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Biomedical subjects

T Aono

Publications and source records attributed to T Aono.

At least 307 records · Page 17Linked to original sources
PubMed1983

Effect of sulpiride-induced hyperprolactinaemia on catecholamine turnover and LRH concentration in the medial basal hypothalamus of rats.

In order to clarify the mechanism of hyperprolactinaemic anovulation, the medial basal hypothalamic (MBH) catecholamine (CA) turnover and LRH concentration, and the serum levels and pituitary contents of gonadotrophins and prolactin (Prl) in hyperprolactinaemic female rats were examined. Hyperprolactinaemia (HPrl) was produced by oral administration of sulpiride for 10 consecutive days; each measurement made on the sulpiride-treated rats was compared with that of control dioestrus rats. Prl, LH, FSH and LRH were determined by radioimmunoassay; CA turnover, as assessed by the accumulation of CA following monoamine oxidase inhibition, was assayed by high performance liquid chromatography with electrochemical detection. Sulpiride treatment induced (1) an increase in the serum Prl and a decrease in the serum LH, (2) an increase in the pituitary FSH and LH contents, (3) an increase in the MBH LRH concentration, and (4) an increase in the MBH dopamine (DA) turnover. These results suggest that HPrl may induce anovulation by impaired LH secretion which was caused by the suppression of LRH release due to an increase in DA turnover in the MBH.

Animals↗
PubMed1983

Clomiphene citrate induces luteinizing hormone release through hypothalamic luteinizing hormone-releasing hormone in vitro.

The releasing effects of clomiphene citrate (clomiphene) on luteinizing hormone (LH) and LH-releasing hormone (LRH) were examined in a sequential double chamber superfusion system by superfusing the mediobasal hypothalami (MBH) and/or pituitaries excised from normal female rats in dioestrus. When the MBH and the pituitary were superfused in sequence with medium containing 2 X 10(-10) M oestradiol (E2), two significant peaks in LH release (60-130% increase, P less than 0.05) were observed 40 min and 90 min after the administration of 3 X 10(-8) mol clomiphene. Administration of clomiphene in medium without E2 induced a low peak (25-50% increase, P less than 0.05) of LH released from the pituitary perfused in series with the MBH. Administration of clomiphene did not cause a marked increase of LH from the pituitary superfused alone, when superfused with or without E2 containing medium. The concentration of LRH in the efflux was significantly increased (50-100%) 40 min and 90 min after clomiphene administration when MBH was superfused with medium containing E2, whereas clomiphene had no effect when superfused with medium alone. These data indicate: 1) that clomiphene induces LRH release from the MBH, that it may induce LH release, in part, by acting directly at the pituitary level; 2) that changes in LH after clomiphene administration coincide with LRH release, and 3) that a certain concentration of E2 may be necessary for the secretion of LRH by clomiphene.

Animals↗
PubMed1983

Arginine vasopressin suppresses oxytocin release from the superfused rat hypothalamo-pituitary complex.

The role of arginine vasopressin (AVP) in the regulation of oxytocin secretion was studied in a superfusion system of the hypothalamo-pituitary complex from cycling female rats in dioestrus of the oestrous cycle. After perfusion with Medium 199 alone at 37 degrees C for an equilibration period of 2.5 h, perfusion with Medium 199 containing 10 mU/ml AVP for 30 min caused a prompt and significant (P less than 0.05) decrease in the oxytocin level of up to 60% of that before AVP perfusion, whereas Medium 199 containing 0.1 mU/ml AVP had no effect on oxytocin efflux. This finding suggests that AVP may be involved in the regulation of oxytocin release from the hypothalamo-pituitary system.

Animals↗
PubMed1983

Prostaglandin D2 stimulates secretion of luteinizing hormone from pituitary gland in vitro.

The effect of prostaglandin D2 on the release of luteinizing hormone was studied in a superfusion system by superfusing human pituitary gland. Perfusion with 30 micrograms of prostaglandin D2 induced a significant increase of luteinizing hormone secretion. This is the first evidence of a direct effect of prostaglandin D2 on the secretion of luteinizing hormone from the human pituitary gland. This finding suggests the possible role of prostaglandin D2 in human reproductive function.

Adult↗
PubMed1983

Prostaglandin D2 induces release of luteinizing hormone from the rat pituitary gland without the modulation of hypothalamic luteinizing hormone releasing hormone.

The effect of prostaglandin D2 (PGD2) on release of LH and LH releasing hormone (LHRH) was studied in a sequential double-chamber superfusion system using the medial basal hypothalamus (MBH) and the pituitary gland from female rats at dioestrus. Infusion of PGD2 (5.7 or 57 mumol/l) caused a significant (P less than 0.05) increase in LH release to values 40-60% above the preinjection values from the pituitary gland superfused either alone or in series with the MBH. No release of LHRH in response to PGD2 was observed from the superfused MBH. These data demonstrate that PGD2 causes LH release from the pituitary gland not by inducing release of hypothalamic LHRH but by a direct action on the gland.

Animals↗
PubMed1983

Characterization of a unique nuclear estrogen-binding component in an estrogen-responsive mouse Leydig cell tumor.

An estrogen-responsive mouse Leydig cell tumor line (Tumor 124958) has been shown to contain only a low-affinity binder for estradiol in the cytosol fraction. This differed from the putative estrogen receptor in terms of its hormone-binding specificity as well as affinity. In addition, the possibility that an estrogen receptor-like molecule exists in the nuclei even without hormonal stimuli was examined using purified nuclei. Scatchard plot analyses showed that these nuclei possessed a large amount of estrogen binder having a high affinity for estradiol and diethylstilbestrol. The content of this nuclear binding component was not diminished by using molybdate, a potent inhibitor for receptor activation, and in vitro incubation of collagenase-dispersed cells with estradiol did not cause significant increase in the number of nuclear binding sites when compared with the values obtained by direct incubation of isolated nuclei with estradiol. These results support the view that this nuclear estrogen binder is not due to artificial migration of the cytosol receptor into nuclei during homogenization. The characterization of this nuclear binding component under cell-free conditions revealed that its affinity for estradiol in Mg2+-containing buffer was temperature dependent (Kd 3 nM at 30 degrees and 12 nM at 0 degrees) without significant alteration in the number of maximum binding sites. Introduction of a chelating agent (ethylenediaminetetraacetate) into the buffer system abolished the temperature effect on the affinity, resulting in high affinity for estradiol at both low and high temperatures. These Mg2+ and temperature effects were reversible. In addition, when compared with putative nuclear estrogen receptors, this nuclear binding was observed to be relatively resistant to high salt or micrococcal nuclease treatments in relation to solubilization from nuclei. However, trypsin digestion was found to result in a marked decrease in the nuclear binding sites, indicating that this unique nuclear binding component contains a protein unit(s). These results suggest the possibility that this tumor line contains a unique unoccupied nuclear estrogen binder which might be able to transmit estrogen signals to tumor cell nuclei with regard to tumor growth.

Animals↗
PubMed1982

Effect of sulpiride on poor puerperal lactation.

Forty-two primiparous and 54 multiparous women with total yields of milk not exceeding 50 ml for the first 3 postpartum days were treated with 100 mg of oral sulpiride or placebo for 4 days from the third postpartum day. In the primiparous mothers, the mean daily yield of milk in the sulpiride group increased significantly (p less than 0.01) over that in the control group after the fourth postpartum day. Mean (+/- SE) total volumes of milk for the third to fifth postpartum days were 661.5 +/- 64.4 and 441.2 +/- 51.2 ml in the sulpiride and the control groups, respectively. However, in the multiparous mothers, no significant difference between the control and the sulpiride group was noted in total yield of milk, since a good increase in the secretion of milk was obtained without medication in these mothers. Determinations of daily serum levels of prolactin in 20 primiparous women revealed significantly higher concentrations in the sulpiride group. The ratio of primiparous mothers with complete breast-feeding 1 month after delivery was higher in the sulpiride group (55%) than in the control group (30%), whereas there was no difference between the control group and the sulpiride group of multiparous women. These data indicate that poor initiation of puerperal lactation in primiparous mothers can be effectively treated with oral sulpiride.

Adult↗
PubMed1982

Improved method for determination of catecholamines in rat brain by isolation on boric acid gel and high-performance liquid chromatography with electrochemical detection.

An improved sensitive, simple and time-saving method for determining catecholamine (CA) in rat brain is described. The method involves isolation on boric acid gel and high-performance liquid chromatography with electrochemical detection. Boric acid gel effectively adsorbs CA at weakly alkaline pH and the over-all recoveries of 5 ng and 10 ng samples of authentic norepinephrine (NE) and dopamine (DA) added to a homogenate of rat brain were 98.9 +/- 9.2% and 103.4 %/- 9.3% for NE and 96.2 +/- 4.6% and 99.4 +/- 4.8% for DA, respectively. Intra-assay variation was 5.3% (5 ng) and 3.0% (10 ng) for NE and 4.4% (5 ng) and 3.8% (10 ng) for DA. Inter-assay variation was 7.7% (1 ng) for NE and 5.0% (1 ng) for DA. With this analytical system, the lowest amount of NE or DA detectable was 40 pg. Application of this method to determination of the DA and NE contents of rat hypothalamus during estrous cycle revealed significant increases in the turnovers of both in the proestrus stage. This method should be useful for routine determination of plasma NE and DA because it is sensitive and inexpensive.

Animals↗
PubMed1982

Restoration of oestrogen-positive feedback effect on LH release in women with prolactinoma by transsphenoidal surgery.

The effects of hyperprolactinaemia on the hypothalamo-pituitary axis by iv injection of 100 micrograms luteinizing hormone releasing hormone (LRH) in 7 women with prolactinoma before and 3 months after normalization of the Prl level by transsphenoidal surgery. A dose of 20 mg of conjugated oestrogen (Premarin) was also infected iv into patients with prolactinoma before and 4 months after surgery, and the serum LH levels were determined serially for 120 h after the injection. Surgical treatment caused significant reduction of the mean (+/- SE) serum prolactin (Prl) level from 123.3 +/- 7.8 to 19.4 +/- 5.6 ng/ml. But the differences in the basal levels of HL (11.3 +/- 2.2 to 8.6 +/- 1.5 mIU/ml), FSH (8.3 +/- 2.4 to 10.6 +/- 3.7 mIU/ml) and oestradiol (26.6 +/- 8.6 to 37.5 +/- 5.5 pg/ml) before and 4 months after surgery were not significant. An exaggerated LH response to LRH in untreated prolactinoma patients was also observed after surgical treatment. After surgical treatment, patients showed LH release with a peak between 48 and 72 h after the injection of Premarin, whereas before treatment they did not show any LH discharge. The mean percent increase in LH between 48 and 72 h was also significantly higher after operation than before operation. These results suggest that the hyperprolactinaemia in prolactinoma patients may cause an impaired positive feedback effect of oestrogen on LH release and that this derangement can be reversed by reduction of the Prl level by adenomectomy.

Adenoma, Chromophobe↗
PubMed1982

Progesterone facilitates the LRH releasing action of oestrogen.

The effects of progesterone (P) on the release of LRH and LH were examined in a sequential double chamber superfusion system by superfusing the medial basal hypothalamus (MBH) and/or pituitaries excised randomly from cycling female rats. Addition of 10 microliters of 10(-6) M oestradiol (E2) to the first chamber resulted in a gradual and significant (60-160%) increase in LH release above the pre-injection level from the pituitary in series with MBH. Administration of 10(-8) M P after 10(-6) M E2 caused a prompt and marked increase (300%) of LH (P less than 0.05), whereas 10(-8) M P alone had no effect. Administration of 10(-6) M E2, 10(-8) M P or E2 plus P did not significantly change LH secretion from the pituitary superfused alone. The concentration of LRH in the efflux was significantly increased (150-200%) 150 min after 10(-6) M E2 administration. P administration after E2 injection produced a prompt and significant increase of LRH and the increase of LRH (300-600%) was 2-3-fold that produced by E2. P alone had no effect. These data clearly indicate that P enhances E2-induced LH release by increasing LRH secretion from the MBH.

Animals↗
PubMed1982

Changes in luteinizing hormone-releasing hormone in human placenta throughout pregnancy.

The distribution and content of luteinizing hormone-releasing hormone (LH-RH) in human placental tissues were detected by enzymatic antibody and immunofluorescence techniques. Anti-LH-RH was taken up strongly by cytotrophoblasts and the villous stroma at 8 weeks of pregnancy; the uptake decreased with the progress of pregnancy. Anti-LH-RH was not taken up at all by syncytiotrophoblasts throughout pregnancy. These findings suggest that LH-RH is synthesized in the cytotrophoblast and villous stroma. The role of placental LH-RH in the synthesis of human chorionic gonadotropin is discussed.

Female↗
PubMed1981

Induction of ovulation in patients with normoprolactinemic amenorrhea by combined therapy with bromocriptine and clomiphene.

Bromocriptine is known to be effective in the treatment of women with hyperprolactinemic anovulation or amenorrhea-galactorrhea. A new schedule of combined treatment with bromocriptine and clomiphene citrate was applied to 23 patients with normoprolactinemic amenorrhea who failed to respond to clomiphene alone. Ovulation was restored by treatment in 14 of these patients (60.9%), resulting in pregnancy in 3 women. Treatment resulted in immediate suppression of serum prolactin levels and a gradual increase in serum luteinizing hormone levels and estradiol levels followed by a luteinizing hormone surge. The present results indicate that bromocriptine/clomiphene combination therapy is effective in the treatment of amenorrheic patients with normoprolactinemia who do not respond to clomiphene alone, and suggest that bromocriptine restores the responsiveness of the hypothalamic-pituitary-ovarian system to clomiphene.

Adult↗