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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The surface ultrastructure of porcine early corpus luteum cells (days 1-3 of the luteal phase) was studied in SEM and correlated with progesterone secretion. Luteal cells were divided into 2 groups: small cells (10-20 microns) and large cells (20-30 microns) and their surface features were observed after 1, 3, and 5 h of incubation in the control medium and in a medium supplemented with prolactin (PRL). The surface morphology of control cells was characterized by numerous smooth blebs and the presence or absence of thin microvilli. Small and large cells showed a tendency to adhere to the glass during the experiment, but on the large cells the number of thin adhesive filopodia was greater. After the 1st and 3rd h of incubation with PRL the number of microvilli and numerous filopodia on the small cells increased substantially. Nodular blebs were scattered and appeared to protrude from the cell surface. Many small cells adhered to the glass by thick, layered and thin thread-like cytoplasmic processes. After the 5th h distinct smoothing of the surface of the small cells was seen. The number of microvilli seen on the PRL stimulated surface of the large cells was smaller and in some cases even entirely absent. After the 1st and 3rd h of the experiment the large cell surface was ruffled with minute folds. Numerous nodular blebs protruded from the cell surface. The number of adhesive filopodia attaching the cells to the glass decreased or vanished during the experiment. After the 5 h of incubation most of the cells had smooth surface with smooth blebs. Progesterone secretion was measured by radioimmunoassay. The cells in the medium without exogenous hormone (control) secreted relatively low levels of progesterone throughout 1-5 h of the incubation period. After addition of PRL to the medium the amount of secreted progesterone increased.
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PMID:The corpus luteum of the pig. Scanning electron microscopic study of surface features at different times of incubation. 263 80

Plasma concentrations of prolactin (PRL), corticosterone (B), and luteinizing hormone (LH) were determined in hourly samples collected over a 24-h period from unrestrained, long-term ovariectomized (OVX) turkey hens maintained in cages in an isolation room on a 14 h light: 10 h dark photoperiod. Mean plasma concentrations of all three hormones were found to vary significantly with the time of sampling. Mean plasma PRL levels reached a peak (6.50 +/- 1.70 ng/mL, means +/- SEM) during the latter half of the photophase, declined to a nadir (5.22 +/- 1.20 ng/mL) prior to the onset of darkness, and then rose gradually during the scotophase to reach another peak (8.96 +/- 1.80 ng/mL) 1 h prior to lights on. Mean plasma LH levels rose significantly (P less than .001) from a nadir of 4.11 + .29 ng/mL prior to lights out to a peak of 4.74 + .34 ng/mL during the dark period. No evidence of random fluctuations in LH levels was observed in any individual, suggesting that episodic LH release may not occur in OVX turkey hens. Individual patterns of B secretion varied substantially so that, although significant increases and decreases in mean plasma B levels were observed, no clearly defined peaks in mean plasma B levels were identified. Individual secretory profiles revealed that peaks in PRL secretion often coincided with peaks in B secretion, but B peaks were usually more numerous. It is concluded that PRL and LH are secreted in a daily rhythm in the OVX turkey hen, with the highest levels of both hormones occurring during the scotophase.
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PMID:Daily changes in plasma prolactin, corticosterone, and luteinizing hormone in the unrestrained, ovariectomized turkey hen. 270 74

In order to improve the knowledge of prolactin receptors (PRL-R) in human breast tumors, we studied PRL-R modulation by lactogenic and steroid hormones in the PRL-R rich human breast cancer cell-line, T-47 D. The PRL-R were assayed on a preparation of cell total membranes. We demonstrated an abnormal homologous in vitro regulation of PRL-R. Concentrations of human growth hormone (hGH) greater than 500 ng/ml were required to cause a decrease in PRL-R, with a maximal down-regulation at 2000 ng/ml and for 48 hours. Human placental lactogen (hPL) induced a decrease in PRL-R at concentrations greater than 500 ng/ml but later than hGH; ovine prolactin (oPRL) had no effect on PRL-R. Moreover, we also demonstrated that progestins specifically modulated the expression of PRL-R in T-47D cells: Org 2058, a synthetic progestin induced a statistically significant increase in PRL-R after a twenty-four hour incubation period: this effect was already observed at 10(-9) M and was maximal for 10(-6) and 10(-5) M (186% +/- 3.5% (+/- SEM) for total PRL-R). At 10(-6) M, the stimulation occurred early at three hours and was maximal at twenty-four hours. Conversely estradiol (10(-9) to 10(-6) M), cortisol (10(-9) to 10(-6) M), dexamethasone (10(-9) to 10(-5) M) and RU 486 (10(-9) to 10(-5) M), a progestin and glucocorticoid antagonist, had no effect on PRL-R levels. The Org 2058 PRL-R stimulation was abolished in the presence of RU 486. The abnormal PRL-R down-regulation in the human breast cancer cell-line, T-47D, may contribute a growth advantage to these malignant cells over normal tissues. The progestin PRL-R dependence suggests that high levels of PRL-R may reflect a functional progesterone receptor (Pg-R) and a highly hormone-dependent-phenotype of the tumor. These results support a potential role of PRL in the etiology of breast tumors and may have important implications in the management of human breast cancer.
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PMID:Modulation of prolactin receptors (PRL-R) by lactogenic and steroid hormones in human breast cancer cells in long-term tissue culture (T-47D). 276 10

Counterregulatory effect following administration of biosynthetic human proinsulin (BHPI) and human insulin (BHI) were compared during hypoglycemia standardized by means of a glucose controlled insulin infusion system (GCIIS). A total of 0.148 +/- 0.010 U/kg of BHPI had to be given by the GCIIS in order to obtain a minimal blood glucose (BG) of 26 +/- 2 mg/dl (means +/- SEM) at 43 +/- 2 min. In contrast, 0.083 +/- 0.004 U/kg of BHI were sufficient to produce a minimal BG of 21 +/- 1 mg/dl (n.s.) at 35 +/- 1 min. (P less than 0.005). Moreover, BHPI infusion resulted in prolonged hypoglycemia and delayed blood glucose recovery. On a molar basis, the acute BG lowering effect of BHPI was about 13% that of BHI (BHPI 3.94 +/- 0.27 vs. BHI 0.51 +/- 0.03 nmol/kg). Serum proinsulin after BHPI reached its maximum of 19.4 +/- 2 pmol/ml at 20 min. and still exceeded basal values markedly at the end of the test period at 240 min. Serum insulin peaked at 10 min. (162 +/- 47 microU/ml) and had already returned to basal values (7.5 +/- 1 microU/ml) after 45 min. No severe side effects were observed and there was no need for glucose administration, but clinical symptoms of hypoglycemia were more pronounced after BHPI. Compared to BHI, BHPI produced a higher cortisol peak (252 +/- 16 vs. 168 +/- 10 ng/ml), a more pronounced secretion of ACTH and GH as well as a stronger decline of serum potassium (3.20 +/- 0.06 vs. 3.58 +/- 0.08 mmol/l). Counterregulatory prolactin secretion did not differ significantly. Urinary epinephrine secretion following hypoglycemia after BHPI exceeded that after BHI (10.3 +/- 4.8 vs. 3.0 +/- 0.5 ng/120 min.). Serum lactate increase after BHPI was more prolonged (1.68 +/- 0.24 vs. 0.37 +/- 0.14 mmol/l at 120 min.). BHPI-induced inhibition of lipolysis, as determined by free fatty acid patterns, was delayed and less pronounced. Our results indicate that the observed more distinct glucose counterregulation is due to prolonged hypoglycemia rather than to any specific BHPI action on the hypothalamic-pituitary axis. We regard this as a consequence of the prolonged circulating and biological half-life. A preferential proinsulin action on the liver may play an additional role. Whether this "depot effect" may be beneficial in the treatment of diabetes mellitus remains to be established.
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PMID:Comparative study of hormonal counterregulation during GCIIS-guided hypoglycemia tests using human proinsulin and human insulin (recombinant DNA). 284 67

The responses of plasma adrenocorticotrophin (ACTH), cortisol, growth hormone (GH) and prolactin to insulin-induced hypoglycaemia were studied in six lean male subjects (age 22-29 years). Intravenous insulin tests were performed with and without oxytocin infusion. Blood sugar nadir occurred at the onset of symptoms (time S) with no significant differences between oxytocin and saline infusion. During the oxytocin infusion mean plasma oxytocin increased from 1.9 pmol/l to 138 pmol/l. Peak increase in plasma ACTH (oxytocin 266 +/- 54 ng/l; saline 281 +/- 43 ng/l, mean +/- SEM) was at S + 10 min while peak plasma cortisol (oxytocin 680 +/- 47 nmol/l: saline 656 +/- 40 nmol/l) was measured at S +/- 60 min, peak GH (oxytocin 96 +/- 17.8 mU/l; saline 106 +/- 18.6 mU/l) at S + 60 min and prolactin (oxytocin 1332 +/- 239 mU/l; saline 1242 +/- 273 mU/l) at S + 30 min. There were no significant differences in plasma concentrations of ACTH, cortisol, GH or prolactin between saline and oxytocin infusion. The results indicate that oxytocin has no effect on plasma ACTH, cortisol, GH and prolactin responses to insulin-induced hypoglycaemia. In particular they fail to support previous studies which suggested an inhibitory role for oxytocin in ACTH secretion.
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PMID:The effect of oxytocin infusion on adenohypophysial and adrenal cortical responses to insulin-induced hypoglycaemia. 285 20

We have previously reported an impaired growth hormone (GH) response and abnormal prolactin release to insulin-hypoglycaemia in obesity. We suggested that obese women with an absent prolactin response to hypoglycaemia ('non-responders') have a disorder of hypothalamic function. We have now investigated the GH response to i.v. growth hormone releasing factor, GHRF (1-29)NH2, in 14 obese women and nine age-matched normal-weight women. We found a significantly reduced GH response to GHRF in the obese women as compared with controls (mean peak +/- SEM: obese 8.9 +/- 2 mu/l, controls 28 +/- 2 mu/l; P less than 0.01). When the obese women were divided on the basis of their prolactin response to insulin-hypoglycaemia (seven 'non-responders', mean weight 102 +/- 5 kg; seven responders, mean weight 108 +/- 8 kg) a similar GH response to GHRF was found between the two groups but the GH response to hypoglycaemia was significantly less in the 'non-responder' women (mean peak 'non-responders' 10.5 +/- 3 mu/l, responders 27 +/- 4 mu/l; P less than 0.05). We conclude that obesity may be characterized by an impaired GH response to both i.v. GHRF and insulin-hypoglycaemia, which suggests altered hypothalamic-pituitary function. The finding that the GH response to hypoglycaemia is significantly less in the obese prolactin 'non-responder' women supports the hypothesis for a hypothalamic disorder.
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PMID:Impaired growth hormone response to growth hormone releasing factor and insulin-hypoglycaemia in obesity. 286 16

Previously we observed that prolactin (PRL) is secreted in response to gonadotropin-releasing hormone (GnRH) in normal women during the periovulatory phase of the menstrual cycle. Because sedative drugs affect the neurotransmitters involved in the regulation of PRL secretion, we investigated PRL responsiveness to GnRH in pre- and postmenopausal female subjects during prolonged treatment with benzodiazepines (six-60 months). In both pre-and postmenopausal patients who were not on benzodiazepine treatment, GnRH infusion (0.2 micrograms/min for 3 hr) was ineffective in eliciting a PRL response. In six premenopausal women treated with benzodiazepines, basal PRL concentrations were not influenced by the drug in four subjects (range 4.0-15.7 ng/ml) and were slightly elevated in two subjects (23 and 30 ng/ml). In six treated postmenopausal women, basal PRL concentrations were in the normal range (7.5-11.0 ng/ml). GnRH infusion induced a progressive increase in PRL concentrations which reached a peak at 120 min in the premenopausal subjects (mean % SEM increase: 64 +/- 30.5%) and at 60-90 min in the postmenopausal subjects (mean % increase: 110.6 +/- 34.7%). A saline infusion, performed on a separate day during benzodiazepine treatment as a control, did not influence PRL.
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PMID:Plasma prolactin response to gonadotropin-releasing hormone during benzodiazepine treatment. 290 41

Prolactin levels were measured by radioimmunoassay in paired breast milk and plasma samples of 11 hyperprolactinemic women with galactorrhea and various menstrual disorders (amenorrhea, n = 8; oligomenorrhea, n = 2; luteal phase defect, n = 1) before and during treatment with bromocriptine (Parlodel, Sandoz). Pretreatment levels of prolactin in the milk and plasma were 80 +/- 13 ng/mL (mean +/- SEM) and 47 +/- 7 ng/mL (P less than 0.05), respectively. While on treatment, the concentration gradient for prolactin remained in favour of the milk, with values for milk and plasma 59 +/- 11 and 29 +/- 3 ng/mL (P less than 0.01), respectively. Thus, bromocriptine lowered the prolactin concentrations in both breast milk and plasma. Since prolactin in milk is biologically active, these findings may be relevant to the initiation and maintenance of lactation in women with abnormal lactogenesis.
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PMID:Immunoreactive prolactin in breast milk and plasma of women with hyperprolactinemia, galactorrhea and menstrual dysfunction. 290 79

Amniotic fluid prolactin is a product of maternal decidualized endometrium that is derived by translocation of the hormone across the reflected fetal membranes. Amniotic fluids from 26 second-trimester (14 to 23 weeks) and 75 third-trimester (29 to 40 weeks) normal singleton pregnancies were evaluated for prolactin content by radioimmunoassay and bioassay with the Nb2 rat lymphoma cell line. The relative bioactivity was calculated as the ratio of bioassay to radioimmunoassay for each fluid. Data segregated by gestational age and fetal genetic sex identified a highly significant difference (p = 0.0004) in amniotic fluid prolactin radioimmunoassay concentrations (mean +/- SEM) that surround male (682 +/- 49, n = 42) versus female (440 +/- 39, n = 33) fetuses of third-trimester age. Paired bioassay values were significantly lower (p = 0.002) than radioimmunoassay values among males (626 +/- 52) but equivalent (p = 0.1066) among females (464 +/- 44). The bioassay/radioimmunoassay ratios of third-trimester fetal female-associated amniotic fluid prolactin were significantly higher (p = 0.0004) than those of third-trimester males and second-trimester males and females. The results suggest a fetal gender-related factor is associated with both the production and the biologic activity of the maternally derived hormone. Thus the fetus appears to have some control over the dynamics of uterine prolactin production.
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PMID:Fetal control of maternal prolactin production and bioactivity in utero. 291 13

The effects of 17 beta-estradiol (E17 beta) on prolactin (PRL) cell proliferation and on the expression of PRL and growth hormone (GH) proteins and mRNAs were analyzed in cultured pituitary cells by immunocytochemistry, in situ hybridization, and Northern blot hybridization studies. Three different cell cultures were used: (a) normal pituitary cells; (b) GH3 tumor cell line; and (c) MtT/W15, a transplantable PRL and GH-producing pituitary tumor. E17 beta (10(-7) M) caused a significant increase in PRL cell proliferation in normal pituitary [3.9 +/- 0.4 versus 7.7 +/- 0.9% (SEM) of immunostained PRL cells with thymidine incorporation] [P less than 0.01] but produced a significant decrease in PRL cell proliferation in MtT/W15 primary cell cultures [6.7 +/- 1.0 versus 3.7 +/- 0.8%] [P less than 0.05]. PRL mRNA was significantly increased in normal pituitary and in GH3 tumor cells by E17 beta treatment. There was a significant decrease in PRL mRNA and an increase in GH mRNA expression in cultured MtT/W15 tumor cells by immunocytochemistry and in situ hybridization analyses. The percentage of cells producing both PRL and GH or mammosomatotropic cells analyzed by two different techniques declined after one week in culture in normal pituitary cells and in cultured MtT/W15 tumor cells after E17 beta treatment. These results show that E17 beta has a direct stimulatory effect on normal pituitary and GH3 cells and a direct inhibitory effect on MtT/W15 tumor cells with respect to cell proliferation and PRL hormone and mRNA expression.
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PMID:Effects of estradiol on prolactin and growth hormone messenger RNAs in cultured normal and neoplastic (MtT/W15 and GH3) rat pituitary cells. 291 54


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