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PubMed1979

Prolactin secretion during prolonged lactational amenorrhoea.

Basal serum prolactin levels were elevated up to 66 weeks postpartum in lactating amenorrhoeic women. The serum prolactin level in fully breast-feeding women was significantly higher than in women who were partially breast-feeding. The mean basal serum prolactin level in menstruating, lactating women was significantly higher than the mean level in women who had weaned and had normal menstrual cycles. The rise in prolactin due to suckling was seen up to 66 weeks postpartum. The marked variability and lack of reproducibility of individual suckling responses may obscure the importance of prolactin secretion in the postpartum period. Nevertheless, this study confirms that prolactin secretion is increased in women with prolonged lactational amenorrhoea.

Amenorrhea↗
PubMed1975

Studies on the minimal dosage of melatonin required to inhibit pineal antigonadotrophic activity in male golden hamsters.

Blinding adult male golden hamsters was followed by atrophy, within 12 weeks, of the testes and accessory sex organs (seminal vesicles and coagulating glands) and by a significant reduction in pituitary prolactin levels. In experiment 1 blind hamsters received subcutaneously implanted melatonin-beeswax (1:24 mg) pellets at the following intervals: once per week, per 2, 3, 4, 6 weeks, or only one pellet during the 12-week experimental period. The melatonin-beeswax pellets, regardless of the frequency of implantation, overcame completely the inhibitory effects of blinding on reproduction and nearly completely the depressant action of light deprivation on pituitary prolactin levels. In the second study the melatonin-beeswax pellets were implanted subcutaneously into blind hamsters every 2 weeks. The pellets contained either 1 mg, 500, 100, 50, or 1 mug melatonin. With the exception of the 1-mug dosage, melatonin again negated almost totally the inhibitory action of darkness on the gonads and accessory organs and also, for the most part, prevented the drop in pituitary prolactin levels. Based on these studies, when melatonin is chronically administered subcutaneously in a beeswax pellet the minimal dosage of melatonin required to counteract the inhibitory effect of darkness on reproduction seems to be less than 3.6 mug/day. The effects of chronic melatonin treatment are similar to those of pinealectomy.

Animals↗
PubMed1976

Effect of a new LH-RH analogue (D-Ser(TBU)6-EA10-LH-RH) on gonadotrophin and gonadal steroid secretion in men.

The effect of a new analogue of the gonadotrophin-releasing hormone LH-RH, D-Ser(TBU)6-EA10-LH-RH, on the secretion of LH, FSH, as well as testosterone, oestradiol, HGH, prolactin, TSH, and cortisol was studied in normal men. The same subjects were injected intravenously in 4-day intervals with 1.0, 2.5, 5.0, and 10.0 mug of this substance. A significant LH but no FSH release was seen after doses of 1.0 and 2.5 mug LH-RH analogue, while after 5.0 and 10.0 mug dose-dependent increases of LH and imposed elevations of FSH were observed. Peak levels of LH were reached after 30 min, those of FSH after intravenous injection after 120 min. LH and FSH remained elevated for 8-10 h. LH peak levels after 5 mug of LH-RH analogue were comparable to those seen after injection of 100 mug of the decapeptide LH-RH. Following the release of LH and FSH after doses of 5.0 and 10.0 mug LH-RH analogue, there was a late stimulating effect in testosterone and oestradiol secretion. HGH, TSH, prolactin, and cortisol were not influenced by the LH-RH analogue.

Adult↗
PubMed1979

Hormone serum levels and hormone receptor contents of endometria in women with normal menstrual cycles and patients bearing endometrial carcinoma.

Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (HPRL), 17 beta-estradiol (E2) and progesterone (P) were estimated in 46 subjects with normal menstrual cycles in whom hysterectomies were performed. Estrogen (ER) and progesterone receptor (PgR) levels in endometrial samples of these patients were estimated, and histological dating of the cycle day was carried out. Similarly, hormone serum levels and ER as well as PgR were estimated in 17 patients with endometrial carcinoma. No correlation between LH, FSH, HPRL and ER as well as PgR was noted in the normal subjects. Correlation between P and ER was observed in this group. Parallel variations between E2 and PgR were recorded in the normal females. In the carcinoma group no correlations between hormone serum levels and receptor contents were found, but ER and PgR correlated with each other. Receptor levels was highest in the well-differentiated group of endometrial carcinoma. The present experiments provide a rationale for progestagen therapy of carcinoma of the endometrium.

Endometrium↗
PubMed1976

Acute and chronic estrogen effects upon serum somatomedin activity, growth hormone, and prolactin in man.

Estrogen (E) reduces bioassayable GH-dependent serum somatomedin (SM) activity in acromegalics without affecting plasma growth hormone (GH) levels and inhibits the rise of SM activity normally produced by GH administration in GH-deficient subjects. We have now investigated the effect of E administration on serum SM activity and on plasma GH and prolactin (PRL) in 6 adult male subjects without pituitary pathology. Chronic E administration (ethinyl estradiol 0.5 mg/day for 7 to 70 days) reduced serum SM activity by 40 to 62% in each of 4 subjects (P less than 0.02 to less than 0.001). In 3 of the subjects, basal GH levels increased by 75 to 300% (P less than 0.05 to less than 0.001) and basal PRL levels increased by 90 to 200% (P less than 0.01 to less than 0.001). While iv administration of normal saline did not significantly affect either SM or GH, iv administration of E (bolus injection of 25 mg conjugated estrogens, USP) to 5 subjects resulted in: a) a 46 to 80% decrease in serum SM activity in all subjects, proceeding with an apparent half-life of 2 hours, becoming significant (P less than 0.05) at 2 hours (1 subject) to 3 hours (4 subjects), maximal at 6 hours, and persisting for 12 to 24 hours; b) GH elevation to 3 to 16 times baseline level (P less than 0.01) at 2 to 3 hours in 4 subjects; and c) no significant change of PRL levels in any subject. The mean GH response to iv E was maximal at a time (2 hours) when the mean SM activity had decreased only 20% and subsided well before the nadir of SM activity. The one patient without GH response to chronic or acute E administration may have been affected by absorption of triamcinolone being applied topically during the study. These results demonstrate that in males with normal pituitary function, E reduces serum SM activity, enhances basal GH and PRL secretion, and, upon iv injection, stimulates acute GH release. Although opposite chronic E effects upon GH and SM activity support a putative negative SM-GH feed-back mechanism, iv E administration apparently provokes acute GH release by a different mechanism. The half-life of serum SM activity in the human is probably much shorter than previously estimated.

Adult↗
PubMed1977

Hormonal evaluation of the intrauterine progesterone contraceptive system.

Nine women were studied for one menstrual cycle prior to the insertion of an intrauterine progesterone contraceptive system (IPCS) delivering 65 microng progesterone/day into the uterus and again at 1 month after its insertion. Eight of these women were again studied between 6-8 months after the insertion of the IPCS. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol-17beta, progesterone, prolactin and relaxin were measured in each plasma sample. The data from each study were combined according to the day of the LH peak. Ovulation occurred in all the cycles studied in spite of an elevation in plasma estradiol-17beta and a depression of prolactin and relaxin immunoactivities at the 6-8 month follow up. Menstruations noted at the 6-8 month of use occurred while levels of estradiol-17beta and progesterone were elevated.

Adult↗
PubMed1977

Pituitary autonomy in hyperprolactinemic secondary amenorrhea: results of hypothalamic-pituitary testing.

Twenty-seven women with secondary amenorrhea of greater than six months duration were subjected to multiple testing of hypothalamo-pituitary function. They were divided into normo-prolactinemic (Group 1 mean serum prolactin (PRL) 9.8 ng/ml; range 6.8 to 13.0 ng/ml; n=9) and hyperprolactinemic (Group 2 mean 37.5 ng/ml; range 19.2 to 93.7 ng/ml; n=18) groups on the basis of 4 weekly baseline determinations. Group 2 had significantly (P less than .05) lower serum LH and urinary pregnanediol levels than did Group 1; there was no statistical difference between the groups in serum FSH, T4, T3 or urinary estrogen measurements. Two women in Group 2 were found to have a pituitary chromophobe adenoma. Group 2 women showed no significant rises in serum PRL following stimulation tests with thyrotropin releasing hormone (TRH, 200 microng iv) and metoclopramide (10 mg orally), which caused significant responses in Group 1. The TSH response to TRH was, however, preserved in Group 2, while it was subnormal in Group 1 subjects. Both groups showed similar FSH and LH responses to luteinizing hormone-releasing hormone (LHRH, 25 microng iv). No significant suppression of serum PRL was seen in Group 2 patients given L-Dopa (500 mg orally),, which produced a significant response (P less than 0.05) in Group 1 subjects, while all patient showed marked reduction in serum PRL values following 2-bromo-alpha-ergocryptine (CB-154, 2.5 mg orally). When compared with other Group 2 members, the 2 cases with proven pituitary adenomata gave similar responses to the stimulation-inhibition tests and were not clearly distinguished on this basis. We conclude: 1. The pattern of PRL responses to dynamic tests, although of pathophysiological interest an autonomous pituitary lesions in patients with hyperprolactinemic secondary amenorrhea. 2. Such dynamic tests, although a pathophysiological interest, provide no clinical information additional to that provided by the mean basal serum PRL value. 3. In clinical practice, such dynamic tests should be confined to patients with mean serum PRL levels at around the upper limit of the normal range.

Adult↗
PubMed1977

Changes in the prolactin response to thyrotropin-releasing hormone (TRH) during the menstrual cycle of normal women.

Serum prolactin (PRL) and thyrotropin (TSH) levels were measured after iv administration of 200 microng of synthetic thyrotropin-releasing hormone (TRH) in 20 normal women ages 18 to 34. Ten women received TRH on days 7 to 8 of the menstrual cycle and 10 women received TRH on days 21-22. Although there was no difference in the dose of TRH relative to body weight in the two groups of women, the peak PRL level after TRH stimulation was greater in the women studied on day 21-22 (48.5+/-5.7 ng/ml, mean+/-SE) than on day 7-8 (35.2+/-4.2 ng/ml) of the cycle (P less than 0.05). In contrast, TSH rose to a greater degree in the preovulatory phase (13.8+/-1.8 micronU/ml) than the luteal phase (7.7+/-0.7 micronU/ml of the cycle (P less than .01). Studies of the PRL and TSH response after TRH administration should take the phase of the menstrual cycle into account.

Adult↗
PubMed1978

The relationship of changes in serum estradiol and progesterone during the menstrual cycle to the thyrotropin and prolactin responses to thyrotropin-releasing hormone.

The responses of serum TSH and PRL to TRH (500 microgram) were studied in normal young women in the early follicular, periovulatory, and midluteal phases of the menstrual cycle in order to examine the relationship of these responses to the levels of estradiol relationship of these responses to the levels of estradiol (E2) and progesterone. Each woman was studied twice in each phase in order to assess intraindividual variability. There was no significant difference in either the TSH or PRL responses among the phases of the menstrual cycle nor was either response affected by the periovulatory rise in E2 or by the luteal rise in both E2 and progesterone. Thus, the interpretation of the TSH and PRL responses to TRH in normal women is not affected by the menstrual cycle although both responses are greater in women that in men. Both the peak TSH and peak PRL after TRH were highly correlated with the basal levels of TSH (r = 0.85; P less than 0.01) and PRL (r = 0.67; P less than 0.01), respectively, indicating that the TSH and PRL responses to TRH in women are directly proportionate to the basal levels of the respective hormones, as previously shown for the TSH response in men. The mean intraindividual variability (coefficient of variation) of the TSH response to TRH was 18%, but ranged as high as 56%, while that of the PRL response was 16% and ranged up to 31%; variability was not affected by the phase of the menstrual cycle. The normal range of the peak TSH after TRH in women is 7-33 microU/ml (mean +/- 2 SD); however, because of the variability, a normal woman may sometimes have a peak TSH after TRH as low as 4 microU/ml. Repeating the test will result in a normal value if the woman is truly normal. Similarly, the normal peak PRL after TRH in women is 22-111 ng/ml (mean +/- 2 SD); usually, however, the lower limit is 30 ng/ml with lower values due to intraindividual variation. The data suggest that the higher average level of E2 in women compared to women, but that the cyclic changes in serum E2 or progesterone in women have little or no additional effect.

Adult↗
PubMed1976

Influence of suckling and of suckling followed by TRH or LH-RH on plasma prolactin, TSH, GH and FSH.

Ten women were studied during the first post-partum week. Suckling for 20 min induced a marked increase in plasma prolactin, reaching a maximum within 0-25 min after the end of suckling and then returning to pre-suckling levels after 120 min. Suckling induced no changes in plasma thyrotrophin (TSH), growth hormone (GH) or follicle stimulating hormone (FSH). The iv injection of 200 mug of thyrotrophin releasing hormone (TRH) immediately after suckling resulted in an additional increase in plasma prolactin and a rise in TSH. When given 120 min after suckling TRH was followed by increased plasma levels of prolactin and TSH, which for both hormones were of a magnitude comparable to the TRH induced increment seen immediately after suckling. Thus, suckling did not inhibit the effect of TRH on the release of TSH. These studies indicate that TRH is probably not involved in the suckling induced increase in prolactin secretion. The mean plasma FSH level was below the limit of detection before and after suckling. Neither plasma FSH nor prolactin showed any appearant changes following the iv injection of 25 mug of luteinizing hormone releasing hormone (LH-RH), when given immediately after and 120 min after suckling. When given after suckling as indicated above, TRH induced no changes in plasma GH or FSH and similarly LH-RH was without influence on plasma GH and TSH.

Adult↗
PubMed1976

Influence of low dose oestrogen on circulating prolactin. LH and FSH levels in post-menopausal women.

The effect on serum prolactin, LH and FSH levels of 25 mug ethinyloestradiol administered daily per os during 27 consecutive days was investigated in 5 post-menopausal women aged 52-78. Blood samples were collected before, during and after treatment. The hormones were assayed in serum by radioimmunological methods. Both LH and FSH decreased progressively and significantly from 120 and 115 mIU/ml before treatment to 52 and 51 mIU/ml, respectively after three weeks of oestrogen administration. Two weeks after interruption of treatment, LH (90mIU/ml) and FSH (112 mIU/ml) were significantly higher than during the last week of treatment. Mean prolactin level increased from 127 muU/ml before treatment to 237 muU/ml after 10 days of oestrogen administration (P less than 0.001). This increase was significant after 4 to 8 days and the levels remained about twice as high as the control values for the rest of the treatment period. Two weeks after interruption of treatment, serum prolactin had fallen (136 muU/ml) to the pre-treatment levels. Such results raise the question of possible effects of elevated levels of this hormone during long term oestrogen medication in post-menopausal women on the development of breast cancer.

Administration, Oral↗
PubMed1977

Influence of LH/FSH releasing hormone (LRH) on the basal secretion of gonadotrophins in relation to plasma levels of oestradiol, progesterone and prolactin during the post-partum period in lactating and in non-lactating women.

The pituitary responsiveness to LH/FSH releasing hormone (LRH) was studied in the puerperium in lactating and in non-lactating women. The response of both groups of patients to 25 mug LRH iv was tested 8-10 days, 15-17 days, and 29-32 days after a normal delivery at full term. The basal levels of FSH were low during the first 10 days after delivery. A rise was then observed, and about 4 weeks after delivery levels above or in the upper normal range of a normal follicular phase were recorded. The levels were significantly higher in the lactating group. When compared with the normal follicular phase, the relative increase in FSH basal levels was higher than the increase in LH basal levels in both groups of patients. The period of non-responsiveness of the pituitary to LRH was found to be of equal length in the two groups. In both groups the FSH response returned more rapidly than the LH response. About 2 weeks after delivery a reverse pattern of gonadotrophin response to LRH was seen with a FSH response that was greater than the LH response compared with what is generally observed in the various phases of the menstrual cycle in eumenorrhoeic women. This pattern was more pronounced in the lactating group about 4 weeks after delivery. Oestradiol levels were low and roughly equal on the three test occasions in each group, but in the non-lactating group there was a tendency to higher concentrations. Prolactin levels were highest about one week after delivery and then showed a tendency to decrease, and this was more pronounced in the non-lactating group. Progesterone levels were invariably low in both groups.

Adult↗
PubMed1977

Hypogonadism, galactorrhoea and hyper-prolactinaemia: Evaluation of pituitary gonadotrophins reserve before and under bromocriptine.

Twenty patients with hypogonadism (19 women with amenorrhoea and 1 man with impotence and infertility), galactorrhoea and hyper-prolactinaemia (range: 36 to 344 ng/ml) were studied. The radiological study of the sella turcica, including in all cases hypocycloidal tomograms, allowed classification of the patients into 3 groups: group I (n = 4) had a grossly enlarged sella turcica, group II (n = 12) had localized alterations indicating the probable existence of a prolactin-secreting microadenoma ("microdeformation") while group III patients presented no radiological abnormality. Before treatment, all the patients were submitted to a complete evaluation of the function of their anterior pituitary, including the LH and FSH responses to iv administration of Gn-RH. All the group I patients had low basal LH levels and a blunted response to Gn-RH. The basal LH and in response to Gn-RH were normal in most of the group II patients and in all of the group III patients. An exaggerated FSH response to Gn-RH was observed in 6/12 patients with microdeformation (group II) but not in groups I and III patients. A low LH and a blunted LH response to Gn-RH is highly suggestive of the existence of a pituitary prolactin-secreting adenoma in case of amenorrhoea and hyper-prolactinaemia patients; a normal response does not however rule out such a diagnosis. The reasons for a exaggerated FSH response to Gn-RH in patients with suspected prolactin-secreting microadenoma remain to be investigated though this pattern can also occur in other cases of amenorrhoea. Hence the Gn-RH test might contribute to the assessment of the hypothalamo-pituitary axis of patients with hyper-prolactinaemia. Six patients treated for 4 months with bromocriptine (CB-154) were submitted to re-evaluation of their pituitary gonadotrophins reserve. All the women experienced restoration of menses with 39 days of treatment and the male patient regained potency. It was observed that bromocriptine treatment and subsequent normalized prolactin levels in the 4 group II women tested were associated with normalization of their previously exaggerated FSH response to Gn-RH; LH responses were also diminished in these cases. These data are compatible with the hypothesis that hyper-prolactinaemia per se could interfere with the endogenous secretion of Gn-RH at the hypothalamic level. In one patient with grossly enlarged sella turcica and a previous lack of an LH and FSH response to Gn-RH, bromocriptine treatment restored a normal gonadotrophins response, confirming that, in this case, the alteration of this response was indeed due to a prolonged lack of endogenous Gn-RH secretion.

Adolescent↗
PubMed1977

Pituitary gonadotrophin secretion during the first weeks of pregnancy.

A longitudinal study of basal plasma LH and FSH and their responses to 25 microng LRH iv as well as basal levels of oestradiol, progesterone, prolatin and HCG was performed every week in 3 women, pregnant after heterologous insemination, from conception until the 6th week of gestation. A comparative study was carried out in 7 women in cycles in which no conception occurred after insemination. All hormones were assayed with radioimmunoassay. LH was measured with a specific assay for native HL, which did not cross-react with HCG. A decrease in basal levels of LH and FSH as well as decreasing responses to LRH was found during the first 2 weeks of gestation. These changes did not differ from what was observed during the luteal phase in the non-conception cycles. One week later the basal FSH levels and the FSH response in the pregnant women showed a further decrease, while in the non-pregnant women, now reaching the early follicular phase, a rise in FSH basal levels occurred. The basal levels of LH and the LH response, however, did not differ from that found in the non-pregnant woment at this time. FSH basal levels remained below the lower normal limit in eumenorrhoic women from the 3rd week of gestation. By this time the FSH response was almost completely inhibited. The LH basal levels, however, remained above the lower normal limit in eumenorrhoic women, but the LH response to LRH progressively decrease and was completely inhibited by the 5th week of gestation. In the non-conception cycles the LH response varied with the levels of oestradiol in plasma. This was not found in the pregnant women as the decrease in gonadotrophin response occurred while oestradiol remained at mid-cycle levels during the first 4 weeks of gestation. Rather it seems that the increasing and continuously elevated level of progesterone, in the presence of appropriate levels of oestradiol, might be the main go nadal steroid responsible for the diminishing pituitary secretion. The contribution of HCG to the further decrease in gonadotrophin secretion after the 2nd week of pregnancy cannot be answered by the present studies. Prolactin remained at non-pregnant levels until the 6th week of gestation, and appeared to have no influence on the secretion of gonadotrophins during early pregnancy.

Adult↗