Characteristic expression of cholesterol sulfate in rabbit endometrium during the implantation period

Sialic acids and sulfate residues are the major negative-charged cellular components, which are considered to be crucial in embryonal adhesion to the endometrium. To explore the mechanism of implantation, we examined the change in the amounts of these substances in the rabbit endometrium during the implantation period. Gangliosides and sulfatides were present in very small quantity in the endometrium irrespective of the reproductive stage. Though the content of cholesterol sulfate was relatively low in the nonpregnant endometrium, it abruptly increased at day 5 of pregnancy, i.e. at the beginning of implantation, followed by a gradual decline toward day 9. Cholesterol sulfate level in the inter-implantation sites was about twice as much as that in the implantation sites and was comparable with that in the pseudopregnant endometrium. These results demonstrate that cholesterol sulfate is a major negative-charged lipid in the peri-implantation endometrium in rabbits. We further point to the difference in the concentration of cholesterol sulfate between implantation and interimplantation sites, thus suggesting cholesterol sulfate as a major participant in the process of implantation.

A decline in prolactin levels in amniotic fluid and decidua at term pregnancy after the initiation of labour

Prolactin is known to inhibit the production of prostaglandins, key substances in the initiation of labour. To explore a possible role of prolactin in human parturition, prolactin levels were therefore measured in amniotic fluid and decidua at full-term pregnancy. Prolactin levels in amniotic fluid before labour were about three times higher than those at labour and they tended to decrease with time during labour. Prolactin levels in decidua before labour were about twice as high as those at labour. These findings suggest a possible involvement of prolactin in human parturition.

Exaggerated prolactin response to thyrotropin-releasing hormone in infertile women with the luteinized unruptured follicle syndrome

Ten cases of luteinized unruptured follicle (LUF) syndrome out of 250 women with unexplained infertility were detected on ultrasonography, giving a frequency of 4%. Hormonal analysis revealed lower serum progesterone levels at mid-luteal phase in LUF cases, suggesting a link between LUF syndrome and inadequate luteal phase. Prolactin response to thyrotropin-releasing hormone was exaggerated in LUF cases as compared with ovulatory cases. Aberrant prolactin release may be a contributory factor in the pathophysiology of the LUF syndrome.

Estradiol stimulates the binding of epidermal growth factor in cultured rat granulosa cells

The effect of estradiol on the binding of epidermal growth factor (EGF) was investigated in a rat granulosa cell culture system. Cultured granulosa cells without estradiol possess an EGF receptor with a Kd value of 7.4 x 10(-10) M and binding sites of 1.45 x 10(3) molecules per cell. The addition of estradiol to the culture media resulted in an increase in the binding of EGF in a dose-dependent manner at concentration between 10(-9) M and 10(-7) M. Estradiol at 10(-7) M produced a 2.5-fold increase in the number of binding sites without affecting the binding affinity. An increase in the binding was observed as early as after 6 h incubation. The addition of testosterone alone had no effect on the EGF binding. However, in the presence of follicle stimulating hormone, it increased the binding dose-dependently. The stimulatory effect of testosterone was completely abolished by an aromatase inhibitor, thus suggesting that estradiol converted from testosterone could be a contributing factor in the mechanism of testosterone action. These observations imply that estradiol may play a role in regulating growth and the differentiation of granulosa cells by modulating the EGF binding.

[Inhibitory effect of arachidonic acid on the synthesis of prolactin in human decidual tissues]

Much evidence indicates that human tissues produce prolactin. However, little is known as to which agents regulate its production in decidual tissues. Therefore, it is of interest to examine the effect of arachidonic acid on the production of prolactin, since it is present in considerably large amounts in decidual tissues. The addition of arachidonic acid to culture media resulted in a significant reduction in the amount of prolactin secreted from incubated decidual tissues in a dose-related fashion. Other poly-unsaturated fatty acids, i.e. linoleic and gamma-linolenic acid also inhibited its secretion, whereas saturated fatty acid and mono-unsaturated fatty acids, such as oleic acid, were without effect. The addition of phospholipase A2 and phospholipase C, enzymes to liberate arachidonic acid from phospholipids, also suppressed the secretion of prolactin. Indomethacin and BW-755C, inhibitors of cyclooxygenase and lipoxygenase, respectively, had essentially no effect on the secretion of prolactin. Translatable mRNA for prolactin was detected in decidual tissues. Arachidonic did not alter either the amount of mRNA in prolactin of the amount of its mRNA as a percentage of total mRNA. Thus, it appears that arachidonic acid possibly plays a role as a physiological regulator of prolactin secretion in human decidual tissues. The action of arachidonic acid is not mediated by cyclooxygenase or lipoxygenase products, suggesting that arachidonic acid itself, or its metabolites other than prostaglandin and leukotriene, may be involved in the regulation of prolactin secretion.

[Effects of epidermal growth factor (EGF) on prostaglandin E2 synthesis by cultured human endometrial cells]

Prostaglandins are considered to participate in the nidation of the embryo. However, so far little is known about the regulation of prostaglandin synthesis in endometrial tissue. In this study, we examined the effect of epidermal growth factor (EGF) on the release of PGE2 with primary cell culture of human endometrium. EGF stimulated PGE2 release dose-dependently in the range between 0.1 ng/ml and 100 ng/ml. PGE2 release was augmented significantly as early as 30 minutes after the addition of EGF, reaching a plateau at 3 hours. The stimulatory effect of EGF was eliminated by the concomitant addition of lipocortin, an inhibitor of phospholipase A2. However, the effect of EGF was not influenced by cycloheximide. Estradiol alone had a weak effect on PGE2 release. However, the stimulatory effect of EGF was more pronounced in cells pretreated with estradiol. In conclusion, this report offers evidence that EGF stimulates the release of PGE2 from human endometrial cells, thus implying the involvement of EGF in implantation.

[Influence of peritoneal fluid with endometriosis on the development of mouse embryos]

To clarify the mechanism of infertility associated with endometriosis (EM), the effect of peritoneal fluid (PF) on early embryogenesis was examined. The addition of PF (5%) had no effect on the development of mouse 2-cell embryos. Since the PF is supposed to enter the oviductal cavity, PF may influence reproductive processes by modulating the intraoviductal microenvironment. As expected, PF with EM inhibited the development of 2-cell embryos co-cultured with oviducts whereas PF without EM had no effect. An increase in interleukin 1 (IL-1) has been identified in PF with EM. As with PF with EM, IL-1 inhibited the development of 2-cell embryos inasmuch as the oviducts were co-cultured. Indomethacin, an inhibitor of prostaglandin (PG) synthesis, effectively abolished the inhibitory action of both PF with EM and IL-1 on embryonic development. Moreover, PGE2 directly inhibited embryonic development. PGE2 was shown to inhibit the synthesis of protein by early embryos. These results demonstrate that PF with EM inhibits the development of early mouse embryos by acting on the oviducts. From these results it seems that an increase in IL-1 may be a causative factor in the embryo-toxic properties of PF with EM. We further suggest that PGE2 secreted from the oviducts by stimulation with PF with EM, may be an ultimate contributing factor in embryo-toxicity by inhibiting protein synthesis by early embryos.

Epidermal growth factor-like immunoreactivity in human endometrium

Epidermal growth factor (EGF)-like immunoreactivity was detected in human endometrial tissues. The concentrations of the immunoreactivity fluctuated during the menstrual cycle. The highest levels were observed in the late proliferative phase with the concentrations being 0.50 +/- 0.06 ng/mg protein (M +/- SE, n = 5). Considering the presence of EGF receptors in human endometrium, EGF-like peptides may act in autocrine or paracrine fashions in human endometrium.

A syndrome of hyperandrogenism, insulin resistance, and acanthosis nigricans associated with polycystic ovary syndrome: clinical and laboratory features

We describe an adolescent Japanese girl with acanthosis nigricans and irregular anovulatory menstruation following menarche. Serum LH levels were elevated, whereas serum FSH levels were within normal range. An exaggerated response to LHRH was observed. Further, serum androstenedione levels were markedly elevated. Ultrasonogram revealed bilateral polycystic changes of ovaries. She had a mild degree of insulin resistance. Insulin binding studies using erythrocytes demonstrated a decreased binding capacity of insulin. From the above findings, this patient presents the syndrome consisting of hyperandrogenism, insulin resistance, and acanthosis nigricans and also has clinical and biochemical features compatible with polycystic ovary syndrome.

[Regulation of aromatase activity by gonadotropin-releasing hormone and its agonists in cultured rat granulosa cells]

The effects of Gn-RH and its agonists on the activity of aromatase were examined by means of a rat granulosa cell culture system. A potent Gn-RH agonist, buserelin ([D-Ser (but)6 des-Gly-NH2(10)] Gn-RH ethylamide), alone stimulated aromatase activity in a dose-dependent manner at concentrations between 10(-13) and 10(-6) M. Both Gn-RH and another Gn-RH agonist, TAP144 ([D-Leu6, des-Gly-NH2(10)] Gn-RH ethylamide), also exhibited a stimulatory effect. Buserelin enhanced the activity of aromatase stimulated by FSH at concentrations of 1 and 10 ng/ml. However, it decreased the activity stimulated by a higher level of FSH (100 ng/ml). These results indicate that Gn-RH agonist increases the activity of aromatase in the absence of FSH. However, in the presence of FSH it exerts different effects on the aromatase activity depending on the concentrations of FSH.

[Relationship between luteal function and prolactin in infertile women with endometriosis]

Luteal function in 44 infertile women with endometriosis were studied with reference to prolactin (PRL) and compared with 34 unexplained infertile women without endometriosis. To assess luteal function, serum progesterone (P4) levels were measured on the 3rd, 7th and 10th days of the luteal phase. On the 7th day, serum estradiol (E2) levels and PRL levels were also determined. The response of PRL secretion to TRH was examined at 30 and 60 after following TRH (500 micrograms, im.) administration. The incidence of hyperprolactinemia (basal PRL level greater than or equal to 25 ng/ml) and latent hyperprolactinemia (peak PRL level in TRH challenge test greater than or equal to 150 ng/ml) were 19% and 31%, respectively, in the endometriosis group and 14% and 33%, respectively in the control group. At the midluteal stage, serum P4 levels in endometriosis group were decreased significantly (p less than 0.05), whereas no difference was found between the serum E2 levels in the endometriosis group and the control. In the endometriosis group, there was no correlation between P4 and E2 levels and abnormal secretion of PRL such as hyperprolactinemia and latent hyperprolactinemia. These results indicate the close association of endometriosis with an inadequate luteal phase. However, it seems that the aberrant secretion of PRL has no relation to the impared luteal function in endometriosis.

[Roles of epidermal growth factor (EGF) in the growth and differentiation of human endometrium]

Endometrial tissues undergo drastic changes during menstrual cycle. After menstruation, they proliferate and differentiate into cells with secretory activity in the preparation for egg implantation. Although sex steroids play an important role in the development of endometrial tissues, sequential events occurring in the endometrium can not be fully explained by the direct actions of sex steroids. In this study, we offer evidences that EGF is released from endometrial cells and they possess the receptor for EGF. These findings prompted us to explore the biological roles of EGF in endometrial tissues. Here we clearly demonstrate that EGF is involved in the proliferation of endometrial cells. Moreover, EGF is found to enhance both glycogenesis and glycogenolysis, thus increasing the supply of glucose for blastocysts. We further set forth that EGF augments the capacity of progestin receptor and release of prostaglandins in endometrial cells. In summary, this study emphasizes that EGF may participate in the development of human endometrial tissues in concert with sex steroids, thus contributing to the acquisition of receptivity of eggs in the endometrium.

[Fundamental and clinical studies on biochemical properties of endometriosis in comparison with endometrium]

1. Regulatory mechanism of cell growth of endometriosis in comparison with endometrium. Estradiol alone has no growth-promoting effect on both endometriotic and endometrial cells. Epidermal growth factor (EGF) stimulates cell growth of both cell types. Endometrial cells but not endometriotic cells produce and release EGF into culture media so that stimulatory effect of exogenous addition of EGF is blunted in endometrial cells. Estradiol exerts its mitogenic action by enhancing the mitogenic effect of EGF in endometrium. By contrast, the effect of estradiol is minimal in endometriotic cells, showing less dependency on estradiol for their proliferation. Progesterone inhibits cell growth of the both cell types in the same manner. 2. A biological role of EGF in endometriosis. Endometriotic cells possess EGF receptors. The affinity of the receptor is the same as that of endometrial cells. However, the number of receptor per cell is about half of that for endometrium. Estradiol increases the number of EGF receptors in endometrial cells which may explain the mitogenic effect of estradiol in the face of EGF. However, stimulatory effect of estradiol for EGF receptors is less pronounced in endometriotic cells. Mitogenic action of EGF is suggested to be mediated by phosphorylation of tyrosine residues of 170 kd protein in the tissues. EGF increases the production of tissue plasminogen activator (t-PA) and activates the aromatase activity of the both cell types. However, the stimulatory action of EGF on progestin receptor is observed only in endometrial cells. 3. Biochemical characterization of endometriotic cells in comparison with endometrial cells. Endometriotic tissues accumulate less amount of glycogen and XIII factor of blood coagulation as compared to endometrial tissues. The ability of endometriotic cells to release prostaglandin is also weaker, suggesting suppressed differentiated function of endometriotic cell. Endometriotic cells produce the same amount of CA125 as endometrial cells. Danazol and EGF inhibit the release of CA125 into culture media when standardized per cell. Therefore, normalization of CA125 levels during the treatment dose not always mean the reduction of the lesions but reflect the suppressed function of the endometriotic tissues. 4. Altered microenvironment of endometriotic tissues. An analysis of peritoneal fluid. The amount of peritoneal fluid (PF) with endometriosis increased throughout the menstrual cycle. A number of macrophage is reported to increase in PF with endometriosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Stimulatory action of prolactin on gonadotropin secretion in vitro

The action of prolactin (PRL) on the secretion of gonadotropin was investigated by means of a cell culture system of rat anterior pituitary gland. Anterior pituitary glands were removed from Wistar male rats, enzymatically digested and cultured. Luteinizing hormone (LH) release into medium was increased by adding PRL dose-dependently in the range between 10 ng/ml and 1 microgram/ml. This effect of PRL was further augmented by the presence of either gonadotropin-releasing hormone or estradiol. The intracellular LH concentration was also increased by PRL. PRL also caused an increase in follicle-stimulating hormone release into medium dose-dependently. In conclusion, PRL was shown to stimulate the secretion of gonadotropin at the pituitary level, thus suggesting a paracrine mode of PRL action in the anterior pituitary gland.

Danazol stimulates the release of follicle-stimulating hormone and inhibits the release of prolactin in vitro studies on rat pituitary cell cultures

The actions of danazol on the release of gonadotropins and prolactin (PRL) were investigated by using a culture of rat anterior pituitary gland cells. The addition of danazol in the range between 10(-9) M and 10(-5) M elevated the levels of follicle-stimulating hormone (FSH) in a dose-dependent manner. Danazol at 10(-5) M caused a 70% increase in FSH levels over the control. The intracellular contents of FSH was also increased by danazol, suggesting its stimulatory effect on both the synthesis and release of FSH. Danazol had no effect on the release of luteinizing hormone (LH). Danazol diminished the sensitivity of gonadotrophs to luteinizing hormone-releasing hormone (LHRH) in that the LHRH-induced release of both FSH and LH was suppressed. The amount of PRL released into medium was decreased by danazol in a dose-dependent way.

Inhibitory effects of estradiol on glycogen synthesis in primary cell cultures of human endometrium

The effect of estradiol on glycogen synthesis was examined in a primary cell culture system of the human endometrium. Estradiol inhibited glycogen synthesis in a dose dependent manner with a minimum effective dose of 10(-9)M. Progesterone-induced glycogen synthesis was completely abolished by the simultaneous addition of estradiol. Estradiol did not affect the activity of glycogen phosphorylase in endometrial cells, but the activity of glycogen synthetase was decreased by estradiol irrespective of the presence of progesterone. The inhibitory effect of estradiol on the glycogen synthesis of endometrial cells seemed to be mediated by estradiol receptor, because LY156758, an antiestrogenic drug at receptor site, reversed the inhibitory effect of estradiol.

Changes in prolactin levels caused by luteinizing hormone releasing hormone

The acute effects of luteinizing hormone releasing hormone (LHRH) on the release of prolactin (PRL) were investigated in 12 normal cycling women and 42 women with various menstrual disorders. LHRH (100 micrograms) was bolusly injected intramuscularly and PRL levels were measured immediately before the injection and at 30 minutes and 60 minutes after the injection. LHRH elicited an increase of more than 25% in PRL levels in 15 cases (27.8%) at both 30 minutes and 60 minutes after the injection, whereas PRL levels were decreased by more than 25% in 7 cases (13.0%). The PRL response to LHRH seemed to be related to basal PRL levels. Especially when the PRL concentration was 20 ng/ml or more, LHRH decreased PRL levels in 7 cases out of 16. On the other hand, LHRH increased PRL levels in the majority of cases with a PRL concentration less than 20 ng/ml. In conclusion, the LHRH injection occasionally alters PRL levels in either a positive or negative manner, depending upon the basal PRL levels.

Cyclic changes in epidermal growth factor receptor in human endometrium during menstrual cycle

Epidermal growth factor (EGF), a potent mitogenic peptide, is known to be present in the fluid of the uterine cavity. Recent studies have demonstrated the messenger RNA for EGF in the rat uterus. Therefore, in an attempt to clarify its physiological role, we investigated the receptors for EGF in human endometrial tissues. The particulate fractions from endometrium possessed the capacity to bind EGF in a specific, saturable and reversible manner. The Scatchard plot was linear, showing a single class of the receptor with an apparent Kd of 3.8 X 10(-9) M. The amount of specific EGF binding was very low during menstruation and increased gradually, reaching its peak in the late follicular phase. There was an abrupt decline in the binding after ovulation with no change in the Kd value. These results imply the possible involvement of EGF in the process of proliferation of human endometrial tissues.

[Polycystic ovary--classification and treatment by bromocriptine]

Plasma levels of androstenedione (A) and dehydroepiandrosterone sulfate (DHAS) were measured in 29 women with PCO in an attempt to classify PCO. A and/or DHAS were elevated in all cases. In cases with DHAS levels below 2,000 ng/ml, the A levels were found to be over 1.4 ng/ml. This group was defined as an ovarian type because the major source of A is the ovary. In contrast, women whose DHAS levels were higher than 2,000 ng/ml were classified as an adrenal type. In both groups, the hormonal features were elevated LH levels and exaggerated LH response to LHRH. The mean A levels were 2.43 +/- 0.31 ng/ml in ovarian type and 2.20 +/- 0.42 ng/ml in adrenal type. The mean DHAS levels for the adrenal type were 3,052 +/- 299 ng/ml, or about 3 times as high as normal values. On the other hand, those for the ovarian type were on the upper borderline of the normal range. In both groups, dexamethasone lowered DHAS levels by about 80% with no discernible effect upon A levels. The successful rate for ovulation-induction by clomiphene was 20% in the ovarian and 33% in the adrenal. Bromocriptine induced ovulation in 8 out of 9 cases of the ovarian type. However, only one of 6 responded to bromocriptine in the adrenal type. Bromocriptine-unresponsive cases of the adrenal type ovulated following treatment with combination of clomiphene and prednisolone. In summary, we attempted to classify PCO into ovarian and adrenal types by analyzing the elevated androgen level. This classification seems to be useful in the treatment of PCO and also provides some insight into the pathogenesis of PCO.

Hormonal regulation of the synthesis of casein and alpha-lactalbumin in a primary mammary cell culture system

The addition of 5 micrograms/ml of both insulin and prolactin, 3 microM cortisol and 5% fetal bovine serum stimulated casein synthesis during a 5 day culture of mammary epithelium from lactating mice using a floating collagen gel as a culture substratum. Omission of any of the three hormones or serum decreased casein synthesis substantially. The use of 10% serum or the attached gel culture system also decreased casein synthesis. Cells cultured with the combination of the three hormones and 5% serum contained a low level of casein mRNA on day 2, but it increased to much higher levels on day 4 and 5, amounting to over 30% of total mRNA on day 5. In contrast to casein synthesis, the maximal increase in alpha-lactalbumin synthesis required the presence of 0.03 microM cortisol. The combination of insulin, prolactin and 3 microM cortisol or insulin and prolactin elicited smaller increases. The translatable mRNA for alpha-lactalbumin in cells cultured with insulin, cortisol and prolactin for 5 days was detected, but not in cells with insulin and cortisol. Both a high and low concentration of cortisol in combination with insulin increased prolactin binding capacity of cultured cells to the same extent, whereas cells cultured with insulin alone contained much lower levels of prolactin binding. The difference in the capacity of prolactin binding between cells cultured with insulin alone and those cultured with insulin and cortisol correlated well with their ability to synthesize casein in response to prolactin.

Studies on prolactin in human milk

A possible physiological role of prolactin (PRL) in human milk was studied. The concentrations of milk PRL were 36.5 +/- 5.8 ng/ml on the first day after delivery and increased rapidly on the second day. Higher levels continued up to the fifth day. The levels of milk PRL showed no significant correlation with milk yield. Milk PRL was capable of binding to its receptors, suggesting its biological activities. In conclusion, human milk contains significant amounts of immunoreactive PRL. Milk PRL appears to be biologically potent, which raises the possibility that it may have certain physiological significance for the newborn.

Epidermal growth factor stimulates cell proliferation and inhibits functional differentiation of mouse mammary epithelial cells in culture

Mouse mammary epithelial cells cultured on collagen gels multiplied and produced casein and alpha-lactalbumin in response to insulin, cortisol, and PRL. The addition of epidermal growth factor (EGF) at 50 ng/ml increased the total number of epithelial cells by 30-40% and thymidine incorporation into DNA 4.7-fold after 5 days of culture. In contrast, EGF inhibited hormonal induction of the synthesis of casein and alpha-lactalbumin in those cells by about 45% and 55%, respectively, without inhibiting total protein synthesis. Furthermore, EGF decreased casein mRNA activity by 55% and increased total mRNA activity by 66% in cells cultured with the three hormones. These effects of EGF were apparent at 0.1 ng/ml and were maximal at 50-100 ng/ml and could be reversed by its removal from the medium, followed by the addition of anti-EGF antibody. The inhibition of casein synthesis by EGF was unaffected by the concentrations of insulin, cortisol, and PRL. Other growth factors, such as fibroblast growth factor, multiplication-stimulating activity, nerve growth factor, and platelet-derived growth factor, did not simulate the effects of EGF. Cytarabine (1 microgram/ml), which inhibited thymidine incorporation into DNA by 94%, did not block the inhibitory action of EGF on casein synthesis. These results suggest that EGF serves as a regulator of hormone-dependent growth and differentiation of mammary epithelial cells.

Biological action of epidermal growth factor and its functional receptors in normal mammary epithelial cells

Normal murine mammary epithelial cells possessed the capacity to bind epidermal growth factor (EGF) in a specific and saturable manner. Scatchard plot analysis showed a curvilinear pattern. Assuming that this is not due to negative cooperativity of EGF binding, the data suggest the presence of two classes of receptors with a high and a low affinity: Kd values = 1 x 10(-10)M and 3.6 x 10(-9)M, respectively. The number of high- and low-affinity receptors was estimated to be 800 per cell and 8,600 per cell, respectively. The occupancy of EGF receptors for a half-maximal stimulation of DNA synthesis or inhibition of casein synthesis was about 10% and 6% of total receptors, respectively. A potent tumor promoter, 12-O-tetradecanoylphorbol 13-acetate, acted synergistically with EGF in terms of stimulation of DNA synthesis but not in terms of inhibition of casein synthesis when the two agents were added at a suboptimal concentration. The presence of the tumor promoter increased the amount of EGF bound to mammary cells in culture and also decreased a loss in the amount of EGF in the culture medium. These results indicate that mammary epithelial cells possess functional receptors for EGF, which are modulated by the tumor promoter.

Tumor promoter 12-O-tetradecanoylphorbol 13-acetate, like epidermal growth factor, stimulates cell proliferation and inhibits differentiation of mouse mammary epithelial cells in culture

12-O-Tetradecanoylphorbol 13-acetate (TPA) is a potent tumor promoter and shares several biological activities of epidermal growth factor (EGF). Recently we have shown that EGF stimulates DNA synthesis and inhibits milk protein synthesis induced by insulin, cortisol, and prolactin in a primary mouse mammary epithelial cell culture [Taketani, Y. & Oka, T. (1983) FEBS Lett., in press]. Using this system, we examined the biological action of TPA in reference to that of EGF. TPA stimulated cell proliferation and inhibited the synthesis of milk proteins casein and alpha-lactalbumin during a 5-day culture. The ED50 was about 2.5 ng/ml for DNA synthesis and 0.1 ng/ml for milk protein synthesis. Removal of TPA from the medium normalized DNA synthesis completely and casein synthesis partially. The ability of various TPA analogs to stimulate DNA synthesis and inhibit casein synthesis correlated with their potency as tumor promoters. Both TPA and EGF decreased the specific prolactin binding of cultured cells by approximately equal to 50%. These results indicate that TPA, like EGF, switches the developmental course of mammary epithelium from differentiation to proliferation.

Possible physiological role of epidermal growth factor in the development of the mouse mammary gland during pregnancy

Epidermal growth factor stimulated cell proliferation in a primary mammary epithelial cell culture derived from mice at different stages of pregnancy. Moreover, the peptide hormone inhibited casein production induced by the synergistic actions of insulin, cortisol and prolactin. The inhibitory effect of epidermal growth factor was influenced by the gestational stages of the mammary gland. These effects of epidermal growth factor were exerted at physiological concentrations. The dual actions of epidermal growth factor on mammary cells implicate its participation in regulation of the growth and differentiation of the mammary gland during pregnancy.

[Endocrinological analysis of hypothalamic primary amenorrhea (author's transl)]

Primary amenorrhea, in which serum concentrations of gonadotropins are low or normal, has been considered to be relatively rare. Recent analysis in our outpatient clinic revealed that the incidence of hypothalamic primary amenorrhea is higher than previously appreciated, comprising 26.7% of the total primary amenorrheas. Endocrinological functions of the hypothalamo-hypophyseo-ovarian axis in these patients were therefore investigated. Studies on gonadotropin secretion indicated that a disturbance in LH-RH secretion and a lack of estrogen positive feedback were principle features of this disease. In addition to the dysfunction of gonadotropin secretion, the control of PRL secretion was disturbed in this disease since there was a poor PRL response to chlorpromazine in spite of normal responsiveness to TRH. Thus, "isolated gonadotropin deficiency" hitherto used to describe this disease is not pertinent. Furthermore, these results suggest that PRL might be involved in the onset of puberty in humans. Clinically, the induction of ovulation with HMG (Human Menopausal Gonadotropin) is possible in hypothalamic primary amenorrhea, although the ovarian responsiveness to gonadotropin is poor. Therefore, an endocrinologically precise diagnosis of hypothalamic primary amenorrhea is important in the gynecological clinic because fertility has been considered to be almost impossible in primary amenorrhea.

[Effects of hypothalamic deafferentation and estrogen on the distribution and content of hypothalamic LHRH (author's transl)]

Anterior (AHD), or complete (CHD) hypothalamic deafferentation was performed in female rats to ascertain the origin of LHRH in the arcuate median eminence region (ARC-ME). Furthermore, effects of estrogen on the distribution and content of hypothalamic LHRH in AHD castrated rats were examined to elucidate the mechanism of feedback action of estrogen. Hypothalamic tissues were sectioned serially at 220 micrometers in thickness in the frontal plane and LHRH activity in each section was measured by RIA. AHD induced a significant reduction of LHRH in the ARC-ME. The reduction of LHRH was more prominent in CHD rats. In control castrated rats, serum LH significantly decreased 24 hr and 48 hr after estrogen treatment, and subsequently increased, accompanied with reciprocal change of LHRH in the ARC-ME. Conversely, estrogen caused continuous suppression of serum LH with elevated LHRH content in the ARC-ME of AHD rats. In conclusion, considerable amount of LHRH in the ARC-ME is synthesized in the preoptic area (POA) and transported to the ARC-ME, and some part of LHRH in the ARC-ME is produced in the ARC-ME itself. Axonal transport of LHRH from the POA to the ARC-ME is essential for positive feedback action of estrogen. Moreover, estrogen is suggested to act on the hypothalamus, initially by inhibiting the release of LHRH, which results in subsequent release of LHRH after the disappearance of this temporary inhibition.

Effect of hypothalamic deafferentation on the distribution of luteinizing hormone-releasing hormone (LHRH) in the rat brain

Anterior (AHD) and complete hypothalamic deafferentation (CHD) were performed in female rats to ascertain the origin of LHRH detected in the external layer of ME. Deafferented brains were serially sectioned in a cryostat in the frontal plane. LHRH activity in each section was determined by RIA. While AHD, using a knife with a small radius caused no change in the distribution of LHRH in the brain, AHD, using a knife with a large radius resulted in a significant decrease in LHRH content in the ARC-ME. CHD caused a more marked decrease in the ARC-ME LHRH than AHD. The decrease was more marked in the anterior and posterior portions of the ARC-ME than in the middle one. These effects of CHD on the distribution of LHRH in the ME were ascertained by immunohistochemical studies. In contrast, LHRH content in the POA showed no significant change after AHD and CHD. However, a few LHRH containing fibers were observed in the area lying just proximal to the cut by immunohistochemistry. These results strongly suggest that a part of the LHRH detected in the external layer of ME is derived from that synthesized outside the MBH, possibly in the POA and another part is derived from that synthesized inside the MBH, possibly in the ARC.

Distribution of LHRH in the rat and mouse brain with special reference to the tanycytes

The distribution of luteinizing hormone-releasing hormone (LHRH) was studied in the rat and mouse brain by means of light and electron microscopic immunohistochemistry using the peroxidase-antiperoxidase method. An immunoreactive product to LHRH antiserum was found near the blood vessels of the vascular organ of the lamina terminalis. In the arcuate nucleus-median eminence region, an immunoreactive material occurred bilaterally in the hypothalamic tissue around the tuberoinfundibular sulci. Electron microscopy revealed that immunoreactive fibers observed light microscopically contain numerous granules 100--130 nm in diameter. No immunoreactive product was located in the tanycytes of the median eminence, the perikarya of hypothalamic neurons, and the parenchyma of several circumventricular organs (subfornical organ, subcommissural organ, pineal organ, area postrema).