increases in T and E(2) in response to steroid precursors, but not human chorionic GtH (hCG), or salmon or carp GtH. At incubation times of 18 h, all GtHs stimulated T and, or E(2) production, whereas after 42-h incubation, GtH effects on E(2) production had disappeared. Steroid precursors remained effective at 18 and 42 h. T and E(2) glucuronides were formed in small quantities but did not account for loss of treatment effects at long incubation times. Instead, this could be explained by accumulation of E(2) in controls as a result of continued basal steroid production. Follicles absorbed substantial amounts of both endogenous and exogenous steroid from the medium, however, this did not appear to have any influence on changes in treatment effects with incubation time. Flounder follicles were most sensitive to hCG, followed by salmon and carp GtH at approximately 10-fold higher concentrations. Ovarian segments were not sensitive to any GtH but did convert exogenous steroid precursors indicating that tissue access by GtH may be a limiting factor under certain in vitro conditions. HCG augmented the conversion of 17-hydroxyprogesterone (17P) to T but not T to E(2), consistent with the relative GtH-insensitivity of aromatase in other species. Follicles converted a range of steroid precursors with equal competence, indicating that no step in the cleavage pathway is strongly rate-limited, and that choice of precursor is unlikely to affect the assessment of steroidogenic activity.     

The developing Xenopus oocyte specifies the type of gonadotropin-stimulated steroidogenesis performed by its associated follicle cells

As a response to gonadotropin, amphibian ovarian follicles primarily synthesize and secrete estradiol-17 β (E2) during vitellogenesis and progesterone (P) when fully grown. Stage IV (vitellogenic) and stage VI (full-grown) ovarian follicles from Xenopus laevis, as well as intermediate sizes, were used to explore this change in steroidogenesis. Optimum steroidogenesis occurred in both stage IV and stage VI follicles exposed for 6 h to 20 IU human chorionic gonadotropin/mL. Although the total amounts of steroid found were about the same, the E2/P ratios ranged from 26 to 35 for intact stage IV follicles, but only 0.02–0.03 for intact stage VI follicles. Steroid-producing follicle cells were isolated from stage IV and stage VI follicles by non-enzymatic procedures, were washed and were tested for steroidogenic activity in the absence of oocytes. In both cases, P was the predominant steroid produced (E2/P = 0.004–0.04), so the presence of stage IV, but not stage VI, oocytes appears to be necessary for E2 production as a response to gonadotropin. Octanol had no significant effect on the E2/P ratio of intact stage IV follicles. Dissected oocyte/follicle cell preparations from stage IV follicles were also periodically challenged with gonadotropin over 72 h, during which time most follicle cells detached from the oocyte and formed a monolayer over the bottom of the culture dish. The relatively high E2/P ratios for such preparations showed no significant change when stimulated with gonadotropin at various times over the 72 h, as long as the medium was not replaced. We conclude that the estrogenic effect of stage IV oocytes is most likely mediated by a secretory product rather than by gap junctions or by cell contact. Because the X. laevis oocyte has been shown to be a self-differentiating cell, the steroidogenic shift that occurs in developing ovarian follicles appears to be fundamentally regulated by the growing oocyte as it undergoes a physiological change rather than by different gonadotropins.     

Onset of steroidogenic enzyme gene expression during ovarian follicular development in sheep

Steroidogenesis is a major function of the developing follicle. However, little is known about the stage of onset of steroid regulatory proteins during follicular development in sheep. In this study, several steroidogenic enzymes were studied by immunohistochemistry and/or in situ hybridization; cytochrome P450 side chain cleavage (P450(scc)), cytochrome P450 17alpha-hydroxylase (17alphaOH), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cytochrome P450 aromatase (P450(arom)), steroidogenic factor 1 (SF-1), steroidogenic acute regulatory protein (StAR), and LH receptor (LH-R). To define the stages of follicular growth, ovarian maps were drawn from serial sections of ovine ovaries, and follicles were located and classified at specific stages of growth based on morphological criteria. In this way, the precise onset of gene expression with respect to stages of follicular growth for all these proteins could be observed. The key findings were that ovine oocytes express StAR mRNA at all stages of follicular development and that granulosa cells in follicle types 1-3 express 3beta-HSD and SF-1. Furthermore, the onset of expression in theca cells of StAR, P450(scc), 17alphaOH, 3beta-HSD, and LH-R occurred in large type 4 follicles just before antrum formation. This finding suggests that although the theca interna forms from the type 2 stage, it does not become steroidogenically active until later in development. These studies also confirm that granulosa cells of large type 5 follicles express SF-1, StAR, P450(scc), LH-R, and P450(arom) genes. These findings raise new questions regarding the roles of steroidogenic regulatory factors in early follicular development.     

Estrogen regulation of nitric oxide synthesis in the porcine oocyte

The endothelial type (NOS-3) of three isoforms of nitric oxide (NO) synthase occurs in porcine oocytes and granulosa cells, but the regulation of NO synthesis in oocytes remains unknown. The present study was designed to evaluate steroid control in the process of oocyte NO synthesis. Cumulus-oocyte complexes (COCs), obtained from small-sized antral follicles of immature porcine ovaries, were cultured in estrogen-deprived medium, and the effect of steroids or steroid-free porcine follicular fluids on the NO release from oocytes was investigated. Oocytes that were isolated from cultured COCs were incubated with 1 microM ionomycin. The NO metabolites were identified using a NO detector-high-pressure liquid chromatography system. Oocytes from COCs cultured with 10 nM 17beta-estradiol (E2) released NO in response to ionomycin, whereas progesterone and testosterone had little effect on the synthesis of NO. An inhibitor of NOS suppressed the synthesis of NO. The maximal synthesis was observed after a 15 h-culture with E2. However, oocytes freshly obtained from antral follicles did not response to ionomycin, and the E2 action was suppressed by the addition of steroid-free follicular fluids. Analyses of RT-PCR and Western blotting showed that E2 did not increase NOS-3 expression. In addition, estrogen receptor beta was detected in oocytes and cumulus cells, and estrogen receptor alpha was detected only in cumulus cells. These findings suggest that oocyte NOS-3 is promoted for the synthesis of NO by E2 without increases in NOS-3 expression, but the synthesis of NO is suppressed, at least in the oocytes of early antral follicles.     

Steroidogenesis in ovarian follicles of chub mackerel, Scomber japonicus

We incubated different radiolabeled steroid precursors with intact chub mackerel ovarian follicles to clarify the synthetic pathways of steroid hormones during vitellogenesis and following final oocyte maturation (FOM). During vitellogenesis, estradiol-17beta (E2) was synthesized from pregnenolone via 17-hydroxypregnenolone, 17-hydroxyprogesterone, androstenedione, and testosterone. The physiological significance of the intermediate metabolites of E2 in the ovarian follicles was examined by comparing follicular steroidogenesis between gonochoric and hermaphroditic fish species. After vitellogenesis, the steroidogenic pathway shifted from E2 to maturation-inducing hormone (MIH) production owing to the inactivation of 17,20-lyase and the activation of 20 beta-hydroxysteroid dehydrogenase. Of the new steroids produced during FOM, 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) was most effective at inducing germinal vesicle breakdown in vitro. Circulating levels of 17,20beta-P increased specifically around the time of germinal vesicle migration, while another FOM-specific 20beta-hydroxylated progestin, 17,20beta,21-trihydroxy-4-pregnen-3-one, was present at consistently low levels during FOM. These results indicate that 17,20beta-P is the MIH of chub mackerel.     

Steroidogenic characteristics of in vitro cultured epididymal epithelial cells of the rat

The paper presents the steroidogenic features of cultured epithelial cells of rat epididymis and their ability to synthesize steroid hormones. The cytoplasm of epididymal epithelial cells accumulated lipid droplets and contained active enzymes of steroidogenesis. Numerous mitochondria with lamellar cristae occurred near lipid droplets. Frequently, mitochondria formed a direct contact with lipid droplets and smooth endoplasmic reticulum. The hormone assay showed that the epididymal epithelial cells cultured without dihydrotestosterone synthesized and released the following steroids: dehydroepiandrosterone (DHEA), testosterone (T) and 17beta-estradiol (E). The levels of DHEA and T were very low. The concentration of E detected in media of cultured epididymal epithelial cells exceeded many times the concentration of E in control media. The cytoplasmic presence of organelles and enzymes that participated in the steroid synthesis indicated their similarity to steroidogenic cells. Epididymal epithelial cells were capable of moderate in vitro synthesis of androgens. It cannot be excluded that steroidogenesis in the cultured epididymal epithelial cells is maintained to sustain 17beta-estradiol synthesis pathways.     

Sulfoconjugation of steroids and the vascular pathway of communication in dogfish testis.

The zonal testis of the dogfish (Squalus acanthias) has proven advantageous to study biochemical changes in relation to stage of spermatogenesis, including information on steroidogenic enzymes and steroid receptors. To investigate whether sulfotransferase is part of a mechanism regulating the availability of biologically active hormone in close proximity to receptors, we measured in vitro conversion of [3H]estrone (E1) to sulfoconjugated metabolites in cytosolic subfractions of testes grossly dissected according to germ cell composition (premeiotic-PrM, meiotic-M, and postmeiotic-PoM stages). Assays were carried out in the presence of adenosine 3'-phosphate 5'-phosphosulfate (PAPS) at 22 degrees C and optimized for time (60 min) and protein (500 micrograms/ml). Michaelis-Menten kinetics and saturation analysis gave the following reaction constants for [3H]E1: Km = 0.33 microM, Vmax = 2.5 pmol/min/mg; and for PAPS: Km = 33 microM, Vmax = 1.1 pmol/min/mg; competition studies carried out in the absence or presence of 1- or 5-fold excess radioinert steroids indicated that estrogen (E2 > E1) as well as androgens (T = DHEA > 5 alpha dihydrotestosterone, DHT) were effective inhibitors. Sulfotransferase activity was found to be stage-related, being highest in PoM regions (2.31 +/- 0.24 pmol/min/mg protein) when compared to M and PrM regions (1.22 +/- 0.22 and 1.28 +/- 0.21 pmol/min/mg protein, respectively). Sulfoconjugation and the intratesticular distribution of steroid sulfates were also measured in vivo by perfusion of the intact testis with [3H]androgen or -estrogen. The pathway of blood flow via the genital artery was epigonal organ-->PoM-->M-->PrM (mature-->immature). Perfused [3H]E2, T, and DHT were all extensively metabolized in a one-pass, 1 hr perfusion, less than 10% of perfused [3H] steroid being recovered from testicular tissues as unchanged steroid. In general, recovery of polar metabolites was greater than non-polar metabolites from all three substrates. Sequential hydrolysis with glucuronidase and glusulase indicated that sulfoconjugation is a minor component (< 20%) of several "inactivating" pathways, which include glucuronide conjugation, 17-ketosteroid synthesis, and pathways leading to unidentified polar metabolites. No consistent stage-related distribution patterns were observed for any of the metabolite subfractions; however, total recovered radioactive steroid (polar plus non-polar) formed a decreasing concentration gradient from point of entry of perfusate (PoM region) to point of exit (PrM region). These data support the conclusion that access to receptors by steroid ligands may be controlled by a balance between activating and inactivating pathways.(ABSTRACT TRUNCATED AT 400 WORDS)     

Interactions between androgen and growth factors in granulosa cell subtypes of porcine antral follicles

Androgens acting via the androgen receptor (AR) have been implicated in regulation of folliculogenesis in many animal species. These effects are possibly mediated via enhancement of FSH and/or insulin-like growth factor (IGF)-I activity in granulosa cells, which contain high levels of AR protein. We examined the in vitro effect of dihydrotestosterone (DHT) on DNA synthesis and progesterone secretion by follicular cells in response to FSH and IGF-I, alone or in combination. Cells from separate pools of 1- to 3-mm and 3- to 5-mm antral follicles were aspirated from gilt ovaries and fractioned into mural granulosa cells (MGCs) and cumulus-oocyte complexes (COCs) for subsequent cell culture. Androgen alone or with any combination of mitogen had minimal effect on proliferative and no effect on steroidogenic responses of MGCs from 3- to 5-mm antral follicles. Conversely, in MGCs from 1- to 3-mm follicles, DHT significantly enhanced IFG-I-stimulated proliferation and had variable influence on progesterone secretion. The effects of DHT on proliferative responses of COCs were also dependent on follicle size: DHT significantly augmented either IGF-I-stimulated proliferation (1- to 3-mm follicles) or FSH-stimulated proliferation (3- to 5-mm follicles). However, the steroidogenic responses of all COCs were identical, whereby DHT significantly suppressed progesterone secretion, predominantly in the presence of FSH. Addition of an AR antagonist, hydroxyflutamide, generally reversed the proliferative responses invoked by DHT but not the steroidogenic responses. We conclude that androgen-receptor-mediated activity in granulosa cells of antral follicles is dependent on follicle size, is influenced by proximity of cells to the oocyte, and possibly involves both classic and nonclassic steroid mechanisms.     

Glucocorticoid influence on porcine granulosa cell IGF-I and steroid hormone production in vitro

The effect of cortisol on granulosa cell (GC) insulin-like growth factor I (IGF-I) synthesis, and IGF-mediated steroid production was examined at various stages of follicle maturation. Granulosa cells were recovered from gilts on Days 14, 18, and 20 of the estrous cycle, while luteinizing GC were recovered on Day 21, just prior to ovulation. The cells were cultured in serum-free medium with increasing concentrations of cortisol (0, 1, 10, and 100 microg/mL) for 5 d with or without IGF-I stimulation (10 ng/mL). During culture all cells were supplemented with FSH and androstenedione (A4). Cellular IGF-I, progesterone (P4) and estradiol-17beta (E2) production was determined by specific radioimmunoassays (RIA), and cell proliferation was assessed. Granulosa cell IGF-I and steroid hormone synthesis increased (P<0.05) with follicle maturation. Direct exposure to high cortisol concentrations, however, altered both IGF-I synthesis and action. Cortisol treatment lowered (P<0.05) IGF-I production by GC recovered on Days 18, 20, and 21. Furthermore, it reduced (P<0.05) IGF-stimulated P4 synthesis at all stages and decreased (P<0.05) IGF-stimulated E2 synthesis by cells recovered on Day 14. In contrast, cortisol enhanced (P<0.05) FSH-stimulated P4 production by GC collected on Days 14 and 18. The opposing effects on FSH and IGF-I action indicate that cortisol did not promote an overall suppressive effect on cell function, nor did it impair cell proliferation. Hence, these results demonstrate that elevated cortisol concentrations can disrupt both IGF-I synthesis and IGF-mediated actions by porcine GC under in vitro conditions, and that specific disruptions are dependent on the stage of follicle maturation.     

Blood steroid profile and in vitro steroidogenesis by ovarian follicles and testis fragments of adult sea lamprey,Petromyzon marinus

The main purpose of the study was to identify the principal gonadal steroids synthesized by male and female sea lampreys, Petromyzon marinus. To achieve this, we used high performance liquid chromatography to separate the steroids in the serum of sexually mature animals, and to separate the steroids produced by gonadal tissue incubated in the presence of radiolabelled precursor steroids, as a means of identifying the major steroidogenic pathways. We were unable to detect evidence of the 'classical' steroids, such as 17beta-estradiol (E(2)) or testosterone (T) in the serum of either male or female lampreys. Instead, the principal chromatographic peaks contained very polar compounds that had elution times consistent with 15alpha-hydroxylated estrogens and androgens, and there were sex-specific differences in the chemical nature and the quantity of these compounds. Testis fragments or ovarian follicles co-incubated with tritium-labelled pregnenolone ([3H]P(5)), 17-hydroxyprogesterone ([3H]17OHP(4)), or androstenedione ([3H]A(4)), provided additional confirmation that the gonads synthesize a range of very polar steroids, and the metabolites found were consistent with the presence of a 15alpha-hydroxylated (15alphaOH) metabolic pathway common to testis and ovary. For ovarian tissue, the major 'end product' metabolites from all three precursors were 15alphaOH-estrogens, and for testis tissue 15alpha-hydroxyprogesterone (15alphaOHP(4)) and 15alpha-hydroxytestosterone (15alphaOHT) and small amounts of 15alphaOH estrogen. Small amounts of E(2) were also produced by both ovarian (all substrates) and testicular tissue (some substrates). Although it was assumed that the E(2) was synthesized via the aromatization of T, [3H]T was not found as an intermediate metabolite. The study suggests that the principal gonadal steroids in sea lamprey are 15alpha-OH compounds, and that only small amounts of E(2) or T are synthesized by the gonads at this stage of reproductive development. There was no direct evidence of progesterone (P(4)) synthesis from [3H]P(5), although the metabolites synthesized by both testis and ovary were indicative of a metabolic pathway that involved P(4) as an intermediate.     

In vitro effect of leptin on steroids' secretion by FSH- and LH-treated porcine small, medium and large preovulatory follicles

The role of exogenous leptin in the follicular steroidogenesis in pigs has not been fully elucidated and available data are controversial. In the current study porcine follicles were recovered from ovaries during early, middle, and preovulatory stages of the follicular phase of the estrous cycle. Follicles were cultured in the presence of the recombinant ovine leptin (oLEP) with or without LH (100 ng/ml) or FSH (100 ng/ml). Medium estradiol (E(2)), testosterone (T) and progesterone (P(4)) concentrations were determined after 48h of culture. Leptin at a dose of 2 ng/ml had no effect on basal E(2) and T secretion by small and medium follicles but decreased E(2) secretion by large follicles. Significant synergistic action of FSH and leptin resulting in a 2 - 5 fold stimulation of E(2) secretion by small and medium follicles was observed. The aromatase inhibitor, CGS 16949A augmented T secretion and inhibited E(2) secretion by control and FSH-treated medium follicles. In FSH and leptin-treated follicles, the inhibitory action of CGS 16949A on E(2) secretion was observed. However, there was no augmentation of T secretion. In leptin-treated follicles the stimulatory action on P(4) secretion was observed only during the preovulatory stage. In these follicles, significant synergistic action of leptin with LH on P(4) secretion was also noted. These results indicate that there is a maturation-dependent action of leptin on both E(2) and P(4) secretion. They also suggest a synergistic action of leptin and FSH on E(2) secretion by small and medium follicles as well as leptin and LH on P(4) secretion by large follicles in pigs.     

Anabolic steroids induce cardiac renin-angiotensin system and impair the beneficial effects of aerobic training in rats

We evaluated the effects of swimming and anabolic steroids (AS) on ventricular function, collagen synthesis, and the local renin-angiotensin system in rats. Male Wistar rats were randomized into control (C), steroid (S; nandrolone decanoate; 5 mg/kg sc, 2x/wk), steroid + losartan (SL; 20 mg.kg(-1).day(-1)), trained (T), trained + steroid (T+S), and trained + steroid + losartan (T+SL; n = 14/group) groups. Swimming was performed 5 times/wk for 10 wk. Serum testosterone increased in S and T+S. Resting heart rate was lower in T and T+S. Percent change in left ventricular (LV) weight-to-body weight ratio increased in S, T, and T+S. LV systolic pressure declined in S and T+S. LV contractility increased in T (P < 0.05). LV relaxation increased in T (P < 0.05). It was significantly lower in T+S compared with C. Collagen volumetric fraction (CVF) and hydroxyproline were higher in S and T+S than in C and T (P < 0.05), and the CVF and LV hypertrophy were prevented by losartan treatment. LV-ANG I-converting enzyme activity increased (28%) in the S group (33%), and type III collagen synthesis increased (56%) in T+S but not in T group. A positive correlation existed between LV-ANG I-converting enzyme activity and collagen type III expression (r(2) = 0.88; P < 0.05, for all groups). The ANG II and angiotensin type 1a receptor expression increased in the S and T+S groups but not in T group. Supraphysiological doses of AS exacerbated the cardiac hypertrophy in exercise-trained rats. Exercise training associated with AS induces maladaptive remodeling and further deterioration in cardiac performance. Exercise training associated with AS causes loss of the beneficial effects in LV function induced by exercising. These results suggest that aerobic exercise plus AS increases cardiac collagen content associated with activation of the local renin-angiotensin system.     

Prolactin concentrations in follicular fluid following ovarian hyperstimulation for in vitro fertilization

Prolactin (PRL) and sex steroid concentrations were measured in follicular fluids of women treated either with (1) clomiphene/hCG or with (2) clomiphene + hMG/hCG. Method 1 of ovarian stimulation resulted in lower follicular PRL and higher oestradiol-17 beta (E2) and progesterone (P) concentrations than method 2. There was no difference in the PRL and sex steroid concentrations of follicles with fertilized and of those yielding unfertilized ova, but in both stimulation types, follicles from which no oocytes were obtained had high PRL and low E2 and P levels. Significant positive correlations were evident for PRL and T and E2 and P, respectively, while PRL and P were negatively correlated.