Prolactin as a neuroendocrine clue in sexual function of women across the reproductive life cycle: an expert point of view

Prolactin is a proteic hormone best known for its role in enabling the production of milk by female mammals. Secreted by the pituitary gland in response to the stimuli of eating, estrogen treatment, mating, ovulation and nursing, prolactin is involved in over 300 separate processes in a range of vertebrates, including humans. The hormone is released in a pulsatile manner and plays an essential role in metabolism, as well as in the regulation of the immune system and pancreatic development. Nevertheless, prolactin exerts other relevant roles, as it acts at the central nervous system level to modulate behavior, arousal and sexuality. In this experts' opinion, we aim to give insights into the main activities of prolactin to advance the ability of medical doctors and specialists in obstetrics and gynecology to provide more emphasis in their clinical practices to the link between prolactin and sexuality.

[Research progress of kisspeptin in female reproductive endocrine and assisted reproductive techniques]

In recent years, it has been found that kisspeptin plays some key roles in the physiological processes of the brain, such as gender differentiation, positive and negative feedback of sex hormones, onset of puberty, and transduction of energy signals in the body, which suggests that kisspeptin may be a key molecule for the maturation and regulation of female reproductive function. In addition to the systemic roles of the kisspeptin, its local roles in reproductive organs are constantly being discovered. With the discovery that kisspeptin is involved in the pathological process of reproductive endocrine diseases such as isolated hypogonadotropic hypogonadism (IHH), polycystic ovary syndrome (PCOS), premature ovarian failure (POF) and pathological hyperprolactinemia, exogenous application of kisspeptin to solve reproductive problems has become a new hot topic. The review focuses on the research progress of kisspeptin in the female reproductive system, especially on its application in assisted reproduction.

Prolactin is Not Associated with Disability and Clinical Forms in Patients with Multiple Sclerosis

An association between prolactinemia with disability, clinical forms, and sex of patients with multiple sclerosis (MS) remains unclear. The aim of this study was to evaluate the association of prolactin with clinical forms and accumulating disability over time in patients with MS. A longitudinal study was carried out with 101 patients with relapsing-remitting MS (RRMS) and 19 with progressive forms of MS (ProgMS). The disability over time, as well as prolactin and ferritin serum levels were evaluated at baseline (T0), 8-month follow-up (T8), and 16-month follow-up. The disability at T0, T8, and T16 was higher among patients with ProgMS than those with RRMS. Prolactin and ferritin levels did not differ over time between both groups. Initially, prolactin was associated with MS disability. After introducing age and sex, the effects of prolactin on disability were no longer significant. Prolactin was associated with age and sex, whereby age was positively associated with disability. In the same way, after introducing age and sex, the effects of diagnosis on prolactin levels, as well as the association between prolactin and ferritin, were no longer significant (P = 0.563 and P = 0.599, respectively). Moreover, 21.6% of the variance in the disability was predicted by age (P < 0.001), and sex (P = 0.049), while prolactin was not significant. In conclusion, the effects of prolactin on the disability and clinical forms of MS patients may be spurious results because those correlations reflect the positive associations of age with the disability and the negative association of age with prolactin.

Hypothalamic-pituitary-gonadal axis dysfunction: An innate pathophysiology of schizophrenia?

The female hormone 17β-estradiol is postulated to be protective against schizophrenia onset and severity. Hypoestrogenism is a common phenomenon in women with schizophrenia that has serious effects that adds to the burden of an already very onerous disease. The cause of hypoestrogenism is largely attributed to antipsychotic-induced hyperprolactinemia. Evidence suggest however that a significant portion of female schizophrenia patients develop hypoestrogenism either before antipsychotic treatment or without regard to the level of prolactin, suggesting that for a sizeable segment of female patients, gonadal abnormality may be an innate and early aspect of the disease. This review aims to summarise the available literature that examines gonadal dysfunction in schizophrenia through this prism as well as to outline some recent developments in treatment strategies that may provide feasible ways to successfully tackle hypoestrogenism in schizophrenia.

Prevalence and reproductive manifestations of macroprolactinemia

PURPOSE

Macroprolactinemia is characterized by predominance of macroprolactin molecules in circulation and generally has extra-pituitary origin. Macroprolactin is viewed as biologically inactive, therefore asymptomatic, and thus may not require any treatment or prolonged follow-up. In addition, data on prevalence of macroprolactinemia and its clinical manifestation are also rare. Therefore, the present study was aimed to find out prevalence of macroprolactinemia and its association, if any, with reproductive manifestations.

MATERIAL AND METHODS

Macroprolactin was measured in 102 hyperprolactinemia cases (>100 ng/ml prolactin level), 135 physiological hyperprolactinemia cases (50 pregnant and 85 lactating females; >100 ng/ml prolactin level) and 24 controls. Poly ethylene glycol (PEG) precipitation method was carried out to screen macroprolactin. Prolactin recovery of <25% was considered overt macroprolactinemia. Detailed clinical data was recorded which included complete medical history, physical examination and hormone measurements besides CT/MRI for pituitary abnormalities.

RESULTS

Prevalence of macroprolactinemia was 21.57% (22/102) in hyperprolactinemia (prolactin >100 ng/ml). There was no case of macroprolactinemia in physiological hyperprolactinemia, or healthy control females. Reproductive manifestations were present in 72.73% (16/22) macroprolactinemia cases, out of which macroprolactinemia was the sole cause of associated reproductive manifestations in 68.7% (11/16) cases. Reversal of reproductive dysfunction/s was observed in five cases with appropriate treatment for high macroprolactin.

CONCLUSION

Macroprolactinemia prevalence was found to be 21.5%, out of which 72.73% cases had associated reproductive dysfunctions.

Gynecomastia and hormones

Gynecomastia-the enlargement of male breast tissue in men-is a common finding, frequently observed in newborns, adolescents, and old men. Physiological gynecomastia, occurring in almost 25 % of cases, is benign and self-limited; on the other hand, several conditions and drugs may induce proliferation of male breast tissue. True gynecomastia is a common feature often related to estrogen excess and/or androgen deficiency as a consequence of different endocrine disorders. Biochemical evaluation should be performed once physiological or iatrogenic gynecomastia has been ruled out. Non-endocrine illnesses, including liver failure and chronic kidney disease, are another cause of gynecomastia which should be considered. Treating the underlying disease or discontinuing medications might resolve gynecomastia, although the psychosocial burden of this condition might require different and careful consideration.

[Current diagnosis and treatment of hyperprolactinemia]

Hyperprolactinemia is a frequent neuroendocrinological condition that should be approached in an orderly and integral fashion, starting with a complete clinical history. Once physiological causes such as pregnancy, systemic disorders such as primary hypothyroidism and the use of drugs with dopamine antagonistic actions such as metochlopramide have been ruled out, the most common cause of hyperprolactinemia is a PRL-secreting pituitary adenoma or prolactinoma. Prolactinomas are usually classified as microprolactinomas (less than 1 cm) or macroprolactinomas (larger than 1 cm), which can either be confined or invasive. The hormonal consequence of hypeprolactinemia is hypogonadism; in women, this is manifested as amenorrhea/oligomenorreha, anovulation and galactorrhea, whereas in men the main complaints are a diminished libido and erectile dysfunction. Macroprolactinomas can also present with symptoms and signs resulting form mass effect of the tumor, such as headaches and visual field defects. Other structural causes of hyperprolactinemia include non-functioning pituitary adenomas and infiltrative disorders, which can interrupt the inhibitory, descending dopaminergic tone. The primary treatment of prolactinomas is pharmacological with dopamine agonists such as cabergoline.

[HYPERPROLACTINEMIA AND SELECTIVE SEROTONIN REUPTAKE INHIBITORS. A NARRATIVE REVIEW OF THE LITERATURE]

A large number of scientific papers have reported the relationship between the development of hyperprolactinemia and the use of psychotropic drugs, especially the role of antipsychotics which are antidopaminergic drugs. However, less information is known about the role of antidepressants in the development of hyperprolactinemia, specially the selective reuptake inhibitors (SSRIs). The prevalence of hyperprolactinemia as a pharmacological side effect of SSRIs is still unknown, despite the widespread use over the last decade. The aim of this review is to explore the relationship between hyperprolactinemia and SSRIs.

Neuroendocrine causes of amenorrhea--an update

CONTEXT

Secondary amenorrhea--the absence of menses for three consecutive cycles--affects approximately 3-4% of reproductive age women, and infertility--the failure to conceive after 12 months of regular intercourse--affects approximately 6-10%. Neuroendocrine causes of amenorrhea and infertility, including functional hypothalamic amenorrhea and hyperprolactinemia, constitute a majority of these cases.

OBJECTIVE

In this review, we discuss the physiologic, pathologic, and iatrogenic causes of amenorrhea and infertility arising from perturbations in the hypothalamic-pituitary-adrenal axis, including potential genetic causes. We focus extensively on the hormonal mechanisms involved in disrupting the hypothalamic-pituitary-ovarian axis.

CONCLUSIONS

A thorough understanding of the neuroendocrine causes of amenorrhea and infertility is critical for properly assessing patients presenting with these complaints. Prompt evaluation and treatment are essential to prevent loss of bone mass due to hypoestrogenemia and/or to achieve the time-sensitive treatment goal of conception.

The effects of novel and newly approved antipsychotics on serum prolactin levels: a comprehensive review

Since the 1970s, clinicians have increasingly become more familiar with hyperprolactinemia (HPRL) as a common adverse effect of antipsychotic medication, which remains the cornerstone of pharmacological treatment for patients with schizophrenia. Although treatment with second-generation antipsychotics (SGAs) as a group is, compared with use of the first-generation antipsychotics, associated with lower prolactin (PRL) plasma levels, the detailed effects on plasma PRL levels for each of these compounds in reports often remain incomplete or inaccurate. Moreover, at this moment, no review has been published about the effect of the newly approved antipsychotics asenapine, iloperidone and lurasidone on PRL levels. The objective of this review is to describe PRL physiology; PRL measurement; diagnosis, causes, consequences and mechanisms of HPRL; incidence figures of (new-onset) HPRL with SGAs and newly approved antipsychotics in adolescent and adult patients; and revisit lingering questions regarding this hormone. A literature search, using the MEDLINE database (1966-December 2013), was conducted to identify relevant publications to report on the state of the art of HPRL and to summarize the available evidence with respect to the propensity of the SGAs and the newly approved antipsychotics to elevate PRL levels. Our review shows that although HPRL usually is defined as a sustained level of PRL above the laboratory upper limit of normal, limit values show some degree of variability in clinical reports, making the interpretation and comparison of data across studies difficult. Moreover, many reports do not provide much or any data detailing the measurement of PRL. Although the highest rates of HPRL are consistently reported in association with amisulpride, risperidone and paliperidone, while aripiprazole and quetiapine have the most favorable profile with respect to this outcome, all SGAs can induce PRL elevations, especially at the beginning of treatment, and have the potential to cause new-onset HPRL. Considering the PRL-elevating propensity of the newly approved antipsychotics, evidence seems to indicate these agents have a PRL profile comparable to that of clozapine (asenapine and iloperidone), ziprasidone and olanzapine (lurasidone). PRL elevations with antipsychotic medication generally are dose dependant. However, antipsychotics having a high potential for PRL elevation (amisulpride, risperidone and paliperidone) can have a profound impact on PRL levels even at relatively low doses, while PRL levels with antipsychotics having a minimal effect on PRL, in most cases, can remain unchanged (quetiapine) or reduce (aripiprazole) over all dosages. Although tolerance and decreases in PRL values after long-term administration of PRL-elevating antipsychotics can occur, the elevations, in most cases, remain above the upper limit of normal. PRL profiles of antipsychotics in children and adolescents seem to be the same as in adults. The hyperprolactinemic effects of antipsychotic medication are mostly correlated with their affinity for dopamine D2 receptors at the level of the anterior pituitary lactotrophs (and probably other neurotransmitter mechanisms) and their blood-brain barrier penetrating capability. Even though antipsychotics are the most common cause of pharmacologically induced HPRL, recent research has shown that HPRL can be pre-existing in a substantial portion of antipsychotic-naïve patients with first-episode psychosis or at-risk mental state.

[Clinical practice guideline for the diagnosis and treatment of hyperprolactinemia]

BACKGROUND

Hyperprolactinemia is a common finding within clinical practice in both endocrinology and general practice fields, amongst other specialties. The general practitioner and other specialists must know the indications and serum prolactin determination parameters in order to, once detected, derive the patient for a correct assessment and begin treatment.

OBJECTIVE

Formulate a clinical practice guideline evidence-based for the diagnosis and treatment of hyperprolactinemia.

METHOD

It took the participation of eight gynecologists, two pathologists and a pharmacologist in the elaboration of this guideline due their experience and clinical judgement. These recommendations were based upon diagnostic criteria and levels of evidence from treatment guidelines previously established, controlled clinical trials and standardized guides for adolescent and adult population with hyperprolactinemia.

RESULTS

During the conformation of this guideline each specialist reviewed and updated a specific topic and established the evidence existent over different topics according their field of best clinical expertise, being enriched by the opinion of other experts. At the end, all the evidence and decisions taken were unified in the document presented here.

CONCLUSIONS

It is presented the recommendations established by the panel of experts for diagnosis and treatment of patients with high levels of prolactin; also the level of evidence for the diagnosis of hyperprolactinemia, handling drug-induced hyperprolactinemia and prolactinomas in pregnant and non-pregnant patients.

Evaluation of body weight, insulin resistance, leptin and adiponectin levels in premenopausal women with hyperprolactinemia

The effects of hyperprolactinemia on metabolic parameters are not clear and a few data evaluating adiponectin levels in prolactinoma and idiopathic hyperprolactinemia exist. The aim of this study was to evaluate the effects of hyperprolactinemia on body weight, insulin resistance, beta cell function, and leptin and adiponectin levels in premenopausal women with hyperprolactinemia. Forty premenopausal women with prolactinoma or idiopathic hyperprolactinemia were compared to 41 age-matched healthy premenopausal women with regard to body weight, body mass index, waist and hip circumferences, waist to hip ratio, fasting plasma glucose, insulin levels, insulin resistance measured by homeostasis model assessment (HOMA)-insulin resistance index, beta cell function measured by HOMA-β index, leptin and adiponectin levels. Plasma insulin levels and HOMA indexes (both insulin resistance and beta indexes) were significantly higher in hyperprolactinemic women. The other parameters were similar between both groups. There was a positive correlation between prolactin levels and fasting plasma glucose in hyperprolactinemic women. The results of this study showed that high prolactin levels may be associated with hyperinsulinemia and insulin resistance in premenopausal women. This effect seems to be independent of body weight, leptin and adiponectin levels. High prolactin levels may directly stimulate insulin secretion from pancreas and directly cause hepatic and whole-body insulin resistance.

Hyperprolactinaemia associated with increased thyroid volume and autoimmune thyroiditis in patients with prolactinoma

OBJECTIVE

The aim of this investigation was to evaluate the effects of hyperprolactinaemia on thyroid function, volume and nodularity in patients with prolactinoma.

CONTEXT

Hyperprolactinaemia has been associated with various autoimmune diseases; however, the data on the correlation between the level of prolactin (PRL) and thyroid disorders have not been adequately clarified.

DESIGN

Case-control study.

PATIENTS

Forty-eight subjects with new diagnosis of hyperprolactinaemia (group 1) and 39 subjects undergoing treatment for prolactinoma (group 2) were recruited from our outpatient clinic. Fifty-two healthy subjects were included as a control group (group 3).

MEASUREMENTS

The serum PRL, thyroid-stimulating hormone (TSH), thyroxine (free T4), thyroidal microsome (anti-TPO) and antithyroglobulin antibodies (TgAb) levels were evaluated, and ultrasonographic thyroid volume was calculated.

RESULTS

The frequencies of positive anti-TPO and TgAb were significantly higher in group 1 than in groups 2 and 3 (P = 0·008). Also, the percentage of patients with thyroid heterogeneity were significantly higher in groups 1 and 2 than in group 3 (P < 0·05). The percentage of patients with thyroid nodules were higher in group 1 than in groups 2 and 3 (p1-2 = 0·03, p1-3 = 0·05 and p2-3 = 0·637). The mean thyroid volume was significantly higher in group 1 (P = 0·001), and a positive correlation was found between thyroid volume and the level of PRL (r = 0·616; P = 0·0001). Prolactin had a significant effect on the total volume according to stepwise multiple linear regression analysis (adjusted R(2) is 0·268; P < 0·0001).

CONCLUSIONS

Patients with hyperprolactinaemia have significantly increased thyroid volume, thyroid autoimmunity and nodule prevalence.

Is chronic nipple piercing associated with hyperprolactinemia?

Literature on hyperprolactinemia in the setting of a nipple piercing is limited to individuals with concomitant breast/chest wall infection. It is unclear if chronic nipple stimulation from a piercing alone can cause sustained elevations of serum prolactin. Nipple piercing is emerging as a more mainstream societal form of body art, and the answer to this clinical question would potentially alter patient management. Our aim was to assess serum prolactin levels in subjects with nipple piercing. Inclusion criteria were as follows: men and women ≥ 18 years old with nipple piercing(s) present > 6 months. Exclusion criteria included: women who are pregnant, lactating or < 6 months postpartum; subjects on medications known to increase prolactin levels; chest wall/breast infection at the time of phlebotomy or conditions known to be associated with hyperprolactinemia. Three men and eight women were enrolled. Median (range) ages for men and women were 33 (24-42) and 27 years (23-42), respectively. All except one subject had bilateral piercings. The median interval from nipple piercing to blood draw was 4.0 (2.0-12.0) years. None of the subjects had hyperprolactinemia. Median (range) prolactin levels for men and women were 5.6 ng/mL (3.8-7.4) and 8.0 ng/mL (2.8-10.9), respectively. Our results suggest that in the absence of any concomitant infection, chronic nipple piercing is not associated with hyperprolactinemia.

Macroprolactinemia in women with hyperprolactinemia: a 10-year follow-up

OBJECTIVES

To determine the frequency of macroprolactinemia in a cohort of hyperprolactinemic women, describing 1) the association of macroprolactinemia with clinical variables and morphological changes in the pituitary gland and 2) clinical status and prolactin levels after 10 years of follow-up.

DESIGN

Blood samples were obtained from 32 patients for hormonal assessment. Treatment with cabergoline or bromocriptine was interrupted 3 months before the determination of serum prolactin and macroprolactin. Macroprolactin was measured using the polyethylene glycol (PEG) precipitation method. Computed tomography was performed in all patients.

RESULTS

The frequency of macroprolactinemia was 28.1%. In 19 patients prolactin remained elevated (persistent hyperprolactinemia). In 13, prolactin returned to normal (former hyperprolactinemia). Nine patients with PEG recovery between 40 and 50%, and the only two macroprolactinemic patients with previous hyperprolactinemia were excluded from the analysis of clinical outcomes. Only one of seven macroprolactinemic patients had an abnormal pituitary image (empty sella). None had galactorrhea.

MAIN FINDINGS

Classic symptoms of hyperprolactinemia and abnormal imaging findings are not common in patients in whom macroprolactin is the predominant form of PRL.

CONCLUSIONS

Women with hyperprolactinemia, especially if asymptomatic, should be routinely screened for macroprolactinemia. Macroprolactinemia remains stable in the long term.

Comparison of quetiapine and risperidone in Chinese Han patients with schizophrenia: results of a single-blind, randomized study

OBJECTIVE

To evaluate the efficacy and safety of 750 mg/day quetiapine fumarate (Seroquel) in the treatment of Chinese Han patients with schizophrenia.

METHODS

In this 6-week, multicenter, randomized, rater single-blind study, a total of 119 patients with schizophrenia were randomly assigned to quetiapine (n = 60, 750 mg/day) or risperidone (n = 59, 4 mg/day). The efficacy was assessed by the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression-Change (CGI-C) and the Calgary Depression Scale for Schizophrenia (CDSS). Safety and tolerability assessments included treatment-emergent adverse events, laboratory tests and electrocardiograms.

RESULTS

The primary analysis demonstrated no significant difference between treatment in the two groups (quetiapine vs. risperidone: 31.9 ± 17.5 vs. 33.3 ± 17.3; P = 0.668). Improvements with both treatments were comparable for total PANSS, positive and negative subscores, general psychopathology subscales, and excitement and attack symptoms. Improvements in CGI-S were similar between treatment groups (P = 0.046). A more favorable trend was detected for quetiapine than risperidone in the reduction of CDSS scores from baseline, especially at week 1 (1.1 ± 2.2 vs. 0.3 ± 2.1, P < 0.050). The rate of extrapyramidal symptom (EPS) and hyperprolactinemia-related adverse events was significantly lower in the quetiapine group than the risperidone group (13.3% vs. 43.3%, P < 0.001). Dizziness and somnolence were more common in the quetiapine group than the risperidone group.

CONCLUSION

Quetiapine fumarate (750 mg/day) has broad clinical efficacy comparable to 4 mg/day risperidone. Dizziness was common in the quetiapine group (P = 0.029), but the rate of somnolence was similar between the two groups (P = 0.114). EPS and hyperprolactinemia rates were significantly higher with risperidone (P < 0.001). Key limitations of this study include small sample size, short treatment periods, and no increase to 6 mg/day for risperidone because of its safety profile.

Clinical and radiological findings in macroprolactinemia

Hyperprolactinemia is the most common abnormality of the hypothalamic-pituitary axis. The aim of this study was to investigate the clinical and radiological features of patients with macroprolactinemia. The study population consisted of patients with elevated serum prolactin (PRL) concentrations who presented to our Endocrinology outpatient clinic. Detection of macroprolactin (macroPRL) was performed using the polyethylene glycol precipitation method. Patients in which macroPRL made up more than 60% of total PRL levels were stratified into the macroPRL group, while the remaining patients were placed in the monomeric prolactin (monoPRL) group. A total of 337 patients were enrolled with a mean age of 33.8 ± 10.8 (16-66) years and a male/female ratio of 29/308. Eighty-eight of the patients (26.1%) had an elevated macroPRL level. The mean age in the monoPRL group was higher than in the macroPRL group (35.0 ± 10.1 vs. 30.7 ± 9.8, P = 0.016). The mean PRL levels (ng/ml) in the macroPRL and monoPRL groups were similar (168.0 ± 347.0 vs. 238.8 ± 584.9, P = 0.239). Frequency of amenorrhea, infertility, irregular menses, gynecomastia, and erectile dysfunction were also similar in both groups. More patients in the macroPRL group were asymptomatic compared to the monoPRL group (30.2 vs. 12.0%, P = 0.006). Compared to the macroPRL group, the monoPRL group had a higher frequency of galactorrhea (39.2 vs. 57.1%, P = 0.04) and abnormal magnetic resonance imaging findings (65.3 vs. 81.1%, P = 0.02). Elevated macroPRL levels should be considered a pathological biochemical variant of hyperprolactinemia that may present with any of the conventional symptoms and radiological findings generally associated with elevated PRL levels.

Hyperprolactinemia and infertility

Prolactin-secreting pituitary tumors are a common cause of amenorrhea and infertility in premenopausal women. The goals of therapy are to normalize prolactin, restore gonadal function and fertility, and reduce tumor size, and dopamine agonists are the preferred therapy. Clinically significant tumor enlargement during pregnancy is uncommon and dependent on tumor size and prepregnancy treatment.

Sub-clinical hypothyroidism in infertile Nigerian women with hyperprolactinaemia

Studies on the impact of subclinical hypothyroidism in infertility are scarce and this seeks to determine the proportion of infertile Nigerian women with hyperprolactinaemia that had subclinical hypothyroidism. Serum prolactin and thyroid stimulating hormone were determined using ELECSYS 1010 auto analyzer. Two hundred infertile women were evaluated and 67(33.7%) had hyperprolactinaemia. Subclinical hypothyroidism was observed in 14.9% of women with hyperprolactinaemia, 4.5% and 10.5% of women with primary and secondary infertility, while hyperprolactinaemia was observed in 29.9% and 70.1% in primary and secondary infertility respectively. Mean levels of thyroid stimulating hormone and prolactin were higher in secondary infertility than primary infertility. Subclinical hypothyroidism and hyperprolactinaemia were higher in secondary infertility than primary infertility. The ratio of proportions between hypothyroidism and hyperprolactinaemia was 1:7.

The renin-angiotensin-aldosterone axis in patients with nontumoral [corrected] hyperprolactinemia

OBJECTIVE

In physiological conditions, renin-angiotensin-aldosterone (RAA) axis is under continuous tonic inhibition by dopamine. The aim of this study was to evaluate the relationship of nontumoural hyperprolactinemia with the activity of adrenocortical and RAA axis, before and after administration of bromocriptine.

DESIGN

Twenty women with nontumoural hyperprolactinemia and 20 healthy women matched for body mass index and age were recruited in this study. All participants were placed on fixed salt intake for 2 weeks before the experiments. The study was conducted in three phases. In phase I, the participants received an intravenous infusion of angiotensin II in three consecutive doses of 2, 4 and 6 ng/kg BW changed every 30 min. In phase II, the patients were started on bromocriptine in gradually increasing doses of 1.25, 2.5, 5, 7.5 and 10 mg/day for 10 weeks. In phase III, the protocol of phase I was repeated in the patient group. Circulating levels of cortisol, plasma renin activity (PRA), aldosterone and prolactin were assayed.

RESULTS

Baseline values of prolactin, and PRA (2.6±0.18 nM vs 0.45±0.05 nM P<0.001 and 142.2±14.4 vs 30.7±2.7 pM/h, P<0.001, respectively) but not aldosterone (P=0.081) were significantly higher in the patient group. The angiotensin infusion test induced a significantly greater response in the patient group. Administration of the dopamine agonist restored the basal levels and diminished the response to angiotensin infusion for all the parameters tested. No change in the blood pressure was recorded.

CONCLUSIONS

Our study demonstrates that in nontumoural hyperprolactinemia there is an increased reactivity of renin-angiotensin-aldosterone (RAA) axis that is almost completely restored after treatment with a dopamine agonist.

Antipsychotics and hyperprolactinaemia: mechanisms, consequences and management

Hyperprolactinaemia is a common side effect in people receiving antipsychotics. The propensity to cause hyperprolactinaemia differs markedly between antipsychotics as a result of differential dopamine D(2) receptor-binding affinity and ability to cross the blood-brain barrier. Sexual dysfunction is common and under-recognized in people with severe mental illness and is in part caused by hyperprolactinaemia. There are a number of long-term consequences of hyperprolactinaemia, including osteoporosis. Regular monitoring before and during treatment will help identify those developing antipsychotic-induced hyperprolactinaemia. The treatment includes dose reduction and change in antipsychotic. Where this is not possible because of the risk of relapse of the mental illness, sex steroid replacement may be helpful in improving symptoms secondary to hypogonadism and reducing the risk of osteoporosis. Tertiary prevention of complications should also be considered.

Female gonadal function before and after treatment of acromegaly

CONTEXT

The menstrual cycle is often abnormal in women with acromegaly. Gonadotropin deficiency may be due to a tumor mass effect (macroadenomas) and/or hyperprolactinemia and/or GH excess.

AIM OF THE STUDY

The aim of the study was to analyze the causes of ovarian dysfunction in a large series of patients with acromegaly followed up in a single center.

PATIENTS AND METHODS

Gonadal function was assessed on the basis of menstrual status and hormone assays before and after treatment of acromegaly, between 1985 and 2005, in 55 patients aged from 17 to less than 45 yr.

RESULTS

Seventeen women (31%) were considered to be eugonadal because they had regular menstrual cycles and/or conceived spontaneously. The remaining 38 women had anovulatory cycles. Of these, 11 had hyperprolactinemia and six had hypogonadism due to a mass effect. The cause of the menstrual disturbances was mixed or unclassifiable in 14 cases. In the seven remaining cases, the gonadal dysfunction was likely related to the GH/IGF-I excess, which exerts a direct effect on the gonadotropic axis. Two had polycystic ovary syndrome, which disappeared after normalization of serum GH/IGF-I levels, suggesting that GH/IGF-I excess may also have a direct effect on the ovary. Thirty-eight women became pregnant, and all had healthy children, despite active acromegaly in 12 cases (31%).

CONCLUSION

Gonadal dysfunction is very common in premenopausal women with acromegaly. The potential causes include the lactogenic effect of prolactin, GH, or both on gonadotropic axis. Tumor mass effect or direct effect of GH or IGF-I on the ovary may also participate in ovarian dysfunction.

Benefits of switching women schizophrenic patients to aripiprazole: a case study and brief review of the literature

Hyperprolactinemia, an adverse side-effect of the use of typical and some atypical antipsychotics, has both acute and chronic clinical consequences. When observed in schizophrenic patients, it may be treated by switching the patient to an antipsychotic agent with a lower liability for the induction of hyperprolactinemia. The effects of substituting aripiprazole for other antipsychotic agents on schizophrenic patients with antipsychotic-induced hyperprolactinemia have been previously reported in several studies. Many studies have also noted that aripiprazole can sometimes lead to increases in psychotic symptoms, especially in the period immediately following the switch or when aripiprazole is combined with a dopamine antagonist. Here, we report observations on five female patients who were experiencing symptomatic hyperprolactinemia and psychotic exacerbation while on antipsychotic treatment, yet improved in both conditions after being switched to aripiprazole monotherapy. We also provide a brief review of the existing studies that report the results of switching patients from other antipsychotics to aripiprazole.

The influence of other than prolactin hormones on bone mineral density in women with hyperprolactinaemia of various origins

OBJECTIVE

Hyperprolactinaemia may lead to bone loss, both due to hypogonadism and other hormonal disturbances. Aim of the case-control study was the analysis of influences of hormonal profiles associated with hyperprolactinaemia on the bone mineral density (BMD) in women with hyperprolactinaemia of various origin.

MATERIAL AND METHODS

The subjects were 32 patients with prolactinoma, 43 ones with functional hyperprolactinaemia and 29 healthy controls. All of them were studied for BMD (lumbar spine, proximal femur, forearm, total body) by dual-energy X-ray absorptiometry and their correlations with hormones levels (prolactin, oestradiol, luteinising hormone, follicle stimulating hormone, sex hormone binding globulin (SHBG), testosterone, dehydroepiandrosterone sulphate (DHEA-S), insulin-like growth factor-1 and intact parathyroid hormone) using Spearman correlation analysis and multiple regression analysis model.

RESULTS

Correlation analysis revealed the anabolic influence of PTH on lumbar spine in women with prolactinoma, and on ultradistal radius in functional hyperprolactinaemia. In multiple regression analysis, oestradiol had greatest influence on lumbar spine and total body BMD. Moreover, positive influence of testosterone, SHBG on spine BMD, and of oestradiol, testosterone, SHBG and DHEA-S on total body BMD were observed in patients with prolactinoma.

CONCLUSION

Hormonal disturbances associated with hyperprolactinaemia influence BMD more in patients with prolactinoma than in ones with functional hyperprolactinaemia.

Gene expression of lymphocyte prolactin receptor was suppressed in lactating mothers

Prolactin (PRL) receptor (PRL-R) was proven to be ubiquitously expressed by cells in the immune system, while the physiological role of PRL was established in milk production in mammary glands. We analyzed the mRNA content of PRL-R in human lymphocytes in normo- and hyperprolactinemic conditions to document the presence of functioning PRL-R of human lymphocytes. Blood samples were obtained prior to treatment, and with written informed consent, from outpatients with ovarian dysfunction and hyperprolactinemia (n = 8; 19 ~ 41 y/o), from breast-feeding mothers after normal delivery (n = 12; 27 ~ 36 y/o), and from healthy volunteers: men (n = 9; 33 ~ 40 y/o) and women (n = 9; 26 ~ 36 y/o). Subsequently, total RNA was prepared from the lymphocytes separated. The quantity of PRL-R mRNA was examined by reverse transcription and polymerase chain reaction and normalized with a simultaneously measured amount of b actin. The resultant mRNA level of PRL-R was analyzed for its correlation with serum concentration of PRL measured by immunoassay. PRL-R mRNA levels of lymphocytes were significantly suppressed in lactating mothers, while there was a statistically significant negative correlation between PRL-R mRNA and serum PRL levels. However, there was no significant difference of PRL-R mRNA in the pathological condition of outpatients with ovarian dysfunction and/or hyperprolactinemia. While a few investigators reported the extra-mammary regulation on PRL-R by PRL, our data suggest that the PRL-R levels of circulating lymphocytes could be down-regulated by the elevated serum levels of PRL and that pituitary PRL may participate in regulating the expression of PRL-R genes on cells of the human immune system, especially in physiological circumstances such as in the postpartum period.

[Radon therapy as a component of spa-and-resort treatment of patients with functional hyperprolactinemia]

A method for the treatment of patients with functional hypoprolactinemia attributable to adhesive processes in the small pelvis has been developed based on the use of radon therapy in combination with acupuncture. Inclusion of this approach in combined spa-and-resort therapy increases its overall effectiveness by 18-20%, facilitates correction of hypoprolactinemia, elimination of hypoluteinism, recovery of regular menstruations and fertility. Taken together, these effects substantially improve the patients' quality of life.

Gender effects on cardiac valvular function in hyperprolactinaemic patients receiving cabergoline: a retrospective study

BACKGROUND

Ergot-derived dopamine agonists are associated with increased risk of valvular dysfunction in Parkinson's disease. The risk of valvular disease associated with lower doses of cabergoline used to treat prolactinomas remains controversial.

OBJECTIVE

To determine whether there is an association of cabergoline and valvular function in patients with hyperprolactinaemia according to gender.

DESIGN

Case-record retrospective study.

SETTING

Outpatient neuroendocrine clinical centre at a tertiary care hospital.

STUDY PARTICIPANTS

One hundred patients (48 men and 52 women) with hyperprolactinaemia who had an echocardiogram while receiving cabergoline for at least 6 months.

CONTROLS

One hundred controls (48 men and 52 women) selected from Massachusetts general hospital (MGH) database of echocardiograms without clinically significant findings, matched to patients for age, gender, body mass index (BMI) and hypertension.

MAIN OUTCOME MEASURE

Echocardiogram.

RESULTS

There were no significant differences in valvular function in patients compared with controls. However, women patients had a higher prevalence of mild tricuspid regurgitation (TR) than female controls (15.4%vs. 1.9%, P = 0.03). Among men only, patients had more trace TR than controls (68.8%vs. 45.8%, P = 0.02). The mild valvular regurgitation in patients was not clinically significant and did not correlate with dose, duration or cumulative dose.

CONCLUSIONS

Overall cabergoline was not associated with valvulopathy. However, subdivided by gender, hyperprolactinaemic men and women had higher prevalence of trace or mild TR, respectively, compared with gender matched controls. There may be gender differences in valvular dysfunction associated with cabergoline. Longer term, larger studies are necessary to evaluate definitively an effect of cabergoline on valvular function in hyperprolactinaemic patients.

[Effect of hyperprolactinemia upon clinical symptoms of patients with polycystic ovary syndrome]

OBJECTIVE

To determine the effects of hyperprolactinemia (hyperPRL) upon the symptoms of patients with polycystic ovary syndrome (PCOS).

METHODS

Age, body mass index, levels of hormone, lipid, beta-cell function and family medical history of 224 women with PCOS and 30 women with hyperPRL + PCOS were compared.

RESULTS

Patients with hyperPRL + PCOS were younger to develop endocrine disturbances, an increased incidence of acne (64% vs 28% respectively), a high level of androstenedione (20 + or - 7 vs 13 + or - 5) nmol/L respectively and prolactine in serum (1492 + or - 1175 vs 367 + or - 164) mIU/L respectively; The PCOS patients were divided into the groups of hyperandrogenism PCOS and non-hyperandrogenism PCOS depending on the serum level of androgen. A higher level of T and A was found in serum in PRL-PCOS than non-hyperandrogenism patients and similar as hyperandrogenism PCOS patients. They had reduced ApoB (680 + or - 230 nmol/L vs 943 + or - 179 mmol/L respectively) and Lpa level (46 + or - 22 nmol/L vs 162 + or - 194 mmol/L respectively) and high HOMA-IR when compared with non-hyperandrogenism PCOS; Patients' sisters with hyperPRL + PCOS had a significantly greater incidence of acne, higher rates of infertility and PCOS when compared with PCOS patients. Levels of other hormones, metabolic profiles and other family histories did not differ between patients with PCOS and hyper-PRL+PCOS.

CONCLUSION

Patients with hyperPRL + PCOS develop the endocrine disturbances at a younger age, a greater incidence rate of acne, level of prolactin and androstenedione, they have reduced ApoB and increased HOMA-IR. Patients' sisters with hyperPRL + PCOS have significantly greater incidence of acne, higher rates of infertility and PCOS as when compared with PCOS patients.

Does pituitary stalk function improve with age?

Ectopic posterior pituitary hyperintensity on MRI is a common feature associated with growth hormone deficiency. The presence of at least some residual components of the pituitary stalk is necessary for adequate anterior pituitary function. Little is known about long-term change in pituitary function or MRI findings in patients with ectopic posterior pituitary and interrupted pituitary stalk. We describe a case of childhood growth hormone deficiency and hyperprolactinemia associated with absent pituitary stalk. As an adult, prolactin levels normalized and GH secretion improved associated with changes in MRI findings.

Sexual dysfunction in patients with hypothalamo-pituitary disorders

Four different studies of sexual problems and sexual dysfunction in patients with hypothalamo-pituitary disorders have been undertaken and data about the sex life of the patients have been correlated with diagnosis, tumour extension and pathology, endocrine insufficiency and pituitary hormone hypersecretion. In the first study 48 out of 53 (76.2%) adult males with pituitary tumours reported decreased or absent sexual desire. The corresponding figure in the second study was 29 out of 37 (78.4%) among adult males with pituitary tumours and hyperprolactinaemia. Twenty (31.7%) and 18 (48.6%) patients, respectively, reported decreased sexual desire as the first symptom of their tumour. A highly significant correlation between a decrease in serum testosterone and a decrease in sexual desire was found. Some males with normal serum testosterone but hyperprolactinaemia also reported decreased sexual desire. In the third study, 109 females (aged 20-60) with morphologically verified hypothalamo-pituitary disorders, 68 (62.4%) had noticed a decrease in sexual desire. This problem was registered for 53 (84.1%) out of the 63 women in this group who had hyperprolactinaemia but only in 15 (32.6%) out of the 46 women with normal serum prolactin (p less than 0.001). In the last study 48 women with well-defined hypothalamo-pituitary disorders underwent a comprehensive interview about sexual function and sexual appreciation. Thirty-eight (79.2%) of the women had developed a lack of or a considerable decrease in sexual desire. Problems with lubrication or orgasms were reported by 31 (64.6%) and 33 (68.7%) of the women, respectively. Preservation of normal menstrual pattern, age, and intrasellar tumour growth was correlated to normal sexual desire and function.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin alters the mechanisms of B cell tolerance induction

OBJECTIVE

Autoimmune diseases predominantly affect women, suggesting that female sex hormones may play a role in the pathogenesis of such diseases. We have previously shown that persistent mild-to-moderate elevations in serum prolactin levels induce a break in self tolerance in mice with a BALB/c genetic background. The aim of this study was to evaluate the effects of hyperprolactinemia on the mechanisms of B cell tolerance induction.

METHODS

Effects of prolactin on splenic B cell subsets were studied in female BALB/c mice. B cell receptor (BCR)-mediated apoptosis and proliferation of transitional B cells were analyzed by flow cytometry. Expression of apoptotic genes was examined by microarrays and real-time polymerase chain reaction analysis. B cells coexpressing kappa/lambda light chains were assessed by flow cytometry and immunohistochemistry. Activation status of transitional type 3 (T3) B cells was evaluated by BCR-induced calcium influx studies.

RESULTS

BCR-mediated apoptosis of the T1 B cell subset, a major checkpoint for negative selection of autoreactive specificities, was decreased in prolactin-treated mice. Microarray studies indicated that this event may be mediated by the prolactin-induced up-regulation of the antiapoptotic gene interferon-gamma receptor type II and down-regulation of the proapoptotic gene Trp63. Prolactin treatment also altered the amount of receptor editing, as indicated by the increased number of transitional B cells coexpressing kappa/lambda light chains. Additionally, hyperprolactinemia modified the level of B cell anergy by increasing the degree of BCR-induced calcium influx in the T3 B cells.

CONCLUSION

Persistently elevated serum prolactin levels interfere with B cell tolerance induction by impairing BCR-mediated clonal deletion, deregulating receptor editing, and decreasing the threshold for activation of anergic B cells, thereby promoting autoreactivity.

Effects of chronic intracerebral prolactin on the oxytocinergic and vasopressinergic system of virgin ovariectomized rats

Chronic intracerebroventricular (icv) infusion of prolactin (PRL) into the cerebral ventricles and mimicking central hyperprolactinemia in lactation has recently been shown to reduce anxiety and neuronal as well as neuroendocrine responses to acute stressor exposure. Here, we studied the effects of icv PRL on the activity of the oxytocin (OXT) and arginine vasopressin (AVP) systems of virgin female, ovariectomized, estradiol-substituted Wistar rats. Ovine PRL was delivered via osmotic minipumps at 0.01, 0.1 or 1 microg/h for 5 days. Under basal conditions, both plasma OXT and AVP concentrations were increased after chronic PRL treatment (1 microg/h). At hypothalamic level, this was accompanied by an increased c-fos and OXT mRNA expression within the supraoptic nucleus, the main source of plasma OXT, whereas AVP mRNA levels remained unchanged. No effect of PRL on c-fos or on nonapeptide mRNA expression was found in the hypothalamic paraventricular nucleus. Moreover, chronic PRL abolished the rise in plasma OXT induced by acute exposure to 30 min restraint stress in vehicle-treated rats. However, restraint stress did not significantly alter OXT or AVP mRNA expression in the hypothalamus of either vehicle- or PRL-treated animals. From these results we conclude that brain hyperprolactinemia alters the synthetic activity of OXT neurons and the secretory performance of OXT and AVP neurons within the hypothalamus, resulting in elevated plasma concentrations of both hormones under basal conditions. These changes are comparable to adaptations seen in the female peripartum period.

[Antipsychotics and hyperpolactinaemia: pathophysiology, clinical relevance, diagnosis and therapy]

Hyperprolactinaemia is a frequent but often neglected side effect of typical, but also of many atypical antipsychotics such as amisulpiride, risperidone or ziprasidone. Besides galactorrhoea, potential consequences are suppression of the hypothalamic-pituitary-gonadal axis with hypogonadism, sexual dysfunction, infertility and in women also irregularities of the menstrual cycle and amenorrhoea. Potential long term consequences are mainly osteopenia and osteoporosis with an enhanced risk of fractures. Hyperprolactinaemia, if not clearly caused by a prolactin inducing antipsychotic, should always be thoroughly investigated. Ideally, prolactin should be measured before starting a patient on a new antipsychotic. Furthermore, before neuroleptic treatment is begun, and also in regular intervals after that, patients should be asked about potential clinical signs of hyperprolactinaemia. Hyperprolactinaemia which is clearly due to antipsychotics but without clinical symptoms only requires regular controls of bone mineral density. However, if clinical symptoms occur, switching to a prolactin sparing antipsychotic may be necessary. In these cases fertility is often regained and the women concerned have to be informed about the enhanced risk of pregnancy and counselled regarding contraception. If switching is not possible, estradiol has to be substituted in women. Also in men with hypogonadism hormonesubstitution (with testosterone) is usually indicated. Generally hyperprolactinaemia in psychiatric patients should be taken more seriously in the future.

Evaluation of insulin sensitivity in hyperprolactinemic subjects by euglycemic hyperinsulinemic clamp technique

The background and aim of the study is to evaluate insulin sensitivity in hyperprolactinemic subjects via euglycemic hyperinsulinemic clamp technique. Sixteen hyperprolactinemic subjects and 12 healthy subjects were included in the study. HOMA-B and HOMA-IR values of groups were calculated. Euglycemic hyperinsulinemic clamp technique was performed in both groups, and the M value of the groups was defined. Mann-Whitney U and chi-square tests were used in statistical analysis. Basal insulin level of hyperprolactinemic patients were higher than the control group (6.85 +/- 4.68; 3.66 +/- 0.88 microU/ml respectively; P < 0.05). Mean HOMA-IR and HOMA-B values of patients were higher than control group (1.49 +/- 1.30; 0.78 +/- 0.27 respectively; P = 0.02 and 136.28 +/- 72.53; 64.77 +/- 23.31, respectively, P < 0.001). M values of the patients were statistically lower than the control group (5.64 +/- 2.36; 7.05 +/- 1.62 kg/mg/min respectively; P < 0.05). (1) Hyperprolactinemic patients were more insulin resistant than control subjects. (2) Insulin resistance in hyperprolactinemic patients is not associated with obesity or anthropometric parameters such as fat content, waist circumference and BMI.

The effects of hyperprolactinemia on bone and fat

Many patients with prolactin secreting pituitary tumors have decreased bone mineral. The bone loss is associated with an increase in bone resorption and is secondary to prolactin-induced hypogonadism. In both sexes trabecular bone in the spine and hip is more affected than cortical bone in the distal radius. Normalization of prolactin and restoration of gonadal function increases bone density but is not associated with normalization of bone mass. It is not known whether the bone loss in hyperprolactinemic subjects represents a failure to achieve peak bone mass or is due to accelerated bone loss. Despite low bone density hyperprolactinemic subjects do not demonstrate increased fractures. The association between prolactin, weight gain and obesity suggests that prolactin may also be a modulator of body composition and body weight. It is not known whether hyperprolactinemia associated weight gain is due to stimulation of lipogenesis or due to disruption of central nervous system dopaminergic tone. Hyperprolactinemia is also associated with insulin resistance and endothelial dysfunction which may improve after normalization of prolactin. The clinical significance of these findings and the precise role of prolactin in regulation of weight and metabolism remain to be elucidated.

Prolactin inhibition at the end of lactation programs for a central hypothyroidism in adult rat

Malnutrition during lactation is associated with hypoprolactinemia and failure in milk production. Adult rats whose mothers were malnourished presented higher body weight and serum tri-iodothyronine (T(3)). Maternal hypoprolactinemia at the end of lactation caused higher body weight in adult life, suggesting an association between maternal prolactin (PRL) level and programming of the offspring's adult body weight. Here, we studied the consequences of the maternal PRL inhibition at the end of lactation by bromocriptine (BRO) injection, a dopaminergic agonist, upon serum TSH and thyroid hormones, thyroid iodide uptake, liver mitochondrial alpha-glycerophosphate dehydrogenase (mGPD), liver and pituitary de-iodinase activities (D1 and/or D2), and in vitro post-TRH TSH release in the adult offspring. Wistar lactating rats were divided into BRO - injected with 1 mg/twice a day, daily for the last 3 days of lactation, and C - control, saline-injected with the same frequency. At 180 days of age, the offspring were injected with (125)I i.p. and after 2 h, they were killed. Adult animals whose mothers were treated with BRO at the end of lactation presented lower serum TSH (-51%), T(3) (-23%), and thyroxine (-21%), lower thyroid (125)I uptake (-41%), liver mGPD (-55%), and pituitary D2 (-51%) activities, without changes in the in vitro post-TRH TSH release. We show that maternal PRL suppression at the end of lactation programs a hypometabolic state in adulthood, in part due to a thyroid hypofunction, caused by a central hypothyroidism, probably due to decreased TRH secretion. We suggest that PRL during lactation can regulate the hypothalamus-pituitary-thyroid axis and programs its function.

Drugs and prolactin

Medications commonly cause hyperprolactinemia and their use must be differentiated from pathologic causes. The most common medications to cause hyperprolactinemia are the antipsychotic agents, although some of the newer atypical antipsychotics do not do so. Other medications causing hyperprolactinemia include antidepressants, antihypertensive agents, and drugs which increase bowel motility. Often, the medication-induced hyperprolactinemia is symptomatic, causing galactorrhea, menstrual disturbance, and erectile dysfunction. In the individual patient, it is important differentiate hyperprolactinemia due to a medication from a structural lesion in the hypothalamic-pituitary area. This can be done by stopping the medication temporarily to determine if the prolactin (PRL) levels return to normal, switching to another medication in the same class which does not cause hyperprolactinemia (in consultation with the patient's physician and/or psychiatrist), or by performing an MRI or CT scan. If the hyperprolactinemia is symptomatic, management strategies include switching to an alternative medication which does not cause hyperprolactinemia, using estrogen/testosterone replacement, or cautiously adding a dopamine agonist.

[Decreased bone mineral density in pre-menopause women with prolactinoma]

Tumoral hyperprolactinemia and consequent hypogonadism have been associated with osteoporosis. Bone mineral density (BMD) was measured by dual-energy RX absorptiometry in 24 patients with prolactinoma (15 macro and 9 micro adenomas; age range = 18 to 49 years). Student unpaired t or Mann-Whitney tests were used to compare groups, and Spearman test studied correlations. Lumbar spine (LS) was the most affected, as LS Z-score was < -2 SD in 20.83% of the patients. No difference was found in densitometric parameters for the comparison between macro and microprolactinoma, or those with normal prolactin versus hyperprolactinemia. LS BMD and LS Z-score were higher in the patients with > 8 menstrual cycles in the preceding year then in those with oligoamenorrhea (p = 0.030). The number of cycles was correlated to LS BMD (r = 0.515, p = 0.017) and body mass index to femoral neck BMD (r = 0.563, p = 0.006) and total femur BMD (r = 0.529, p = 0.011).

CONCLUSIONS

Decreased bone mineral density was detected in 20.83% of our young patients with prolactinoma. The great involvement of trabecular bone skeletal regions, such as vertebrae, suggests the participation of hypogonadism in the pathogenesis of bone disease. Irrespective of prolactin levels, return to normal menses seems the best index of good control.

Experimental estrogen-induced hyperprolactinemia results in bone-related hearing loss in the guinea pig

Our group (Horner KC, Guieu R, Magnan J, Chays A, Cazals Y. Neuropsychopharmacology 26: 135-138, 2002) has earlier described hyperprolactinemia in some patients presenting inner ear dysfunction. However, in that study, it was not possible to determine whether hyperprolactinemia was a cause or an effect of the symptoms. To investigate the effect of hyperprolactinemia on inner ear function, we first developed a model of hyperprolactinemia in estrogen-primed Fischer 344 rats and then performed functional studies on pigmented guinea pigs. Hyperprolactinemia induced, after 2 mo, a hearing loss of approximately 30-40 dB across all frequencies, as indicated by the compound action potential audiogram. During the 3rd mo, the hearing loss continued to deteriorate. The threshold shifts were more substantial in males than in females. Observations under a dissection microscope revealed bone dysmorphology of the bulla and the cochlea. Light microscopy observations of cryostat sections confirmed bone-related pathology of the bony cochlear bulla and the cochlear wall and revealed morphopathology of the stria vascularis and spiral ligament. Scanning electron microscopy revealed loss of hair cells and stereocilia damage, in particular in the upper three cochlear turns and the two outermost hair cell rows. The data provide the first evidence of otic capsule and hair cell pathology associated with estrogen-induced prolonged hyperprolactinemia and suggest that conditions such as pregnancy, anti-psychotic drug treatment, aging, and/or stress might lead to similar ear dysfunctions.

[Peculiatities of cerebral hemodynamics and brain bioelectric activuty in patients with hyperprolactinemia]

28 patients aged from 17 to 38 years old with non-tumor and tumor forms of hyperprolactinemia were examined to study the peculiarities of cerebral hemodynamics and brain electrobiological activity in hyperprolactinemia. The investigation revealed disturbances in cerebral structure activity at different levels of truncus cerebri in overwhelming majority of patients (86,8%). The investigation demonstrated pathologic process in the same structures of C.N.S. More significant changes in the character of electric activity of brain were revealed in the presence of macroadenoma. More permanently repeated symptoms of EEG changes were affections in the region of diencephalic structures of brain and striopallidal complex (of emotiogenic zones of brain), that may be conditioned by the rise of PRL level - one of the main factors in development of stress reaction.

[Expression of the enzymes of dopamine synthesis in non-dopaminergic neurons: functional significance and regulation]

Dopamine(DA), the most widely distributed in the nervous system and functionally important chemical signal, is synthesized in DA-ergic neurons from L-tyrosine by means of two enzymes, tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). Apart from the enzymes, specific DA transporter is an attribute of DA-ergic neurons. In the mid eighties of the last century, in addition to DA-ergic neurons, those expressing only one enzyme, TH or AADC, have been discovered. These "monoenzymatic" neurons occurred to be more numerous and more widely distributed in the brain compared to DA-ergic neurons that manifests their wide involvement to the brain functioning. It has been demonstrated that the monoenzymatic neurons expressing complementary enzymes of DA synthesis produce this neurotransmitter in cooperation. In this case, L-tyrosine is transformed to L-DOPA in TH containing neurons that is followed by L-DOPA release and uptake from the intercellular space to AADC containing neurons for DA synthesis. Moreover, the L-DOPA uptake to DA-ergic or serotoninergic neurons results either in the increase or the onset of DA synthesis in addition to serotonin, respectively. The expression of the enzymes of DA synthesis in non-dopaminergic neurons is one of the adaptive reactions serving to compensate the functional insufficiency of DA-ergic neurons. For instance, hyperprolactinemia and the deficiency of DA, prolactin-inhibiting hormone, which is developed under degeneration of DA-ergic neurons of the arcuate nucleus, are compensated with time due to the increase of the number of monoenzymatic neurons and cooperative synthesis of DA in the nucleus. It is supposed that the same compensatory cooperative synthesis of DA is turned on under the degeneration of DA-ergic neurons of the nigrostriatal system that is manifested by the appearance of non-dopaminergic neurons expressing enzymes of DA synthesis in the deafferentated striatum. The expression of the enzymes of DA synthesis in non-dopaminergic neurons is under the control by intercellular signals, catecholamines, neurotrophic (growth) factors and, perhaps, hormones. Thus, non-dopaminergic monoenzymatic neurons expressing enzymes of DA synthesis produce this neurotransmitter in cooperation that is a compensatory reaction under functional insufficiency of DA-ergic neurons, in neurodegenerative diseases, hyperprolactinemia and Parkinson's disease, in particular.

Assessment of prolactin secretion in children: a profile of circadian prolactin secretion and the principles for interpreting it

INTRODUCTION

Prolactin (Prl) is secreted in a circadian pattern, although no method of interpreting it has yet been established. The aim of the study was to assess Prl secretion in children on the basis of the Prl circadian profile and to establish principles for the interpretation of the results obtained by this method.

MATERIAL AND METHODS

The analysis comprised 41 healthy short children (25 boys); aged 5.2-16.3 years, in whom hormonal disorders and chronic diseases had been excluded. The children were divided into prepubertal or pubertal subgroups. Serum Prl concentrations were measured every 3 hours for 24 hours. To assess the rhythm the parameters of macroscopic analysis were calculated and receiver operating characteristic (ROC) analysis was performed. The group for comparison consisted of 30 children aged 8.9-17.2 years with hyperprolactinaemia.

RESULTS

In each subgroup significantly higher Prl concentrations were observed at night than by day. No statistical differences were noticed between the groups regarding Prl concentrations at particular time points or parameter values during circadian Prl rhythm evaluation. In the group analysed weak correlations were found between age and Prl peak and trough levels. On the basis of ROC analysis criteria for the existence of normal circadian Prl rhythm in children were established.

CONCLUSIONS

1. The presence of normal circadian Prl rhythm is observed if at least one of the following three criteria is fulfilled: amplitude >1.8779; X(n)/X(d) ratio >1.685; regression index <-0.4107. 2. No interpretation in relation to sex, age and stage of puberty is necessary for the circadian prolactin secretion rhythm in children.

Bone mineral density and bone turnover in hyperprolactinaemia of various origins

INTRODUCTION

Osteopenia and osteoporosis because of hyperprolactinaemia caused by prolactinoma may be followed by an increased risk of fracture. There are no data on the bone effects of functional hyperprolactinaemia. The aim was to assess the influence of hyperprolactinaemia of various origins on bone turnover and density in different skeletal sites.

MATERIAL AND METHODS

The study was carried out in 75 women (aged 30.53 +/- 7.8): Group I--32 women with prolactinoma and Group II--43 women with functional hyperprolactinaemia. Both groups of patients were subdivided into those with hypogonadism and those with normal gonadal function. The control group consisted of 29 healthy women aged (33.59 +/- 4.7). In all subjects PRL and bone turnover markers (BAP, OC, ICTP) were studied. BMD measurements (lumbar spine, forearm, proximal femur and total body) were carried out using DXA.

RESULTS

Higher PRL concentrations were observed in patients than in controls. The values of bone turnover markers (BAP, ICTP) were shown to be higher in patient groups and subgroups than in controls. In patients with prolactinoma lumbar spine BMD was lower than in patients with functional hyperprolactinaemia and controls. Total body BMD was also lower, albeit to a lesser extent.

CONCLUSIONS

Hyperprolactinaemia caused by prolactinoma in women influences bone metabolism unfavourably, more by the impact on the activity of bone turnover markers than on BMD. This provides an opportunity for earlier assessment of bone metabolism disturbances before the BMD changes can be observed. Functional hyperprolactinaemia does not determine such a harmful effect on bone metabolism as hyperprolactinemia due to prolactinoma.

The relationship between prolactin levels and glucose homeostasis in antipsychotic-treated schizophrenic patients

OBJECTIVES

To determine if prolactin levels are associated with glucose-insulin homeostasis in antipsychotic-treated patients with schizophrenia.

METHOD

Prolactin levels and glucose homeostasis (quantified using oral glucose tolerance testing, insulin measurement, and homeostasis model assessment) were measured in 15 patients with elevated prolactin levels secondary to antipsychotic treatment of schizophrenia (mean age, 30.4 years; SD, 5.3 years). The effect of reducing prolactin levels by switching patients' antipsychotic treatment to clozapine was ascertained by performing the measures before and after the switch to clozapine.

RESULTS

There was no significant correlation between prolactin and glucose-insulin measures at baseline. There was a large reduction in prolactin (593 mIU/L) after switching to clozapine, but this was not associated with changes in glucose-insulin measures.

CONCLUSIONS

Prolactin is not a significant determinant of glucose-insulin homeostasis in patients taking antipsychotics for schizophrenia. There was no benefit from lowering prolactin levels using clozapine. This could be because prolactin does not have a major effect on glucose homeostasis or that the effects of prolactin reduction are countered by clozapine.