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Biomedical subjects

A Miyake

Publications and source records attributed to A Miyake.

At least 253 records · Page 14Linked to original sources
PubMed1987

Substance P stimulates gonadotropin-releasing hormone release from rat hypothalamus in vitro with involvement of oestrogen.

The effects of substance P on the release of LH and GnRH were examined in a sequential double-chamber perifusion system by perfusing the medio-basal hypothalamus and/or pituitary excised from normal female rats in dioestrus or ovariectomized rats. When the medio-basal hypothalamus and pituitary from normal rats were perifused in series with substance P (10(-6) mol/l), the concentration of LH in the efflux was significantly (P less than 0.05) increased by 70-120% compared with that before the injection, but substance P had no effect on LH release from the pituitary perifused alone. This LH release by substance P increased in a dose-dependent manner and was blocked by substance P antagonist. Administration of 10(-6) mol/l substance P induced a significant release (40-80% increase, P less than 0.05) of GnRH from the medio-basal hypothalamus. Infusion of 10(-6) mol/l substance P induced significant release (50-100% increase, P less than 0.05) of LH and GnRH in ovariectomized rats with an implanted oestradiol capsule, but caused no significant increase in LH release in ovariectomized rats without an oestradiol capsule. Progesterone injection to both ovariectomized rats and ovariectomized rats with an implanted oestradiol capsule had no significant effect on the response of LH to substance P. These findings suggest that substance P induces GnRH release from the medio-basal hypothalamus, resulting in LH release from the pituitary, and that oestrogen may be involved in these processes.

Animals↗
PubMed1987

Time- and dose-dependent responses of brain histamine to intracerebroventricular and intraperitoneal administrations of growth hormone-releasing factor (GRF1-44).

Changes in the level of histamine (HA) in rat brain induced by intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administrations of growth hormone-releasing factor (GRF1-44) were studied. HA was determined by high-performance liquid chromatography (HPLC) in the anterior hypothalamic region, posterior hypothalamic region, median eminence, adenohypophysis, neurohypophysis, hippocampus and prefrontal cortex. GRF1-44 (1-10 micrograms, i.c.v.) induced significant time- and dose-dependent increases in the concentration of HA in the hypothalamo-hypophyseal system and time-dependent decrease of HA in the hippocampus. In contrast, after i.p. administration of GRF1-44 (10 micrograms) the level of HA in the hypothalamus tended to decrease but the total amount of H-1 receptors in the hypothalamo-hypophyseal system did not change. Circadian variations in the GRF-induced HA and growth hormone responses were also observed, responses being lower in the evening than in the morning. It is concluded that GRF interacts with HA at the central level to optimize the function of the somatotropinergic system.

Animals↗
PubMed1987

Orally active 1-(cyclohexyloxycarbonyloxy)alkyl ester prodrugs of cefotiam.

Orally active 1-(alkyl substituted cyclohexyloxycarbonyloxy)alkyl ester prodrugs (9b-h) of 7 beta-[2-(2-aminothiazol-4-yl)acetamido]-3- [[[1-(2-dimethylaminoethyl)-1H-tetrazol-5-yl]thio]-methyl]ceph+ ++-3- em-4-carboxylic acid (cefotiam, CTM) have been studied as well as the thia (9i) and aza (9j) analogs. These represent derivatives of the 1-(cyclohexylacetoxy)ethyl ester (2) of CTM. The syntheses and oral bioavailability (BA) in mice are described. Among them, the 1-(cyclohexyloxycarbonyloxy)butyl ester (9h) gave the highest BA, 93.5%; the esters having a cyclohexyloxy group in the ester moiety gave BAs of more than 75%, although the BA of the 1-(ethoxycarbonyloxy)ethyl ester (9a) was only 23.9%. The thia analog showed a moderate BA, 46%, but the aza analog, 9j, did not show a BA of CTM. These results indicate that the 1-(substituted cyclohexyloxycarbonyloxy)alkyl group was the suitable promoiety to improve the oral BA of CTM. Chiral 1-(alkoxycarbonyloxy)alkyl groups used as the ester moiety, gave an almost 1: 1 mixture of diastereoisomeric esters. These were tested as such. However, an experiment in which the separated isomers of the 1-(cyclohexyloxycarbonyloxy)ethyl ester (9d) were administered orally confirmed that both diastereoisomers gave identical BAs.

Administration, Oral↗
PubMed1986

Potential treatment of herpes simplex virus encephalitis by brain-specific delivery of trifluorothymidine using a dihydropyridine in equilibrium pyridinium salt type redox delivery system.

A newly described, drug-carrier delivery system in which a lipophilic derivative is enzymatically converted to a hydrophilic compound was used to treat experimental herpes simplex virus (HSV) encephalitis. Because trifluorothymidine (TFT) does not cross the blood brain barrier, the lipophilic dihydropyridine derivative 3'-(N-methyl-1, 4-dihydronicotinoyl)-5-'pivaloyltrifluorothymidine (DHTFT) was synthesized and characterized by HPLC. After intravenous administration of 20 mg/kg of DHTFT to rats, the quaternary, intermediate compound 3'-N-methyl-1,4-nicotinoyltrifluorothymidine was measured at levels of 7-8 micrograms/g brain at 1 hour and 13.5 +/- 0.8 micrograms/g brain at 4 hours. This compound had antiviral activity equivalent to that of TFT against HSV-1 in a plaque reduction assay (ID 50 = 0.5-1.0 microgram/ml), either directly or by conversion to TFT. Although survival was not prolonged in a rat model of HSV encephalitis, a statistically significant reduction in titer of HSV/g brain was achieved with daily intravenous treatment with DHTFT. TFT was not detected in brains of rats at 1 and 4 hours after intravenous DHTFT, but a low level was observed at 18 hours, 0.3 +/- 0.05 microgram/g brain. These data suggest that the lipophilic compound DHTFT or a lipophilic metabolite crossed the blood brain barrier and was converted to a quaternary compound, which accumulated in the brain and which was either active directly or was converted to TFT. The drug-carrier delivery system described here can potentially be used in the treatment of HSV or other viral encephalitides.

Animals↗
PubMed1986

Recovery of reproductive function in patients with anorexia nervosa: a 10-year follow-up study.

The recoveries of reproductive function and body weight of 21 patients with anorexia nervosa were studied in a 10-yr period from the time of their first presentation. The recovery rates of both menstruation and eating behavior were 81.0%, although at the end of the study period the rate of amenorrhea (19.0%) was still higher than that (6%) in women in the general population. The change of mean body weight in patients in whom regular menstruation was restored was not significantly different from that of patients in whom amenorrhea persisted. Of the patients, 16 married after treatment and 14 of these (87.5%) became pregnant after spontaneous (11 patients) or induced (3 patients) ovulation, and 12 delivered a baby. The present study suggests that resumption of regular menstruation may not depend only upon body weight gain, and that most patients may be able to have a child after appropriate treatments.

Adult↗
PubMed1986

Wen-jing-tang, a traditional Chinese herbal medicine increases luteinizing hormone release in vitro.

For examination of the effect on luteinizing hormone (LH) release of Wen-Jing-Tang, a traditional Chinese herbal medicine, the pituitary from normal female rats in diestrus was perifused alone or in sequence with the mediobasal hypothalamus (MBH) in a sequential double-chamber perifusion system. Wen-Jing-Tang at 5 or 500 micrograms/ml induced significant LH release (60-95% increase) from the pituitary in series with the MBH, but had no effect on LH release from the pituitary perifused alone. These data suggest that Wen-Jing-Tang induces LH release from the pituitary through hypothalamic LH-RH.

Animals↗
PubMed1986

Monoamine oxidase in rat ovary during the estrous cycle. A histochemical study by a new coupled peroxidatic oxidation method.

A new coupled peroxidatic oxidation method for histochemical detection of monoamine oxidase (MAO) was applied to rat ovary. With this new method, fixed tissues could be used, and two forms of MAO could be identified by use of selective inhibitors. MAO activity was observed in the corpora lutea, interstitial gland cells, and blood vessels. In the corpora lutea, no activity was detected during the first estrous cycle, but strong activity was observed in the next two cycles. MAO in blood vessels showed characteristic changes of activity during the estrous cycle. The results suggest that MAO activity might possibly be involved in ovulation and progesterone metabolism in the ovary. Like other organs, rat ovary was found to contain two types of MAO; type A MAO was predominant in the corpora lutea. On the other hand, only one type of MAO, type B, was found in the blood vessels.

Animals↗
PubMed1986

Hydatidiform mole in a triplet pregnancy following gonadotropin therapy.

A first case is reported of complete hydatidiform mole with two coexistent fetuses in a triple pregnancy following human menopausal gonadotropin human chorionic gonadotropin (hMG-hCG) therapy. The molar mass and two fetuses were delivered separately at 17 weeks of gestation. The fetuses were female (155 g) and male (160 g) with individual placentae (85 g, 90 g). The hydatidiform mole (650 g) had a normal 46,XX karyotype. The sexes of the two fetuses and the karyotype of the mole are consistent with previous reports that the chromosomes of fetuses and moles are derived from both parents and the father, respectively.

Adult↗
PubMed1985

Dopamine decreases release of luteinizing hormone releasing hormone from superfused rat mediobasal hypothalamus.

The effects of dopamine hydrochloride (DA) on the releases of LHRH and LH were examined in a serial sequential double chamber perifusion system by perifusing the mediobasal hypothalamus including the preoptic area and/or pituitaries excised from diestrus female rats. DA, perifused at a dose of 4.2 X 10(-4) M, significantly (p less than 0.05) lowered LH secretion from the pituitary in series with the hypothalamus 40-80% below the preinfusion level, but it had no effect on LH efflux from the pituitary perifused alone. DA also significantly (p less than 0.05) reduced the LHRH level 20-40% below the initial level. Perifusion with the DA receptor blocker haloperidol at a concentration of 10(-6) M abolished the suppressive effect of DA on LH secretion. These findings indicate that DA suppressed hypothalamic LHRH release, resulting in decrease in LH secretion from the pituitary in diestrus rats.

Animals↗
PubMed1985

Down-regulation of testicular follicle-stimulating hormone receptors by human menopausal gonadotropin in infertile men.

We measured testicular FSH receptors in 27 infertile men before, or 1, 3, 5, 7, or 14 days after a single administration of 150 IU of hMG. The administration of hMG reduced Bmax for FSH receptors to about 50% of that in the preadministration testes for 5 days. From the seventh day, Bmax of FSH receptors began to increase and returned to the preadministration level 14 days after the administration.

Binding Sites↗