Immunoreactive Prolactin Research Articles

Silent subtype 3 pituitary adenoma: a clinicopathologic analysis of the Mayo Clinic experience

Macroadenomas represent 50% of pituitary tumours and are often (30%) nonfunctioning. Their immunophenotype suggests differentiation toward a specific pituitary cell line. A substantial proportion of tumours with particularly aggressive behaviour are so called 'silent subtype 3 adenoma'. Its diagnosis requires ultrastructural confirmation. Although once included among silent corticotroph adenomas, this aggressive, morphologically distinctive tumour is now recognized as a major form of plurihormonal adenoma and, in fact, some patients might present with clinical hormonal excess. The cytogenesis and pathobiology of silent subtype 3 adenomas is unsettled. We undertook a systematic clinicopathologic examination of the Mayo Clinic experience with this poorly understood tumour. This retrospective, single institution study found 27 confirmed examples of silent subtype 3 adenoma, a frequency of 0.9% of adenomas. Despite histologic and immunophenotypic variation, their ultrastructural features were diagnostic and the sole basis for case inclusion. The study group was comprised of 16 men (59%) and 11 women (41%); two patients (7%) had definitive diagnosis of multiple endocrine neoplasia type 1 (MEN1). Three tumours (11%) were discovered incidentally. Nine patients each (38%) presented with headaches or visual field loss. Endocrine hyperfunction was noted in eight cases (30%), including GH excess in five (19%) and clinically significant PRL elevation in three (11%). Hypogonadism was noted in 17 cases (63%) and growth arrest in one (4%). All tumours were macroadenomas; 16 (60%) showed radiographic evidence of invasion. Most tumours were plurihormonal, featuring immunoreactivity for PRL (17), GH (15), TSH (16) or ACTH (3); only one lesion was immunonegative. Although a gross total resection was achieved in 19 cases (70%), re-operation for recurrence(s) was required in seven of these (37%). Follow-up (mean, 69 months) showed a high (59%) rate of persistent or recurrent of tumour. Overall, 14 patients (54%) underwent radiotherapy after surgical treatment: three patients (12%) for substantial residual tumour, eight (31%) as adjuvant therapy and three (12%) for tumour regrowth. Silent subtype 3 adenoma, a plurihormonal tumour, is rare and aggressive in nature. This adenoma must be considered in the differential of often clinically nonfunctioning but plurihormonal adenomas featuring variable cytologic atypia. Electron microscopy is required for confirmation of the diagnosis. The cytogenesis of silent subtype 3 adenoma remains unsettled.

Immunodetection of Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), Thyroid Stimulating Hormone (TSH) and Prolactin (PRL) in Brachionus calyciflorus (Rotifera: Monogononta)

The endocrine system controls and coordinates behavioral, biochemical, and physiological processes through signal mechanisms using neuropeptides or products of neurosecretory cells. Among invertebrates, this system is poorly studied in rotifers, in which estrogens and androgens significantly affect sexual reproduction. This is the first report of the presence of the Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), Thyroid Stimulating Hormone (TSH) and Prolactin (PRL) in rotifers. Analyses included the avidin-biotin-peroxidase complex method with primary antibodies LH (Anti-Rat LH serum for RIA), PRL (Anti-Rat PRL serum for RIA), FSH (Anti-Rat FSH serum for RIA) and TSH (Anti-Rat TSH serum for RIA). These hormones were found in females, males and parthenogenetic and sexual eggs of the freshwater Brachionus calyciflorus. The immunoreactivity of FSH, LH, TSH and PRL in females was observed in: ovaries, cerebrum, mastax, stomach, lorica, and the stomach gland. However, in males LH was observed only at the trochal disk and cerebrum. The hormones FSH, TSH and PRL, were observed in testicles, contractil vesicles, and cementary gland of males. Regarding amictic or parthenogenetic eggs, the hormones LH, FSH, TSH, and PRL were located mainly in the micromeres, and the staining in the macromeres was weak. On the other hand, in the mictic or sexual eggs the inner shell is stained for the hormones PRL and LH, opposite to the staining of FSH and TSH, located mainly in the embryo. In general, immuno-reactivity was observed in areas important for the reproductive, excretory, digestive and developmental processes.

Serum Total Prolactin and Monomeric Prolactin Reference Intervals Determined by Precipitation with Polyethylene Glycol: Evaluation and Validation on Common ImmunoAssay Platforms

Macroprolactin is an important source of immunoassay interference that commonly leads to misdiagnosis and mismanagement of hyperprolactinemic patients. We used the predominant immunoassay platforms for prolactin to assay serum samples treated with polyethylene glycol (PEG) and establish and validate reference intervals for total and monomeric prolactin. We used the Architect (Abbott), ADVIA Centaur and Immulite (Siemens Diagnostics), Access (Beckman Coulter), Elecsys (Roche Diagnostics), and AIA (Tosoh) analyzers with samples from healthy males (n = 53) and females (n = 93) to derive parametric reference intervals for total and post-PEG monomeric prolactin. Concentrations of immunoreactive prolactin isoforms in serum samples from healthy individuals were established by gel filtration chromatography (GFC). We then used samples from 22 individuals whose hyperprolactinemia was entirely attributable to macroprolactin and 32 patients with true hyperprolactinemia to compare patient classifications and prolactin concentrations measured by GFC with the newly derived post-PEG reference intervals. Parametric reference intervals for post-PEG prolactin in male and female serum samples, respectively, were (in mIU/L): 61-196, 66-278 (Centaur); 63-245, 75-381 (Elecsys); 70-301, 92-469 (Access); 72-229, 79-347 (Architect); 73-247, 83-383 (AIA); and 78-263, 85-394 (Immulite). Concordance between GFC and immunoassay-specific post-PEG reference intervals was observed in 311 of 324 cases and for 31 of 32 patients with true hyperprolactinemia and 17 of 22 patients with macroprolactinemia. Results leading to misclassification occurred in a few analyzers for 5 macroprolactinemia patient samples with relatively minor increases in post-PEG prolactin (mean 61 mIU/L). Our validated normative reference data for sera pretreated with PEG and analyzed on the most commonly used immunoassay platforms should facilitate the more widespread introduction of macroprolactin screening by clinical laboratories.

Expression and cellular localization of prolactin and the prolactin receptor in mammalian retina

Prolactin (PRL), originally associated with milk secretion, is known to have a wide variety of biological actions and diverse sites of production beyond the pituitary gland. Recent studies have demonstrated that PRL is synthesized in retinal tissue. To gain insights into the functional role of PRL in the mammalian retina, we mapped the distribution of the PRL protein and the expression and localization of the PRL receptor (PRLR) in the retina of adult rats and green monkeys. PRL was examined in retinal sections by double immunolabeling combining anti-PRL antibodies with antibodies specific for glutamine synthetase (labeling Müller cells), glial fibrillary acidic protein (labeling astrocytes), or neuronal nuclei protein (labeling neurons). PRL was detected throughout the rat retina: in the photoreceptor outer segments, Müller cells, interneurons, ganglion cells, and astrocytes. The PRLR was examined by RT–PCR, in situ hybridization, immunohistochemistry, and Western blot. The long isoform of the PRLR was localized in the photoreceptor nuclear layer, inner nuclear layer, and ganglion cell layer of rat retina. The monkey retina showed a similar distribution of PRL and PRLR immunoreactivities. These findings suggest that PRL functions as a local regulator of various cell types in the mammalian retina.

Prolactin is involved in glial responses following a focal injury to the juvenile rat brain

A cerebral growth hormone axis is activated following brain injury in the rat and treatment with growth hormone is neuroprotective. We have now investigated whether the closely related prolactin axis has similar properties following injury to the developing rat brain. From one day following a unilateral hypoxic ischemic injury, prolactin immunoreactivity was increased in the affected cortex parallel to the development of the injury ( P<0.001). Initial prolactin and prolactin receptor staining on penumbral neurons progressively decreased whereas astrocytes remained strongly immunopositive. Reactive microglia also became strongly prolactin immunoreactive. Unlike growth hormone, central treatment with prolactin failed to rescue neurons in this paradigm. This was confirmed in vitro; rat prolactin failed to protect neurons under conditions for which growth hormone was neuroprotective. However, prolactin had trophic and pro-proliferative effects on glia ( P<0.001). We confirmed the expression of the prolactin receptor in vitro by reverse transcriptase polymerase chain reaction, and show its strong association with astrocytes as compared with neurons by immunocytochemistry. In summary, we show for the first time that hypoxia ischemia induces a robust activation of the prolactin axis in regions of the cerebral cortex affected by injury. The lack of neuroprotective properties in vivo and in vitro indicates that, unlike growth hormone, prolactin is not directly involved in neuronal rescue in the injured brain. Its strong relation to glial reactions and its gliatrophic effects suggest that the prolactin axis is primarily involved in a gliogenic response during recovery from cerebral injury.

Charles River Sprague Dawley Rats Lack Early Age-Dependent Susceptibility to DMBA-Induced Mammary Carcinogenesis

Developmental stages of mammary glands influence their susceptibility to initiating events related to carcinogenesis. The "window of susceptibility" to mammary carcinogenesis is classically defined as the time in early puberty when the mammary gland morphology is most sensitive to initiation events. Administration of the polyaromatic hydrocarbon, 7,12-dimethylbenz(a)anthracene (DMBA), in a single oral dose yields maximal mammary tumor formation when administered in this "window". We examined the DMBA treated mammary glands, precursor lesions, and morphology of the uninvolved mammary epithelium for the first 100 days of life for Charles River Sprague Dawley CD(R) IGS. Our goal was to determine the DMBA dose at which 50% of the rats (IC50) developed carcinoma in situ (CIS) within three months of dosing. Here we demonstrate, rather than the classical U-shaped dose curve in which there is maximum sensitivity for DMBA at 50 days, there is an increasing degree of sensitivity with age in the CD(R) IGS rat. Additionally, we report that vehicle-treated animals developed mammary CIS without any known initiator, and 100 day virgin animals demonstrated lactational changes, independent of DMBA exposure or dose. Lastly, we demonstrate this strain of virgin female rats has elevated pituitary prolactin immunoreactivity independent of the level of mammary differentiation. We conclude this strain of Charles River Sprague Dawley rats has prolactin-induced pituitary stimulation, and therefore, the window of susceptibility for mammary tumorigenesis is absent.

Determination of Ultrafilterable Prolactin: Elimination of Macroprolactin Interference With a Monomeric Prolactin-Selective Sample Pretreatment

Macroprolactin (macroPRL), present in as many as 25% of serum specimens with elevated serum prolactin concentrations, can cause apparent hyperprolactinemia in the absence of clinical features and lead to unnecessary clinical, laboratory, and neuroradiological workups. To develop an ultrafiltration method that eliminates macroPRL interference from PRL immunoassays. The method involves centrifugation of undiluted serum in a Centricon-100 filter device followed by a PRL assay of the serum ultrafiltrate. Ultrafiltrates prepared by this technique are devoid of gamma globulins and contain (mean +/- SE) 19% +/- 7% of the albumin concentration of the original serum. These ultrafiltrates contain 85% +/- 7% of the total PRL immunoreactivity of serum spiked with 23 kd recombinant human prolactin (rHuPRL) and less than 2% of the 50 kd big PRL (bPRL) of whole serum. The fractional recovery of ultrafilterable PRL (uPRL) from serum samples of 54 female patients was 0.78 (confidence interval 0.73-0.83) of the total. The run-to-run coefficient of variation of the uPRL assay was 4.3%. The uPRL concentration (mean +/- SD) in a group of healthy female controls was 8.0 +/- 3.1 ng/mL. Ultrafiltration is a rapid and simple method for eliminating analytical interference by macroPRL. Ultrafiltrates can be analyzed by most, if not all, currently available PRL immunoassays and represent a practical and precise alternative to gel filtration chromatography for the estimation of the monomeric prolactin concentration of serum.

Application of new homologous in vitro bioassays for human lactogens to assess the actual bioactivity of human prolactin isoforms in hyperprolactinaemic patients

Prolactin (PRL) plays a central role in mammary gland development and lactation. Due to its molecular heterogeneity, measurement of PRL immunoreactivity does not necessarily reflect its intrinsic bioactivity. For many years the Nb2 rat lymphoma cell bioassay has been the only reference bioassay for human lactogens. This bioassay, however, does not always correlate with the clinical features found in some patients exhibiting normal or elevated immunoreactive serum PRL concentrations. (1) To determine the concentrations of bioactive PRL in serum samples from individuals with normoprolactinaemia or with different forms of hyperprolactinaemia using two recently described homologous in vitro bioassays (i.e. a transcriptional bioassay in HEK-293 cells and a proliferation assay in Ba/F3 cells); and (2) to compare these results with those generated by the classical Nb2 cell bioassay. Cross-sectional study. An institutional biomedical research laboratory. Ten patients with symptomatic hyperprolactinaemia due to prolactinoma, 11 patients with asymptomatic hyperprolactinaemia and macroprolactinaemia, and nine normal women. Measurement of immunoreactive and bioactive concentrations of serum PRL. Samples from normal women and patients with tumoral hyperprolactinaemia due to prolactinoma exhibited similar within-group concentration values of bioactive and immunoreactive serum PRL when tested by the three bioassays and the immunoradiometric assay employed. By contrast, measurement of bioactive PRL in samples from patients with macroprolactinaemia revealed that macroprolactin was poorly active in the homologous receptor bioassays, while it was more active in the Nb2 bioassay. The reduced bioactivity of PRL in patients with macroprolactinaemia may further explain the absence of clinical features of hyperprolactinaemia in these individuals. In addition, our findings indicate that species-specificity and sensitivity of the bioassays are determinant factors in the measurement of the intrinsic biological activity of circulating PRL.

Interacting Influences of Pregnancy and Corneal Injury on Rabbit Lacrimal Gland Immunoarchitecture and Function

Previous reports indicated that pregnancy and corneal injury (CI) trigger alterations of lacrimal gland (LG) growth factor expression and redistributions of lymphocytes from periductal foci to acini. The purpose of this study was to test our hypothesis that pregnancy would exacerbate the changes induced by CI. Corneas were injured with scalpel blades, and, 2 weeks later, LGs were collected for immunocytochemistry and Western blot analysis. Lacrimal fluid was collected under basal- and pilocarpine-stimulated conditions for protein determination and Western blot analyses. There were significant increases of immunoreactivity for prolactin, TGF-beta1, and EGF in duct cells during pregnancy and after CI, most prominent in pregnant animals with CI. Pregnancy decreased baseline lacrimal fluid secretion, whereas CI did not have a noticeable effect; pregnancy and CI combined resulted in increased fluid production. Pregnancy and CI each increased pilocarpine-induced lacrimal fluid production, whereas protein concentrations were decreased. Prolactin, TGF-beta1, and EGF were detected in LG by Western blot analysis but were minimally detectable in lacrimal fluid. RTLA+ and CD18+ cells were redistributed from periductal to interacinar sites during pregnancy and after CI, most prominent in pregnant animals with CI. Like pregnancy, CI is associated with redistribution of immune cells from periductal to interacinar sites and enhanced immunoreactivity of prolactin, TGF-beta1, and EGF in ductal cells. Although baseline lacrimal fluid secretion varied, the glands of all three experimental groups produced significant amounts of fluid in response to pilocarpine, but protein concentrations were decreased.

Human Scalp Hair Follicles Are Both a Target and a Source of Prolactin, which Serves as an Autocrine and/or Paracrine Promoter of Apoptosis-Driven Hair Follicle Regression

The prototypic pituitary hormone prolactin (PRL) exerts a wide variety of bioregulatory effects in mammals and is also found in extrapituitary sites, including murine skin. Here, we show by reverse transcriptase-polymerase chain reaction and immunohistology that, contrary to a previous report, human skin and normal human scalp hair follicles (HFs), in particular, express both PRL and PRL receptors (PRL-R) at the mRNA and protein level. PRL and PRL-R immunoreactivity can be detected in the epithelium of human anagen VI HFs, while the HF mesenchyme is negative. During the HF transformation from growth (anagen) to apoptosis-driven regression (catagen), PRL and PRL-R immunoreactivity appear up-regulated. Treatment of organ-cultured human scalp HFs with high-dose PRL (400 ng/ml) results in a significant inhibition of hair shaft elongation and premature catagen development, along with reduced proliferation and increased apoptosis of hair bulb keratinocytes (Ki-67/terminal dUTP nick-end labeling immunohistomorphometry). This shows that PRL receptors, expressed in HFs, are functional and that human skin and human scalp HFs are both direct targets and sources of PRL. Our data suggest that PRL acts as an autocrine hair growth modulator with catagen-promoting functions and that the hair growth-inhibitory effects of PRL demonstrated here may underlie the as yet ill-understood hair loss in patients with hyper-prolactinemia.

Morphologic changes of prolactin-producing pituitary adenomas after short treatment with dopamine agonists

Treatment of patients with prolactin (PRL)-producing pituitary adenomas with dopamine agonists has proved successful for most cases. Dopamine agonists inhibit PRL secretion, suppress cell proliferation, and may induce apoptosis to adenoma cells. Dopamine agonists induce striking morphologic changes in the majority of treated PRL-producing adenomas. To date, these morphologic effects have been primarily described only after long-term treatment. To the best of our knowledge, no similar studies have investigated apoptotic alterations induced after short-term therapy. The purpose of this report is to describe the morphologic changes seen in PRL-producing adenomas after short-term dopamine agonist treatment. We present two cases of PRL-producing macroadenomas, both from male patients who received treatment with dopamine agonists, the first for 5 and the second for 8 days. In contrast to long-term treatment, no striking reduction of PRL immunoreactivity was noted. Slight stromal fibrosis was noted in case 1, which contained several cells all in late phase of apoptosis. In addition to typical apoptotic cells, numerous "dark" cells representing another common form of cell death were also noted. These novel findings represent characteristic features of short-term dopamine agonist treatment, which are not seen in long-term treatment.

CRH receptor type 1 mediates continual hypoxia-induced changes of immunoreactive prolactin and prolactin mRNA expression in rat pituitary

We have reported that, in rats, hypoxia (10.8% O 2) stimulates prolactin (PRL) release from the pituitary. This study is designed to compare the response of pituitary PRL to acute hypoxia (AH), continual hypoxia (CH), intermittent hypoxia (IH), cold, and restraint, individually and combined with hypoxia. This study also investigates the involvement of the corticotropin-releasing hormone receptor 1 (CRH R1) in the hypoxia-induced PRL response. Hypoxia was induced by exposing the rats to high altitudes of 2 km (16.0% O 2) or 5 km (10.8% O 2). The PRL levels in the pituitary (iPRL) and in plasma (pPRL) were measured by immunocytochemistry and RIA assay, respectively. The acute hypoxia of 5 km for 2–24 h caused a biphasic change (early decrease and late increase) of PRL. Both CH and IH at 2 or 5 km for 1–5 days markedly increased pPRL but decreased iPRL. Continual severe hypoxia (10.8% O 2) for periods of 10, 15, and 25 days significantly enhanced pPRL but this effect was less marked at the lower altitude (16.0% O 2) and did not occur during intermittent hypoxia (at both altitudes). The increased pPRL was significantly enhanced by restraint, restraint + hypoxia, hypoxia, and cold + hypoxia exposure. Treatment with a CRH R1 antagonist (CP-154,526) reversed hypoxia-decreased immunoreactive PRL and upregulated PRLmRNA in the pituitary. The data suggest that both CH and IH can stimulate rat PRL release in a time-course- and intensity-dependent manner. However, compared to the relatively low CH-induced response, restraint induced a more powerful response than either cold or hypoxia alone. CRH R1 mediates PRL secretion and PRL mRNA expression in the pituitary under hypoxic exposure. Hypoxia-enhanced PRL response over the lifespan may play a significant role in adaptation to an extreme environment.

Macroprolactin; high molecular mass forms of circulating prolactin

Two high molecular mass forms of prolactin (PRL) in serum have been identified by gel filtration chromatography (GFC): macroprolactin (big-big PRL, > 100 kDa) and big PRL (40-60 kDa). Macroprolactin has a variable composition and structure, but is most frequently a complex of PRL and IgG, with a molecular mass of 150-170 kDa. It is formed in the circulation following pituitary secretion of monomeric PRL but has a longer half-life, and the PRL in the complex remains reactive to a variable extent in immunoassays. In the majority of subjects little or no macroprolactin can be detected in serum, but in some individuals it may be the predominant immunoreactive component of circulating PRL and the cause of apparent hyperprolactinaemia. Owing to its high molecular mass, macroprolactin appears to be confined to the intravascular compartment and much evidence indicates that it has minimal bioactivity in vivo and is not of pathological significance. Nevertheless, hyperprolactinaemia due to macroprolactin can lead to diagnostic confusion and unnecessary further investigation and treatment if it is not recognized as such. Macroprolactin is a common cause of apparent hyperprolactinaemia with some assays and it is essential that laboratories introduce screening programmes to examine samples with elevated total immunoreactive PRL for the presence of macroprolactin and determine the monomeric PRL component which is known to be bioactive in vivo. A number of screening tests have been described; that based on the precipitation of macroprolactin with polyethylene glycol has been the most widely validated and applied. The reference technique of GFC should be available for confirmation and further investigation of samples, giving equivocal results in screening tests. In comparison with macroprolactin, little is known about big PRL. It is a more consistent component of total serum PRL but rarely, if ever, the cause of hyperprolactinaemia. Further research is required into the nature of macroprolactin and big PRL, the relationships between high molecular mass forms of PRL, and their clinical significance.

Morphological events in the primate endometrium in the presence of a preimplantation embryo, detected by the serum preimplantation factor bioassay

Hormonal modulation of the endometrium towards receptivity is well established; however, the role of embryonic stimuli in modulation of the endometrium prior to implantation, especially in primates, is unknown. The aim of the present study was to evaluate the endometrial histology when the embryo was present in its vicinity prior to implantation. Preimplantation factor (PIF) bioassay was used as a tool to detect the presence of an embryo in the uterine lumen of mated bonnet monkeys (Macaca radiata) (n=9). The control group comprised seven non-mated animals. The specificity of the PIF bioassay for the presence of an embryo was tested by studies in pregnant humans and monkeys. The effects of embryonic stimuli on the endometrial morphology were analysed by routine haematoxylin-eosin staining. The expressions of CD34, an endothelial cell marker, alpha-smooth muscle actin (alpha-SMA), a marker for blood vessel maturation, and prolactin, a marker of endometrial decidualization, were studied by immunohistochemistry. That PIF is embryo specific was established by its presence in sera of pregnant humans, monkeys and also in embryo culture media. Six mated bonnet monkeys were found to be PIF positive. Morphologically, the endometria from these PIF-positive animals showed the presence of the pre-epithelial plaque reaction, increased angiogenesis and stromal compaction. The significantly increased number of CD34- and alpha-SMA-positive blood vessels (P<0.05) in the endometria of PIF-positive animals indicated increased angiogenesis in response to embryonic stimuli. The endometrial expression of immunoreactive prolactin was also significantly increased (P<0.05) in the PIF-positive animals, indicating decidualization. Using PIF as a marker to detect early pregnancy in bonnet monkeys, we have shown that the embryo induces a pre-epithelial plaque type of reaction, increased angiogenesis and decidual reaction in the endometrium prior to implantation.

Early development of the pituitary gland in Acipenser naccarii (Chondrostei, Acipenseriformes): an immunocytochemical study.

The distribution and appearance of secretory cells in the pituitary gland were investigated for the first time in a chondrostean species, Acipenser naccarii, from embryos to juveniles, by immunohistochemistry with mammalian and teleost hormone antisera. On 5.5 day post-fertilization (2.5 days pre-hatching), the pituitary of embryos appears as an oval cell mass with a narrow central cavity (hypophysial cleft), close to the ventral border of diencephalon under the third ventricle. At that time no neurohypophysis is observed, the adenohypophysis is not yet structurally divided into pars intermedia (PI) and pars distalis (PD) and only immunoreactive growth hormone cells are detectable. Seven days post-fertilization (1 day pre-hatching) the immunoreactive thyrotropic cells appear in the ventral region and the immunoreactive adrenocorticotropic cells in the posterior dorsal one. At hatching, some immunoreactive melanotropic (ir-MSH) cells are visible in the posterior dorsal region and some immunoreactive prolactin cells in the anterior one. Eight days later the immunoreactive somatolactin cells appear along the posterior dorsal border and the immunoreactive gonadotropic I (ir-GtH I) cells in the ventral region. Here, a few ir-GtH II cells finally appear in 76-86 day old juveniles. The gland elongates after hatching and in 8-day-old larvae two adenohypophysial regions are identified: a posterior (the presumptive PI) and an anterior one (the presumptive PD). In 156-166-day-old juveniles three regions (rostral and proximal pars distalis and pars intermedia) appear and a high number of ir-MSH cells are visible in the rostral region. The first protrusion of neurohypophysis into adenohypophysis is observed in 76-86-day-old juveniles and increases with age, branching into PI. The rostro-caudal distribution of the immunoreactive cells follows the spatial expression of the corresponding hormone gene families observed in zebra fish, suggesting similar differentiating mechanisms in teleosts and chondrosteans.

Prolactin in eyes of patients with retinopathy of prematurity: implications for vascular regression.

Disruption of the anti-angiogenic environment of the retina leads to neovascular eye diseases, including retinopathy of prematurity (ROP). Prolactin (PRL), the hormone originally associated with milk secretion, is proteolytically processed to 16K-PRL, a fragment with potent antiangiogenic, proapoptotic effects. Whether 16K-PRL is produced in eyes of patients with ROP and promotes the regression of intraocular blood vessels associated with this disease was investigated. PRL was quantified in the aqueous humor, subretinal fluid, and serum from patients with stage 5 ROP and in patients with non-neovascular eye disorders. Intraocular expression of PRL was evaluated by RT-PCR, in situ hybridization, and Western blot analysis. AntiPRL antibodies were injected intravitreously in neonatal rats, and apoptosis of hyaloid vessels determined by TUNEL and ELISA. PRL was elevated in ocular fluids and serum from ROP patients. There was no correlation between PRL in ocular fluids and its level in serum, whereas PRL in aqueous humor and subretinal fluid were significantly correlated. PRL mRNA was expressed in blood vessels and leukocytes within retrolental fibrovascular membranes of ROP patients, and these membranes contained a 16 kDa immunoreactive PRL. The 16K-PRL isoform was more concentrated in subretinal fluid than in serum and was generated from PRL by subretinal fluid proteases. Intravitreous injection of neutralizing antiPRL antibodies inhibited the apoptosis of hyaloid vessels in neonatal rats. 16K-PRL derived from PRL internalized from the circulation or synthesized intraocularly can stimulate apoptosis-induced vascular regression and contribute to the development and progression of ROP.

Removing the confound of time in investigating the regulation of serial behaviours: testosterone, prolactin and the transition from sexual to parental activity in male American kestrels

Understanding the relationships among variables can be difficult if the variables covary with time. Using a simple, commonly used statistical procedure to control for the passage of time, we demonstrate that some hormonal changes traditionally assumed to be causally related to the transition from sexual to parental behaviour can be explained by seasonal changes in the hormones and the fact that parental behaviour follows sexual behaviour in the course of breeding. We quantified immunoreactive prolactin (ir-prolactin) and testosterone concentrations in laboratory-housed and free-living male American kestrels, Falco sparverius, over the course of the breeding season and during sexual and parental phases of reproduction. We found that ir-prolactin increased while testosterone decreased with the transition from sexual to parental behaviour. ir-Prolactin increased with date (i.e. seasonally), whereas testosterone peaked when the frequency of clutch initiation was greatest and then decreased with date thereafter. Controlling for the effects of date eliminated the change in ir-prolactin associated with the transition from sexual to parental behaviour, revealing that prolactin variation associated with this behavioural transition in male kestrels is due, in large part, to seasonal changes in hormone concentrations and the serial nature of these behavioural states. Controlling for the effects of date further revealed that the testosterone difference between sexual and parental males decreases seasonally. It is possible that other phenomena traditionally attributed to environmental, behavioural, social, or other variables also may be explained by the association between such variables and the passage of time.

Familial Acromegaly: A Familial Report and Review of the Literature

Familial acromegaly without features of multiple endocrine neoplasie type 1 (MEN 1) is an exceptional clinical entity. We report in this article three cases of acromegaly due to pituitary macroadenomas without any other endocrinopathy in a family. A 31‐year‐old woman (subject A) and her 34‐year‐old sister (subject B) with elevated basal rolactin (PRL) levels, elevated growth hormone (GH) levels during the oral glucose tolerance test (OGTT) and a pituitary adenoma in Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) were diagnosed as acromegaly. Subject A was treated only with radiotherapy and Lysuride. Subject B underwent transsphenoidal microsurgical extirpation 15 years ago. 11 years later her 24‐year‐old son (subject C) also presented with typical signs of acromegaly, elevated basal PRL level and elevated GH levels during OGTT. A pituitary macroadenoma was identified by MRI and he also underwent transsphenoidal adenomectomy. Pathology reports confirmed the diagnosis of GH‐secreting pituitary adenoma in subject B and C. Immunocytochemistry revealed that tumours of subject B (> 20% of tumour cells) and C (> 50% of tumour cells) were positive for GH. Tumours of subject B (> 10% of tumour cells) and C (> 50% of tumour cells) also exhibited immunoreactivity for PRL. On investigation of histocompatibility antigens, it was observed that the subject A, B, and C shared the same haplotypes [HLA A24(9), HLA B13(6), HLA B35, HLA DQ7(3), HLA DR13(6)] and so it is very possible that investigation of HLA antigens in patients with pituitary tumour, contributes to better identification of its familial nature and frequency. Here we describe an acromegaly family and the distributions of HLA antigens.

Clinical and biological characterization of macroprolactinemia with and without prolactin-IgG complexes.

Macroprolactinemia, which can be detected by a polyethylene glycol (PEG) precipitation test, is a clinically and biologically heterogeneous condition. In this study, we analyzed whether the clinical presentation, the hormonal findings and the in vitro lactogenic activity differed between macroprolactinemic patients with and without circulating prolactin (PRL)-IgG complexes. Clinical data were reviewed and additional hormonal studies were performed in 50 hyperprolactinemic patients with macroprolactinemia. Macroprolactinemia was identified by a PRL recovery after PEG precipitation of <50%, as measured by an automated commercial immunoassay system and circulating PRL-IgG complexes by an abnormal PRL binding to anti-IgG agarose. PRL-IgG complexes were found in 46 patients. The origin of hyperprolactinemia in these 46 patients was idiopathic in 33 patients, while a pituitary lesion or stalk magnetic resonance imaging or computed tomography scan was detected in 13 patients found compression. Galactorrhea was found in 11 of these 46 patients, while this condition was present in three of the four patients without circulating PRL-IgG complexes. The median free PRL concentration was significantly lower in patients with PRL-IgG complexes than in the group without complexes (243 vs 969 mIU/l; P<0.005), whereas median total PRL immunoreactivity and median PRL bioactivity in the Nb2 assay were not significantly different. In patients with circulating PRL-IgG complexes, Nb2 bioassay results correlated significantly with total PRL immunoreactivity (r=0.64; P<0.0001), but not with free PRL results (r=0.24; P<0.17). These results indicate that PRL-IgG complexes (i) account for most cases of macroprolactinemia--as identified by PEG precipitation--in hyperprolactinemic patients presenting with a variety of diagnoses, (ii) are not associated with a specific clinical presentation, (iii) can be found in patients with diverse pituitary pathologies, and (iv) possess an in vitro lactogenic activity in the Nb2 bioassay in relation to their immunoreactivity.

Macroprolactinaemia associated with prolactin adenoma.

Macroprolactinaemia, defined as hyperprolactinaemia with a predominance of, or only, the big big prolactin (bbPRL) isoform, is considered idiopathic and poorly symptomatic. Since its association with a PRL adenoma is poorly documented, we examined a series of 13 patients with tumoral hyperprolactinaemia for the presence of macroprolactinaemia. From a series of 36 patients with hyperprolactinaemia studied for PRL isoforms, we selected 13 with hyperprolactinaemia and a prolactinoma, and divided them into two groups on the basis of the predominant PRL isoform, the large PRL group (five patients), with a predominance of the big big PRL isoform, and the monomeric PRL (mPRL) group (eight patients), with a predominance of the mPRL isoform. Plasma PRL concentrations were measured by radioimmunoassay, while plasma PRL heterogeneity was studied by gel filtration chromatography. The plasma autoantibody-bound PRL and the histology of the tumours were also studied. Macroprolactinaemia was seen in five out of the 13 patients with a PRL adenoma. The clinical and biological characteristics of the groups with and without macroprolactinaemia were similar. In the large PRL group, no evidence for anti-PRL autoantibodies was found and the prolactinomas were either typical or exhibited unusual aggregates of immunoreactive PRL deposits, the latter suggesting the tumoral origin of these large forms. Our results suggest that PRL adenoma may be associated with macroprolactinaemia.