Hideki Sakamoto

Glutamic Acid Decarboxylase-Containing Axons Synapse on LHRH Neurons in the Rat Medial Preoptic Area

A double-label electron microscopic immunostaining procedure was employed to examine the interconnections of glutamic acid decarboxylase(GAD)- and LHRH-immunoreactive neurons in the medial preoptic area of the rat. The results provide ultrastructural evidence that GABA-ergic neurons establish symmetric (Gray II) synapses on LHRH neurons.

The cellular effects of estrogens on neuroendocrine tissues.

Estrogen action on sensitive neurons in the rat diencephalon has been studied by morphologic techniques; evidence of estrogen action at every level is presented, including tracts, cells, circuitry and subcellular organelles. The demonstration in the arcuate nucleus of estrogen-induced synaptic remodelling, estrogen-induced postsynaptic membrane phenotypes, changes in intracellular membranes and rapid estrogen actions on neuronal endo-exocytosis indicates that cellular estrogen actions may underlie the neuronal control of reproduction.

Endometrial stromal sarcoma: A clinicopathologic study of 11 cases with determination of estrogen and progestin receptor levels in three tumors

Eleven cases of endometrial stromal sarcoma were obtained from the files of Yale New Haven Hospital from 1969 to 1981 for clinicopathologic correlation and determination of the outcome after hormonal therapy with progestational agents. Histologically, nine of the tumors were classified as low grade stromal sarcomas, and two were of a high grade. All of the patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy as the main modality of treatment. Two patients received radiation, three adjuvant chemotherapy, two hormonal therapy (Megace 160 mg qd), three received no therapy at all, and the treatment is not known in one case. Two of the patients who received no therapy had recurrences and were placed on hormonal therapy. The remaining patient was a stage IV and died of disease 3 months after diagnosis. All four of the patients who were treated with hormonal therapy are alive, free of disease, or with stable tumor from 2 to 6 years after diagnosis. The presence of estrogen receptors (ER) and progestin receptors (PR) was demonstrated in the tumor in some of the cases; this may explain the sensitivity of this neoplasm to hormonal therapy.

Gap junctions and myometrial steroid hormone receptors in pregnant and postpartum rats: A possible cellular basis for the progesterone withdrawal hypothesis

Myometrial gap junctions, levels of cytosol and nuclear estradiol and progesterone receptors, and serum estradiol and progesterone levels were determined simultaneously in pregnant and postpartum rats. Between days 15 to 20 after conception, levels of progesterone nuclear receptors decreased (776.8 +/- 88.5 versus 241.1 +/- 56.5 fmol/mg of DNA, p less than 0.05). The mean serum progesterone also fell by about 50% during this period, but variation in individual levels between days 15 to 20 did not allow for this group to achieve statistical significance until day 21. As the progesterone nuclear receptors decreased, estradiol remained stable, but estradiol nuclear receptors increased (day 21 versus 22: 1710.6 +/- 61.1 versus 3254.8 +/- 203.8 fmol/mg of DNA, p less than 0.05), preceding the increase in gap junctions observed at parturition (day 21 versus 22: 2.0 +/- 0.2 versus 8.0 +/- 3.2 [per 1000 micron plasma membrane], p less than 0.05). Gap junctions fell to prepartum levels by 12 hours, when progesterone nuclear receptors were markedly increasing (6 versus 12 hours post partum: 637.7 +/- 324.8 versus 1509.6 +/- 283.2 fmol/mg of DNA, p less than 0.05). Relationships between gap junctions and cellular estradiol and progesterone nuclear receptors are clearer than could be forecast by circulating hormone measurements alone, and may offer a cellular basis for the role of progesterone in controlling labor.

Steroid-receptor proteins in nonepithelial malignancies of the ovary

Tissue samples from 20 patients with nonepithelial ovarian malignancies were assayed for cytosol estrogen (ERc) and in selected samples progestin-receptor (PRc) proteins. The nine germ cell malignancies assayed were low in ERc. One recurrent granulosa cell tumor had an ERc concentration of 36 fmole/mg cytosol protein (fmole/mg c.p.) while three other stromal tumors were low in ERc. Three of seven mixed mesodermal tumors had a high ERc concentration (34-91 fmole/c.p.). Two primary and one recurrent granulosa cell tumors and one endodermal sinus tumor had borderline to elevated PRc levels (18-254 fmole/c.p.). Four of seven mixed mesodermal tumors had borderline to slightly elevated PRc concentrations (13-22 fmole/c.p.). The low ERc in germ cell malignancies of the ovary is consistent with previous clinical observations that the growth of these tumors is not influenced by removal of the contralateral ovary. The high ERc levels detected in three of seven mixed mesodermal ovarian tumors and one of three granulosa cell tumors suggest that hormone-related therapy should be investigated in the management of patients with these malignancies.

An Exchange Assay for the Measurement of Cell Nuclear Estrogen Receptors in Microdissected Brain Regions

Abstract: An exchange assay is described for the measurement of nuclear estrogen receptors (ERn) in micro‐dissected brain regions. The distribution of ERn in the hypothalamus and amygdala of the rat 1 h after an injection of estradiol (E) is presented. Combining the exchange assay with a previously described method for measurement of cytosol estrogen receptors (ERc) in microdissected brain samples, gonadectomized male and female rats were compared for ERc and ERn. While ERc concentrations tended to be higher in females than in males in all regions of the hypothalamus, with a significant sex difference in the arcuate‐median eminence, no sex difference in ERn concentrations was observed after E injection. These results suggest that ERc measurements alone are not sufficient to establish the capacity of the E receptor system: ERn measurements are also necessary to establish the relationship between receptor levels and physiologic estrogen responsiveness.

Solitary pelvic neural tumors with high steroid receptor content.

Two pelvic benign neural tumors, a neurofibroma and a neurilemmoma, were found to have high levels of cell nuclear estrogen receptors and both cytoplasmic and nuclear progestin receptors. A review of the literature reveals that neurogenic tumors occur predominantly in young women. This observation together with the recent findings of elevated sex steroid receptor proteins in meningiomas supports a hypothesis for the common hormonal dependence of neoplasms arising from the neural supporting tissues.

Pharmacologic levels of nitrendipine do not affect actin-myosin interaction in the human uterus and placenta☆☆☆

Because of the potential of dihydropyridine calcium channel blockers in the management of premature labor, we have studied the direct effects of nitrendipine on actomyosin in the pregnant and nonpregnant uterus and in the term human placenta. Actomyosin adenosinetriphosphatase in the three tissues and another model of actin-myosin interaction, superprecipitation of placental actomyosin, were inhibited by nitrendipine. The inhibition was not diminished by high concentrations of calcium. To identify the mechanism, placental myosin was phosphorylated in the absence and presence of 0.8 X 10(-4) mol/L of nitrendipine. The myosin phosphorylated in the presence of nitrendipine had lower actin-activated adenosinetriphosphatase, which is consistent with the inhibition of myosin light chain phosphorylation. However, nitrendipine did not affect the adenosinetriphosphatase activity of myosin nor did further reduce the adenosinetriphosphatase of the already phosphorylated placental actomyosin. Thus nitrendipine inhibition is directed to the phosphorylation reaction but not to the adenosinetriphosphatase site of myosin. Myometrial relaxation in vivo or in vitro occurs at the pharmacologic nitrendipine levels of 10(-9) to 10(-8) mol/L, which is at least 10,000 times lower than that of the concentration of 50% inhibition of myosin light chain phosphorylation (0.0026 +/- 0.00015 mol/L of nitrendipine, mean +/- SEM) demonstrated in the present work. Because of this difference, the direct intracellular actions of dihydropyridine calcium channel blockers are not expected to cause adverse effects in the uteroplacental system when these drugs are used in the prevention or treatment of premature labor.