A. Miyake

Relationship between Metabolic Syndrome and Uterine Leiomyomas: A Case-Control Study

Background/Aims: Uterine leiomyomas are the most common gynecological benign tumor and greatly affect reproductive health and well-being. The pathophysiology and epidemiology of fibroids are poorly understood. Obesity and elevated blood pressure have been reported to be predisposing factors. In this study, we investigated whether fibroids are associated with some criteria of the metabolic syndrome. Methods: The case patients were 213 women who underwent hysterectomy or myomectomy for fibroids, and the control subjects were 159 women who underwent operation for benign indications other than fibroids. Preoperative information on body mass index (BMI), blood pressure (BP), serum triglyceride (TG) and fasting plasma glucose (FPG) was obtained from medical records. The patients were classified as overweight if they had a preoperatively measured BMI of ≧24.0, hypertensive if BP was ≧140/90 mm Hg, hypertriglyceridemic if TG was ≧150 mg/dl, and hyperglycemic if FPG was ≧110 mg/dl. Results: BMI, BP, TG and FPG were significantly higher in the case group compared with the control group. In logistic regression analysis, fibroids were statistically significantly associated with being overweight and hypertensive. With the combination of these risk factors, the risk of fibroids increased. Conclusion: Uterine leiomyomas may share pathogenic features with the development of metabolic syndrome.

The interferon family stimulates the secretions of prolactin and interleukin-6 by the pituitary gland in vitro

The effects of interferon-α, interferon-β1 and interferon-γ on the secretions of prolactin (PRL) and interleukin-6 by primary cultured rat anterior pituitary cells were examined. These three interferons caused dose-dependent increases in PRL secretion within 30 min, and dose-dependent stimulation of interleukin-6 were weaker than the effects of interleukin-1 and tumor necrosis factor-α. These results suggest that interferons regulate PRL secretion from the pituitary gland, and that there may be a pathway in which interferons stimulate PRL secretion through interleukin-6 release.

Metal Transcription Factor-1 Is Involved in Hypoxia-Dependent Regulation of Placenta Growth Factor in Trophoblast-Derived Cells

Placenta growth factor (PlGF) is a placental angiogenic factor. Metal-responsive transcription factor (MTF)-1 was reported to take part in the hypoxic induction of PlGF in RAS-transformed mouse fibroblasts. We contrarily showed that PlGF mRNA and protein levels decreased under hypoxia in a choriocarcinoma BeWo cell line derived from trophoblast. In this report, we examined whether hypoxia-dependent regulation of the PlGF gene in these cells also depends on MTF-1. We analyzed the effect of hypoxia on MTF-1 expression, and it was revealed to be decreased. Moreover, MTF-1 small interfering RNA treatment decreased PlGF mRNA level. To investigate the transcription of PlGF under hypoxia, we cloned promoter region of the human PlGF. Promoter deletion analysis suggested that triple repeats of metal-responsive element located between -511 and -468 bp in the promoter are important for the hypoxic regulation of PlGF. Treatment with MTF-1 small interfering RNA resulted in the significant decreased luciferase activity in PlGF reporter constructs. Chromatin immunoprecipitation showed the binding of the MTF-1 protein to the promoter region. We examined MTF-1 immunoreactivity in trophoblasts of term placental tissue from patients with normal pregnancies and preeclampsia, which represents a condition of placental hypoxia. Immunoreactivity of the MTF-1 protein was decreased in placentas from pregnant women with preeclampsia when compared with those from normal pregnant women. Taken together, these findings suggest that MTF-1 is involved in hypoxia-dependent regulation of PlGF in trophoblast-derived cells.

Gestational changes of glucose transporter gene expression in the mouse placenta and decidua

Glucose is required for fetal development and energy metabolism. The glucose transfer from maternal circulation to fetus, in which glucose transporter (GLUT) should play an important role, is fundamental in the utero-placental-fetal system. In this study, the gestational changes of GLUTI and GLUT3 mRNA level in the mouse placenta and decidua were analyzed by Northern blot analysis. The levels of GLUT1 mRNA in the mouse placenta and decidua increased as gestational day proceeded. Although the level of GLUT3 mRNA in the decidua slightly decreased as pregnancy proceeded, there was a switch in size of a major band of GLUT3 from 4.1 kb to 2.7 kb in the mouse placenta detected by Northern blot analysis. These findings suggest the presence of a difference in the gestational modulation of the level of GLUT1 and GLUT3 in the uteroplacental system.

Cytokine-induced neutrophil chemoattractant gene expression in the rat hypothalamus by osmotic stimulation

Cytokine-induced neutrophil chemoattractant (CINC) is one of the chemokines and has chemotaxity for neutrophils. Recently, we found the presence of stress-sensitive CINC expression in the hypothalamic nuclei such as the paraventricular nucleus. Since CINC was predominantly co-localized with vasopressin in the supraoptic nucleus (SON), we investigated the effect of hyperosmotic challenge on CINC mRNA in the hypothalamus. We found that CINC mRNA expression in the hypothalamus was augmented within 30 min following osmotic stimulation and immediately returned to the basal level. The suckling, which is a stimulation to oxytocin neurons in the SON, has no effect on CINC mRNA expression in the hypothalamus. This is the first evidence that the chemokine in the brain is activated by osmotic stimulation.

Ovariectomy increases the level of estrogen receptor mRNA and estrogen receptor binding sites in female rat adipose tissue

The roles of estrogen in the changes in estrogen receptor (ER) mRNA and ER binding sites in rat adipose tissue were studied in female rats. To elucidate the mechanism(s) behind ovariectomy (OVX)-induced obesity, the levels of ER mRNA and ER binding sites in adipose tissue were analyzed three weeks after OVX using Northern blot analysis of ER mRNA and the [3H]E2 binding assay, respectively. OVX induced an increase in body weight, and replacement of estradiol (E2) prevented that increase. Significant increases in the amounts of ER mRNA and in [3H]E2-specific binding were observed after OVX, and E2 replacement reduced both of those increases. These results suggest that E2 may regulate rat obesity directly through ER in adipose tissues.

Pituitary folliculo-stellate-like cell line produces a cytokine-induced neutrophil chemoattractant.

In previous studies, we reported that cytokine-induced neutrophil chemoattractant (CINC) was produced in the pituitary gland. Here we investigated the possibility of detection of CINC immunoreactivity in the pituitary folliculo-stellate (FS)-like cell line (TtT/GF). Intense immunoreactivity was observed by immunocytochemistry in the cytoplasm and cell processes of TtT/GF cells. CINC immunoreactivity was detected by an enzyme-linked immunosorbent assay in as little as 3 h after conditioning the medium with TtT/GF cells, and it increased significantly in a time-dependent manner during the first 24 h of the culture. This immunoreactivity could be induced by lipopolysaccharide and tumor necrosis factor-alpha in a time- and dose-dependent manner. We also observed the expression of CINC mRNA in TtT/GF cells and LPS increased CINC mRNA accumulation in TtT/GF cells. These findings indicate that CINC produced by FS cells may play a role as a paracrine factor of the anterior pituitary gland, and TtT/GF will provide a useful model system for studying the regulation of CINC secretion by FS cells.

Possible involvement of lipoxygenase pathway of arachidonic acid in rat pituitary hormone release in vitro

The roles of arachidonic acid (AA) and its lipoxygenase products in control of secretion of anterior pituitary hormones were studied in vitro using cultured cells. AA (10−4M) and 5-hydroxyeicosatetraenoic acid (5HETE) (5×10−6M) significantly (p< 0.05) stimulated the releases of LH, TSH, GH, PRL, ACTH and β-endorphin (β-E). Added leukotriene B4 (LTB4) (5×10−6M) also caused significant increases in the secretions of LH, GH, ACTH and β-E. The other lipoxygenase metabolites tested, 12HETE, 15HETE, LTA4, LTC4 and LTD4, had no effect on the releases of anterior pituitary hormones. These results suggest that AA and 5-lipoxygenase metabolites may be involved in the control of the releases of anterior pituitary hormones.

Intraventricular administration of estradiol modulates rat prolactin secretion and synthesis.

The effect of estradiol (E2) on rat tuberoinfundibular dopaminergic (TIDA) neurons was examined in vivo, employing chronic intraventricular (icv) infusion technique using an osmotic mini-pump. The activity of TIDA neurons was assessed by the release and synthesis of prolactin (PRL) in the rat pituitary gland and by the changes in the 3, 4-dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) levels and in the DOPAC/DA ratio in the rat hypothalamus. We also examined the [3H] E2 binding in the rat hypothalamus. Ovariectomized female Wistar rats with E2 replacement were treated with daily icv infusion of 1μM of E2 or saline vehicle for 1, 3, and 7 days using the Alzet osmotic mini-pump and brain infusion kit. At 1 day of icv infusion of E2, the serum PRL level was significantly decreased compared with that in the vehicle group. Northern blot analysis of the total RNA isolated from the pituitary glands demonstrated a decrease in the PRL gene transcript level in the E2 group. At 3 days of E2 treatment, however, the serum PRL level was significantly increased compared with that of the vehicle-injected group and Northern blot analysis also demonstrated that the PRL gene transcript level was increased in the E2 group. At 7 days of E2 administration, there were no significant differences between the E2 and vehicle groups in either serum PRL or PRL gene transcript levels. There was a significant increase in the DOPAC/DA ratio after 1 day in the E2 group. However, no significant effects of E2 on this ratio were observed at 3 and 7 days of treatment. The DOPAC concentration in the E2 group was significantly increased at day 1 and significantly decreased at day 3, compared with that of the respective time in vehicle group. At day 7 there was no significant change in DOPAC concentration in either groups. The DA concentrations in the hypothalamus was not changed on any day in either group. Specific [3H] E2 binding was observed in the rat hypothalamus. These data suggest that E2 may have a biphasic effect on the accumulation of PRL gene transcripts and on the PRL secretion in the rat pituitary by first stimulating and then inhibiting the TIDA neuronal activity.

Repressive effect of the phytoestrogen genistein on estradiol-induced uterine leiomyoma cell proliferation.

Objective. Uterine leiomyomas are the most common gynecological benign tumor and greatly affect reproductive health and well-being. They are the predominant indication for hysterectomy in premenopausal women. Current epidemiological study reported that soy products intake is inversely associated with diseases leading to hysterectomy. Genistein is a soy-derived phytoestrogen and its inhibitory effect on leiomyoma cell proliferation is reported. In this study, we investigated the siginificant inhibitory effect of genistein on estradiol (E2)-induced leiomyoma cells proliferation. Study design. The Eker rat-derived uterine leiomyoma cell line ELT-3 cells were used. Cell proliferation was assessed by counting the number of cells. The expression of estrogen receptors and peroxisome proliferator-activated receptor-γ (PPARγ) was evaluated by Western blot analysis. Results. PPARγ was expressed in ELT-3 cells and genistein acted as PPARγ ligand. This inhibitory effect of genistein was attenuated by the treatment of cells with PPARγ antagonist bisphenol A diglycidyl ether (BADGE) or GW9662. Conclusion. These experimental findings in vitro show that the repressive effect of genistein on E2-induced ELT-3 cell proliferation is through the activation of PPARγ. Genistein may be useful as an alternative therapy for leiomyoma.