Development of a human granulosa cell culture model with follicle stimulating hormone responsiveness

In order to study the effects of follicle-stimulating hormone (FSH) on differentiation of granulosa cells, a well-defined and validated in-vitro culture system is indispensable. In this study, pooled follicular aspirates were stimulated in vitro with FSH and luteinizing hormone (LH) for 2, 4 and 6 days, either immediately after plating or after 7 days of preincubation. Cultures were assayed for progesterone and oestradiol production. Fresh cells displayed very high basal progesterone production which could be stimulated with LH but not FSH. After preincubation, addition of LH and FSH resulted in dose-dependent increases of progesterone and oestradiol. When cultured on human fibronectin-coated wells, similar basal but higher progesterone concentrations after stimulation were observed. In comparison with serum-free media, addition of Serum-Plus resulted in higher basal and stimulated progesterone concentration, possibly due to the presence of serum factors. This study demonstrates firstly that after 7 days preincubation, cultures gained responsiveness to FSH but remained responsive to LH during 4 days of stimulation. This suggests a persisting differentiated cell population in vitro. Secondly, the use of human fibronectin extracellular matrix and serum promotes steroid production, either due to factors promoting cell growth and function or to availability of steroid precursors. Therefore one has to be cautious with interpretation of data obtained from this widely used culture system, employing highly differentiated cells obtained after ovarian stimulation for in-vitro fertilization for study of local regulation of granulosa cell function.

Model of antral follicle dynamics during the 5-day cycle in rats based on measurement of antral follicle inflow

Antral follicles were counted in ovaries from young adult Wistar rats, collected on the 5 days of the ovarian cycle. Follicles were classified as healthy, early atretic or late atretic and divided into five volume classes. From these data, a model was developed in which the inflow of healthy follicles into the various size classes was quantified. This model describes the follicle dynamics during a normal 5-day cycle. It was concluded that the stage of early atresia takes between 20 and 24 h. The inflow of follicles into the antral stage (volume > or = 100 x 10(5) microns2) was continuous but not constant. The highest inflow was found during pro-oestrus and oestrus, at about the time of the first and second FSH surge. The total inflow during each cycle was about 120 follicles of which only 10% ovulated. These ovulating follicles were recruited during the previous pro-oestrus and oestrus. Follicle selection took place in volume classes 1 and 2 (volume 100-350 x 10(5) microns3) during oestrus and dioestrus 1. At dioestrus 2, the follicles that will ovulate have been selected and can be recognized on the basis of their bigger size.

The differential effects of FSH and LH on the human ovary

The basic foundation for normal puberty and adult reproductive function is established during fetal life with the adequate development of the hypothalamus, pituitary and gonads. Further maturation and differentiation of the hypothalamic-pituitary-gonadal axis continues throughout childhood, puberty, adult life and senescence. Pituitary FSH and LH play a central role in the cascade of events in the hypothalamic-pituitary-gonadal axis by mediating between the brain and hypothalamus on one hand and the end-organ, the ovary, on the other. Absent or low pituitary secretion of FSH and LH, as occurs in hypothalamic/pituitary hypogonadism, leads in women to anovulation, amenorrhoea and absent ovarian follicular development. The ability of gonadotrophins to modulate ovarian function depends on their rate of synthesis by the pituitary gonadotrophs, on their circulating concentrations (which vary throughout life and throughout the menstrual cycle), on the relative abundance of the multiple forms of gonadotrophins that have varying biological activity, on the presence of their receptors on the different cell types of the ovary, on the intracellular adenylate cyclase enzyme that causes the production of cAMP, and on the extra- and intragonadal factors that are able to modulate the effects of gonadotrophins in the ovary. Recent clinical and basic research with recombinant gonadotrophins, molecular biological studies on the localization, function and regulation of the long sought after gonadotrophin receptors, as well as research on the interaction between gonadotrophins and local intragonadal factors have widened our knowledge about the function and role of FSH and LH in the ovary and have provided new insights into previously unanswered questions of ovarian physiology and pathophysiology and will provide the basis for the design of new treatment strategies to overcome ovulatory gonadotrophin-dependent dysfunction in the future.

[Control of terminal follicular maturation during the follicular phase in domestic mammals]

Terminal follicular maturation in the ovine and the bovine species involves growth and differentiation processes in follicles between 1-2 mm diameter and the preovulatory stage. During this maturation, the follicle acquires the ability to ovulate and the oocyte becomes able to be fertilized and to develop after fertilization. Selection of ovulatory follicles results from the integration of different parameters such as the circulating levels of gonadotropins, the structure of follicular populations and the sensitivity of the hypothalamo-pituitary axis to ovarian hormones. Differences between follicles for FSH and LH responsiveness can be amplified by paracrine intrafollicular regulations. These mechanisms are probably determinant for selection of ovulatory follicles.

Changes in follicular estradiol-17 beta, progesterone and inhibin immunoactivity in healthy and atretic follicles during preovulatory maturation in the pig

Follicular hormones, growth and granulosa cell gonadotropin sensitive adenylate cyclase activity were determined in healthy and atretic follicles during preovulatory maturation in pigs. Ovaries were recovered at slaughter which was 1, 3, 5 or 7 d after the last administration of a progesterone agonist (altrenogest). Plasma FSH decreased (P < .05) by 64% between days 1 and 3 and remained low through day 5. The number of large (> 5 mm) follicles increased from 2.7 on day 1 to 14.8 on day 3 and did not differ significantly among days 3, 5 and 7. The number of small (1-2 mm) and medium (3-5 mm) follicles decreased (P < or = .05) by 82% between days 3 and 5. Follicles first became estrogen-active (EA) (> or = 100 ng of estradiol-17 beta/ml of follicular fluid) on day 3, with 14.3% of medium and 73.8% of large follicles being EA. About 30% of small and 13% of medium follicles were morphologically atretic on days 1 and 3. However, by day 5, the proportion of atretic small and medium follicles had increased (P < or = .05) to 100 and 59%, respectively. Follicular fluid inhibin immunoactivity and estradiol-17 beta were lower (P < or = .05) and progesterone was greater (P < or = .05) in atretic than healthy follicles. Granulosa cells from large follicles produced (P < or = .05) more cAMP than cells from healthy or atretic small/medium follicles. Compared to control or pFSH treatment, pLH increased cAMP production by granulosa cells from large follicles on all days and from small/medium follicles on days 1 and 5; pLH had no effect on granulosa cells from atretic follicles. Compared to control, pFSH increased cAMP production in granulosa cells from healthy small/medium follicles only on day 1; no effect was detected in granulosa cells from large or atretic follicles on any day. We conclude that decreased secretion of FSH increased loss and atresia among non-ovulatory follicles. Atretic follicles were marked by loss of granulosa cell gonadotropin-sensitive adenylate cyclase activity and by low concentrations of estradiol-17 beta.

[Ovarian stimulation: a new approach based on recent physiological and clinical data. Future perspectives]

Taking into account the experience gained in medically assisted conception and ovulation induction, the pregnancy rate and more particularly the baby home rate after ovarian stimulation protocols remain stable. Today, could we expect to improve our results from our recent knowledge on the role of the different factors involved in the follicular maturation process and ovulation? The improvement of our results means to mimic or to amplify the ovarian physiology, taking into account the FSH actions, the key hormone for follicular maturation. At the beginning of the menstrual cycle, FSH is responsible of the "rescue" of one or more follicles selected for ovulation, of their growth and their differentiation allowing the evolution of an androgen intrafollicular environment toward an estrogen intrafollicular environment which is necessary for a good quality. In late follicular phase, whereas FSH is acting continuously on the multiplication and differentiation of granulosa cells, in particularly on the stimulation of the aromatase activity, small quantities of LH (included between 1 and 6-8* IU/L) allow final follicular maturation (androgen production, synergic action with FSH and antagonist action on FSH action). If, low dose of LH complements FSH action in final follicular maturation process, high levels (> 6-8 IU*/l) are deleterious for follicle or oocyte quality. Numerous studies demonstrate a significant correlation between high levels of LH and the lack of pregnancy either the follicle is submitted to high concentrations at the beginning, at mid or at the end of follicular phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Pituitary hormone FSH directs the CREM functional switch during spermatogenesis

The CREM (cyclic AMP-responsive element modulator) gene encodes multiple regulators of the cAMP-transcriptional response by alternative splicing. A developmental switch in CREM expression occurs during spermatogenesis, whereby CREM function is converted from an antagonist to an activator (CREM tau; ref. 2) which accumulates to extremely high levels from the premeiotic spermatocyte stage onwards. To define the physiological mechanisms controlling the CREM developmental switch, we have hypophysectomized rats and observed the extinction of CREM tau expression in testis, thereby demonstrating a central role of the pituitary-hypothalamic axis. We then used the seasonal-dependent modulation of spermatogenesis in hamsters to dissect the hormonal programme controlling this developmental process. By this approach, combined with direct administration of pituitary-derived hormones, we have established that follicle-stimulating hormone (FSH) is responsible for the CREM switch. FSH appears to regulate CREM expression by alternative polyadenylation, which results in a dramatic enhancement of transcript stability.

Sertoli cell secreted growth factor. Cellular origin, paracrine and endocrine regulation of secretion

Rat and human Sertoli cells in culture secrete a growth factor, Sertoli cell secreted growth factor (SCSGF). The aims of the present study were (1) to evaluate other testicular cell types as additional sources of SCSGF, as well as their paracrine effect, and (2) to study the hormonal regulation of SCSGF secretion using an A431 cell growth assay. The Sertoli cell was the only testicular cell type tested that secreted SCSGF activity in vitro. Peritubular cells enhanced Sertoli cell attachment and SCSGF secretion. Spermatogenic cells had no effect. The secretion of SCSGF was specifically stimulated by follicle-stimulating hormone (FSH) and testosterone. Treatment with agents that increase intracellular cAMP levels and adenosine stimulated the secretion of mitogenic activity into Sertoli cell-conditioned medium by three- to fivefold. This growth factor, secreted by the Sertoli cell and regulated by FSH and testosterone, may play a critical role in the regulation of spermatogenesis.

Follicle-stimulating hormone increases the turnover of G-protein alpha i-1- and alpha i-2-subunit messenger RNA in Sertoli cells by a mechanism that is independent of protein synthesis

We have shown previously that FSH differentially regulated G-protein alpha i-subunit mRNA levels in primary cultures of rat Sertoli cells. The mechanism by which FSH regulated the steady state levels of these mRNAs was investigated by assessing the effect of FSH on G-protein alpha-subunit mRNA stability and the potential involvement of newly synthesized proteins. The half-life (t 1/2) of alpha-subunit mRNA was determined by inhibiting Sertoli cell transcription with actinomycin-D and quantifying alpha-subunit mRNA levels by Northern blot analyses. Transcripts for alpha i-2 and alpha 3 were extremely stable, possessing t1/2 of 44 and 51 h, respectively. In contrast, the t1/2 of alpha i-3 mRNA was only 3.6 h. Turnover of alpha i-1 mRNA occurred as a two-phase decay, with an initial t1/2, fast of 0.8 h, followed by a second phase with t1/2, slow of 11.1 h. Treatment of Sertoli cells with FSH in the presence of actinomycin-D destabilized the alpha i-1 mRNA to a single phase decay with a t1/2 of 5.7 h. FSH also decreased the stability of the alpha i-2 mRNA from a t1/2 of 51 h to a t1/2, fast of 16.5 h. These effects of FSH on alpha i-1 and alpha i-2 mRNA stability may contribute to the ability of FSH to decrease steady state alpha i-1 and alpha i-2 mRNA levels. The effect of FSH on alpha i-3 mRNA stability was not significant, suggesting an alternative mechanism regulating the FSH-mediated increase of alpha i-3 mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions between FSH, estradiol-17 beta and transforming growth factor-beta regulate growth and differentiation in the rat gonad

Estradiol-17 beta (E2) is a mitogen in vivo for the proliferation of granulosa cells in the rat ovary. E2 is synthesized by the preovulatory follicle through a series of gonadotrophin-dependent events: LH stimulates thecal cells to synthesize androgens (androstenedione and testosterone) which are substrates for FSH-induced aromatization to estrogens in granulosa cells. More recently, we have found that transforming growth factor-beta (TGF-beta) stimulates DNA synthesis in rat granulosa cells in vitro and this effect is augmented by FSH. Since E2 is a mitogen in vivo and TGF-beta is the only known growth factor to stimulate proliferation in vitro, the possible link between the actions of E2 and TGF-beta were examined. E2 stimulated the secretion of a TGF-beta-like factor by rat granulosa cells in culture, and with time DNA synthesis was stimulated. The mitogenic action of E2 was enhanced in the presence of FSH, and attenuated by a neutralizing antibody to TGF-beta. The latter observations have identified TGF-beta as the "missing-link" in the mitogenic actions of E2 on rat granulosa cells. In addition to the growth-promoting actions of TGF-beta plus FSH, TGF-beta enhanced FSH-induced aromatase activity. Consequently, FSH plus TGF-beta stimulates both the proliferation and aromatization capacity of rat granulosa cells. We propose that interactions between FSH, E2 and TGF-beta lead to the exponential increase in serum E2 levels that occurs during the follicular phase of the cycle. Similarly, FSH stimulates the aromatization of exogenous androgens to estrogen by Sertoli cells isolated from immature rat testes, and there is a correlation between FSH-induced aromatization and mitotic activity. We have shown that FSH plus TGF-beta stimulates DNA synthesis in Sertoli cells. Since E2 increases the secretion of TGF-beta by Sertoli cells, interactions between FSH, E2 and TGF-beta may provide the mitogenic stimulus for Sertoli cells during the prepubertal period. In summary, our findings suggest that the estrogen-induced growth of rat granulosa cells is mediated through the production of TGF-beta, which acts as an autocrine regulator of proliferation. We also propose that the growth-promoting actions of FSH on Sertoli cells may depend upon a cascade series of events involving estrogens and TGF-beta.

Responsiveness of porcine large and small luteal cells to luteotropic or luteolytic hormones and cell morphologic changes during the estrous cycle and pregnancy

Isolated porcine luteal cells from d 10 and 15 of the estrous cycle (estrus = d 0) were incubated with or without combinations of FSH (0, 10, 10(2), 10(3) ng), LH (0, 10, 10(3) ng), oxytocin, or prostaglandin F2 alpha (PGF2 alpha) (each at 0, 10, 10(3), and 10(5) pg). Progesterone (P4) content was determined after overnight incubation (0 h) then at 2 and 24 h of incubation. The basal (0 h) P4 production of large cells (LC) from d 10 corpora lutea (CL) was 31-fold higher than that by small cells (SC) at 0 h. The LC and SC from d 10 but not those from d 15, were stimulated to a small extent by LH (P < .05). The FSH inhibited P4 production (P < .05) by SC at 24 h on d 10 and by LC after 2 or 24 h of incubation on d 15. There was no interaction between LH and FSH on P4 production. Oxytocin and PGF2 alpha decreased P4 production by d 15 LC at 2 h of incubation (P < .05) and by d 15 SC after 2 or 24 h of incubation (P < .05 and P < .01). The morphology of cells from CL of the cycle or early or mid pregnancy were examined using scanning and transmission electron microscopy (EM). Freshly isolated LC (using scanning EM) from d 10 contained many microvilli arranged in apparent networks on their membranes, but SC had smooth surfaces and contained only a few microvilli. Internally, LC had more small mitochondria than did SC and a different organization of smooth endoplasmic reticulum (SER). The SC from CL of pregnant (d 30 to 60) gilts contained more mitochondria than SC from CL of cyclic gilts. The results indicate that FSH, oxytocin, and PGF2 alpha can have a direct cellular luteolytic effect in the late luteal phase in pigs. The FSH influenced LC, whereas oxytocin and PGF2 alpha effected a more pronounced decrease in P4 from SC. The lower amount of P4 produced overall by SC may be associated with fewer microvilli, mitochondria, and SER in SC.

Pure FSH alone induces ovulation and subsequent pregnancy in the mouse resulting in fetal development

The role of FSH in inducing folliculogenesis is well established. Recently, the availability of pure FSH has led to a reevaluation of its role in the process of ovulation. Previously, these functions have been examined separately, usually with pregnant mares' serum gonadotropin (PMSG) followed by FSH for ovulation or FSH for folliculogenesis followed by hCG for ovulation. To determine if FSH alone can induce both folliculogenesis, ovulation and establish a functioning corpus luteum without exogenous LH, we injected sexually mature intact mice (CD-1) with either ovine FSH (oFSH, 5 micrograms; < 0.2% LH contamination) or recombinant FSH (RCFSH, 1 IU; devoid of any LH activity) to stimulate folliculogenesis, followed forty-eight hours later by a second injection of the same preparation (oFSH, 15 micrograms; RCFSH, 1 IU, respectively) to induce ovulation. Injected female mice were mated individually with a fertile male. On days 15-17, pregnancy rates and fetal development were obtained for each animal and were compared with controls, mice injected with PMSG (1 IU) followed by hCG (1 IU). oFSH/oFSH and RCFSH/RCFSH results were combined since no statistical significant differences were detected between these groups. The pregnancy rate for the group receiving FSH/FSH (78.3%, n = 23) was higher than that of the PMSG/hCG group (48.3%, n = 27; p = .02). The number of fetuses produced per mouse in animals receiving FSH alone (8.5 +/- 1.1; mean +/- S.E.) also was greater than the controls (4.5 +/- 99; p = .01). We conclude that the ability of these animals to proceed beyond ovulation to implantation with fetal development demonstrates FSH's ability to cause not only follicular maturation and rupture, but also granulosa cell luteinization, further identifying the potentially important role of FSH in the ovulatory process.

Gonadotropin-releasing hormone has a biphasic action on aromatase activity through protein kinase C in granulosa cells

Gonadotropin-releasing hormone (GnRH) exerts direct effects on the ovary by binding to its specific receptor, and stimulates inositol phospholipid turnover in granulosa cells. This study was undertaken to determine the involvement of protein kinase C in the action of GnRH on follicle-stimulating hormone (FSH)-stimulated aromatase activity in rat granulosa cells. The aromatase activity was examined by conversion of exogenously supplied androstenedione to estrogen. FSH stimulated aromatase activity, with a low rate of estrogen production for the first 18 hours, followed by a high rate of production on further incubation. Addition of GnRH potentiated the aromatase response to FSH in the first 18 hours, but caused a dose-dependent inhibition of the FSH-stimulated aromatase activity from 20 to 45 hours of incubation. Half-maximal effects of GnRH occurred at 10 nM. Both of the biphasic actions of GnRH on aromatase response to FSH were mimicked by protein kinase C activators, phobol myristate acetate (PMA) and oleoylacetyl glycerol; maximal effects occurred at 1 to 10 ng/mL. When the cells were exposed first to FSH for 18 hours and then to PMA, the second phase of estrogen production was also suppressed. The second phase, producing quantitative estrogen, might result from induction of the enzyme, because cycloheximide (100 ng/mL) prevented the FSH-induced activation of aromatase from 20 hours of incubation. These results indicate that the biphasic actions of GnRH on FSH-stimulated aromatase activity are mediated by protein kinase C. The inhibitory action of GnRH on quantitative steroidogenesis caused by prolonged FSH stimulation might be expressed through the impaired induction of aromatase.

Culture of human preovulatory granulosa cells: effect of extracellular matrix on steroidogenesis

Human luteal granulosa cells, harvested from preovulatory follicles during in vitro fertilization attempts, were cultured in a serum-precoated substratum ('serum cells') or on a collagen matrix ('collagen cells'). Concerning the 'serum cell' model, E2 secretion was very low in the absence of androgen; when androstenedione was added to the culture medium, cells secreted 180 +/- 52 pmol/ml/24 h of estradiol, 440 +/- 78 pmol/ml/24 h of testosterone and lower quantities of estrone and estriol. Follicle stimulating hormone induced a significant increase in estradiol and estriol, while the secretion of the other steroids was not altered. The secretion of progesterone was 3.15 +/- 1 nmol/ml/24 h and significantly enhanced by luteinizing hormone (+ 95%; P < 0.01). The secretions of 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone were low and not modified by luteinizing hormone. 'Collagen cells', in basal conditions, showed an increased secretion of estradiol (+ 50%, P < 0.05), became rounded and were less responsive to gonadotropins when compared with 'serum cells'. Thus, the use of a collagen matrix, similarly to gonadotropins, stimulated granulosa cell steroidogenesis in relation to modifications of cell shape. The higher responsiveness of serum cells to gonadotropins makes this model more suitable for physiological and pharmacological studies than the collagen one.

Expression of the FSH receptor in the testis

FSH has multiple and changing roles in the regulation of spermatogenesis. The first function of FSH is to increase the number of Sertoli cells by stimulation of their mitotic activity. During the prepubertal phase of development, FSH is important for the maturation of the Sertoli cells. Hormonal stimulation of tight junction formation and specific protein secretion are essential. In the adult rat, some of the functions carried out by FSH in prepubertal animals are assumed by testosterone. However, there is evidence that even in the adult rat, FSH is important for quantitatively normal spermatogenesis. The gene for the FSH receptor is large (greater than 85 kb) and complex (10 introns) and is structurally similar to the genes for the LH and TSH receptor. The promoter region of the FSHR gene has been identified and is active in the expression of transgenes in transfected Sertoli cells. We have shown that the FSH receptor mRNA is present in the testes of the adult rat and that the levels of this mRNA are changing during the cycle of the seminiferous epithelium. The presence of relatively high levels of FSHR mRNA in stages XIV-II of the cycle and the relatively low levels in stages VII-VIII suggest that the FSH receptor is carefully regulated in adult rats and presumably has an important function in spermatogenesis. The levels of FSHR mRNA in cultured Sertoli cells are immediately reduced in the presence of FSH or phorbol esters, but the levels soon return to normal.

An update on the roles of inhibin, activin, and follistatin as local regulators of folliculogenesis

The local actions of the inhibin-related peptides inhibin, activin, and follistatin in folliculogenesis, luteinization and atresia are reviewed. On the basis of in vitro data, it is concluded that (a) inhibin has a paracrine action positively regulating LH-induced androgen production by theca cells in addition to a peripheral role regulating FSH secretion; (b) activin has a negative paracrine action on LH-induced androgen production by theca cells; (c) activin, either alone or with FSH, has an autocrine action on granulosa cells, promoting differentiation during the preantral and early antral stages of folliculogenesis and preventing premature luteinization in the later stages of antral follicle development, leading overall to promotion and maintenance of the folliculogenic state of the follicle; and (d) follistatin modulates granulosa cell function in favor of luteinization or atresia, and its mechanism of action involves neutralizing the actions of activin by its binding properties and by a direct action of follistatin on progesterone metabolism by granulosa cells. A hypothesis for a role of activin in the acquisition of responsiveness of granulosa cells of preantral follicles to FSH is proposed.

Transforming growth factor-beta (TGF-b) induced phosphorylation of the myristoylated alanine rich C kinase substrate (MARCKS) protein in ovarian granulosa cells is modulated by follicle stimulating hormone (FSH)

The mechanism by which TGF-b1 affects granulosa cell physiology as well as the modulation of TGF-b1 activity by FSH are not understood. We tested the hypothesis that TGF-b1 exerts its effects on granulosa cells via activation of protein kinase C (PKC). Immunoprecipitation of the MARCKS protein from 32P labeled rat granulosa cells was used to assay PKC activation. 20 minute treatment with TGF-b1 (8 ng/ml), forskolin (30 microM), and TPA (200 nM) all caused an increase in MARCKS phosphorylation as quantified by densitometric scanning. FSH did not increase MARCKS phosphorylation above control levels while exposure of cells to both FSH and TGF-b1 (10 ng/ml) decreased phosphorylation of the MARCKS protein to control levels. These data suggests that (1) TGF-b1 signal transduction in rat granulosa cells may partially involve phosphorylation of the MARCKS protein; and, (2) in granulosa cells FSH can modulate TGF-b1 induced MARCKS phosphorylation.

Endocrine control of the immunosuppressive activity of the submandibular gland

Extracts of the submandibular gland (SMG) of rats contain fractions that stimulate the in vitro proliferation of Con A-treated lymphocytes. One of the stimulatory fractions was also shown to induce in vivo immunosuppression in rats and mice in several experimental models. Since many other biologically active factors of the SMG had been found to be hormone dependent, we investigated the effects on the immunosuppressive factor of hypophysectomy (Hx) and of hormonal reconstitution in male Fischer rats. Hx induced a marked atrophy of the SMG together with an almost complete disappearance of both the in vitro lymphocyte-stimulating activity and the in vivo immunosuppressive activity, the latter assayed with the contact sensitivity reaction in mice. The treatment of the Hx rats with pituitary hormones demonstrated that prolactin (PRL), thyroid stimulating hormone (TSH), and luteinizing hormone (LH) induced a significant reconstitution of these biological activities, growth hormone led to the recovery of the lymphocyte-stimulating activity but not of the immunosuppressive activity, while follicle-stimulating hormone, and adrenocorticotropic hormone did not induce any recovery of these biological activities. In view of the positive results obtained with TSH and LH further experiments were done to compare the effects of thyroid and sex hormones with those of PRL. The results demonstrated that testosterone and thyroid hormones induced significant recovery of the lymphocyte-stimulating and the immunosuppressive activity. The combination of these two hormones with PRL produced the most effective results. On the other hand, estrogens and progesterone had no significant effects. These results confirm the effectiveness of androgens and thyroid hormones in stimulating the production of biologically active factors by the SMG. Moreover, they demonstrate that PRL, a hormone not previously considered to increase the activity of the SMG, stimulates the production of immunoregulatory factors in Hx animals.

[Inhibitory effect of transferrin on the binding and maintenance of FSH receptors in rat granulosa cells]

It has been recently demonstrated that transferrin (TRF) can inhibit the functional differentiation of rat granulosa cells, but the mechanism remains unknown. In present experiment, the effect of TRF on the binding of 125I-rFSH to receptors and on the maintenance of FSH receptors in granulosa cells from immature, diethylstilbestrol treated rats were studied. The results show that the physiological range of TRF partially blocked the binding of 125I-rFSH to granulosa cells in a dose-dependent manner. TRF also dose-dependently inhibited the maintenance of FSH receptors in accordance with the reduced production of progesterone and estradiol. In view of the present and our previous investigation, it could be concluded that mechanisms of the inhibitory effect of TRF on the functional differentiation of granulosa cells mainly involve blockade of FSH binding to its receptors and inhibition of FSH receptor maintenance by FSH.

[Identification of molecular species in porcine luteal glutathione S-transferase and its hormonal regulation by hypophyseal gonadotropins]

The glutathione S-transferase (GST) was purified to homogenous state from cytosol fraction of porcine corpora lutea. Present studies showed that the final enzyme preparation was consisted of a single molecular species of GST 1-1 (ligandin), which has been identified from its enzymatic properties, amino acid sequences and immunological reactivity. Furthermore, it has been suggested that the ovarian GST involves in the steroidogenesis, especially in the step of progesterone synthesis, from the following results. 1) The final enzyme preparation has a significant delta 5-3-ketosteroid isomerase activity. 2) GST activity in the cultured porcine granulosa cells was remarkably increased in the luteinizing process, which was induced by an addition of hypophyseal gonadotropins such as FSH and LH to the culture system. 3) Changes of GST activity induced by FSH and LH were closely associated with progesterone production. 4) The GST localized in the luteal cells and theca interna, but not in the granulosa cells, which has been revealed by an immunohistochemical staining using anti-luteal GST antibodies.

Human Sertoli cells in vitro. Lactate, estradiol-17 beta and transferrin production

Human Sertoli cell parameters, namely lactate, estradiol-17 beta, and transferrin production, were determined after a 24-hour incubation with either human follicle stimulating hormone (FSH) or dbcAMP in the presence or absence of testosterone plus a phosphodiesterase inhibitor (1-methyl-3-isobutylxanthine; MIX). Testicular tissues were obtained from 10 young patients (mean age, 29 years); using a 3-step enzymatic treatment, Sertoli cell enriched preparations (> 92%) were studied after 4 days as primary cultures. No significant changes in lactate, estradiol-17 beta, and transferrin outputs have been observed according to age in patients ranging in age from 16 years to 47 years. Sertoli cell production of the compounds is controlled by testosterone plus MIX; FSH (or dbcAMP) treatment only slightly improves their synthesis. It is suggested that human Sertoli cell function, as far as the parameters measured in this study are concerned, is likely regulated by cAMP-dependent and independent pathways.

Effect of unilateral ovariectomy and subsequent ovum implantation in mice

Unilateral ovariectomy (ULO) was done on any stage of the cycle and the animals were mated within day 1 to day 21 to observe the acute and long term effect of ULO on ovum implantation. Implantation reduced in proportion to single ovary if the animals were mated within 24 hr of ULO. Increase in ovarian weight along with an increase in implantation number continued in mated mice and reached at peak on day 19-21 of ULO (sacrificed after 6 days i.e., 25-27 days of ULO). After ULO the remaining ovary compensated within day 5-6 of ULO even during pregnancy. Ovarian histology showed stimulation of small antral follicles in mice mated on day 3 of ULO (sacrificed after 6 days i.e., day 9 of ULO) along with a decrease of large antral follicles and pre-antral follicles. Preantral follicles were at peak on day 12-14. Large antral follicles attained a peak on day 4 which slowly decreased. The occurrence of implantation in such ULO conditions are discussed.