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Biomedical subjects

H Kogo

Publications and source records attributed to H Kogo.

At least 19 recordsLinked to original sources
PubMed1992

Indomethacin inhibits the secretion of inhibin and oestradiol-17 beta stimulated by pregnant mare serum gonadotrophin in the immature female rat.

The involvement of prostaglandins (PGs) in the regulation of inhibin and oestradiol-17 beta secretion from the ovary was studied by determining the effects of indomethacin and/or pregnant mare serum gonadotrophin (PMSG) on the levels of ovarian hormones in immature female rats. An increase in serum and ovarian levels of inhibin and oestradiol-17 beta was observed with a reciprocal reduction in serum follicle-stimulating hormone (FSH) levels from within 26 to 50 h after a single injection of 5 IU PMSG (s.c.) when the rats were 26 days of age. Administration of indomethacin to suppress PGs synthesis, simultaneously with PMSG, resulted in a substantial reduction in the levels of ovarian PGF2 alpha and serum inhibin and oestradiol-17 beta, which were both enhanced by PMSG treatment, 24 h after treatment with drugs. Indomethacin also reduced the basal serum level of inhibin. In the indomethacin-treated animals, the serum level of FSH was significantly increased regardless of the treatment with PMSG, indicating that the negative feedback regulation between FSH and inhibin is operating in these animals. These results demonstrate the inhibitory effects of indomethacin on PMSG-enhanced inhibin and oestradiol-17 beta production, suggesting that PGs play a regulatory role in the secretion of inhibin and oestradiol-17 beta from the gonadotrophin-stimulated ovary.

Animals↗
PubMed1992

Inhibitory and stimulatory actions of danazol in rat ovarian and uterine tissues.

We examined whether danazol has a direct action on ovarian steroid secretion and/or uterine prostaglandin (PG) F2 alpha catabolic activity in immature rats in which the first ovulation was induced and in adult ovariectomized rats. The preovulatory surge of estradiol and progesterone was markedly suppressed together with that of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by danazol administration under conditions that blocked the first ovulation. Uterine weight and PGF2 alpha catabolic activity enhanced by endogenous estrogen were greatly decreased by danazol treatment at a dose that did not block the first ovulation in immature rats. When danazol (30 mg) was given s.c. once daily for 2 days to ovariectomized rats, the uterine weight and PGF2 alpha catabolic activity per uterus were clearly increased, and the compensatory increase in FSH levels as a result of castration was not influenced, although the compensatory increase in LH levels was inhibited. These results demonstrate that danazol has a direct action on the ovary and uterus, and give further support to the view put forward in our previous paper that these actions of danazol may contribute to its therapeutic effects.

Administration, Oral↗
PubMed1992

Agonistic-antagonistic actions of clomiphene citrate on PGF2 alpha fluctuations in ovariectomized rat uterus.

Effects of clomiphene and/or estrogen on uterine prostaglandin (PG) F2 alpha fluctuations in ovariectomized rats were examined. Uterine PGF2 alpha fluctuations were measured at the indicated times after injection of clomiphene and/or estradiol. Antiestrogenic effects of clomiphene on urine weight and PGF2 alpha levels were observed at 6 hr, and its effect on uterine 13,14-dihydro-15-keto-PGF2 alpha forming capacity was observed at 24 hr. At 48 and 72 hr, additive effects were recognized in all parameters. These results indicate that clomiphene possesses agonistic-antagonistic actions on the PGF2 alpha fluctuations in the uterus.

Animals↗
PubMed1991

Inhibition of the first ovulation and ovarian prostaglandin F2 alpha metabolism by danazol in rats.

The present study was conducted to investigate the mode of action of danazol by monitoring the first ovulation, serum luteinizing hormone (LH) levels and ovarian prostaglandin (PG) F2 alpha metabolism in pregnant mare serum gonadotropin (PMSG)-primed immature female rats. When danazol (750 mg/kg) was given p.o. once a day for 5 days (day 24-28), the occurrence of the first ovulation, the increase in capacity to form 13,14-dihydro-PGF2 alpha and PGF2 alpha levels induced by PMSG (5 IU) injected on day 26 were clearly inhibited on day 29. Danazol also markedly suppressed the LH surge occurring on day 28. Although the danazol-induced blockage of ovulation was restored by injection of human chorionic gonadotropin, the number of oocytes was significantly decreased as compared with that of controls. The present data indicate that the inhibitory actions of danazol on ovulation and ovarian PGF2 alpha metabolism may occur via some direct effects on the ovary in addition to the suppression of gonadotropin release from the pituitary gland.

Animals↗
PubMed1991

The effects of ovarian steroids in controlling rat uterine prostaglandin F2-alpha during the peri-implantation period.

Rats with delayed implantation, induced by ovariectomy or hypophysectomy, as well as those with normal pregnancy were used to examine the changes in uterine prostaglandin F2 alpha (PGF2 alpha) associated with implantation. In normal pregnant rats, while maximal uterine production of PGF2 alpha was found at 09:00, maximal catabolic enzyme activity (CEA) was seen at 17:00 of day 4. Uterine content of PGF2 alpha was high at 17:00 of day 4, but decreased by 80% within the next 24 h. There was no change in PGF2 alpha production during the first 6 h after injection of estradiol to hypophysectomized animals. There was, however, a dramatic decrease in production within the next 6 h. In contrast, CEA was not different in animals treated with estrogen than in those receiving only progesterone. In ovariectomized animals, uterine PGF2 alpha production also was lowered by estrogen but in these animals CEA was significantly elevated 18 h after injection of estradiol. Estrogen caused a greater increase in PGF2 alpha content in the hypophysectomized, compared to the ovariectomized, rats. The results are consistent with the view that ovarian steroids play an important role in controlling the changes in uterine PGF2 alpha around the time of implantation in rat.

Animals↗
PubMed1991

Effects of antiestrogens on ovarian aldo-keto reductase in relation to ovulation in rats.

The pharmacological effects of antiestrogens on ovarian aldo-keto reductase and ovulation were investigated in rats. The activities of reduction of 13,14-dihydro-15-keto-PGF2 alpha, 4-benzoylpyridine and menadione in ovarian cytosol were significantly decreased by antiestrogen treatments, and the ovulation was completely inhibited. However, administration of luteinizing hormone-releasing hormone at 3:00 p.m. on the day of proestrus restored both enzyme activities and ovulation, which were inhibited by antiestrogens, to control levels. These results indicate that nonsteroidal antiestrogen inhibits the luteinizing hormone surge on the day of proestrus in 4-day cycling rats and that ovarian aldo-keto reductase may be closely involved in the ovulatory process in rats.

Alcohol Oxidoreductases↗
PubMed1990

Initiation of embryo implantation and maintenance of early pregnancy in the rat by chlordecone (Kepone).

The effect of chlordecone (Kepone), an insecticide/fungicide with reproductive toxicity, on the early stages of pregnancy in the rat was studied. Intraperitoneal injection of chlordecone into adult virgin female Holtzman strain rats before mating, in doses as high as 80 mg/kg, did not prevent fertilization, early development of the embryo to the blastocyst stage, transport of the embryo through the oviduct, or its implantation into the uterus. However, a single dose of 60 or 80 mg/kg, but not 20 or 40 mg/kg, before mating significantly reduced the concentration of progesterone in the serum of rats undergoing normal embryo implantation 5 days later. A dose of 80 mg/kg of chlordecone reduced progesterone levels in the serum by more than 50% within 48 hr in ovariectomized rats with Silastic tubing implants containing crystalline progesterone. This dose of chlordecone induced deciduomata formation in progesterone-primed ovariectomized rats to the same extent as 1 microgram of estradiol benzoate. The minimal effective single dose of chlordecone to initiate implantation of blastocysts in the uteri of hypophysectomized progesterone-primed rats, and to maintain embryo development for at least 5 days, was 50 mg/kg. Daily doses of 20 mg/kg for 3 or 5 days were effective at initiating implantation but did not maintain pregnancy. The latter treatment, however, did not prevent initiation of implantation or embryo development induced by subsequent administration of estrone. The results are consistent with the view that chlordecone is a weak estrogen that has both nongenomic and genomic estrogenic actions.

Animals↗
PubMed1989

Relationship between the production capacity of ovarian 13,14-dihydro-prostaglandin F2-alpha and the process of ovulation in immature female rats pretreated with gonadotropin.

The purpose of this work was to investigate the effects of gonadotropin on the production capacity of ovarian 13,14-dihydro-prostaglandin F2-alpha (13,14H2-PGF2 alpha) and whether or not this capacity had any relation to the process of ovulation in rat. To induce the first ovulation, immature rats were injected subcutaneously with PMSG (5 IU/rat) at 8:00 at 26 days of age and some of these rats were followed by an intraperitoneal injection of hCG (10 IU/rat) at 57 hrs after PMSG treatment. The 13,14H2-PGF2 alpha production capacity was unchanged as compared with vehicle control until 57 hrs after PMSG treatment. However, the capacity showed a striking increase at 60 hrs after PMSG treatment. A maximal increase of about 7 fold was observed at 9 hrs after hCG injection just before ovulation. The production capacity of the Graafian follicle (GF) and the part (WO-GF) of the whole ovary (WO) from which the GF is removed at 2:00 on day 29 and the capacity of early corpus luteum at 8:00 on day 29 was greater than that of GF and WO-GF at 0:00 on day 29. These results suggest that the 13,14H2-PGF2 alpha production capacity in rat ovary is regulated by gonadotropin and is closely associated with the process of ovulation.

Animals↗
PubMed1989

Effect of hCG on the 13,14-dihydro-prostaglandin F2-alpha forming capacity of the ovary after ovulation in PMSG-primed immature female rats.

We have examined the change in the ovarian 13,14-dihydro-prostaglandin F2 alpha (13,14H2-PGF2 alpha) forming capacity after the first ovulation induced by injection of pregnant mare serum gonadotropin (PMSG 5 IU, sc) at 26 days of age. After ovulation, the 13,14H2-PGF2 alpha forming capacity in the whole ovary (WO) and in non-luteal ovarian tissues (WO-CL) gradually decreased, whereas a rapid decrease of the synthesizing capacity was observed in corpus luteum (CL). The capacity in WO 4 days after ovulation (33 days of age) was markedly stimulated by human chorionic gonadotropin (hCG 10 IU, ip) administration, whereas CL at 33 days of age did not respond to the stimulatory effect of hCG. A single injection of hCG on day 7 after hypophysectomy resulted 12 hrs later in a significant increase in the forming capacity of 13,14H2-PGF2 alpha in WO-CL. These results indicate that the 13,14H2-PGF2 alpha forming capacity in CL rapidly decreases after the first ovulation and the WO-CL, but not CL, retain the ability to form 13,14H2-PGF2 alpha in response to exogenous gonadotropin for a long time.

Animals↗
PubMed1989

The mode of action of indomethacin, aspirin and melatonin on the blockage of the first ovulation in immature rat pretreated with PMSG.

The purpose of this paper was to evaluate the anti-ovulatory effects of indomethacin, aspirin and melatonin by examining the LH sensitive 13,14-dihydroprostaglandin F2 alpha forming capacity in rat ovary. When ovulation was blocked by aspirin or melatonin, the forming capacity was strongly suppressed, and these effects were reversed by hCG injection. However, the ovulation blockage by indomethacin did not accompany the inhibition of the forming capacity. These results show that aspirin and melatonin block the ovulation via the hypothalamus-pituitary level, and indomethacin acts directly on the ovary.

Animals↗
PubMed1989

Physiological role of ovarian carbonyl reductase and effect of antiestrogen on its activity in rats.

In order to clarify physiological role of carbonyl reductase in rat ovary and effect of antiestrogen on its activity, we investigated effects of five antiestrogens on changes in ovarian enzyme activities towards three carbonyl compounds. All of five antiestrogens tested, significantly decreased 13,14-dihydro-15-ketoprostaglandin F2 alpha 4-benzoylpyridine and menadione reducing activities in ovarian cytosol by both consecutive treatments and single treatment. This inhibition of ovarian enzyme activities by antiestrogen was dramatically antagonized by human chorionic gonadotropin treatment at 3:00 p.m. on the day of proestrus. These results suggest that antiestrogen inhibits LH surge at afternoon of proestrus in rats and that the ovarian enzyme catalyzing reduction of carbonyl compounds is involved in ovulatory process.

Alcohol Oxidoreductases↗
PubMed1988

Multiple estrogenic action of O,P'-DDT: initiation and maintenance of pregnancy in the rat.

The estrogenic action of O,P'-DDT has been known for many years. The majority of studies have used immature or ovariectomized adult rats to demonstrate estrogenic responses that require interaction with an intranuclear receptor and genic expression. However, evidence is accumulating that not all estrogenic effects are mediated by such a receptor; initiation of implantation being one such effect. The present study examined the ability of O,P'-DDT to initiate embryo implantation in the progesterone-primed uterus of a hypophysectomized adult rat. Not only did O,P'-DDT initiate implantation, it also maintained pregnancy for at least 3 days. However, when administered at the time of mating or early after fertilization, the same dosage caused loss of pre-implantation embryos. The results are consistent with the interpretation that O,P'-DDT has multiple estrogenic actions that may involve more than 1 kind of receptor.

Animals↗
PubMed1987

Mode of action of chlorpromazine (CPZ) blockage on 13,14-dihydroprostaglandin F2-alpha formation in rat ovary.

The mode of action of the inhibitory effect of CPZ on 13,14-dihydroprostaglandin F2-alpha (13,14H2-PGF2-alpha) formation in rat ovary was examined. The inhibition of 13,14H2-PGF2-alpha formation and of ovulation induced by a proestrus were completely recovered by an injection of hCG (25 IU/rat) or LH-RH (500 ng/rat) at 15:00 on the same day. 13,14H2-PGF2-alpha formation and ovulation were not inhibited by a single injection of prolactin (PRL:6 IU/rat) at 13:00 on the day of proestrus. Repeated injection of PRL inhibited cyclic ovulation and 13,14H2-PGF2-alpha formation. The estrus cycle of PRL treated animals showed a continuous state of diestrus. Although 13,14H2-PGF2-alpha formation and ovulation were inhibited by the repeated injection of CPZ, the repeated-simultaneous injection of CPZ and bromocriptine at 10:00 once a day for 3 days from the first day of diestrus partly restored both and entirely reversed the suppression of the cyclic-changes in the in the vaginal smear pattern. These results indicate that the inhibition of 13,14H2-PGF2-alpha formation induced by a single injection of CPZ probably occurs via the suppression of LH-RH release from the hypothalamus, whereas PRL secretion may participate in the inhibitory effects of repeated injections of CPZ.

Animals↗
PubMed1986

Inhibition of the formation of 13,14-dihydroprostaglandin F2-alpha induced by chlorpromazine in rat ovary.

The present study was designed to investigate the effects of chlorpromazine (CPZ) on the formation of 13,14H2-PGF2 alpha in rat ovary and the possibility that the "critical period" observed in the effect of CPZ for the blockade of ovulatin may be appreciated by measuring the formation of 13,14H2-PGF2 alpha as a parametor. When CPZ (4.0 mg/kg) was given s.c. at 10:00 a.m. once a day for 3 days from the first day of diestrus to the expected day of proestrus followed by sacrifice after 24 hours of the final injection, a significant inhibition was recognized in the formation of 13,14H2-PGF2 alpha in ovary. The effects of a single injection of CPZ were also determined 24 hours after injection at 10:00 a.m. on the day of diestrus I, diestrus II or proestrus. The results showed that the drug treatment on the day of proestrus significantly decreased the formation of 13,14H2-PGF2 alpha, but not on the day of diestrus I or II. When the formation of ovarian 13,14H2-PGF2 alpha was inhibited by CPZ treatment, the blockade of ovulation was also confirmed. A single injection of CPZ at 05:00 and 07:00 after the "critical period" on the day of proestrus did not inhibit the 13,14H2-PGF2 alpha formation in the rat ovary. It is concluded that the administration of CPZ before the "critical period" on the day of proestrus is effective in suppressing the ovarian 13,14H2-PGF2 alpha formation as well as on the blockade of ovulation.

Animals↗
PubMed1986

Inhibitory effect of clomiphene citrate on the conversion of 13,14-dihydro-15-keto-prostaglandin F2 alpha to 13,14-dihydro-prostaglandin F2 alpha in rat ovary.

The effects of clomiphene citrate (clomiphene) on the in vitro conversion of 13,14-dihydro-15-keto-prostaglandin F2 alpha (15KD-PGF2 alpha) to 13,14-dihydro-prostaglandin F2 alpha (13,14H2-PGF2 alpha) in the presence of rat ovarian homogenate, and the relationship between clomiphene and gonadotropin or estrogen in the conversion were investigated. Although clomiphene inhibited the increased conversion of 15KD-PGF2 alpha to 13,14H2-PGF2 alpha by pregnant mare serum gonadotropin (PMS) in rat ovary, the drug did not inhibit the decreased conversion of 15KD-PGF2 alpha by estradiol. The 3-day administration of clomiphene reduced the conversion of 15KD-PGF2 alpha to 13,14H2-PGF2 alpha dose-dependently. A single administration of clomiphene also decreased the conversion, and this decreasing effect was similar to that of estradiol. On the other hand, the repeated administration of clomiphene decreased the ovarian and uterine weights and also inhibited the increase of the uterine weight by PMS or estradiol. These results suggest that clomiphene affects the ovarian enzyme catalyzing the conversion of 15KD-PGF2 alpha to 13,14H2-PGF2 alpha.

Animals↗
PubMed1985

Significance of gonad and renal prostaglandin E2 in the antihypertensive effect of pindolol in spontaneously hypertensive rats.

The effect of gonadectomy on the antihypertensive action of pindolol in male spontaneously hypertensive rats (SHR) was investigated. And we also examined the relationship between the antihypertensive effect of this drug and the renal prostaglandin E2 (PGE2) level. In gonadectomized SHR, the reduction of blood pressure was not observed by the oral administration of pindolol, although the drug exhibited a marked antihypertensive activity in sham operated SHR. Urinary PGE2 in sham operated SHR was increased following the administration of pindolol, but not in gonadectomized SHR. Similar results were obtained in the experiments using Wistar rats. The PG synthesis inhibition induced by indomethacin suppressed the antihypertensive action of pindolol. Results in the present study suggest that renal PGs, particularly PGE2, are involved in the antihypertensive mechanism of pindolol, and that male gonad takes part in the regulation of the stimulation of the renal PGE2 producing system induced by pindolol.

Animals↗
PubMed1985

[Anti-inflammatory activity of the dry distillation tar of delipidated soybean (Glyteer) (1)].

The anti-inflammatory activity of the dry distillation tar of delipidated soybean (GL, 0.1 approximately 10%) was investigated by its topical application to mice, rats and guinea pigs; and the effects were compared with those of betamethasone 17-valerate (BV, 0.12%), ibuprofen (IP, 5%), phenylbutazone (PB, 5%) and flufenamic acid (FA, 5%), which were all prepared with the same ointment base. GL (1 approximately 10%) showed a concentration-dependent inhibition of the increased vascular permeability induced by histamine and bradykinin in guinea pigs. GL significantly inhibited rat paw edema induced by carrageenin, but in serotonin-induced paw edema, GL showed only a weak effect. GL also inhibited the erythema formation induced by ultra-violet rays, and the activity was equal to that of PB. The inhibitory potency of GL against the erythema formation induced by arachidonic acid in guinea pigs was equal to that of IP. It is suggested from these results that the mode of action of GL is similar to that of other acidic non-steroidal anti-inflammatory drugs. However, GL did not inhibit paper disk granuloma in rats. Furthermore, GL markedly inhibited the delayed-type hypersensitivity induced by picryl chloride, and the activity was stronger than that of IB, PB and FA. Here GL showed the mode of action seen with steroidal anti-inflammatory drugs. The present data provide evidence that GL applied externally possesses a potent effect as an anti-inflammatory drug.

Administration, Topical↗