Yoshio Aizawa

Catabolism of prostaglandin F2α in rat ovary : Differences between ovarian and uterine tissues

Abstract The catabolism in vitro of prostaglandin F2α(PGF2α) in rat ovarian homogenate was studied comparing with uterine homogenate. Two kinds of metabolite were recognized by incubation of PGF2α with ovarian or uterine homogenate; 13,14-dihydro-15-keto-PGF2α(15KD-PGF2α) and 13,14-dihydro-PGF2α(13,14H2-PGF2α) in ovarian homogenate and 15-keto-PGF2α(15K-PGF2α) and 15KD-PGF2α in uterine homogenate. Incubation of 15KD-PGF2α with ovarian homogenate resulted in the formation of 13,14H2-PGF2α but incubation with uterine homogenate did not produce 13,14H2-PGF2α. 13,14H2-PGF2α was in accord with Rf value of a compound formed by reduction of 15KD-PGF2α with sodium borohydride.

Effect of estradiol of prostaglandin metabolism in rat uterus

The purpose of this work was to investigate the effect of a single injection of estradiol (10 microng/rat) on prostaglandin(PG) metabolism in rat uterus. The PG content of uterus was increased within 6 hr after estradiol injection but the incorporation of 3H-arachidonic acid into PG in uterus was not changed within same period. The uptake of 3H-PG was increased within 6 hr after estradiol injection. In these results, it is discussed that PG from other tissue are also involved in the metabolism of PG in uterus.

Stimulation of the formation of 13,14-dihydroprostaglandin F2α by gonadotropin in rat ovary

Abstract Effects of pregnant mare serum gonadotropin and human chorionic gonadotropin on the formation of 13,14-dihydroprostaglandin F2α, a biologically active compound, were investigated in rat ovarian homogenate. The mass number of the compound, which was formed from prostaglandin F2α via 13,14-dihydro-15-ketoprostaglandin F2α in rat ovarian homogenate but was not produced in rat uterine homogenate, accorded with that of the authentic 13,14-dihydroprostaglandin F2α by negative ion chemical ionization mass spectrometry. In the present experiment, the radioactivity of [3H]prostaglandin F2α added to ovarian homogenate was decreased linearly and immediately until the incubation time of 10 min. The formation of 13,14-dihydroprostaglandin F2α was increased up to 60 min. The formation of 13,14-dihydroprostaglandin F2α from prostaglandin F2α was markedly increased by pregnant mare serum gonadotropin and human chorionic gonadotropin. However, there was no additive or synergistic effect of these hormones. The formation of 13,14-dihydroprostaglandin F2α from 13,14-dihydro-15-ketoprostaglandin F2α was also greatly stimulated by pregnant mare serum gonadotropin and human chorionic gonadotropin. The formation of 13,14-dihydro-15-ketoprostaglandin F2α steeply declined until 24 h after treatment with human chorionic gonadotropin in pregnant mare serum gonadotropin-primed rats. In contrast, the formation of 13,14-dihydroprostglandin F2α was markedly increased until 24 h after human chorionic gonadotropin treatment, and the level was about 2.5-fold higher than that at 0 h, 48 h after injection of pregnant mare serum gonadotropin.

Variation of melatonin and serotonin content in rat pineal gland with sex and oestrous phase difference determined by high-performance liquid chromatography with fluorimetric detection

Simultaneous determination of melatonin and serotonin in rat pineal gland is described using reversed-phase high-performance liquid chromatography with fluorimetric detection. These indoles were analysed isocratically within 15 min. In this work, veratric acid (3,4-dimethoxybenzoic acid), which has fluorescence characteristics (lambda ex = 290 nm, lambda em = 350 nm) around the wavelength of native fluorescence of melatonin (lambda ex = 285 nm, lambda em = 345 nm), was used as an internal standard. This method was applied to the determination of melatonin and serotonin in male and female rat pineal gland. No significant differences between the two groups were observed in the pineal melatonin and serotonin contents. The pineal melatonin and serotonin contents were compared with the oestrous and the di-oestrous phases of female rats. They were not widely different from each other.

The effect of ovarian steroids on prostaglandin F2α catabolism in ovariectomized rat uterus

The effects of ovarian steroids, estradiol and progesterone, on the prostaglandin F2 (PGF2) catabolism in vitro in rat uterus were examined by using labeled PGF2. The formation of 13,14-dihydro-15-keto-PGF2 (13,14H2-15K-PGF2) from PGF2 was stimulated by a single injection of estradiol (10 micrograms) or progesterone (1 mg). A remarkable increase in the 13,14H2-15K-PGF2 formation was recognized at 12 hours after estradiol treatment and the formation reached the maximal level at 24 hours. Progesterone also raised the gradual increase of PGF2 catabolism at 24 and 48 hours. In the case of the simultaneous administration of estradiol and progesterone, the additive effect in the PGF2 catabolism was not observed at 24 hours after a single injection of steroids. However, the additive effect was observed by the repeated treatment (once a day for 3 days) of both estradiol (1 microgram) and progesterone (1 mg). These results indicate that PGF2 catabolism in rat uterus is accelerated by ovarian steroids, and also suggest that ovarian hormones closely take part in the regulation of the levels of PGF2 in rat uterus.

Double isotope derivative dilution method for the determination of prostaglandin F and E type metabolites in urine.

This method was developed for the quantitative determination of the main ureinary metabolite (MUM) of prostaglandin (PG) F and E type in man or experimental animal. This method was based on the extraction of PG-MUM after addition of 3H-PG-MUM, the esterification with 14C-acetic anhydride and the separation and purification by column chromatography. Excretion values of adult men were PGF-MUM 1.46--15.01 microgram/8 hr (n=11), PGE-MUM 0.8*--15.42 microgram/8 hr; and with women, PGF-MUM 0.41--7.75 microgram/8 hr (n=11), PGE-MUM 0.60--11.39 microgram/8 hr.

A simple and convenient method for quantitation of corticosterone by high-performance liquid-chromatography-ultraviolet detection

This paper describes the quantitation of corticosterone in the rat serum and adrenal gland by high-performance liquid chromatography-Ultraviolet detection. The extraction and separation were optimized, resulting in an 80% recovery of corticosterone with a detection limit of 10 ng/ml serum. The separation was achieved in less than 5 min on a micro silica gel column using isocratic elution with hexane: chloroform: methanol (7:1:1, v/v) as the mobile phase. The levels of corticosterone in rat serum in the morning and the afternoon were 105.6 +/- 11.96 ng/ml (10:00 a.m., n = 28) and 174.8 +/- 17.60 ng/ml (17:00 p.m., n = 20), respectively. Because of its simplicity, this method provides a new promising analysis for determining hypothalamus-pituitary-adrenal function.

Effects of anti-inflammatory drugs on urinary excretion of prostaglandin metabolites in cotton pellet inflammation

The influence of cotton pellet inflammation in rats and the effect of prednisolone and indomethacin on the excretion of the main urinary metabolite (MUM)s of prostaglandin (PG) F and E types were studied. After cotton pellet implantation, the excretion of PGE-MUM and F-MUM was progressively increased. In the early phase of inflammation, the excretion of PGE-MUM and PGF-MUM was suppressed by administration of indomethacin. However, prednisolone suppressed only PGF-MUM excretion in the early phase of inflammation. These results indicate that no direct interaction was obtained between the inhibition of the inflammatory response by prednisolone and indomethacin and PGs-MUM excretion in inflamed rats.

Release of prostaglandin-like substance from inflamed synovial tissue of rat.

Influence of inflammation on the release of prostaglandin-like substance (PG) from synovial tissue of rat was studied. 1) In carrageenin inflammation, PG release was proportional to the increase in synovial tissue weight. 2) PG release was only increased in the later phase of dextran inflammation. 3) Aspirin suppressed PG release from both non-inflamed and inflamed synovial tissues, but hydrocortisone suppressed that only in inflamed tissue.

[Effect of prostaglandin E2 and F2 alpha on steroid biosynthesis in rat ovary (author's transl)].

Conversion in vitro of pregnenolone to progesterone by the ovaries from immature rats after treatment of PMS and HCG was inhibited by addition of PGE2 (1.4 X 10(-7)M) or PGF2 alpha (1.4 X 10(-7)M). Result of conversion in vitro of pregnenolone to progesterone and estradiol-17 beta by ovary of adult rat in estrus showed that the progesterone biosynthesis in the ovary was inhibited by PGF2 alpha (1.4 X 10(-7)M) but the releasing rate of progesterone from the ovary into the medium increased by about 1.25 fold. Progesterone in the medium decreased dramatically following incubation. Estradiol-17 beta in the ovarian tissue and in the medium did not differ from the control rate with addition of PGF2 alpha. When the effect of PGF2 alpha (1.4 X 10(-7)M) in vitro on the conversion of testosterone to estrone and estradiol-17 beta by the ovary from adult rat in estrus was studied, we found that the releasing rate of estrone from the ovary into the medium was increased by addition of PGF2 alpha; the rate was significantly different from control level after addition of PGF2 alpha 30 min of incubation (p less than 0.01). Thus a minute amount of PGE2 and PGF2 alpha influences steroid biosynthesis in the rat ovary.