ISSN:0028-3835    

DOI:10.1159/000122964

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The prolactin (PRL)-releasing effect of domperidone (DOM), a novel antidopaminergic drug which does not cross the blood-brain barrier, was investigated in normoprolactinemic subjects, in subjects with physiologic puerperal hyperprolactinemia or pathological hyperprolactinemia. DOM (4 mg i.v.), administered to 8 normoprolactinemic women, induced a clear-cut and sustained rise in plasma PRL, with peak levels occurring 15–30 min postinjection; the effect of the drug was also evident in 3 normoprolactinemic women at the dose of 0.25 mg i.v. Also in 8 puerperal women (postpartum day 2) intravenous administration of 4 mg DOM was followed by an increase in plasma PRL (51–517% of baseline levels, 15–45 min postinjection). Administration of DOM (4 mg i.v.) to 16 subjects with pathological hyperprolactinemia, evidenced the presence of 14 DOM-nonresponder (maximum percent increase of baseline PRL 48%) and 2 DOM-responder subjects. In 8 of the DOM-nonresponder subjects the existence of a pituitary tumor was established at surgery by selective removal of an adenoma (7 subjects) or a teratoma (1 subject): of the 6 subjects who did not undergo surgery, 3 had biochemical and/or radiologic evidence suggestive of a PRL-secreting tumor and 1 was acromegalic. These results indicate that DOM is capable of releasing PRL both in normoprolactinemic subjects and subjects with puerperal hyperprolactinemia. In contrast, DOM is unable to modify PRL levels in most of subjects with pathological hyperprolactinemia, with proven or suspected pituitary t

ISSN:0028-3835    

DOI:10.1159/000122965

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The presence of a transplanted prolactin- and GH-secreting pituitary tumor (Furth MtT·W15) in inbred male rats resulted in increased hypothalamic LHRH and pituitary LH content, decreased serum LH and testosterone concentrations, and very high serum prolactin values. The pituitary tumor also inhibited LH release by the in situ pituitary in response to orchidectomy, or orchidectomy and adrenalectomy, and reduced the LH response to LHRH administration. Testes weight was significantly reduced and adrenal weight was significantly increased in the rats carrying pituitary tumors. These results suggest that the inhibitory effects of the transplanted pituitary tumor on LH and testosterone secretion were affected both a reduction in hypothalamic LHRH release and a reduced responsiveness of the pituitary to LHRH

ISSN:0028-3835    

DOI:10.1159/000122966

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The effects of 3rd ventricle injection of metiamide, an H2-histamine receptor antagonist and pyrilamine, an H1-histamine receptor antagonist, on the increase of plasma prolactin induced by two doses of histamine in normal male rats were studied. Metiamide did prevent the stimulating action of histamine whereas pyrilamine was not effective. Histamine-induced prolactin release was also blocked by low doses of the 2 antihistamines given in combination. Metiamide per se has no effect but high doses of pyrilamine increased plasma prolactin levels and augmented the hormone response to histamine. The results suggest mediation of H2-receptors in the facilitatory action of histamine on prolactin release.

ISSN:0028-3835    

DOI:10.1159/000122967

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Resting plasma concentrations of LH, FSH, estradiol, and progesterone and medial basal hypothalamic concentrations of LHRH (MBH-LHRH) were measured by RIA in 8- to 12-month-old female rats which had begun to exhibit constant estrous (CE) or prolonged diestrous (PD) vaginal smear patterns and compared to young cycling rats on proestrus, estrus, or diestrus. In addition, we examined the effect of ovariectomy on these hormonal profiles. Old CE rats have normal plasma LH, FSH and progesterone concentrations, but exhibit elevated estradiol levels and decreased MBH-LHRH concentrations compared to young cycling rats on the day of estrus. Ovariectomy results in an attenuated rise in plasma LH and FSH and a much lesser decrease in MBH-LHRH when compared to young rats, despite comparable steroid changes. Old PD rats have normal LH and FSH levels, but have elevated estradiol and progesterone concentrations and decreased MBH-LHRH levels when compared to young rats on the day of diestrus. Ovariectomy causes a normal decrease in MBH-LHRH; however, the increased gonadotropin levels are significantly less than seen in young controls.

ISSN:0028-3835    

DOI:10.1159/000122968

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Lesions of the medial preoptic-anterior hypothalamic (MP-AH) continuum made in juvenile male dogs (10–11 weeks of age) were previously reported to reduce juvenile mounting and virtually eliminate male copulatory behavior in adulthood. The effects of these lesions on the developmental patterns of serum testosterone (T) and luteinizing hormone (LH) were examined in the present study. Subjects with MP-AH lesions (MP-AH subjects) had a pubertal rise in serum T almost 2 months before subjects with sham lesions (SHAM subjects). Subsequently mean serum T of MP-AH subjects rose to levels significantly higher than those of SHAM subjects before falling back to the normal 3–4 ng/ml range of SHAM subjects at 10 months. There was no apparent relationship between secretion of LH and the acceleration and enhancement of serum T. These observations indicate that there can be impairment of male sexual behavior with lesions that accelerate and enhance sexual functioning in other respe

ISSN:0028-3835    

DOI:10.1159/000122969

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In an attempt to determine if the high serum follicle-stimulating hormone (FSH) levels of infantile female rats are related to the presence at this age of an FSH-releasing factor different from luteinizing hormone-releasing hormone (LHRH), the FSH and luteinizing hormone (LH) releasing activities as well as the radioimmunoassayable LHRH content of three hypothalamic regions were measured in 12- and 30-day-old rats, ages at which circulating FSH levels are elevated and low, respectively. In 30-day-old rats, the medial basal hypothalamus-median eminence region (MBH-ME) and the postchiasmatic dorsal area (PCH-DA), which included the dorsal anterior hypothalamic area and paraventricular nuclei, had greater radioimmunoassayable LHRH and LH/FSH releasing activities than in the younger animals. The suprachiasmatic-preoptic region (SCH-POA), however, exhibited similar radioimmunoassayable LHRH and gonadotropin-releasing activities in both age groups. The anterior pituitaries from 12-day-old rats, which were employed to assess the biological activity of the hypothalamic extracts, exhibited a greater release of FSH than LH in response to both the extracts and synthetic LHRH. The ratio of FSH to LH released was greater at low doses of the extracts or synthetic LHRH and decreased progressively as the doses were increased. Further dissection of the PCH-DA region of 12-day-old rats revealed that the paraventricular nuclei dorsal anterior hypothalamic area (PVN) released more FSH and LH than the ventral anterior hypothalamic area (VAHA). Surprisingly, however, the radioimmunoassayable LHRH content, measured with two different antisera, was distinctly greater in the VAHA than in the PVN region. Administration of an antiserum to LHRH to 11-day-old females completely prevented the post-castration rise in both serum FSH and LH. The results indicate that the elevated serum FSH levels present in infantile female rats are not related to the presence of an FSH-RF different from LHRH, but rather can be attributed to an enhanced capability of the pituitary to release FSH. In addition, however, they suggest that the paraventricular nuclei and surrounding areas contain a biologically active (form(s) of LHRH which does not exhibit a corresponding radioimmunological activity.

ISSN:0028-3835    

DOI:10.1159/000122970

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The administration of 1.5 mg of progesterone to ovariectomized estrogen-primed rats induced a surge in plasma norepinephrine (NE) preceding the pituitary LH release. The injection of reserpine (2 mg/kg) 2 h prior to progesterone completely blocked the progesterone effects on both NE and LH plasma surges. On the other hand, the adminitration of phenoxybenzamine prior to progesterone, blocked the steroid effect on LH without inhibiting the plasma NE rise. Contrarily, the α-blocker was able to induce a rapid increase in the amine levels 2 h after its injection. The determination of NE in the anterior hypothalamus of these rats revealed that simultaneously with the plasma NE rise induced by progesterone there was a fall in the hypothalamic amine levels. Both reserpine and phenoxybenzamine caused a depletion in the amine content of the anterior hypothalamus. In experiments measuring the arteriovenous difference in the concentration of NE across the brain following progesterone-induced LH release, it was found that most NE comes from the brain. The amine rise was evident in the jugular vein while the arterial NE concentration showed a slight increase. These findings raise the possibility that the changes in circulating NE may reflect an enhanced noradrenergic activity occurring in the brain from which the LH surge results

ISSN:0028-3835    

DOI:10.1159/000122971

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

ACTH release elicited by ether inhalation or ethervenesection and measured by changes in plasma corticosterone level was studied in rats at various time intervals after placing a complete or an anterolateral cut around the medial basal hypothalamus (MBH). There was no rise in ‘resting’ plasma corticosterone after acceptable isolations and, in 5 out of 6 series of experiments, the complete or long anterolateral cuts prevented the rise in plasma corticosterone normally induced by ether stress. In contrast, ethervenesection elicited a significant increment of plasma corticosterone when the basal region of the lateral retrochiasmatic area (RCAL) was not completely transected. Possible reasons why these experiments failed to confirm previous findings are discussed. These results support the hypothesis that corticoliberin-containing fibers enter the MBH from outside and that most of these fibers run through the RCAL on their way towards the neurohemal regions of the infundibu

ISSN:0028-3835    

DOI:10.1159/000122972

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Experiments were conducted in vivo to investigate further if the control of the pulsatile plasma LH phenomenon in ovariectomized (OVX) rats is located in the brain or in the adenohypophysis. Luteinizing hormone releasing hormone (LHRH) was infused at a constant rate (2–100 ng/h) through an indwelling venous cannula in unanesthetized, unrestrained OVX rats. Blood samples were collected at 5-min intervals through a second venous cannula prior to and during LHRH infusion for subsequent radioimmunoassay of plasma LH. LHRH infusion at 12.5, 50 and 100 ng/h did not interfere with the magnitude or the periodicity of LH pulses in plasma but the range within which plasma LH fluctuated was elevated. Phenobarbital (75 mg/kg BW; i.p.) blocked the pulsatile plasma LH and maintained the plasma LH nearly constant at reduced levels. Pulse i.v. injections of LHRH but not constant rate i.v. infusions restored pulsatile LH patterns in phenobarbital-treated OVX rats. The results are consistent with the view that pulsatile LHRH release is responsible for the pulsatile nature of plasma LH in OVX rats. The results do not support the concepts of a short-loop feedback of LH or an ultra-short-loop feedback of LHRH on LH secretion at least on an acute basi

ISSN:0028-3835    

DOI:10.1159/000122973

出版商:S. Karger AG    

年代:1980

数据来源: Karger