Showing papers on "Prolactin published in 1982"
TL;DR: This finding suggests that growth hormone directly stimulates the cells in the growth plate, and does not support the theory that the increase in the plasma concentration of somatomedin that follows growth hormone administration is the cause of this stimulation.
Abstract: Local administration of human growth hormone in vivo to the cartilage growth plate of the proximal tibia of hypophysectomized rats resulted in accelerated longitudinal bone growth. This finding suggests that growth hormone directly stimulates the cells in the growth plate, and does not support the theory that the increase in the plasma concentration of somatomedin that follows growth hormone administration is the cause of this stimulation.
526 citations
TL;DR: The pulsatile secretion of gonadotrophins and ovarian steroids was studied in normal women at different stages of the menstrual cycle with LH showing the most easily identifiable pulses and FSH and PRL showing a similar but less marked change.
Abstract: SUMMARY
The pulsatile secretion of gonadotrophins and ovarian steroids was studied in normal women at different stages of the menstrual cycle. The concentration of LH, FSH, Prolactin (PRL), oestradiol and progesterone were measured in samples of plasma collected every 15 min for 6 h and the frequency and amplitude of each episodic pulse of hormone estimated. Although significant fluctuations occurred in the concentration of each hormone, LH showed the most easily identifiable pulses the frequency of which increased significantly from the early follicular to the late follicular phase of the cycle (3.4±0.3 v. 4.4±0.2 pulses 6 h P<0.01). During the luteal phase the basal concentration of LH (5.6±0.9 U/l), pulse amplitude (7.4±1.7 U/l) and frequency (1.6±0.2/6 h) were much lower than at any stage of the follicular phase (P<0.001). The concentration of FSH and PRL showed a similar but less marked change to that of LH throughout the menstrual cycle with a significant decline in both basal concentration and pulse frequency in the luteal phase of the cycle. Although only 47% of all LH pulses were associated with a pulse of FSH, 70% of FSH and prolactin pulses occurred within 15 min of an LH pulse.
The basal concentration of oestradiol increased significantly from the early follicular to the late follicular phase of the cycle (P<0.001). There was evidence of episodic secretion of oestradiol with the frequency of pulses declining from a maximum of 4.3±0.6/6 h in the mid-follicular phase to 1.8±0.5/6 h in the luteal phase (P<0.02). In the follicular phase 74–80% of LH pulses were followed within 100 min by a significant rise in the concentration of oestradiol. It is suggested that:
1the secretion of LH, FSH, PRL, oestradiol and progesterone is episodic in nature;
2a significant number of secretory episodes of FSH, LH and PRL are coincidental;
3the increased secretion of oestradiol from the pre-ovulatory follicle is associated with a rise in the frequency of episodic pulses of LH.
324 citations
TL;DR: Findings suggest that estradiol increases prolactin mRNA levels by increasing the transcription of the prolact in pituitary cells, and not on the other hand as previously suggested.
270 citations
TL;DR: A random sample of 55 schizophrenic outpatients treated with neuroleptics was selected and sexual dysfunction was found to be associated with high plasma prolactin levels in male patients but not in female patients, and antiparkinsonian medication was not found to been correlated with either sexual dysfunction or menstrual disorder score.
Abstract: A random sample of 55 schizophrenic outpatients, 26 men and 29 women, treated with neuroleptics was selected from our long term follow-up clinic. The patients rated their current sexual functioning on specially designed scales. Fifty-four per cent of male and 30 per cent of female patients reported impaired sexual functioning during neuroleptic treatment. Ninety-one per cent of female patients reported changes in menstruation. Partial correlation coefficients were calculated between sexual dysfunction score and plasma prolactin level adjusting for age. Sexual dysfunction was found to be associated with high plasma prolactin levels in male patients but not in female patients. High prolactin tended also to be associated with menstrual disturbances. Antiparkinsonian medication was not found to be correlated with either sexual dysfunction or menstrual disorder score.
230 citations
TL;DR: Results of this study indicate that nicotine from cigarette smoking increases circulating levels of cortisol, growth hormone, and prolactin in male chronic smokers, indicating that nicotine itself plays a predominate role in smoking-induced hormone increases.
Abstract: Results of this study indicate that nicotine from cigarette smoking increases circulating levels of cortisol, growth hormone, and prolactin in male chronic smokers. Previous studies have not addressed the question of whether the stimulus for smoking-related hormone release is the ‘stress’ of smoking or a pharmacologic action of nicotine and other tobacco substrates. Nicotine exposure is controlled in this study by allowing each subject to smoke only two 2.0 mg nicotine cigarettes during one experimental session and two 0.2 mg nicotine cigarettes in another session. Plasma levels of cortisol, growth hormone, and prolactin for the higher nicotine session were found to be significantly elevated over those for the low-nicotine session, indicating that nicotine itself plays a predominate role in smoking-induced hormone increases. All hormone levels for the 2.0 mg nicotine session had not returned to baseline 60 min after smoking.
223 citations
TL;DR: It is demonstrated that the increased Prolactin synthesis appears to be the result of a rapid stimulation of prolactin gene transcription by EGF, as well as a partial inhibition of cell growth.
Abstract: Epidermal growth factor (EGF) was originally characterized as a growth factor for various cell types1,2 and was subsequently shown to affect a number of cellular and molecular processes3,4, of which many might be considered as a part of the pleiotropic growth response (enhanced uptake of glucose, uridine and amino acids and stimulated synthesis of protein, RNA and DNA). Very early responses to EGF, such as increased sodium fluxes5 and stimulation of tyrosine phosphorylation6, have been proposed to mediate some or all of EGF's effects. In a number of tissues, EGF has been shown to increase the synthesis of specific proteins7-10. We have investigated the effects of EGF on prolactin synthesis in the GH4 rat pituitary cell line to gain further insight into the mechanism of EGF's actions on cellular functions. Addition of EGF to GH4 cells results in a three- to sixfold stimulation of prolactin synthesis, as well as a partial inhibition of cell growth7,8. In this report, we demonstrate that the increased prolactin synthesis appears to be the result of a rapid stimulation of prolactin gene transcription by EGF. It is tempting to speculate that very early transcription by EGF. It is tempting to speculate that very early transcriptional effects on specific genes, such as reported here in te case of the prolactin gene in GH4 cells, may mediate some or all of the later effects of EGF on cell cycle regulation in those cells for which it serves as a growth factor.
195 citations
TL;DR: A synthetic preparation of the 41-aminoacid-residue peptide recently isolated from ovine hypothalami and characterised corticotropin-releasing factor (CRF) suggests that it, or a related peptide, may be a CRF in man, and it may provide the basis for a new clinical test of pituitary ACTH reserve.
184 citations
TL;DR: Old female rats with spontaneous prolactin-secreting pituitary tumors (prolactinomas) and young females with prolact inomas produced by prolonged estrogen treatment had damaged tuberoinfundibular dopaminergic neurons.
Abstract: Old female rats with spontaneous prolactin-secreting pituitary tumors (prolactinomas) and young females with prolactinomas produced by prolonged estrogen treatment had damaged tuberoinfundibular dopaminergic neurons. Since these neurons inhibit the function of pituitary prolactin-secreting cells, their destruction may lead to development of prolactinomas.
181 citations
TL;DR: It is reported here that in male common marmosets carrying their twin offspring, plasma prolactin levels are five times higher, on average, than in males without infants, which suggests that physical contact may be important in producing the effects.
Abstract: In some mammals, both sexes exhibit a high degree of parental behaviour. This is the case in many primates which form pair bonds, such as marmosets, tamarins, owl monkeys and siamangs1–4. It is not known if any endocrine changes occur in male mammals which show parental behaviour. We report here that in male common marmosets carrying their twin offspring, plasma prolactin levels are five times higher, on average, than in males without infants. There are, however, no consistent differences in levels of plasma testosterone. Increases in prolactin are most pronounced during periods when males (rather than other group members) are carrying their offspring. This suggests that physical contact may be important in producing the effects. Although prolactin has been implicated in the control of maternal behaviour in avian and mammalian species5–8 this is the first demonstration that prolactin is elevated during parental behaviour in a male mammal.
176 citations
TL;DR: Patients with anosmia and hypogonadotropic hypogOnadism may have hypothalamic defect(s) responsible for the hypog onadotropin-releasing hormone and perhaps for certain additional deficiencies of anterior pituitary function found in some.
158 citations
TL;DR: The preferential location of angiotensin II receptors in the lactotroph-containing fractions and the close correlation between angiotENSin II binding sites and stimulation of PRL release indicate the functional importance of the pituitary angiotsin II receptor sites.
Abstract: logical properties of angiotensin II receptors in the rat adenohypophysis were analyzed in cultured rat pituitary cells incubated with angiotensin II and known stimuli of pituitary hormone secretion. PRL release during incubation for 3 h with 3 nM angiotensin II was consistently increased by 68 ± 5%, comparable with that elicited by TRH (63.1 ± 4%). The ED50 of 0.5 nM for PRL release by angiotensin II was significantly lower than that of TRH (2.9 nM) in the same cell cultures. The antagonist analog [Sar1,Ala8]angiotensin II prevented the angiotensin- induced rise in PRL production but not that evoked by TRH, whereas dopamine and SRIF inhibited basal, angiotensin, and TRH-stimulated PRL release. Angiotensin II also caused a small increase in ACTH release but had no effect on the release of LH, TSH, and GH. Angiotensin II binding and PRL release were measured in partially purified lactotrophs prepared by elutriation, by which the initial cell suspension was separated into seven fractions. Most of the lactot...
TL;DR: It is postulate that a direct repeat flanking exon I may be the remnant of an insertional event and the general organization of the rat prolactin gene, rPRL, is expanded to assign its haploid gene number and extend its DNA sequence analysis.
Abstract: Prolactin, growth hormone (GH) and placental lactogen constitute a family of polypeptide hormones which share certain structural1–7 and functional8 features. The prolactin and GH genes evolved from a gene duplication about 400 million years ago9 and, in humans, segregated onto chromosomes 6 and 17 respectively10,11. We expand here previous reports12,13 on the general organization of the rat prolactin gene, rPRL, assign its haploid gene number and extend its DNA sequence analysis. We postulate that a direct repeat flanking exon I may be the remnant of an insertional event.
TL;DR: The purpose of this paper is to review the evidence for a direct action of prolactin on the ovary in the context of the effects of Prolactin in the control of normal ovarian cyclicity.
Abstract: There is no doubt that in breast-feeding women, suckling with its associated hyperprolactinaemia prevents the resumption of ovarian activity for prolonged periods (see McNeilly, 1979) The extent of this suppression varies greatly among species but in all for which there are adequate data it appears to depend critically upon the intensity of the suckling stimulus (Lamming, 1978) Our recent data from women show that in the pattern of suckling, frequency and duration, throughout the day, are both key factors in maintaining the elevation of basal levels of prolactin associated with lactation (McNeilly, Howie & Houston, 1980a; Howie & McNeilly, 1982) Suckling also releases large quantities of prolactin, maintaining a physiological hyperprolactinaemic state which is directly associated with the duration of lactational amenorrhoea (Delvoye, Badawi, Demaegd & Robyn, 1978; Duchen & McNeilly, 1980) The question remains, how does suckling suppress ovarian activity? The levels of prolactin in blood during peak lactation appear to be many times the requirement for production of milk It therefore becomes pertinent to ask whether this prolactin is released solely to stimulate milk production or whether it is involved directly in the suppression of ovarian activity If there is a direct involvement then there are two loci for this action; an effect at the hypothalamic-pituitary level or a direct effect on the ovary While the former has received some attention (see McNeilly, 1979, 1980a), relatively little information is available (for species other than the rat) on whether or how prolactin might act on the ovary and, in particular, how high levels might interfere or block follicular development during lactation (McNeilly, 1980b) The purpose of this paper is to review the evidence for a direct action of prolactin on the ovary in the context of the effects of prolactin in the control of normal ovarian cyclicity
TL;DR: Data indicate that alterations in the proestrous gonadotropin and prolactin surges occur early during the aging process in the female rat, which may be important in the age-related transition to estrous acyclicity.
Abstract: Plasma LH, FSH, and prolactin were measured in middle-aged (7- to 9-month-old) breeder and young (3-4 month old) female rats on proestrus. Sixty-eight percent of the middle-aged rats exhibited regular 4-day estrous cycles; the remainder showed irregular cycles 4-7 days in length. All young rats exhibited at least two consecutive 4-day cycles prior to use. The right atria of all rats were cannulated under ether anesthesia between 0700 and 0800 hr (14:10 light-dark cycle, lights on at 0400 hr). Blood was drawn at 0900 hr and at hourly intervals from 1200 to 2200 hr; each rat was bled a maximum of nine times. Plasma LH and FSH rose significantly later and peak concentrations were significantly lower in middle-aged rats. Baseline prolactin concentrations at 0900 and 2000-2200 hr were significantly higher in middle-aged female rats. These data indicate that alterations in the proestrous gonadotropin and prolactin surges occur early during the aging process in the female rat. Such changes may be importa...
TL;DR: The authors provide a rationale for transsphenoidal microsurgery in these patients as opposed to other forms of management, such as bromocriptine therapy and irradiation, and suggest sellar polytomography will significantly decrease in importance in the diagnostic work-up of these patients.
Abstract: ✓ The authors present the results of transsphenoidal microsurgery in 100 women with the amenorrhea-galactorrhea syndrome caused by pituitary adenomas associated with hyperprolactinemia (prolactinomas). As the surgical results were closely related to the preoperative levels of serum prolactin, the patients were divided into two groups: patients with preoperative prolactin less than 200 ng/ml (Group 1), and those with preoperative prolactin greater than 200 ng/ml (Group 2). The results in Group 1 (72 patients) were significantly better. In this group, 56 (78%) patients regained normal menstrual cycles, and 55 (76%) had return of elevated prolactin levels to normal following surgery. In Group 2 (28 patients), however, only 11 (39%) resumed normal menstrual periods postoperatively, and 13 (46%) had return of elevated prolactin levels to normal. There was good correlation between tumor size and the preoperative level of prolactin. Of the 72 women in Group 1, 58 (81%) had tumors less than 1 cm (microadenomas), ...
TL;DR: It is suggested that the higher conception cycle progesterone concentrations during the early part of the luteal phase may constitute a preimplantation component of the maternal recognition of pregnancy in women.
Abstract: Hormonal profiles were obtained throughout 26 conception cycles and 27 non-conception control cycles. The pregnancies followed treatment (clomiphene or bromocriptine) in 12 women but were spontaneous in the remaining 14. No sustained significant difference between the various types of conception cycle was found for LH, FSH, oestradiol or progesterone concentrations. Prolactin concentrations varied widely, suggesting that mean cycle prolactin concentrations ranging from 45 to 760 mi.u./l are compatible with conception. Although there were no significant differences in progesterone secretion within the conception cycles, there were highly significant differences between the conception cycles and the non-pregnant control cycles. Mean progesterone concentrations in the conception group were higher (P less than 0.005) than those in the control women over Days 3-8 following the LH peak. This difference could only be partly accounted for by heterogeneity within the control group (15-20% of the control cycles had low progesterone concentrations and were probably subfertile. It is suggested that the higher conception cycle progesterone concentrations during the early part of the luteal phase may constitute a preimplantation component of the maternal recognition of pregnancy in women.
TL;DR: The synthetic replicate of a 44 amino acid peptide isolated from a human pancreatic tumor possesses high specific activity to release growth hormone (GH) in anesthetized male rats and serves as powerful tools with which to investigate the mechanisms of GH secretion.
TL;DR: The results of the current investigation suggest that neither the canine ovary nor pituitary are quiescent during anestrus and the bitch appears to have sufficient FSH present during ananestrus for follicular growth.
Abstract: Concentrations of estradiol, progesterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin in serum from 6 bitches bled daily for at least 45 days before the onset of proestrus, during proestrus and estrus were determined by radioimmunoassay. Mean concentrations of estradiol in serum were high early in the sampling period (20 to 46 pg/ml) and appeared to decrease prior to the onset of proestrus (8 to 19 pg/ml). There were sporadic increases in serum concentrations of LH throughout the sampling period in each bitch. Five of the 6 bitches sampled had increased serum concentrations of LH following the low mean concentration of estradiol just before the onset of proestrus. Mean concentrations of FSH were highest during anestrus (240 to 294 ng/ml) and near the time of the preovulatory surge of LH (297 ng/ml) and were lowest during proestrus (131 to 200 ng/ml). The mean concentration of progesterone for the 6 bitches remained at less than 1.0 ng/ml throughout late anestrus, but increased to greater than 1.0 ng/ml the day of the maximum mean concentration of LH (preovulatory LH surge). Mean concentrations of prolactin were variable throughout the sampling period and demonstrated no consistent pattern among bitches. The results of the current investigation suggest that neither the canine ovary nor pituitary are quiescent during anestrus. The bitch appears to have sufficient FSH present during anestrus for follicular growth. Serum concentrations of LH appear to increase prior to the onset of proestrus when concentrations of estradiol are lowest, possibly inducing a new follicular phase. Progesterone and prolactin do not appear to be involved in the termination of anestrus in the bitch.
TL;DR: The results suggest that the abnormal cortisol response to dexamethasone in some psychiatric patients may be due to a pituitary gland abnormality rather than to a limbic system abnormality.
Abstract: In addition to its ability to decrease plasma cortisol levels, dexamethasone can also significantly decrease plasma prolactin levels. In 52 psychiatric patients, including 26 patients with primary major depression or schizoaffective depression, primarily affective type, there was a significant association between nonsuppression of plasma cortisol and prolactin after administration of dexamethasone. These results suggest that the abnormal cortisol response to dexamethasone in some psychiatric patients may be due to a pituitary gland abnormality rather than to a limbic system abnormality. The sensitivity and specificity of the dexamethasone suppression test for endogenous depression were less than previously reported.
TL;DR: In primates, as in rodents, systemically administered NMA is capable of eliciting pituitary hormone secretion, although the site of its action in the rhesus monkey remains to be established.
TL;DR: The possible involvement of cAMP in mediating the dopaminergic inhibition of PRL release was studied in primary cultures of anterior pituitary cells from female rats and in lactotroph-enriched subpopulations.
Abstract: The possible involvement of cAMP in mediating the dopaminergic inhibition of PRL release was studied in primary cultures of anterior pituitary cells from female rats and in lactotroph-enriched subpopulations. In the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX), dopamine (DA) depressed cAMP accumulation in a concentrationdependent fashion between 1–100 nM. The effect was significant within less than 1 min and maximal after about 10 min. Inhibition of PRL release by DA occurred at similar concentrations and paralleled the time course of inhibition of cAMP levels. The DA agonist apomorphine also inhibited cAMP levels and PRL release at nanomolar concentrations and acted as a full agonist, whereas the a-adrenoceptor agonist phenylephrine had no effect at 1 μM. The DA receptor blockers spiperone, domperidone, pimozide, Z-sulpiride, and flupentixol reversed the DA-induced inhibition of cAMP accumulation with a rank order of potency comparable to that of reversing DA-induced inhibiti...
Journal Article•
TL;DR: Quantitative adenohypophysial cell classification provides a basis for defining hyperplasia and abnormal distribution of cells that result from various pathologic conditions, drug therapies, and changes in the hormonal environment.
Abstract: Sixty adult human pituitary glands taken at autopsy were stained for prolactin using the immunoperoxidase technique, and percentages of prolactin-bearing cells were assessed. There was no difference between the percentages of prolactin cells seen in the adenohypophyses of adult men and nulliparous women; they averaged 16.9%, with an average of from 8.6% to 31.3%. Percentages did not vary with age, and were higher in women in the perinatal period. In multiparous women percentages were increased, which indicates that prolactin cell hyperplasia of pregnancy does not completely reverse. No regression of prolactin cells was evident in the nontumorous portion of glands that harbored prolactinomas; however, percentages were elevated in glands with non-prolactin-producing adenomas. Quantitative adenohypophysial cell classification provides a basis for defining hyperplasia and abnormal distribution of cells that result from various pathologic conditions, drug therapies, and changes in the hormonal environment.
TL;DR: The present data indicate that high prolactin levels lead to an increased density of striatal dopamine receptors, however, the effect of estradiol may not be explained exclusively by increased prolact in levels since a similar stimulatory effect is observed in hypophysectomized animals.
TL;DR: It is concluded that marked similarities exist in both the receptor system and neuroendocrine mechanism of male pheromone action observed in prepubertal females and that seen in the adult.
Abstract: Young female mice were grouped on Day 21 after birth and subjected to removal of the vomeronasal organ. Soiled bedding from intact adult males failed to advance the onset of first oestrus in these lesioned mice compared to the various control groups. Vomeronasal organ lesions of prepubertal females also prevented increases in uterine weight following exposure to soiled bedding for 48 h on Day 23 when compared to controls. Lowering prolactin by injections of bromocriptine for 48 h on Day 26, but not Day 23, advanced the onset of puberty in intact and vomeronasal organ-lesioned females. Elevating prolactin by injections of domperidone were without effect on the early onset of oestrus when compared to sham-injected controls. It is concluded that marked similarities exist in both the receptor system and neuroendocrine mechanism of male pheromone action observed in prepubertal females and that seen in the adult.
TL;DR: The hypothesis that release of serotonin increases prolactin secretion is supported and the data suggest that serotonergic neurons in the dorsal raphe nucleus are part of a neural pathway which can mediate increases in prolactIn secretion.
Abstract: Administration of the serotonin-releasing drug DL-p-chloroamphetamine (PCA) to rats caused a dose-dependent increase in plasma prolactin levels. The effect was maximal 2 h after administration. The ef
TL;DR: Bromocriptine should be the treatment of choice in patients with large pituitary tumours with extrasellar extensions, provided close supervision is maintained.
Abstract: Bromocriptine has an accepted place in the management of small pituitary tumours that secrete either prolactin or growth hormone. The treatment of large tumours with extrasellar extensions is more difficult, however: though surgery is the standard treatment, it is often unsuccessful in returning excessive hormone secretion to normal and may cause hypopituitarism. A prospective trial was undertaken to assess the frequency with which changes in pituitary function and size of large tumours occurs. Nineteen patients were studied before and during treatment with bromocriptine (7.5 to 60 ml/day) for three to 22 months, using contrast radiology and a detailed assessment of pituitary function. Eighteen patients had hyperprolactinaemia and two of these also had raised concentrations of growth hormones; one patient had an apparently non-functioning tumour. In 12 patients (63%) tumour size decreased with bromocriptine and no tumour enlarged. Nine patients had visual-field defects, which improved in seven, becoming normal in five. Pituitary function improved in nine patients (47%) becoming entirely normal in three. Bromocriptine should be the treatment of choice in patients with large pituitary tumours with extrasellar extensions, provided close supervision is maintained.
TL;DR: Activity in noradrenergic innervation to specific areas of the hypothalamus is altered by ovarian hormones, and it is proposed that some of these changes may be involved in the feedback regulation of LH and PRL secretion by estradiol and progesterone.
Abstract: There is evidence that brain noradrenergic systems participate in the feedback regulation of luteinizing hormone (LH) and prolactin (PRL) secretion by ovarian hormones. The present study tested the hy
TL;DR: Low concentrations of BBS can directly stimulate PRL and GH release by a clonal pituitary cell strain in culture, and the results suggest that BBS may stimulate PRl and GH secretion in vivo by direct action on the pituitsary gland.
Abstract: Bombesin (BBS) has been previously shown to stimulate the secretion of PRL and GH in steroid-primed rats. To determine whether these effects were mediated by the central nervous system or were due to direct action on the pituitary gland, we studied the interaction of BBS with GH4C1 cells, a clonal strain of rat pituitary cells which synthesizes and secretes PRL and GH. The addition of 100 nM BBS to GH4C1 cells for 60 min increased PRL release to 140 ± 3% of the control value (mean ± SE) and GH release to 133 ± 5% of the control value. Stimulation of hormone secretion was observed within 15 min of treatment with 100 nM BBS and continued for at least 2 h. Half-maximal stimulation of PRL release occurred with 0.5 nM BBS, and a maximal effect was observed with 10 nM peptide. The BBS analogs ranatensin, litorin, and [Tyr4]BBS, each at a concentration of 100 nM, caused the same stimulation of PRL release as maximal concentrations of BBS itself. BBS stimulated hormone release selectively in two of five different...