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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pathophysiological role of the central dopaminergic mechanism in human essential hypertension (EH) is still unknown. We studied on the relationship between the dopaminergic activity and the salt-sensitivity. Twenty three hospitalized patients with EH were divided into the salt-sensitive group (SS, n = 12) or non salt-sensitive group (NSS, n = 11) by their responses whether they caused more than 8% increase in mean blood pressure (MBP) when the dietary salt was increased from 2g/day to 20g/day for 7 days of each. The change of central dopaminergic activity by the salt load was evaluated by the decrement of plasma prolactin (PRL) response to small dosage (25 micrograms) of thyrotropin releasing hormone. The mean percent change of PRL response by the salt load in the SS group was -6.5 +/- 8.3% (mean +/- SEM), which was significantly lower than 26.8 +/- 5.5% in the NSS group (p less than 0.01). There was a significant negative correlation between the percent changes of PRL response and the percent changes of MBP by the salt load (r = -0.448, p less than 0.05). These results suggested that the rise in blood pressure by salt load in SS patients with EH might be due to a reduced activity of the central dopaminergic mechanism.
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PMID:[Salt sensitivity and central dopaminergic activity in patients with essential hypertension]. 314 15

Although prolactin (PRL) responses to thyrotropin-releasing hormone (TRH) have been described by many investigators, PRL secretion after insulin stimulation has rarely been documented in patients with anorexia nervosa (AN). We investigated PRL responses to TRH (500 micrograms) and insulin (0.1 U/kg) in 19 women with AN and 10 normal women. Levels of PRL stimulation at 60 min and later following insulin administration were significantly lower in AN than in normal women. PRL increased by at least 10 micrograms/ml after insulin in 42% of women with AN and in 70% of normal women. The maximum PRL increase (max delta PRL) did not differ after the two stimulations in the normal women. However, in AN, the max delta PRL after insulin stimulation (17.2 +/- 4.0 micrograms/l, mean +/- SEM) was significantly lower than that after TRH (49.1 +/- 6.4 micrograms/l). These findings suggest that anorectic women may have a disturbance in hypothalamic functions. Insulin-induced hypoglycemia is useful to determine the integrity of the hypothalamic-pituitary axis for PRL secretion, in combination with TRH stimulation.
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PMID:Prolactin responses to hypoglycemia and thyrotropin-releasing hormone in anorexia nervosa. 314 79

Oral bromocriptine treatment of hyperprolactinemia is frequently associated with gastrointestinal side effects. To assess the efficacy and safety of an alternate route of treatment, we randomly administered 2.5, 5.0, and 7.5 mg of bromocriptine vaginally to five normal women at 1-week intervals. Plasma bromocriptine and prolactin (PRL) levels were measured hourly for 12 hours, then every 2 hours for 12 hours after each dose. At the end of each study, the vagina was flushed with saline for measurement of residual drug. For comparison of serum PRL levels, six additional women were given 2.5 mg bromocriptine orally. After administration of 2.5, 5.0, and 7.5 mg vaginally, plasma bromocriptine was initially detectable at 5.4 +/- 0.4, 4.4 +/- 0.7, and 3.5 +/- 0.6 hours, respectively. For the same vaginal doses, the mean (+/- SEM) peak plasma levels were 555 +/- 164 pg/mL at 12 +/- 0.6 hours, 702 +/- 252 pg/mL at 11.2 +/- 0.9 hours, and 1055 +/- 220 pg/mL at 10.7 +/- 1.7 hours, respectively. After each dose, there was a slow decline in plasma bromocriptine levels, remaining above 50% of peak values at 24 hours. Less than 1% of the administered drug was recovered from the vagina at 24 hours. The pattern of PRL inhibition with all three doses was similar. The mean plasma PRL level decreased by 7 hours, the maximum PRL decrease (64 +/- 3, 75 +/- 1, and 66 +/- 4% after 2.5, 5.0, and 7.5 mg, respectively) occurring at 11 hours, and the plasma PRL levels changed little during the remaining 13 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vaginal bromocriptine: pharmacology and effect on serum prolactin in normal women. 317 19

The concentrations of prolactin in the milk of nine postpartum lactating mothers were determined by radioimmunoassay between days 3 to 280 of the puerperium (n = 324 samples). In addition, prolactin in milk was also determined at the beginning and the end of suckling in three of the same women, who provided 21 paired samples of foremilk and hindmilk between days 7 and 88 of the puerperium. Prolactin content was highest at 43.1 +/- 4 ng/ml (mean +/- SEM) in the early transition milk immediately after the colostrum phase during the first postpartum week, decreasing to 11.0 +/- 1.4 ng/ml in the mature milk (p less than 0.01) when weaning occurred in those mothers who breastfed for up to 40 weeks post partum. During suckling, the foremilk contained significantly more prolactin as compared with the hindmilk (29.5 +/- 2.7 versus 21.0 +/- 3.2 ng/ml; p less than 0.01). These findings, taken together with the known biologic potency of prolactin in breast milk, the osmoregulatory influence of the hormone in mammary and intestinal function, and its absorption by the newborn experimental animal, suggest that the presence of prolactin in milk may play some role in both lactation and the intestinal absorptive function of the suckling newborn.
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PMID:Prolactin in human milk: the influence of nursing and the duration of postpartum lactation. 334 20

In normal individuals, serum cortisol and prolactin concentrations have been shown to rise following a mid-day meal. To determine whether abnormalities of the hypothalamo-pituitary-adrenal axis in bulimics lead to a disrupted hormonal response to eating, cortisol and prolactin responses to meals (600 kcal, 30% protein, 30% fat, 40% carbohydrate) were studied on two consecutive days in six normal weight bulimics and six normal volunteers. Dexamethasone (1 mg orally) was administered at 2330 h after baseline sampling. During baseline sampling, cortisol concentrations were significantly higher in the bulimics (18.2 +/- 0.9 micrograms/dl, mean +/- SEM) than in the normals (12.1 +/- 0.4 micrograms/dl) (p less than 0.001). Post-dexamethasone cortisol concentrations also were higher in the bulimics (5.7 +/- 0.3 micrograms/dl) than in the normals (1.2 +/- 0.2 micrograms/dl) (p less than 0.001). The three bulimics with a major depressive disorder had higher peak post-dexamethasone cortisol concentrations than the nondepressed bulimics. Dexamethasone significantly enhanced the prolactin response to meals among both bulimics (at 90 min post onset of eating) and normals (at 60, 75 and 90 min post onset of eating). This enhancement of the prolactin response to meals by dexamethasone is opposite to the inhibitory effect of dexamethasone on stress-induced prolactin release and suggesting that stress-induced and meal-induced prolactin release involve different neuroendocrine mechanisms.
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PMID:Effect of dexamethasone on cortisol and prolactin responses to meals in bulimic and normal women. 340 24

The endocrine pattern and ovarian characteristics of 110 healthy adolescents with menstrual irregularities were investigated during the early follicular and premenstrual phases and were compared to those of 14 adolescents with regular menstrual cycles and 20 adults. Over a period of six gynecological years a low ovulation rate (49%) was found in the group of subjects with irregular cycles and regular ovulation was noted in only a few subjects. Slight differences in endocrine pattern and ovarian morphology were observed between the group of adolescents with regular cycles and the group of adults. In contrast, adolescents with irregular menses had higher mean values of luteinizing hormone (LH), testosterone (T), and androstenedione (A) in comparison with the other two groups both in follicular and premenstrual phases. Nearly 35% of the subjects with irregular cycles had levels of T, A and LH which were higher than the upper limit of the adult normal range. Lower progesterone (P), 17P and oestradiol values were observed in the premenstrual phase. Within the group of subjects with irregular menses, LH levels were higher in anovulatory than in ovulatory cycles, in both phases of the cycle, while T and A levels were higher and prolactin levels were lower in the premenstrual phase of anovulatory cycles. Unlike irregular anovulatory cycles, irregular ovulatory cycles showed a hormonal pattern similar to that found in the adult group. By ultrasound evaluation, a high percentage of subjects with irregular menses had multicystic ovaries (57.9%) and the mean (+/- SEM) ovarian volume was higher (10.6 +/- 0.5 cm3) than that found in adolescents with regular menses (6.7 +/- 0.8 cm3) and in the adult group (7.7 +/- 0.3 cm3). With the increase in frequency and continuity of ovulation an improvement in the direction of adult volume and ovarian structure was observed. Besides the endocrine similarity the data emphasize the striking similarity, already documented by histological studies, between pubertal ovaries and those seen in micropolycystic ovary syndrome. These endocrine and ovarian characteristics are typical of a large number of adolescents with irregular menstrual cycles: these features may be representative of a developmental step toward adult normality, although the possibility of a pathological evolution for some subjects cannot be excluded.
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PMID:Menstrual irregularities in adolescents: hormonal pattern and ovarian morphology. 349 Oct 30

The effects of discrete lesions of the suprachiasmatic and medial preoptic nucleus on luteinizing hormone-releasing hormone (LHRH) neurons of the female rat were examined. The lesions disrupted the estrous cycle and prevented the preovulatory surge of luteinizing hormone and prolactin. Two to three months following the lesions, control and lesioned animals were perfused, the brains were sectioned, and the tissue processed for LHRH immunocytochemistry using the peroxidase antiperoxidase method and a high-titer, conformational antiserum to LHRH. Faintly stained LHRH cells were observed in the preoptic area and the basal hypothalamus at all stages of the estrous cycle. The number of immunoreactive cell bodies varied from a high of 583 cells on proestrus, to a low of 35 cells on estrus (mean +/- SEM = 323 +/- 59; n = 11). In contrast, the constant estrous animals with lesions showed increased intensity and number of LHRH neurons rostral, lateral and caudal to the lesion. The total number of cells ranged from 625 to 954 cells per animal (mean +/- SEM = 784 +/- 44; n = 8; p less than 0.001 vs. controls). Moreover, all lesioned animals exhibited intense fiber stain in the median eminence region. In conclusion, these data support the hypothesis that persistent estrus is caused by destruction of neurons which directly or indirectly control LHRH neurons.
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PMID:Luteinizing hormone-releasing hormone neuronal system during the estrous cycle of the female rat: effects of surgically induced persistent estrus. 352 98

We investigated the chromatographic pattern of serum prolactin in 41 patients with prolactinoma and correlated the distribution of immunoreactive prolactin with the clinical variables sex, tumour size, age, and response to bromocriptine therapy. In addition, the effect of long-term storage and repeated freezing and thawing on the different molecular weight forms of prolactin was evaluated. Gel chromatography (column 100 cm X 1.5 cm) was performed in 0.1 mol/l phosphate buffer, pH 7.5, using Ultrogel ACA 54 (LKB). No correlation of age or the response to drug therapy to the elution pattern of prolactin was found. Females showed a higher percentage of big prolactin than males (10.4 +/- 1.2% vs 6.8 +/- 0.7%, mean +/- SEM, P less than 0.05) and patients with microprolactinomas too had a higher percentage of big prolactin than those with macroprolactinomas (11.3 +/- 1.8% vs 7.7 +/- 0.7%, P less than 0.05). Serum samples kept frozen for more than 2 years showed a higher percentage of bigbig prolactin (P less than 0.01) than samples stored for less than 12 months suggesting formation in vitro. However, examination of fresh samples prior to freezing also demonstrated bigbig prolactin, indicating that bigbig prolactin circulates in vivo. Repeated freezing and thawing of bigbig prolactin led to almost complete interconversion to little prolactin without any increase in immunoreactivity. This finding supports the concept that bigbig prolactin represents little prolactin loosely associated to a carrier molecule.
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PMID:Size heterogeneity of immunoreactive prolactin in patients with prolactinoma. 357 80

Dopamine receptors on human pituitary adenoma membranes were characterized using [3H] spiperone as the radioligand. The specific [3H]spiperone binding sites on prolactin (PRL)-secreting adenoma membranes were recognized as a dopamine receptor, based upon the data showing high affinity binding, saturability, specificity, temperature dependence, and reversibility. All of 14 PRL-secreting adenomas had high affinity dopamine receptors, with a dissociation constant (Kd) of 0.85 +/- 0.11 nmol/l (mean +/- SEM) and a maximal binding capacity (Bmax) of 428 +/- 48.6 fmol/mg protein. Among 14 growth hormone (GH)-secreting adenomas examined, 8 (57%) had dopamine receptors with a Kd of 1.90 +/- 0.47 nmol/l and a Bmax of 131 +/- 36.9 fmol/mg protein. Furthermore, 15 of 24 (58%) nonsecreting pituitary adenomas also had dopamine receptors with a Kd of 1.86 +/- 0.37 nmol/l and a Bmax of 162 +/- 26.0 fmol/mg protein. These results indicate that some GH-secreting adenomas as well as some nonsecreting pituitary adenomas contain dopamine receptors. But their affinity and number of binding sites are significantly lower (P less than 0.05) and fewer (P less than 0.001) respectively, than those in PRL-secreting adenomas.
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PMID:Demonstration of specific dopamine receptors on human pituitary adenomas. 357 89

The participation of central epinephrine in prolactin secretion was investigated in rats by testing the effects of SK&F 64 139, a selective inhibitor of phenylethanolamine-N-methyltransferase. The drug is reported to dramatically reduce brain epinephrine concentration without affecting norepinephrine or dopamine levels. When SK&F 64 139 was administered (40 mg/kg, ip) to male rats or to female rats during diestrus or proestrus, plasma prolactin levels were not different from those of control groups. Lactating and ovariectomized rats, however, responded to the same SK&F 64 139 dose with an increase in plasma prolactin levels: 210.02 +/- 22.72 vs 378.66 +/- 42.57 (mean +/- SEM) for control of lactating rats, and 4.35 +/- 0.52 vs 6.21 +/- 0.60 ng/ml for control ovariectomized rat. These results suggest that epinephrine may play a functional inhibitory role in prolactin secretion in the lactating and ovariectomized rat.
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PMID:Effect of a selective inhibitor of epinephrine synthesis, SK&F 64 139, on prolactin secretion in the rat. 359 4


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