Different Effects of Cabergoline and Bromocriptine on Metabolic and Cardiovascular Risk Factors in Patients with Elevated Prolactin Levels

Increased Cardiometabolic Risk in Men with Hypoprolactinemia: A Pilot Study

Low prolactin levels in men predispose them to mood disturbances, sexual dysfunction, and diabetes. The purpose of the current study was to assess cardiometabolic risk in males with hypoprolactinemia. This prospective study included three age-matched groups of young and middle-aged men: individuals with cabergoline-induced hypoprolactinemia (n = 15), cabergoline-treated subjects with prolactin levels within the reference range (n = 20), and untreated men with normal prolactin levels (n = 31). In men with hypoprolactinemia, the cabergoline dose was reduced in order to normalize prolactin concentration. Anthropometric parameters, blood pressure, QRISK3 score; plasma concentrations of prolactin, glucose, insulin, lipids, uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine, and testosterone; whole-blood levels of glycated hemoglobin (HbA1C); urinary albumin-to-creatinine ratio (UACR); and carotid intima-media thickness were assessed at baseline and six months later. Men with hypoprolactinemia were characterized by higher body mass index, fat content, waist circumference, systolic blood pressure, fasting and 2 h post-load glucose, HbA1C, HOMA1-IR, uric acid, hsCRP, fibrinogen, homocysteine, and UACR; by lower HDL cholesterol and testosterone; by greater intima-media thickness; and by a higher QRISK3 score than their peers with normal prolactin levels. There were no statistically significant differences in the measured parameters between both groups of men with normal prolactin levels. Normalization of prolactin concentration was accompanied by normalization of biochemical variables, systolic blood pressure, and QRISK3 score. Although cabergoline dose reduction did not cause statistically significant changes in the remaining anthropometric parameters and intima-media thickness, six months later, they did not differ from those observed in the remaining study groups. Our findings suggest that iatrogenic hypoprolactinemia is associated with increased cardiometabolic risk, which is reversible and resolves after the normalization of prolactin levels.

What do we know about abnormally low prolactin levels in polycystic ovary syndrome? A narrative review

Hyper and hypoprolactinemia seem to be related to the occurrence of metabolic alterations in PCOS patients. In contrast, between significantly elevated and significantly low, prolactin levels seem to be protective against metabolic consequences. In the present review, we found 4 studies investigating hypoprolactinemia in patients with PCOS. We also identified 6 additional studies that reported low levels of PRL in PCOS patients. Although its prevalence is not considered high (13.2-13.9%), its contribution is certainly significant to the metabolic alterations observed in PCOS (insulin resistance, obesity, diabetes mellitus, and fatty liver disease). Dopamine inhibits the secretion of prolactin and GnRH. If dopamine levels are low or the dopamine receptor is less expressed or mutated, the levels of prolactin and GnRH increase, and consequently, LH also increases. On the other hand, hyperprolactinemia, in prolactinomas-typical levels, acting through kisspeptin inhibition causes GnRH suppression and hypogonadotropic hypogonadism. In situations of hypoprolactinemia due to excessive dopamine agonist treatment, dosage reduction is important to minimize the decrease in prolactin levels. Nevertheless, there is a lack of prospective studies confirming these hypotheses, as well as randomized clinical trials with appropriate drugs targeting both hyperprolactin and hypoprolactin in patients with PCOS.

Dopamine 2 agonists for the management of type 2 diabetes: a systematic review and meta-analysis

Background

The Dopamine-2 receptor agonists, Bromocriptine and Cabergoline, were originally introduced for prolactinomas, pituitary tumors, and parkinson's disease but have glucose-lowering effects. This paper systematically reviewed the significance of their effects on lowering blood glucose level and conducted a comprehensive systematic search to identify relevant clinical trials of dopamine 2 agonists on glycated hemoglobin (HbA1c) and fasting blood sugar (FBS).

Method

We conducted a systematic review search in the databases (PubMed, Google Scholar, Cochrane Library, Registers, and Citations) until November 30, 2022, using the PRISMA 2020 statement. The Oxford quality score (Jadad score) was used to assess the study's quality. The present study protocol was registered on the PROSPERO database with ID: CRD42023389582. The study included studies with full abstracts, predefined doses, clear interventions, and blood glucose measurements.

Result

Data were synthesized from 23 clinical studies that recruited 6125 study subjects. The pooled effect analysis of the clinical trials revealed that dopamine 2 agonists improved HbA1c [SMD = -1.26; 95% CI (-1.60, -0.93), P < .00001], and FBS [SMD = -1.84; 95% CI (-2.61, -1.07), P < .00001]. Each drug's pooled effect analysis indicates bromocriptine significantly improved HbA1c [SMD = -1.25; 95% CI (-1.64, -0.87), P < .00001] and FBS [SMD = -1.90; 95% CI (-2.79, -1.01), P < .00001] and similarly, cabergoline significantly improved HbA1c [SMD = -1.29; 95% CI (-1.96, -0.62), P < .00001] and FBS [SMD = -1.62; 95% CI (-2.82, -0.41), P < .00001]. The pooled and individual analyses demonstrated that dopamine 2 agonists have a significant ability to lower blood glucose levels in clinical studies.

Conclusion

This study shows that dopamine 2 agonists significantly lowered FBS and HbA1c levels without causing severe negative effects. Even though the results are promising, additional research is necessary to establish the appropriate antihyperglycemic dosage, frequency of daily use, side effects, and potential product interactions when employing dopamine 2 receptor agonists for their antihyperglycemic effect.

Vitamin D Status Determines Cardiometabolic Effects of Cabergoline in Women with Elevated Prolactin Levels: A Pilot Study

Both hyperprolactinemia and vitamin D deficiency appear to be associated with increased cardiometabolic risk. This study aimed to determine whether vitamin D status influences the cardiometabolic effects of cabergoline. The study included three matched groups of women with mild to moderate hyperprolactinemia: vitamin D-naive subjects with vitamin D insufficiency (group A), women with vitamin D deficiency/insufficiency successfully treated with vitamin D (group B), and vitamin D-naive individuals with normal vitamin D status (group C). Plasma prolactin, 25-hydroxyvitamin D, estradiol, glucose homeostasis markers, lipids, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine, and uric acid, as well as the urinary albumin-to-creatinine ratio (UACR), were measured at study entry and after four months of cabergoline treatment. Although cabergoline reduced prolactin levels and increased estradiol levels in all study groups, the effect on prolactin was more pronounced in groups B and C compared to group A. In groups B and C, the drug enhanced glucose homeostasis, increased HDL-cholesterol, and decreased triglycerides, hsCRP, fibrinogen, homocysteine, uric acid, and UACR. In group A, only insulin resistance, hsCRP, and homocysteine were reduced by cabergoline. The effects on insulin sensitivity, HDL-cholesterol, triglycerides, hsCRP, fibrinogen, homocysteine, uric acid, and UACR were proportional to the decrease in prolactin and baseline levels of 25-hydroxyvitamin D. The obtained results suggest that vitamin D status determines cabergoline's cardiometabolic effects.

Cabergoline treatment promotes myocardial recovery in peripartum cardiomyopathy

AIMS

Peripartum cardiomyopathy (PPCM) is a rare heart disease, occurring in previously heart-healthy women during the last month of pregnancy or the first months after delivery due to left ventricular (LV) systolic dysfunction. A common pathomechanistic pathway of PPCM includes increased oxidative stress and the subsequent generation of a cleaved prolactin fragment (16 kDa PRL), which promotes the onset of heart failure (HF) in a microRNA (miR)-146a-dependent manner. Inhibition of prolactin secretion with the dopamine D2 receptor (D2R) agonist bromocriptine combined with standard HF therapy supports cardiac recovery. This study examined whether treatment with the more selective D2R agonist cabergoline prevents HF development in an experimental PPCM mouse model and might be used as an alternative treatment regime for PPCM.

METHODS AND RESULTS

Postpartum (PP) female PPCM-prone mice with a cardiomyocyte restricted STAT3-deficiency (αMHC-Cre^tg/+ ; Stat3^fl/fl ; CKO) were treated over two consecutive nursing periods with cabergoline (CKO Cab, 0.5 mg/kg/day) and were compared with bromocriptine treated CKO (CKO Br) and postpartum-matched WT and CKO mice. Cabergoline treatment in CKO PP mice preserved cardiac function [fractional shortening (FS): CKO Cab: 34.5 ± 9.4% vs. CKO: 22.1 ± 9%, P < 0.05] and prevented the development of cardiac hypertrophy, fibrosis, and inflammation as effective as bromocriptine therapy (FS: CKO Br: 33.4 ± 5.6%). The myocardial up-regulation of the PPCM biomarkers plasminogen inhibitor activator 1 (PAI-1) and miR-146a were prevented by both cabergoline and bromocriptine therapy. A small cohort of three PPCM patients from the German PPCM Registry was treated with cabergoline (1 mg per week for 2 weeks, followed by 0.5 mg per week for another 6 weeks) due to a temporary unavailability of bromocriptine. All PPCM patients initially presented with a severely reduced LV ejection fraction (LVEF: 26 ± 2%). However, at 6 months of follow-up, LV function (LVEF: 56 ± 2%) fully recovered in all three PPCM patients, and no adverse events were detected.

CONCLUSIONS

In the experimental PPCM mouse model, the selective D2R agonist cabergoline prevents the onset of postpartum HF similar to bromocriptine. In PPCM patients, cabergoline treatment was safe and effective as all patients fully recovered. Cabergoline might serve as a promising alternative to bromocriptine. However, these findings are based on experimental data and a small case series and thus have to be interpreted with caution and should be validated in a larger clinical trial.

Cardiometabolic profile of young women with hypoprolactinemia

PURPOSE

Unlike hyperprolactinemia, clinical significance of prolactin deficiency remains poorly understood. The aim of this study was to assess the cardiometabolic profile of patients with low prolactin levels.

METHODS

The study population consisted of three groups of young women. Two groups were chronically treated with cabergoline but differed in prolactin levels, which were either abnormally low (group A; n = 16) or within the reference range (group B, n = 23). Group C, serving as a control group, included 28 drug-naïve women with normal prolactin levels. The dose of cabergoline in group A was then tapered down. Glucose homeostasis markers, plasma lipids and circulating levels of hormones, uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen and homocysteine, as well as the carotid intima-media thickness were assessed at baseline and 6 months later.

RESULTS

Compared with subjects with normal prolactin levels, women with hypoprolactinemia had higher levels of 2-h postchallenge glucose, glycated hemoglobin, triglycerides, uric acid, hsCRP and fibrinogen, lower values of HDL-cholesterol, total testosterone and free androgen index, as well as reduced insulin sensitivity. No differences in these variables were observed between groups B and C. Apart from prolactin normalization, cabergoline dose reduction reversed all laboratory disturbances reported in group A.

CONCLUSION

The obtained results suggest that hypoprolactinemia in women of reproductive age may increase cardiometabolic risk.

Effects of Bromocriptine on Glucose and Insulin Dynamics in Normal and Insulin Dysregulated Horses

The objectives of the study were to study the effects of the synthetic ergot alkaloid (EA), bromocriptine, on glucose and lipid metabolism in insulin dysregulated (ID, n = 7) and non-ID (n = 8) mares. Horses were individually housed and fed timothy grass hay and two daily concentrate meals so that the total diet provided 120% of daily DE requirements for maintenance. All horses were given intramuscular bromocriptine injections (0.1 mg/kg BW) every 3 days for 14 days. Before and after 14 days of treatment horses underwent a combined glucose-insulin tolerance test (CGIT) to assess insulin sensitivity and a feed challenge (1 g starch/kg BW from whole oats) to evaluate postprandial glycemic and insulinemic responses. ID horses had higher basal plasma concentrations of insulin (P = 0.01) and triglycerides (P = 0.02), and lower concentrations of adiponectin (P = 0.05) compared with non-ID horses. The CGIT response curve showed that ID horses had slower glucose clearance rates (P = 0.02) resulting in a longer time in positive phase (P = 0.03) and had higher insulin concentrations at 75 min (P = 0.0002) compared with non-ID horses. Glucose (P = 0.02) and insulin (P = 0.04) responses to the feeding challenge were lower in non-ID compared to ID horses. Regardless of insulin status, bromocriptine administration increased hay intake (P = 0.03) and decreased grain (P < 0.0001) and total DE (P = 0.0002) intake. Bromocriptine treatment decreased plasma prolactin (P = 0.0002) and cholesterol (P = 0.10) and increased (P = 0.02) adiponectin concentrations in all horses. Moreover, in both groups of horses, bromocriptine decreased glucose clearance rates (P = 0.02), increased time in positive phase (P = 0.04) of the CGIT and increased insulin concentrations at 75 min (P = 0.001). The postprandial glycemic (P = 0.01) and insulinemic (P = 0.001) response following the oats meal was lower after bromocriptine treatment in all horses. In conclusion, in contrast to data in humans and rodents, bromocriptine treatment reduced insulin sensitivity in all horses, regardless of their insulin status. These results indicate that the physiological effects of EA might be different in horses compared to other species. Moreover, because bromocriptine shares a high degree of homology with natural EA, further investigation is warranted in horses grazing endophyte-infected grasses.

The interplay between prolactin and cardiovascular disease

Hyperprolactinemia can be caused by several conditions and its effects on the hypothalamic-pituitary-gonadal axis are understood in more detail. Nevertheless, in recent decades, other metabolic effects have been studied and data pointed to a potential increased cardiovascular disease (CVD) risk. A recent study showed a decrease in total and LDL- cholesterol only in men with prolactinoma treated with dopamine agonists (DA) supporting the previous results of a population study with increased CVD risk in men harboring prolactinoma. However, other population studies did not find a correlation between prolactin (PRL) levels and CVD risk or mortality. There is also data pointing to an increase in high-density lipoprotein levels, and decreases in triglycerides, carotid-intima-media thickness, C-reactive protein, and homocysteine levels in patients with prolactinoma on DA treatment. PRL was also implicated in endothelial dysfunction in pre and postmenopausal women. Withdrawal of DA resulted in negative changes in vascular parameters and an increase in plasma fibrinogen. It has been shown that PRL levels were positively correlated with blood pressure and inversely correlated with dilatation of the brachial artery and insulin sensitivity, increased homocysteine levels, and elevated D-dimer levels. Regarding possible mechanisms for the association between hyperprolactinemia and CVD risk, they include a possible direct effect of PRL, hypogonadism, and even effects of DA treatment, independently of changes in PRL levels. In conclusion, hyperprolactinemia seems to be associated with impaired endothelial function and DA treatment could improve CVD risk. More studies evaluating CVD risk in hyperprolactinemic patients are important to define a potential indication of treatment beyond hypogonadism.

Pilot study assessing the use of cabergoline for the treatment of cats with hypersomatotropism and diabetes mellitus

OBJECTIVES

An affordable and effective treatment is needed to manage feline hypersomatotropism. The aim of this study was to assess whether treatment with oral cabergoline for 90 days in cats with hypersomatotropism and diabetes mellitus improved diabetic and insulin-like growth factor 1 (IGF-1) control.

METHODS

This was a prospective cohort non-blinded pilot study enrolling client-owned cats with spontaneously occurring diabetes mellitus and hypersomatotropism. Cats received oral cabergoline (5-10 µg/kg q24h) for 90 consecutive days. Serum IGF-1 and fructosamine concentrations were measured on days 1, 30 and 90. Quality of life was determined using the DIAQoL-pet questionnaire on days 1 and 90.

RESULTS

Nine cats were enrolled and eight completed the study. There was no significant change in the following: IGF-1 (day 1 median 2001 ng/ml [range 890-2001 ng/ml]; day 30 median 2001 ng/ml [range 929-2001 ng/ml]; day 90 median 1828 ng/ml [range 1035-2001 ng/ml]; χ2(2) = 0.667, P = 0.805); fructosamine (day 1 median 499 µmol/l [range 330-887 µmol/l], day 30 median 551 µmol/l [range 288-722 µmol/l], day 90 median 503 [range 315-851 µmol/l]; χ2(2) = 0.581, P = 0.764); or DIAQoL-pet score (median on day 1 -2.79 [range -4.62 to -0.28], median on day 90 -3.24 [range -4.41 to -0.28]; P = 0.715). There was a significant change of insulin dose (χ2(2) = 8.667, P = 0.008) with cats receiving higher insulin doses at day 90 compared with day 1 (median on day 1 was 0.98 [range 0.63-1.49] and median on day 90 was 1.56 [range 0.49-2.55] units/kg q12h; P = 0.026).

CONCLUSIONS AND RELEVANCE

Cabergoline did not improve diabetic control or normalise insulin-like growth factor concentration, or improve patient quality of life.

The Interaction of Insulin and Pituitary Hormone Syndromes

Pituitary hormone axes modulate glucose metabolism and exert direct or indirect effects on insulin secretion and function. Cortisol and growth hormone are potent insulin-antagonistic hormones. Therefore impaired glucose tolerance, elevated fasting glucose concentrations and diabetes mellitus are frequent in Cushing's disease and acromegaly. Also prolactinomas, growth hormone (GH) deficiency, hypogonadism and hypothyroidism might be associated with impaired glucose homeostasis but usually to a lesser extent. Therefore glucose metabolism needs to be closely monitored and treated in patients with pituitary adenomas. Correction of the pituitary dysfunction is frequently followed by improvement of glucose homeostasis.

Cabergoline as an adjuvant to standard heart failure treatment in peripartum cardiomyopathy: A case report and review of the literature

Introduction

Peripartum cardiomyopathy (PPCM) is a rare and idiopathic form of dilated cardiomyopathy presenting late in pregnancy or early postpartum. Since the 16-kDa fragment of prolactin has been identified as a key factor in the pathophysiology of PPCM, prolactin inhibitors have been used as an adjuvant to standard heart failure treatment. Although bromocriptine is the current first choice, promising results have been reported with cabergoline, albeit scant.

Case Presentation

We presented the case of a 41-year-old woman who received a diagnosis of PPCM one week after delivery and was successfully treated with cabergoline, finally experiencing a complete recovery.

Conclusion

The case adds to the scant evidence supporting the use of cabergoline in PPCM patients. We argue that the favorable pharmacokinetic and metabolic profiles of this drug should prompt its consideration as a valid alternative prolactin inhibitor in these critical patients.

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Peripartum cardiomyopathy is a rare and life-threatening form of dilated cardiomyopathy.

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The management relies on the standard recommendations for heart failure with systolic dysfunction.

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The use of prolactin inhibitors represents the only specific and evidence-based treatment available.

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Given the favorable pharmacokinetics, cabergoline should be considered as the first-line prolactin inhibitor.

Sexual Functioning in Hyperprolactinemic Patients Treated With Cabergoline or Bromocriptine

BACKGROUND

Elevated prolactin levels were found to be associated with impaired sexuality.

STUDY QUESTION

The aim of the study was to compare the impact of bromocriptine and cabergoline on sexual functioning in both genders.

STUDY DESIGN

The study enrolled 39 young women and 18 young men receiving bromocriptine treatment. In 19 women and 8 men, because of poor tolerance, bromocriptine was replaced with cabergoline, whereas the remaining ones continued bromocriptine treatment.

MEASURES AND OUTCOMES

Apart from measuring serum levels of prolactin and insulin sensitivity, at the beginning of the study and 16 weeks later, all included patients completed questionnaires evaluating female or male sexual functioning (Female Sexual Function Index; International Index of Erectile Function-15).

RESULTS

Irrespective of the gender, posttreatment prolactin levels were lower in cabergoline-treated patients than in bromocriptine-treated patients. Baseline sexual functioning did not differ between patients well and poorly tolerating bromocriptine treatment. Neither in men nor in women receiving bromocriptine, posttreatment sexual functioning differed from baseline one. In both genders, cabergoline improved sexual desire. Moreover, in men, the drug improved erectile and orgasmic function, whereas in women, it improved sexual arousal. All these effects correlated with the impact of this drug on prolactin levels and on insulin sensitivity.

CONCLUSIONS

Cabergoline is superior to bromocriptine in affecting male and female sexual functioning and should be preferred in hyperprolactinemic men and women with sexual dysfunction.

Dopamine outside the brain: The eye, cardiovascular system and endocrine pancreas

Dopamine (DA) and DA receptors (DR) have been extensively studied in the central nervous system (CNS), but their role in the periphery is still poorly understood. Here we summarize data on DA and DRs in the eye, cardiovascular system and endocrine pancreas, three districts where DA and DA-related drugs have been studied and the expression of DR documented. In the eye, DA modulates ciliary blood flow and aqueous production, which impacts on intraocular pressure and glaucoma. In the cardiovascular system, DA increases blood pressure and heart activity, mostly through a stimulation of adrenoceptors, and induces vasodilatation in the renal circulation, possibly through D1R stimulation. In pancreatic islets, beta cells store DA and co-release it with insulin. D1R is mainly expressed in beta cells, where it stimulates insulin release, while D2R is expressed in both beta and delta cells (in the latter at higher level), where it inhibits, respectively, insulin and somatostatin release. The formation of D2R-somatostatin receptor 5 heteromers (documented in the CNS), might add complexity to the system. DA may exert both direct autocrine effects on beta cells, and indirect paracrine effects through delta cells and somatostatin. Bromocriptine, an FDA approved drug for diabetes, endowed with both D1R (antagonistic) and D2R (agonistic) actions, may exert complex effects, resulting from the integration of direct effects on beta cells and paracrine effects from delta cells. A full comprehension of peripheral DA signaling deserves further studies that may generate innovative therapeutic drugs to manage conditions such as glaucoma, cardiovascular diseases and diabetes.

Cardiometabolic Risk Factors in Men with Elevated Macroprolactin Content: A Pilot Study

BACKGROUND

Macroprolactinemia is a condition associated with the presence of large amounts of high molecular weight complexes of prolactin. Despite high prevalence, clinical significance of macroprolactin remains poorly understood.

OBJECTIVE

The aim of this study was to assess cardiometabolic risk in men with isolated macroprolactinemia.

METHODS

The study population included 11 men with isolated macroprolactinemia, 14 subjects with monomeric hyperprolactinemia and 14 men with prolactin levels within the reference range. Glucose homeostasis markers, plasma lipids, as well as plasma levels of uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine and 25-hydroxyvitamin D were determined in all included patients.

RESULTS

Compared to healthy counterparts, men with isolated macroprolactinemia had higher levels of 2-h postchallenge glucose, hsCRP and fibrinogen, lower levels of 25-hydroxyvitamin D and reduced insulin sensitivity. Patients with monomeric hyperprolactinemia were characterized by increased plasma levels of 2-h postchallenge glucose, triglycerides, uric acid, hsCRP, fibrinogen and homocysteine, reduced insulin sensitivity and decreased plasma concentrations of HDL cholesterol and 25-hydroxyvitamin D. Subjects with isolated macroprolactinemia differed from patients with monomeric hyperprolactinemia in postchallenge plasma glucose, insulin sensitivity, uric acid, hsCRP, fibrinogen, homocysteine and 25-hydroxyvitamin D. In men with monomeric hyperprolactinemia, uric acid, hsCRP, fibrinogen, homocysteine and 25-hydroxyvitamin D, while in men with elevated levels of macroprolactin, uric acid, hsCRP, fibrinogen and 25-hydroxyvitamin D correlated with a content of monomeric prolactin or macroprolactin, respectively, as well as with a degree of insulin sensitivity.

CONCLUSIONS

The obtained results suggest that macroprolactinemia may increase cardiometabolic risk but to a lesser extent than monomeric hyperprolactinemia.

Different Cabergoline Effect on Metabolic and Anthropometric Parameters in Female Prolactinoma Patients Versus Idiopathic Hyperprolactinemia Patients

BACKGROUND

Hyperprolactinemia can lead to weight gain, insulin resistance, abnormal glucose homeostasis and dyslipidemia. Reversibility of these changes after normalization of prolactin with dopamine agonists is still controversial and needs more clarification.

OBJECTIVE

We aimed to: 1) evaluate and compare metabolic and anthropometric profile in female with newly diagnosed prolactin-secreting adenoma versus female idiopathic hyperprolactinemic patients; 2) compare the effects of one year cabergoline therapy on the metabolic profile and anthropometric parameters (by using visceral adiposity index as index for evaluation of adipose tissue dysfunction) in females with prolactinoma to female idiopathic hyperprolactinemic patients.

PATIENTS AND METHODS

We enrolled 40 female patients with newly diagnosed prolactinoma and 40 female patients with idiopathic hyperprolactinemia, who were matched according to: age; weight; BMI; waist; and prolactin levels. We enrolled the participants in this study at the time of diagnosis before therapy and they were followed up for 12 months.

RESULTS

Cabergoline therapy had significant favorable effects on metabolic and anthropometric parameters, visceral adiposity index and in all patients (apart from HDLc in prolactinoma patients). Cabergoline therapy was significantly more effective in patient with idiopathic hyperprolactinemia than prolactinoma patients with regard to BMI, waist circumference, HDLc and visceral adiposity index despite normalization of prolactin levels in both groups.

CONCLUSION

12 months of Cabergoline treatment improved most of the anthropometric and metabolic parameters, and visceral adiposity index as a marker for adipose tissue dysfunction in both idiopathic hyperprolactinemia and prolactinoma patients. However, Cabergoline treatment was more effective in idiopathic hyperprolactinemic than prolactinoma patients.

Current Views on Dopaminergic Drugs Affecting Glucose Homeostasis

BACKGROUND

For more than three decades, it has been known that manipulation of dopaminergic system could affect glucose homesotasis in experimental animals. The notion that glucose homeostasis in human might be influenced by dopaminergic drugs has attracted a great deal of attention in the past two decades. In spite of rapid advancements in revealing involvement of dopaminergic neurotransmission in insulin release, glucose up-take and pancreatic beta cell function in general through centrally and peripherally controlled mechanisms, there are discrepancies among observations on experimental animals and human subjects.

CONCLUSION

With the expansion of pharmacotherapy in psychotic conditions, depression and endocrine abnormalities along with a sharp increase in prevalence of type two diabetes and disturbances of glucose homeostasis as a major risk factor for many cardiovascular complications and associated mortalities; it seems a critical analysis of recent investigations on drugs which act as agonists or antagonists of dopaminergic receptors in various tissues and organs may provide better insight into how safe and efficient these medicines could be prescribed. Furthermore, the other main objective of present review is to compare clinical data on significance of changes in blood glucose and insulin levels during short term and after long term treatment with these agents. This in turn would be beneficial for determining adequate strategies to combat or to avoid adverse effects associated with dopaminergic drug therapy.

Different Effects of Atorvastatin on Cardiometabolic Risk Factors in Young Women With and Without Hyperprolactinemia

Long-term prolactin excess is often accompanied by numerous metabolic complications. No previous study has compared the effect of statin therapy on circulating levels of cardiometabolic risk factors in patients with elevated and normal prolactin levels. The study population consisted of 3 age-, weight-, and lipid-matched groups of young women: 19 women with untreated hyperprolactinemia (group A), 20 normoprolactinemic women receiving bromocriptine treatment (because of previous hyperprolactinemia) (group B), and 20 untreated women with prolactin levels within the reference range (group C). Because of elevated total and low-density lipoprotein cholesterol levels, all women were then treated with atorvastatin (40 mg daily). Apart from measuring plasma lipids, glucose homeostasis markers, and hormone levels at the beginning of the study and 12 weeks later, we measured circulating levels of uric acid, high-sensitivity C-reactive protein, homocysteine, and fibrinogen. Despite similar baseline levels of plasma lipids, levels of uric acid, high-sensitivity C-reactive protein, homocysteine, and fibrinogen as well as the degree of insulin resistance were higher in group A than in the remaining 2 groups. Atorvastatin reduced total and low-density lipoprotein cholesterol levels in all study groups. However, only in normoprolactinemic women (groups B and C) did atorvastatin reduce circulating levels of nonlipid cardiometabolic risk factors, whereas only in group A did the drug slightly impair insulin sensitivity. The results of the study suggest that cardiometabolic effects of atorvastatin depend on the prolactin status of patients.

The effect of bromocriptine treatment on sexual functioning and depressive symptoms in women with mild hyperprolactinemia

BACKGROUND

Elevated prolactin levels are associated with sexual dysfunction in women. No previous study has investigated the effect of dopamine agonists on sexual functioning in women.

METHODS

The study enrolled 30 young women with mild hyperprolactinemia (serum prolactin levels in the range between 25 and 50ng/mL), 15 of whom were later treated with bromocriptine (5-10mg daily), as well as 14 age- and weight-matched healthy women. All women completed a questionnaire evaluating female sexual function (Female Sexual Function Index - FSFI) and a questionnaire evaluating the presence and severity of depressive symptoms (Beck Depression Inventory Second Edition - BDI-II).

RESULTS

Women with mild hyperprolactinemia had a lower total FSFI score, lower scores in all domains of sexual functioning (desire, arousal, lubrication, and dyspareunia), as well as a lower total BDI-II score than control women. Bromocriptine increased the FSFI score and tended to reduce BDI-II score. Moreover, the drug normalized desire, arousal, lubrication and dyspareunia, as well as improved orgasm and sexual satisfaction and this action correlated with changes in prolactin levels and an improvement in insulin sensitivity. No changes in sexual functioning and depressive symptoms were observed in untreated women with mild hyperprolactinemia and healthy controls.

CONCLUSIONS

Bromocriptine treatment improves female sexual functioning and slightly affects depressive symptoms in women with elevated prolactin levels and this effect is related to its prolactin-lowering and metabolic effects.

Prolactinoma through the female life cycle

Prolactinomas are the most common secretory pituitary adenoma. They typically occur in women in the 3rd-6th decade of life and rarely in the pediatric population or after menopause. Most women present with irregular menses and/or infertility. Dopamine (DA) agonists, used in their treatment, are safe during pregnancy, but in most cases are discontinued at conception with close monitoring for signs or symptoms of tumor growth. Breastfeeding is safe postpartum, provided there was no significant growth during pregnancy. Some women will experience normalization of prolactin levels postpartum. Menopause may also decrease prolactin levels and even those with macroprolactinomas may consider discontinuing their DA agonist with close follow-up. Prolactinomas may be associated with decreased quality of life scores in women, and play a role in bone health and cardiovascular risk factors. This review discusses the current literature and clinical understanding of prolactinomas throughout the entirety of the female life cycle.

A pilot study of cabergoline for the treatment of metastatic breast cancer

PURPOSE

The prolactin (PRL) receptor is over-expressed in breast cancer, and pre-clinical data indicate that it contributes to breast oncogenesis. Cabergoline is a potent dopamine receptor agonist of D2 receptors and has a direct inhibitory effect on pituitary PRL secretion.

METHODS

A phase II study of cabergoline in patients with metastatic breast cancer was conducted. The primary end point of the study was to determine the clinical benefit rate (CBR) at 2 months. Eligible patients had tumors of any receptor status with no limit of prior lines of therapy. Measurable and unmeasurable diseases were allowed. Cabergoline 1 mg orally, twice weekly (1 cycle = 4 weeks) was given until disease progression or unacceptable toxicity. PRL receptor immunohistochemical staining was performed on available baseline tumor tissue; serial serum PRL levels were assessed.

RESULTS

Twenty women were enrolled; 18 were evaluable for CBR. Tumor receptor status was distributed as follows: HR-any/HER2+ 2(10%), HR+/HER2- 18 (90%). The CBR was 33% (6/18), median progression free survival was 1.8 months, and median overall survival was 10.4 months. Two patients experienced disease control for over 12 months. Most common treatment-related adverse events were nausea (30%), fatigue (25%), and elevation in alkaline phosphatase (15%). Nine patients had baseline tissue for analysis; there was no association between baseline tumor PRL receptor expression and clinical benefit (p = 0.24). Change in serum PRL level and response were not correlated after 2 months of treatment (p = 0.64).

CONCLUSION

Cabergoline was well tolerated, and while the ORR was low, a small subset of patients experienced extended disease control.

Effects of bromocriptine mesylate on homocysteine and high-sensitivity C-reactive protein levels in patients with type-2 diabetes mellitus

Introduction: Quick release bromocriptine (BROM-QR), currently approved for glycemic control, reduces the risk of cardiovascular events in adults with type-2 diabetes mellitus (T2DM). This study evaluates the effect of BROM-QR on homocysteine (HOMC) and high sensitive C-reactive protein (hs-CRP), the biochemical markers of coronary atherosclerosis/inflammation, in patients with uncontrolled T2DM.

Methods: In this non-randomized, before-and-after clinical trial, patients with uncontrolled T2DM on stable doses of two oral hypoglycemic agents received BROM-QR for 6 months. The change in serum concentrations of HOMC was the primary endpoint. Anthropometric measurements such as body mass index (BMI) and waist circumference were measured at the baseline and at the completion of treatment along with fasting plasma glucose (FPG), HbA1c, total cholesterol, triglyceride, creatinine and hs-CRP. Multivariate regression analysis was performed to identify factors associated with changes in the levels of HOMC.

Results: In 64 patients (46 completed 6 months of treatment), age was 55±7 years and the duration of T2DM was 8.0 ± 4.4 years. On enrollment, mean HbA1c, FPG, hs-CRP and HOMC levels were 9.0± 1.3 percent, 184 ± 42 mg/dL, 3.8± 3.4 mg/dl and 10.8 ± 6.2 micromole/L; respectively. Mean decrease of 0.7 ± 1.1 percent for HbA1c (P = 0.001) and 22 ± 44 mg/dL for FPG was observed (P = 0.002). HOMC levels decreased to 8.5 ± 5.2 micromole/L (P = 0.011) while hs-CRP levels remained unchanged at 3.7 ± 2.9 mg/dL (P = 0.835).

Conclusion: While HOMC and HbA1c levels decreased significantly after 6 months of treatment with BROM-QR in patients with T2DM, serum levels of hs-CRP, total cholesterol and triglyceride did not significantly change.

The effect of fenofibrate on cardiometabolic risk factors in bromocriptine-treated women with mixed dyslipidemia: A pilot study

BACKGROUND

Elevated prolactin levels are associated with metabolic and hormonal complications. No previous study has investigated the effect of any fibrate on plasma levels of lipids and other cardiometabolic risk factors in patients receiving dopamine agonist therapy.

METHODS

The study included 36 premenopausal women with mixed dyslipidemia and slightly increased prolactin levels, 17 of whom had already been treated with bromocriptine (5.0-7.5mg daily). The included patients received micronized fenofibrate (200mg daily) for 6 months. Plasma lipids, glucose homeostasis markers, as well as plasma levels of prolactin, uric acid, high-sensitivity C-reactive protein (hsCRP), homocysteine and fibrinogen were determined before and after 12 weeks of fenofibrate therapy.

RESULTS

Insulin sensitivity was more expressed while baseline plasma levels of hsCRP and fibrinogen were lower in patients treated with bromocriptine than in women not receiving dopamine agonist therapy. Although fenofibrate improved plasma lipids and insulin sensitivity, as well as reduced plasma levels of the investigated cardiometabolic risk factors in both groups of patients, its action on HDL cholesterol, triglycerides, insulin sensitivity, hsCRP and fibrinogen was stronger in subjects receiving bromocriptine. Moreover, only in bromocriptine-naïve patients, fenofibrate increased plasma homocysteine.

CONCLUSIONS

Our study shows that the effect of fenofibrate on plasma lipids and circulating levels of cardiometabolic risk factors may be potentiated by bromocriptine treatment. They also suggest that hyperprolactinemic women with mixed dyslipidemia and early glucose metabolism abnormalities may receive the greatest benefits from concomitant treatment with a fibrate and bromocriptine.

The Effect of Atorvastatin on Cardiometabolic Risk Factors in Bromocriptine-Treated Premenopausal Women with Isolated Hypercholesterolemia

AIMS

Hyperprolactinemia is often associated with hyperinsulinemia, insulin resistance, atherogenic dyslipidemia, and subclinical atherosclerosis. Dopamine agonists were found to reduce the prevalence of metabolic syndrome and cardiometabolic risk. The aim of this study was to compare the effect of statin therapy on cardiovascular risk factors between patients treated with a dopamine agonist and patients treated with metformin.

METHODS

The study included two age-, weight-, lipid-, and prolactin level-matched groups of premenopausal women with hypecholesterolemia and a history of hyperprolactinemia: patients treated with bromocriptine (5.0-7.5 mg daily, n = 14) and subjects receiving metformin (1.7-2.55 g daily, n = 17). Plasma prolactin, lipids, glucose homeostasis markers, and plasma levels of cardiometabolic risk factors were assessed before and after 12 weeks of atorvastatin treatment.

RESULTS

Baseline levels of the investigated variables were similar in women treated with bromocriptine and metformin. Apart from lowering total and LDL cholesterol, atorvastatin decreased plasma levels of uric acid, hsCRP, homocysteine, and fibrinogen, with no difference between treatment groups.

CONCLUSIONS

The obtained results suggest that the effect of atorvastatin on plasma lipids and circulating levels of cardiometabolic risk factors does not differ between patients receiving bromocriptine and metformin. Bromocriptine-statin combination therapy may be an alternative to metformin-statin combination therapy in hypercholesterolemic patients with glucose metabolism abnormalities in whom metformin administration is either contraindicated or results in adverse effects.