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Biomedical subjects

C Robyn

Publications and source records attributed to C Robyn.

At least 73 records · Page 4Linked to original sources
PubMed1979

Tiapride-induced chronic hyperprolactinaemia: interference with the human menstrual cycle.

Four regularly menstruating volunteers were submitted to an oral treatment, for 3 consecutive cycles and starting on the first day of a cycle, with tiapride at daily doses ranging from 1 x 100 mg to 2 x 100 mg. The first and the last cycle under treatment, as well as a prior control cycle, were thoroughly studied by means of daily measurements of blood concentrations of LH, FSH, prolactin (PRL), oestradiol and progesterone. Tiapride, a benzamide derivative with dopaminergic blocking activity at the level of the lactotrophes, increased mean PRL secretion in each subject but a permanent hyperprolactinaemia above 700 uU/ml was attained only in one subject. Despite these widely fluctuating PRL levels in most subjects, the resulting overall hyperprolactinaemia induced in all cases a progressive deterioration of the function of the corpus luteum: 5 cycles showed luteal phases reduced by 2--5 days, one cycle was characterized by some slight luteinisation but questionable ovulation and the 2 remaining cycles were anovulatory. The interruption of drug intake one week after the onset of menses led thereafter to a cycle with a likely inadequate luteal phase but of normal length. It is concluded that even a non-permanent hyperprolactinaemia can impair the normal function of the hypothalamo-pituitary-ovarian axis, as well as exhibit some effects in a cycle consecutive to the normalization of PRL. With the exception of the impaired luteal progesterone secretion, the pooled hormonal data from the short luteal phase cycles under tiapride-induced hyperprolactinaemia exhibit very little significant differences, as compared to the corresponding values in the control cycles. Some delay in the onset of follicular maturation, however, should be assumed since the follicular phase had been lengthened by 1 to 31 days in 5 of the 6 cycles with luteinisation during treatment. The present results are compatible with a double impact -- both at the ovarian and the hypothalamo-pituitary levels -- of hyperprolactinaemia in its mechanisms of impaired function of the hypothalamo-pituitary ovarian axis.

Administration, Oral↗
PubMed1978

Serum prolactin, gonadotropins, and estradiol in menstruating and amenorrheic mothers during two years' lactation.

Serum prolactin, LH, FSH, and estradiol were measured in single blood samples collected from 465 nursing mothers in Central Africa (Kivu, Zaïre) during the first 2 postpartum years. Lactating mothers were hyperprolactinemic during 15 to 18 postpartum months. Both serum prolactin and FSH were higher in amenorrheic than in menstruating nursing mothers; the difference was more apparent during the first than during the second year. Mean serum LH and estradiol were significantly higher in menstruating then in amenorrheic nursing mothers during the second postpartum year but not during the first. There was a significant association of hyperprolactinemia with amenorrhea. Furthermore, postpartum, the incidence of amenorrhea declined parallel to that of hyperprolactinemia.

Amenorrhea↗
PubMed1978

Double-blind crossover clinical pharmacology study comparing moxestrol (R 2858) and ethinyl estradiol in postmenopausal women.

The potency of 5 migrogram moxestrol (R 2858). 11beta-methoxy-17alpha-ethinyl-estra-1,3,5-[10]-triene-3,17-diol, administered orally, was compared to that of 25 microgram ethinyl estradiol in a double-blind crossover clinical pharmacology study of six postmenopausal women. At these doses, both compounds increased the eosinophilic index and decreased serum LH and FSH levels. A marked effect on circulating prolactin was observed only during ethinyl estradiol treatment.

Aged↗
PubMed1978

Acute endocrine profile of sulpiride in the human.

Normal men and normally menstruating women received i.m. injections of 0.1 to 4.0 mg/kg sulpiride. This psychotropic drug induced a very rapid (already significant after 5 minutes) and sustained (still significant after 7 hours) elevation of prolactin (PRL) concentrations in all subjects with no consistent modification of LH and FSH. After injection of 4.0 mg/kg, there was similarly no modification of mean TSH concentrations in the women tested in the luteal phase, as well as of mean GH levels in men. Sulpiride prevented the inhibitory effect on PRL levels of 500 mg levodopa, administered orally simultaneously; levodopa administered 2 hours prior to sulpiride failed to counteract the PRL-stimulatory effect of sulpiride. Under chronic sulpiride-induced hyperprolactinaemia, levodopa exhibited however a very slight inhibitory effect on PRL concentrations. These data are in agreement with the hypothesis that sulpiride acts mainly at the pituitary level by blocking dopamine receptors of the lactotropes and support the concept that the menstrual cycle perturbations observed under chronic sulpiride administration result from hyperprolactinaemia itself or from a mechanism quite similar to that by which sulpiride induces hyperprolactinaemia.

Adolescent↗
PubMed1978

Simultaneous study of cortisol, growth hormone and prolactin nyctohemeral variations in normal and obese subjects. Influence of prolonged fasting in obesity.

Hourly integrated concentrations (IC) of growth hormone (GH), prolactin (PRL) and cortisol were determined by a continuous sampling procedure in six obese women, before and at the end of a 12 day fast, and in eight normal controls under basal conditions. Hormonal 24 h IC and nyctohemeral variations were calculated from these data. Nyctohemeral rhythms were investigated by the periodogram method. A significant increase over basal values of 24 h IC of PRL, GH and cortisol was observed at the end of the fasting period. Nyctohemeral variations--but not nyctohemeral rhythm--of IC-GH were found in normal subjects. They were abolished in obese patients under basal conditions but restored during fasting. The circadian rhythm of cortisol was not altered in obesity. A shift of the normal nyctohemeral rhythm of PRL was observed in obese patients, but the normal pattern was restored during fasting.

Adult↗
PubMed1978

Alteration of feedback mechanism of estrogen on gonadotropin by sulpiride-induced hyperprolactinemia.

Four normally cycling women received an iv injection of 20 mg Premarin (conjugated estrogens equivalent to 20 mg estrone sulfate) on the seventh day of two consecutive cycles; the second experiment was performed under sulpiride-induced hyperprolactinemia (mean PRL level = 906 microU MRC standard 71/222 per ml; significantly 7.8 times greater than mean control level of 115 microU MRC standard 71/222 per ml, P less than 0.001). In comparison to the control experiment, sulpiride-induced hyperprolactinemia prevented the occurrence of any gonadotropin peak within the 84 h of estrogen administration; the negative feedback effect of estrogen on gonadotropin secretion was maintained and was even potentiated. These alterations of feedback mechanisms of estrogen were considered to be related to hyperprolactinemia itself rather than to sulpiride. Five other normally cycling women received iv injections of 100 microgram LRH on the 22nd day of a cycle under sulpiride-induced hyperprolactinemia since the onset of menstruation. Their mean LH response was somewhat greater (although not statistically significant) and their mean FSH response was considerably greater (P less than 0.001 at all times) than those of a control group of 10 women tested in their luteal phase. The results of these LRH tests under sulpiride-induced hyperprolactinemia give some support to the concept that hyperprolactinemia interferes at the hypothalamic or higher level with cyclic release of indogenous LRH.

Adolescent↗
PubMed1978

Cord serum prolactin in relation to the time of the day, the sex of the neonate and the birth weight.

Serum prolactin was measured in 581 blood samples collected immediately after birth from 563 single new-born and from 9 pairs of twins. Cord serum prolactin is high at birth: the mean level is some 5 times higher than in adults. There is no sex difference in cord serum prolactin concentration in the neonate. Mean serum prolactin is significantly higher at 1.00 and 2.00 a.m. Thus a circadian periodicity in serum prolactin concentration seems to appear already during foetal life well before the organization of sleep rhythm. Cord serum prolactin increases with birth weight ranging from 1500 g to 3500 g. Thus, the control of levels of circulating prolactin changes during foetal life resulting in a progressive increase starting from mid-pregnancy. Mean cord serum prolactin at birth is lower in twins than in single new-borns. There is no significant difference in serum prolactin between the first and the second twin.

Birth Weight↗
PubMed1978

[Effect of ergot alkaloid derivatives on milk secretion in the immediate postpartum period].

30 women received an intramuscular injection of 0.2 mg of methylergobasine immediately after delivery and then 3 tablets of 1 mg of ergotamine tartrate per mouth daily for 6 days post-partum. 28 women received no treatment after delivery. The selection of the two groups was random. The treatment with rye ergot derivatives did not have a significant effect on the quantity of milk that the infant took, nor on the infant's weight gain in the 6 first days of life.

Body Weight↗
PubMed1977

Serum alpha-fetoprotein in adults, in women during pregnancy, in children at birth, and during the first week of life: a sex difference.

In order to investigate whether a sex difference exists in alpha-fetoprotein serum concentration, blood samples were collected from 133 adult men, 52 adult women, 239 pregnant women at different ages of gestation, 16 girls and 18 boys at birth, and seven girls and seven boys during the first week of life. In the case of 15 boys and 10 girls, blood samples were also collected from their mothers at the time of delivery. Serum AFP was measured by a radioimmunoassay method. In all neonates the mean value was 625 times higher than in all mothers at the time of delivery and 13,000 times higher than in adults. No difference was found between mothers of girls and those of boys both during pregnancy and at the time of delivery. However, at birth, the fetal AFP serum concentration was 1.8 (p less than 0.001) times higher in boys than in girls. This sex difference was maintained during the first week of life. The half-life of serum AFP was 5 to 6 days in the neonate. The origin and the possible physiologic significance of such sex difference in AFP deserve further investigations.

Delivery, Obstetric↗
PubMed1977

Serum prolactin levels during the menstrual cycle.

Serum prolactin has been measured in blood samples collected daily during 51 menstrual cycles using an homologous human radioimmunoassay for 17 cycles and an homologous ovine radioimmunoassay for 34 cycles. There was a progressive and significant increase in serum prolactin during the late follicular phase, with a maximal value concomitant to the LH peak. Serum prolactin levels were also significantly higher during the luteal phase than during early follicular phase. In some 70% of the individual cycles, the highest serum prolactin level was found at mid-cycle. Similar patterns were obtained with both radioimmunoassays. However, when using the same laboratory serum standard, the average serum prolactin level calculated for the entire cycle was 1.6 times higher with the homologous ovine assay than with the homologous human assay. The overall pattern of serum prolactin during the menstrual cycle resembles that reported for circulating 17beta-estradiol.

Animals↗
PubMed1977

Mechanism of increased prolactin secretion by sulpiride.

The effect of sulpiride, a neuroleptic agent, on the secretion of prolactin by the anterior pituitary gland of the rat was studied. A significant increase in serum prolactin was observed after subcutaneous administration of the drug. Although sulpiride (0-10 micronmol/1 or 0-14 mmol/1) had no effect on the secretion of newly synthesized or radioimmunoassayable prolactin in vitro, the drug significantly overcame the inhibitory action that dopamine (0-50 micronmol/1) exerted on prolactin secretion. Rats implanted with a prolactin-secreting pituitary tumour MtTW15 showed an inhibition of prolactin biosynthesis and release. Injection of these rats with sulpiride restored prolactin biosynthesis and release of the hormone toward normal levels. These results demonstrate that sulpiride has a direct effect on the pituitary antagonizing the inhibitory effects exerted by dopaminergic mechanisms, although the drug itself does not stimulate the secretion of prolactin in vitro. Sulpiride may have a direct action on the pituitary lactotrophs in vivo, but effects at higher centres have not been excluded.

Animals↗
PubMed1977

[Oestriol effect upon prolactinaemia in postmenopausal women (author's transl)].

Six postmenopausal women were treated at two ocasions with an oral dose of, respectively, 2 mg and 6 mg oestriol per day for 14 days; at least one month interval separated the two treatment periods. Blood was collected for prolactin measurement (homologous human radioimmunoassay) every other day during each treatment period as well as during a 14 days control period in the same subjects. Mean prolactin level during oestriol administration, regardless of the dose, was statistically not significantly different from that observed during the control period.

Administration, Oral↗