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Volume 58, Issue 10
Displaying 1-6 of 6 articles from this issue
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Osamu TSUTSUMI, Kazuo SATOH, Shoichi SAKAMOTO1982 Volume 58 Issue 10 Pages 1321-1332
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSThe steroid hormone has an important role in the early stages of reproduction. There has been abundant histochemical evidence that oocytes contain steroid hormones and are able to synthesize these hormones. But there have been few methods of analyzing one oocyte biochemically because it is too small and light.
In order to study steroidogenesis in the oocyte, a microassay method sensitive enough to analyze the enzyme activities in one oocyte was developed using enzymatic cycling for amplifying the reaction product to 10,000-fold. An oil-well technique and a microtube method were applied in the assay for achieving the reaction in a medium as small as 1.0 to 5.0μl under a stereomicroscope.
Immature Wistar rats were superovulated by PMS-hCG administration. Oocytes were collected by puncturing the follicle and flushing the tube. They were freezedried after washing to remove cumulus cells. The dry weight of one oocyte was 51.2 ± 6.2ng in a quartz fiber fishpole balance. The activity of 3β hydroxysteroid dehydrogenase (3β HSD) (picomol/ oocyte/hr, substrate : pregnenolone) in the PMS-treated oocyte was 2.66 ± 0.59, which corresponds to 3 times the activity of the ovarian homogenate as control, indicating the high capacity of oocytes to produce progesterone. The activity increased significantly (P<0.01) by hCG administration up to 4.17 ± 0.29 after ovulation, suggesting that gonadotropin regulates steroidogenesis in the oocyte. The activities of G6PD and 6PGD were 8.41 ± 1.09 picomol/oocyte/min and 3.85 ± 2.02 picomol/oocyte/hr, respectively. The high activity of G6PD (more than 10 times that of the ovarian homogenate) suggests that the pentose phosphate shunt concerned with steroidogenesis is active in the oocyte. HCG decreased the activities of both G6PD and 6PGD.
The present results show that steroidogenesis in the oocyte is very active under the control of gonadotropin, suggesting that steroid hormones may play an important role in oocyte maturation, ovulation and fertilization.View full abstractDownload PDF (1201K) -
Shunzo KOBAYASHI, Norihiko TOBIOKA, Tsuneo SAMOTO, Hironori TANAKA, Ak ...1982 Volume 58 Issue 10 Pages 1333-1340
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSThe cytoplasmic estrogen receptor was measured in 9 intracranial meningiomas and 8 thymomas. The binding affinities of the estrogen receptor derived from the tumors to various estrogens and antiestrogens were compared with that observed for the receptor from rat normal uterus. The cytoplasmic progesterone receptor was measured concomitantly.
The estrogen receptor was positive in 4 and 3 cases of meningioma and thymoma, respectively. The positive rates of estrogen receptor in those tumors did not differ from each other, however, rather low than that in breast cancer in Japan. The numbers of hormone binding sites were almost equal to those of estrogen receptor in breast cancer from pre-menopausal patients.
The binding affinities of estrogen receptor derived from those tumors to estrogens and antiestrogens were equivalent with that observed for rat uterine receptor. Namely, diethylstilbestrol inhibited the protein binding of tritiated 17β-estradiol to 50% by the same amount addition with the latter. Tamoxifen and epithiostanol caused 50% inhibition with 250 and 100 fold amounts, respectively. 17α-Estradiol showed median affinity. Again no differences were observed between the receptors derived from both tumors.
The progesterone receptor was not detected in all of the assayed cases. Therefore, the positive rates of this receptor seemed very low in those kinds of tumors.
These results suggest that the cytoplasmic estrogen receptor found in diverse human tumors other than meningioma or thymoma may have same biological characteristics.
Therefore, as observed in human breast cancer, so neither the positiveness of estrogen receptor nor the binding affinity to estrogens and antiestrogens will coincide directly with the hormone dependency of those tumors.View full abstractDownload PDF (676K) -
Seiji GOTOH, Toshio OGIHARA, Mitsuaki NAKAMARU, Takeshi HATA, Yuichi K ...1982 Volume 58 Issue 10 Pages 1341-1349
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSProstacyclin (PGI2) may act physiologically as an antihypertensive hormone generated in vessel walls. It remains uncertain, however, whether or not PGI2 may be involved in the etiology of primary hypertension.
As an index of PGI2 production, we measured the levels of venous plasma 6-keto-PGF1α by specific radioimmunoassay after silicic acid column chromatographic purification in 64 normotensive and 48 essential hypertensive males. The subjects were grouped according to the presence or absence of a family history of hypertension in three age groups : young (24-39 years), middle-aged (40-55 years) and elderly (over 56 years) and were matched for age and blood pressure.
Mean levels of plasma 6-keto-PGF1α were 13.9±2.0pg/ml in the normotensive males and 15.5±2.2pg/ml in the hypertensive males. The levels of 6-keto-PGF1α in the hyper-tensive males were not significantly different from the levels in the normotensive males in the young, middle-aged and elderly groups, with or without a family history.
The levels of 6-keto-PGF1α in normotensive young males with a family history (12.2±2.1pg/ml; n=14) were lower than in normotensive young males without a family history (18.0±3.0pg/ml; n=9) (p<0.01). The levels of 6-keto-PGF1α in young hypertensive males with a family history (14.0±1.5pg/ml; n=9) were lower than in young hypertensive males without a family history (23.5±2.3pg/ml; n=8) (p<0.005). The levels of 6-keto-PGF1α in middle-aged hypertensive males with a family history (10.5±2.3pg/ml; n=12) however were lower than in middle-aged hypertensive males without a family history (18.0±2.0pg/ ml; n=9) (p<0.005).
But the levels of 6-keto-PGF1α in middle-aged normotensive males without a family history (15.0 ± 2.9pg/ml; n=11) were not significantly different from the levels in middle-aged normotensive males with a family history (12.5 ± 2.3pg/ml; n=11). The levels of 6-keto-PGF1α in elderly normotensive males without a family history (10.6 ± 1.9pg/ml; n=5) were not significantly different from the levels in elderly normotensive males with a family history (10.5 ± 1.9pg/ml; n=7). The levels of 6-keto-PGF1α in elderly hyper-tensive males without a family history (11.2 ± 2.5pg/ml; n=4) were not different from the levels in elderly hypertensive males with a family history (9.4 ± 2.3pg/ml; n=6).
And the levels of 6-keto-PGF1α in elderly males without a family history were significantly lower than in young or middle-aged males without a family history.
Consequently the levels of plasma 6-keto-PGF1α in males with, a family history may be decreased genetically. The decrease in production of PGI2 in young males with a family history may be a factor in the etiology of hypertension. And PGI2 production may decrease with age in males with a family history.View full abstractDownload PDF (884K) -
Tamio IEIRI, Norio KASE, Yoshihisa HASHIGAMI, Hirobumi KOBORI, Tsutomu ...1982 Volume 58 Issue 10 Pages 1350-1356
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSThe effects of gamma oryzanol (γ-OZ) a ferulic acid of triterpene alcohol, on the synthesis and release of the growth hormone (GH) and prolactin (PRL) in vitro and turnover rates of hypothalamic catecholamines were investigated. A single subcutaneous injection of 20mg/kg of γ-OZ suppressed GH synthesis and PRL release 1 hour after the injection. γ-OZ increased medial basal hypothalamic (MBH) dopamine (DA) content, and the DA content was decreased by a treatment of α-methyl-p-tyrosine (αMpT), a tyrosine hydroxylase inhibitor, indicating increased synthesis and release of DA in MBH by γ-OZ. γ-OZ did not alter norepinephrine (NE) content in MBH, while the NE content was significantly de-creased, indicating unchanged synthesis and increased release of NE in MBH by γ-OZ. These results may explain the previous data concerning the changes in serum levels of GH and PRL by γ-OZ and also suggest that γ-OZ can affect the synthesis and/or release of at least two hypothalamic neurotransmitters, DA and NE, resulting in the alterations of anterior pituitary hormone synthesis and/or release.View full abstractDownload PDF (630K) -
Hirofumi KITAOKA, Katsumi YOSHIDA, Toshiro SAKURADA, Hiroshi FUKAZAWA, ...1982 Volume 58 Issue 10 Pages 1357-1366
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSIn order to investigate the renal handling of 3, 5, 3′-triiodothyronine (T3), we studied the clearance of T3 (CT3) in dogs and the site of tubular secretion and reabsorption of T3 in dog kidney using the stopflow technique (Malvin et al.).
Four female dogs, weighing between 12.2 and 17.8kg, were used for CT3 measurement. Fourteen anesthetized dogs, weighing between 7.8 and 17.5kg, were used for the stopflow study. After the catheter was inserted into the left ureter, 15% mannitol solution and isotonic saline containing both 0.2% PSP and 0.5% creatinine or 0.1% inulin, were infused and then 10-30μg/kg of T3 or 100μg/kg of T4 was injected as a bolus. When the urine flow reached a stable state of at least 5ml/min about one-hr after T3 or T4 injection, the ureteral catheter was clamped shut for 10 min. After the release of the clamp, 20 fractions of urine, 1 ml each, were collected sequentially. The changes in pH and PSP concentrations were used as indices of urine from the distal and proximal tubules, respectively. Urinary T3 was determined by RIA. CT3 was obtained by calculating the ratio of the 24-hr urinary T3 excretion to the serum free T3 concentration. CT3, 51.9 ±12.3ml/min, was greater than the clearance of creatinine (Ccr), 23.8 ± 4.7 ml/min, suggesting that T3 is secreted at the tubules in dogs. Almost immediately after the release of the clamped ureter, the concentration of urinary T3, corrected with excreted urinary creatinine or inulin, was increased, reaching the maximum value at No. 2 or 3 fraction. This maximum urinary T3 value was followed by decreased concentrations of urinary T3, reaching the minimum around No. 13-15 fraction. The fraction with the highest urinary T3 concentration was close to the one with the lowest pH, and the fraction with the lowest urinary T3 concentration was close to the one with the highest PSP concentration.
These data suggest that T3 might be reabsorbed or metabolized at the level of the proximal tubules and secreted into the urine at the level of the distal tubules.View full abstractDownload PDF (953K) -
M. SUZUKI, K. YOSHIDA, T. SAKURADA, H. KITAOKA, K. KAISE, N. KAISE, H. ...1982 Volume 58 Issue 10 Pages 1367-1378
Published: October 20, 1982
Released on J-STAGE: September 24, 2012
JOURNAL FREE ACCESSWe investigated the characteristics of the monodeiodination of thyroxine to T3 and rT3 in human placentas which were obtained at normal delivery. The placentas were homogenized in a cold sucrose Tris-HCl buffer, pH 7.5. The microsomal fraction was incubated at 37°C in air for 1 hr with 2μg of T4 in the presence of 50mM DTT. The T3 and rT3 generated in the reaction mixture were extracted into cold ethanol and measured by RIA.
Among the usual subcellular fractions of the placental homogenate, microsomes were the most potent in deiodinating T4 to rT3. In microsomes, production of rT3 increased with protein concentration, incubation temperature up to 37°C, incubation time up to 120 min and T4 concentration up to 16μg/tube. The production of rT3 from T4 was lost by prior heating of the microsomal fraction to 56°C for 30 min. The net production rate of T4 to rT3 in the microsomal fraction was 17.9 ng/mg protein/11g T4/60 min at pH 7.5. RT3 production from T4 was maximal at pH 7.0. The production of T3 from T4 was negligible in the present system.
Degradation of T3 in the placentas was rapid. Although the addition of anti-T3 anti-body to the reaction mixture suppressed the degradation of T3, it had no effect on the net production of T3, suggesting that the obtained net T3 production rate had not been influenced by its degradation. Degradation of rT3 was negligible.
These results indicate that the human placenta actively deiodinates T4 to rT3 enzymatically. This enzyme system might have some influence on the transplacental passage of the thyroid hormone from the mother to the fetus.View full abstractDownload PDF (982K)
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