Serum prolactin and growth hormone determined by radioimmunoassay and a two-site immunoradiometric assay: comparison with the Nb2 cell bioassay

Serum levels of the two lactogenic hormones prolactin (PRL) and growth hormone (GH) were compared when determined by radioimmunoassay (RIA) and two-site immunoradiometric (IRMA) assays in 83 normal premenopausal women. The mean values for the PRL and GH results determined by RIA were higher than those obtained by IRMA, despite strong correlations between the two (PRL, r = 0.92; GH, r = 0.79). The lactogenic hormones were also determined together by the Nb2 cell bioassay (BA) in 38 of these same women, and the results compared with the sum of the PRL and GH immunoassays. There was a strong correlation between the BA and RIA (r = 0.75), and the BA/PRL+GH RIA ratio averaged 1.6 +/- 0.5. Corresponding values for IRMA were r = 0.66, and BA/PRL + GH IRMA 3.3 +/- 1.1. Thus, the polyclonal RIA antisera appeared to recognize bioactive hormone components not determined by the double monoclonal antibody IRMA. Another 23 women at risk for familial breast cancer, and 14 cystic breast disease patients were also studied. High BA, but normal RIA results, giving mean ratios of 2.4 +/- 1.1 and 3.6 +/- 3.0 respectively, suggest the presence of a further variant with high bioactivity not detected by RIA in these two clinical situations.     

Relationship between bioassay and radioimmunoassay measurement of prolactin in the IPL rat, a hypoprolactinemic rat strain

IPL (Institut Pasteur, Lyon) nude, hypoprolactinemic rats exhibit delayed puberty and a complete lack of lactation. To characterize the secretion of circulating forms of prolactin (PRL) of these rats, PRL concentrations were measured in serum and pituitaries of males and females under various physiological conditions. Two assay methods, a radioimmunoassay (RIA) and a sensitive bioassay (NB2BA) were employed. Normal rats of the Sprague-Dawley strain were tested simultaneously, as controls. The pituitary content of PRL, estimated either by RIA or by NB2BA, in IPL nude males and females was similar to that of normal male and female rats. On the contrary, serum PRL levels of IPL male rats, measured by RIA or NB2BA, were significantly reduced when compared to normal rats. In both groups, there was a close correlation between the results obtained by the two methods, the NB2BA estimates being higher. However, the NB2BA/RIA ratio was significantly decreased in serum from IPL nude rats compared to controls, indicating that the circulating form of PRL was less bioactive in this group. Castrated male rats injected with estradiol showed sharply increased PRL values as estimated by RIA or NB2BA. The increase was greater (35-fold) in IPL nude rats then in normal rats (9-fold), but these increases resulted in serum PRL levels being similar in the two groups. However, the NB2BA/RIA ratio remained significantly reduced in IPL nude rats. In female rats, PRL was measured during different physiological states: estrus, diestrus, proestrus at 1000, 1200, and 1600 h and Days 1 and 21 of gestation and 2 days postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rat lymphoma cell bioassay for prolactin: Observations on its use and comparison with radioimmunoassay

The rat Nb₂ node lymphoma cell bioassay (BA) for prolactin (PRL) was validated for use in our laboratories. During the course of this validation we observed that rat prolactin (NIAMDD-RP-1) stimulated cell division by as much as 16.5 fold over the range of 0.04 to 40.0 ng/ml at the end of 72 hours of incubation. We also observed a dose related increase in the size of the lymphoma cells. Prolactin concentrations in rat plasma, serum, anterior pituitary (AP) homogenates and milk were measured by both radioimmunoassay (RIA) and BA. In individual BA's there was parallelism between samples and standard; but when several dilutions of the same plasma and pituitary homogenates were assayed repeatedly, higher PRL levels were consistently observed for the more concentrated samples. At low or moderate levels of plasma PRL there was excellent agreement between RIA and BA; however, at high levels plasma PRL bioactivity exceeded radioimmunoactivity by a small, but significant, amount. A comparison of pituitary PRL concentrations measured by RIA and BA were in good agreement when homogenization was done at pH 10.6. However, when homogenization was done at pH 7.6, slightly but significantly more PRL was extracted when assayed by BA than when assayed by RIA.     

Prolactin and growth hormone regulate adiponectin secretion and receptor expression in adipose tissue

Adiponectin is a hormone secreted from adipose tissue, and serum levels are decreased with obesity and insulin resistance. Because prolactin (PRL) and growth hormone (GH) can affect insulin sensitivity, we investigated the effects of these hormones on the regulation of adiponectin in human adipose tissue in vitro and in rodents in vivo. Adiponectin secretion was significantly suppressed by PRL and GH in in vitro cultured human adipose tissue. Furthermore, PRL increased adiponectin receptor 1 (AdipoR1) mRNA expression and GH decreased AdipoR2 expression in the cultured human adipose tissue. In transgenic mice expressing GH, and female mice expressing PRL, serum levels of adiponectin were decreased. In contrast, GH receptor deficient mice had elevated adiponectin levels, while PRL receptor deficient mice were unaffected. In conclusion, we demonstrate gene expression of AdipoR1 and AdipoR2 in human adipose tissue for the first time, and show that these are differentially regulated by PRL and GH. Both PRL and GH reduced adiponectin secretion in human adipose tissue in vitro and in mice in vivo. Decreased serum adiponectin levels have been associated with insulin resistance, and our data in human tissue and in transgenic mice suggest a role for adiponectin in PRL and GH induced insulin resistance.     

Dissociation between increased growth hormone and prolactin secretion during the morning hours of early pregnancy in the rat

We investigated whether serum growth hormone (GH) concentration changes in association with the rise in serum prolactin (PRL) concentration known to occur during the early morning hours in the pregnant rat. Animals were kept in a room with the lights on from 0500 to 1900 hours (hr) daily and decapitated for the collection of trunk blood at 2200 or 2400 hr on Day 6 of pregnancy or at 0200, 0400, 0800 or 1000 hr on Day 6 of pregnancy. Serum GH concentration rose more than 4-fold from low levels at 2200 and 2400 hr to higher levels at 0400 and 0800 hr and then declined by 1000 hr. Serum prolactin (PRL) concentration followed a similar pattern except that it returned to low levels earlier, by 0800 hr. Serum luteinizing hormone, follicle-stimulating hormone and thyroid-stimulating hormone concentrations showed no significant changes. Serum GH levels at 0800 hr in pregnant rats were higher than those observed in cyclic rats (13 time periods sampled). The results demonstrate that serum GH concentration is elevated during a circumscribed period in the 6- to 7-day pregnant rat. The time of onset of the rise is similar to that for serum PRL but the elevation in GH levels persists longer than that for PRL.     

Possible involvement of prolactin in endocrine-resistant metastatic prostate cancer

The hormone resistance of prostate cancer has been proved to depend at least in part on enhanced neuroendocrine activity and the resultant increase in blood concentrations of chromogranin A. Other experimental observations have suggested the involvement of prolactin (PRL), which appears to be a potential growth factor for prostate cancer. Abnormally high levels of PRL have been detected in metastatic prostate cancer, but the clinical significance of this finding has still to be clarified. In an attempt to explain the prognostic significance of serum PRL levels in prostate cancer, in this preliminary study we have analyzed the PRL levels in a group of metastatic prostate cancer patients with hormone-dependent or hormone-resistant cancer. The study included 50 patients with metastatic prostate cancer, 15 of whom had hormone-resistant tumors. The serum levels of PRL were measured by the RIA method. Abnormally high concentrations of PRL were found in 11/50 (22%) patients. Moreover, the percent of patients with cancer-related hyperprolactinemia was significantly higher in the hormone-resistant group than in the hormone-dependent group (8/15 vs 3/35, p < 0.01). This study confirms the possible existence of a hyperprolactinemic state in metastatic prostate cancer, as previously reported by other authors. Moreover, it appears to demonstrate that the occurrence of hyperprolactinemia is more frequent in hormone-resistant neoplasms, suggesting the possible involvement of PRL in hormone independence. Further studies concomitantly evaluating PRL and chromogranin A blood concentrations will be necessary to establish whether the hyperprolactinemia precedes and promotes the onset of hormone resistance in prostate cancer, or whether it is simply a consequence of the hormone independence.     

生长激素和催乳素放射免疫测定法的建立与应用

目的：建立测定大鼠垂体和血浆中生长激素（GH）和催乳素（PRL）含量的高特异性、高灵敏度的双抗放射免疫测定（RIA）法;研究急性低氧对垂体激素GH和PRL的作用。方法：用氯胺－T法进行抗原放射性碘标记;采用平衡饱和加样程序的双抗RIA法测定。结果：用该方法测定急性低氧（0．5h）时血浆和垂体GH和PRL含量,7km低氧,垂体GH含量明显升高（P＜0．05）,血浆则相反;7km低氧,明显降低垂体和血浆PRL含量（P＜0．01）;而5km低氧对GH和PRL的作用与对照组比无统计学差异。结论：本双抗RIA法具有高特异性、高灵敏度及简便易行等特性;用该法测定提示急性低氧可抑制大鼠GH和PRL的分泌。     

Serum prolactin responses to TRH in recurrent breast cancer patients.

The response of serum prolactin (PRL) to thyrotropin-releasing hormone (TRH) was evaluated by radioimmunoassay in 6 normal women and 44 breast cancer cases. They were divided into the following 5 groups: group 1:6 normal women; group 2:10 preoperative patients with early breast cancer; group 3:13 preoperative patients with advanced cancer; group 4:13 postoperative patients with no recurrence of cancer for more than 2 years; group 5:8 postoperative patients with cancer recurrence. The maximum increment of serum PRL levels following the administration of TRH was significantly higher in groups 2, 3 and 5 than in groups 1 and 4. These results indicate that patients with recurrent breast cancer have a higher PRL response to TRH than those without recurrence of cancer.     

Melatonin and human cancer

A number of studies performed in vitro and on experimental animals supported the view that pineal gland inhibits neoplastic growth. Data in humans are scanty and controversial. In the present study we measured serum melatonin (MT), prolactin (PRL) and growth hormone (GH) concentrations, at 08.00 and 24.00, in 132 cancer patients and in 58 healthy control subjects. The patients were stratified according to histology and stage of disease as follows: 30 stage I–II and 45 stage III–IV breast cancer (BC); 39 stage III–IV lung cancer; 18 advanced gastrointestinal (GI) cancer. We also measured MT levels, at the same time-points, in 20 women with primary BC before and after radical mastectomy. Finally, we evaluated the circadian rhythm of serum MT in 18 patients with advanced cancer. On the whole, the patients with advanced tumors showed serum MT levels significantly higher than controls, without any correlation with PRL and GH values. When looking at stage III–IV vs stage I–II BC patients, significantly higher MT levels have been found in the former group. The surgical removal of the primary BC was not associated with any changes in MT values at both time points considered. A highly significant rhythm of serum MT was recorded in advanced cancer patients and the rhythmic parameters were substantially superimposable on those of the control subjects.     

Electrophoretic separation of forms of rat growth hormone with different bioassay and radioimmunoassay activities: comparison of intraglandular and secreted forms

Rat adenohypophysial tissue and medium in which pituitary explants had been incubated were processed by polyacrylamide disc gel electrophoresis (pH 9.5). Eluates of 6 regions of the gel columns were tested for growth hormone (GH) by a bioassay (BA; rat tibia test) and a radioimmunoassay (RIA). In the tissue, both assays detected most of the GH (80–99%) in segments with an R_f range of 0.30–0.56. In the medium, both assays recorded a more cathodal distribution of most of the hormone (85–96%) in the R_f region 0.00–0.42. The BA/RIA ratios of the segment containing the prominent stainable GH band (R_f range 0.30–0.42) varied from 0.6–1.8 in tissue and medium. The tissue contained slow migrating (R_f range 0–0.29) GH that had a high BA/RIA ratio (11.1–25.7). The medium contained high ratio GH (32.7–33.8) in a more anodal location (R_f 0.57–0.68). Purified rat prolactin (RP-I) was not active in either the BA or the RIA. The results indicate that rat GH exists in electrophoretically heterogeneous forms which differ in their BA/RIA activity ratios. The proportion of these forms stored in adenohypophysial tissue and secreted by the gland may differ.     

Increase of circulating levels of thymulin in hyperprolactinemia and acromegaly

The production of thymulin by the thymic epithelium is under complex control involving the endocrine system. Experimental models have suggested that prolactin (PRL) and growth hormone (GH) participate in this regulation but this has not been documented in humans. Using a bioassay we measured circulating thymulin levels in patients with hyperprolactinemia (n = 21), acromegaly (n = 15), or both (n = 6). Thymulin was elevated in these three groups of patients compared with normal subjects or with patients with pituitary disease but no excess in PRL or GH. Contrasting with observations in control groups, thymulin did not decrease as a function of age in patients. No correlation between thymulin and PRL or GH levels was observed while thymulin and insulin-like growth factor 1 levels were correlated. A new radioimmunoassay used in some patients for thymulin determination yielded similar results. Overall these data demonstrate that PRL and GH are involved in the hormonal control of thymulin production by the thymic epithelium in the human.     

Radioimmunoassay and Radioreceptor Assays for Prolactin and Growth Hormone: A Critical Appraisal

The promise and the problems associated with using radioimmunoassays(RIA's) for mammalian prolactins (PRL's) and growth hormones(GH's) for the measurements of these hormones in the blood offoreign species (mammalian and nonmammalian) are considered.When crossreactivity is found with the plasma of a foreign speciesin heterologously applied RIA's for these hormones of mammalianorigin, one can have little confidence about the nature of thecrossreacting material that is being measured. Extensive analysisis necessary to establish that a particular RIA system measuresthe PRL or GH in a foreign species. The question of whether RIA's for PRL and GH give physiologicallymeaningful measurements of the blood levels of these hormonesis considered. In the case of PRL, analysis of our own resultsand data in the literature raises serious questions about thephysiological validity of existing RIA's for mammalian PRL's.Evaluation of the available information on RIA's for mammalianGH discloses that there is no basis for concluding that anyof them give measurements of the circulating levels of the hormonethat are physiologically meaningful. It is also apparent thatthe physiological significance of the radioreceptor assays forPRL and GH remains to be established. From analysis of discrepancies between bioassay and RIA estimatesof PRL and GH levels in adenohypophysial tissue, incubationmedium, and plasma or serum, and of studies on the metabolismof purified and secreted forms of both hormones, it is suggestedthat the major intraglandular forms of PRL and GH are in factprohormones.     

The pituitary-thyroid axis in acromegaly

The pituitary-thyroid axis of 12 acromegalic patients was evaluated by measurement of the serum concentrations (total and free) of thyroxine (T4), triiodothyronine (T3) and reverse T3 (rT3) and thyrotropin (TSH), growth hormone (GH) and prolactin (PRL) before and after iv stimulation with thyrotropin releasing hormone (TRH). Using an ultrasensitive method of TSH measurement (IRMA) basal serum TSH levels of the patients (0.76, 0.07-1.90 mIU/l) were found slightly, but significantly (P less than 0.01), lower than in 40 healthy controls (1.40, 0.41-2.50 mIU/l). The total T4 levels (TT4) were also reduced (84, 69-106 nmol/l vs 100, 72-156 nmol/l, P less than 0.01) and significantly correlated (P less than 0.02, R = 0.69) to the TSH response to TRH, suggesting a slight central hypothyroidism. The acromegalics had, however, normal serum levels of TT3 (1.79, 1.23-2.52 nmol/l vs 1.74, 0.78-2.84 nmol/l, P greater than 0.10), but significantly decreased levels of TrT3 (0.173, 0.077-0.430 nmol/l vs 0.368, 0.154-0.584 nmol/l, P less than 0.01) compared to the controls. The serum concentration of the free iodothyronines (FT4, FT3, FrT3) showed similar differences between acromegalics and normal controls. All the acromegalics showed a rise of serum TSH, GH and PRL after TRH. Positive correlation (P less than 0.05, R = 0.59) was found between the TSH and GH responses, but not between these two parameters and the PRL response to TRH. These findings may be explained by the existence of a central suppression of the TSH and GH secretion in acromegalic subjects, possibly exerted by somatostatin. Euthyroidism might be maintained by an increased extrathyroidal conversion of T4 to T3.     

Growth hormone and prolactin secretion after metoclopramide administration (DA2 receptor blockade) in fertile women.

In this report, we will describe the results of a cross-sectional study to assess PRL and GH secretion during the early follicular phase in 22 fertile patients after metoclopramide administration in order to achieve a dopaminergic DA2 receptor blockade. Blood samples were collected at - 15, 0, 15, 30, 45 and 60 minutes. PRL, GH, estradiol, IGF-I, TSH, glucose, and insulin were measured in the samples taken at - 15 and 0 minutes. The existence of a correlation between GH and PRL secretion was investigated. All patients presented normal serum levels of estradiol, prolactin, insulin, fasting glucose and IGF-I. Serum GH levels were not changed after metoclopramide infusion (p = 0.302), but there was a significant alteration in serum PRL (p = 0.0001) with the highest levels after 30 (mean: 237.20 ng/ml +/- 95.86) and 45 (mean: 211.80 ng/ml +/- 83.24) minutes. Serum GH levels did not correlate with serum PRL levels after the dopaminergic DA2 blockade. We conclude that GH secretion was not modulated by a direct effect of type 2 dopamine receptor.     

A retrospective hormonal and immunohistochemical evaluation of 47 acromegalic patients: prognostic value of preoperative plasma prolactin.

This study was performed to investigate the correlations between preoperative prolactin (PRL) plasma values, immunohistochemical picture and the clinical course in growth hormone (GH) secreting pituitary adenomas. In 47 patients (19 males and 28 females; mean age 40 years; range 13 - 70 years), we measured GH, IGF-1 and prolactin plasma values both before and after transsphenoidal surgery, and basal IGF-1 and GH after an oral glucose tolerance test (OGTT) during four years of follow-up. We considered those patients as "controlled" who presented an undetectable growth hormone after OGTT (GH < 1 microg/l), IGF-I plasma values in the normal range, matched for age and sex, and no clinical activity or neuroradiological recurrence after a four-year follow-up. We considered patients as "poorly controlled" who still showed elevated GH and IGF-I plasma levels, uninhibited GH after OGTT (GH > 1 microg/l), presence of clinical activity and/or radiological signs of adenoma recurrence, even if a reduction of tumor size had been demonstrated. RESULTS: Controlled patients (n = 22) exhibited mean preoperative PRL levels (+/- SEM) lower than the group of poorly controlled (n = 25) ones (21.40 +/- 5.51 vs. 38.44 +/- 5.16 microg/l; p < 0.03). From 3 to 12 months after surgery, postoperative PRL levels were also lower in the controlled patients compared to the poorly controlled ones (8.31 +/- 1.20 vs. 25.32 +/- 3.20 microg/l; p < 0.0001). Eighty percent (20/25) of poorly controlled patients showed both PRL and GH positivity after immunostaining. Only 3/22 (13.6 %) of controlled patients showed the same double positivity. In conclusion, preoperative hyperprolactinemia identifies a group of acromegalic patients at elevated risk of disease persistence after surgery. We hypothesize that most of these high-risk patients may have more aggressive mixed GH-PRL secreting adenomas.     

Blood levels of IGF-I in non-small cell lung cancer: relation to clinical data.

Recent observations have demonstrated that somatomedins, mainly insulin-like growth factor-I (IGF-I), are growth factors for non-small cell lung cancer (NSCLC). On the basis of this evidence, a study was started to evaluate serum levels of IGF-I in a group of untreated NSCLC patients. The study included 46 patients, 25 of whom had an operable tumor, while the other 21 showed distant organ metastases. IGF-I and GH serum levels were measured by RIA in each patient; moreover, in operable patients, hormonal detections were made either before, or 7 days after surgery. The control group comprised 38 age-matched healthy subjects. Mean serum levels of IGF-I were significantly higher in cancer patients with respect to controls, while no difference was seen in mean GH values. Moreover, patients with metastases showed significantly higher levels of IGF-I than the patients without. Within the operable group, patients with lung adenocarcinoma had higher levels of IGF-I than those with epidermoid cell carcinoma, but this difference was not significant. Finally, no significant difference in IGF-I mean values was seen before and after surgical removal of tumors. This preliminary study shows that NSCLC patients may present abnormally high levels of IGF-I. Because of the stimulating role of IGF-I on NSCLC growth, this evidence could play a role in the clinical course of neoplastic lung disease.     

A psychoncological study of lymphocyte subpopulations in relation to pleasure-related neurobiochemistry and sexual and spiritual profile to Rorschach's test in early or advanced cancer patients

According to recent advances in psychoneuroimmunology concerning the neurobiochemistry of emotions, the pshychological status of cancer patients should be investigated in relation to the function of the psychoneurodocrine system, in an attempt to put into evidence possible cancer progression-related alterations, particularly those involving the dopaminergic pathways, which play a fundamental role in the perception of pleasure. In fact, the decreased capacity of feeling pleasure is one of the most frequent psychic symptoms occurring in cancer patients. Rorschach's test has been proven to be an appropriate psychological tool to investigate psychic condition including sexual and spiritual profiles. On this basis, a study was planned to evaluate if a relation exists between psychological response to Rorschach's test and immunoneuroendocrine status of cancer patients. The immune status was investigated by measuring lymphocyte subsets and serum levels of IL-2 and IL-10. The neuroendocrine status was analyzed by evaluating the endocrine response of PRL, GH and cortisol to an oral administration of apomorphine (0.01 mg/kg b.w.), a dopaminergic agent able to explore dopaminergic sensitivity. The study included 40 cancer patients (breast cancer: 15; colorectal cancer: 14; lung cancer: 11), 21 of whom showed distant organ metastases. Rorschach's test demonstrated a simultaneous suppression of sexual and spiritual profiles in 31/40 (78%) patients, without significant differences in relation to either tumor histotype or disease state. A normal decline in PRL levels and a normal increase in those of GH and cortisol was observed in 29/40 (73%), 5/40 (13%) and 9/40 (23%) patients. The percent of normal responses of PRL, GH and cortisol was higher in patients with normal than in those with altered response to Rorschach's test, even though only the difference in PRL and cortisol response was statistically significant. Patients with normal sexual and spiritual expression at Rorschach's test showed a significantly higher number of total lymphocytes, T lymphocytes, T helper lymphocytes and NK cells with respect to the patients with altered psychological response, whereas no difference was found in T cytotoxic lymphocyte mean number. IL-2 and IL-10 mean serum concentrations were lower and higher, respectively, in patients with altered than in those with normal response to Rorschach's test, even though only the difference in IL-10 values was statitistically significant. This preliminary study, carried out to analyze the psychological status of cancer patients in relation to neuroendocrine and immune conditions, would suggest that neoplastic disease is characterized by a simultaneous suppression of sexual and spiritual profiles, and that this is associated with neuroendocrine alterations and immunosuppression.     

Long-term bromocriptine therapy and predictive tests in acromegaly

The value of predictive tests in bromocriptine therapy and the effects of long-term bromocriptine therapy were investigated in acromegalic patients. In 72 acromegalic patients, there was a tendency for patients with a plasma GH response to TRH or with an elevated basal plasma PRL level, but without a plasma GH response to LHRH, to have a plasma GH response to bromocriptine, though statistical analysis did not reveal a significant difference. Acute and chronic effects of bromocriptine were significantly interrelated, while the chronic effect of bromocriptine and abnormal plasma GH response to TRH or elevated plasma PRL levels were not, in 18 acromegalic patients. These results suggest that the acute bromocriptine test is a better predictor than the TRH test and plasma PRL levels for evaluating the effects of chronic bromocriptine therapy. To maintain the low plasma GH levels, increasing doses of bromocriptine were needed in most patients, and failure to control the elevated GH level despite increasing doses was observed in 2 of 18 patients.     

Evaluation of self-similar features in time series of serum growth hormone and prolactin levels by fractal analysis: Effect of delayed sleep and complexity of diurnal variation

We assayed the diurnal concentrations of growth hormone (GH) and prolactin (PRL) in 6 healthy male volunteers to evaluate the self-similar features in the time series of each hormone on the basis of fractal theory and to determine the fractal dimension as an index of the complexity of the diurnal variation. In addition, we assessed the effects of a 6-hour delay in the sleep period on the complexity of the diurnal variaton of these hormones. There was a statistically significant fractal feature in the serum levels of GH both under the nocturnal-sleep and delayed-sleep conditions in all subjects. The time series of the serum PRL concentrations also showed a statistically significant fractal feature under the nocturnal-sleep and delayed-sleep conditions in all subjects. The fractal dimensions of the patterns of the GH or PRL levels were 1.879 and 1.929 or 1.754 and 1.785 under the nocturnal-sleep and delayed-sleep conditions, respectively. Two-way ANOVA revealed no significant difference in the fractal dimension between the two sleep conditions but did reveal a significant difference between the fractal dimensions of the GH and PRL levels. These results showed (1) that delayed sleep had no significant effect on the complexity of the diurnal pattern of these hormones, and (2) that the diurnal pattern of the GH levels was more complex than that of the PRL levels.     

Association of gene polymorphisms in prolactin and its receptor with breast cancer risk in Taiwanese women

Given the essential role of prolactin (PRL) and its receptor (PRLR) in breast tumorigenesis, we investigated whether single nucleotide polymorphisms (SNPs) in the PRL and PRLR genes were associated with breast cancer in Taiwanese women. A total of 160 breast cancer patients and 336 unrelated control Taiwanese women were enrolled in this study. Three SNPs (rs1341238, rs2244502 and rs3756824) in the PRL gene and one SNP (rs10941235) in the PRLR gene were genotyped using allele-specific polymerase chain reaction and DNA sequencing. We showed that the PRLR SNP rs10941235 was associated with breast cancer (P < 0.05) and its genotype frequencies in the breast cancer group were significantly associated (P < 0.05) with the levels of cancer antigen 15-3, a serum biomarker of breast cancer. The PRL SNP rs3756824 was significantly associated with breast cancer metastasis (P < 0.05). These findings suggest that the polymorphism rs10941235 in the PRLR gene is associated with breast cancer and cancer antigen 15-3 levels in Taiwanese women.