The effects of hyperprolactinemia and its control on metabolic diseases

Polycystic Ovary Syndrome in the Context of Pituitary Adenomas: Prevalence, Pathophysiology and Clinical Management

OBJECTIVE

Many review articles have explored data regarding the coexistence of specific types of pituitary adenomas (PAs) and polycystic ovary syndrome (PCOS), particularly focusing on the potential pathogenesis of this intersection and overlapping features. However, a comprehensive evaluation encompassing the full spectrum of PAs and their association with PCOS remains lacking. This review aims to provide a broad assessment of the interactions between these entities, emphasizing pathophysiological mechanisms, clinical presentations, diagnostic challenges and therapeutic implications.

METHODS

A comprehensive literature search was conducted in the PubMed/MEDLINE database, focusing primarily on publications from the years 2000 to 2024, while also including seminal papers from the 1950s. The reference lists of selected articles were also manually searched. Inclusion criteria encompassed review articles, retrospective studies, clinical trials, case reports and meta-analyses providing data on the pathogenesis, clinical features, diagnostic challenges and therapeutic approaches related to PCOS and different PAs.

RESULTS

PCOS and functioning PAs often exhibit overlapping clinical features, complicating diagnosis and management. PCOS may precede and delay the diagnosis of growth hormone (GH)-secreting adenomas. The prevalence of PCOS or its features in acromegaly is influenced by disease activity, while approximating 13% in cases with controlled disease. Excess GH and insulin-like growth factor 1 (IGF-1) adversely affect ovarian function through direct pathways and by inducing insulin resistance, contributing to acromegaly-associated PCOS. In Cushing's syndrome (CS), findings consistent with PCOS may be present in 46% of patients, with cortisol excess contributing to menstrual dysfunction, hyperandrogenism and insulin resistance. While the prevalence of PCOS in patients with prolactinomas remains under-researched, recent studies indicate a 2.8%-10% prevalence of prolactinomas in PCOS. Elevated prolactin (PRL) levels in these patients may promote insulin resistance, further contributing to PCOS pathogenesis. Moreover, increased androgen bioavailability may be observed in all three aforementioned adenomas. To date, no studies have provided prevalence data for PCOS in other types of PAs.

CONCLUSIONS

Distinct clinical features, along with biochemical evaluations and imaging, can help differentiate the presence of both PAs and PCOS. Moreover, excluding other mimicking disorders is essential for an accurate diagnosis of PCOS. The persistence or recurrence of menstrual dysfunction, hyperandrogenism and metabolic disturbances in patients with controlled functioning adenomas may indicate a coexisting PCOS diagnosis. Timely diagnosis may optimize management and improve long-term outcomes for both conditions. Future studies should focus on investigating the clinical differences between patients with co-occurring PCOS and PAs compared to those with PCOS alone, ideally in larger cohorts, to better understand unique diagnostic and therapeutic considerations.

Cardiometabolic effects of hypoprolactinemia

The fall of PRL levels below the lower limit of the normal range configures the condition of hypoprolactinemia. Unlike PRL excess, whose clinical features and treatments are well established, hypoprolactinemia has been only recently described as a morbid entity requiring prompt identification and proper therapeutic approach. Particularly, hypoprolactinemia has been reported to be associated with the development of metabolic syndrome and impaired cardiometabolic health, as visceral obesity, insulin-resistance, diabetes mellitus, dyslipidaemia, chronic inflammation, and sexual dysfunction have been found more prevalent in patients with hypoprolactinemia as compared to those with normoprolactinemia. This evidence has been collected mainly in patients on chronic treatment with dopamine agonists for PRL excess due to a PRL-secreting pituitary tumour, and less frequently in those receiving the atypical antipsychotic aripiprazole. Nowadays, hypoprolactinemia appears to represent a novel and unexpected risk factor for cardiovascular diseases, as is the case for hyperprolactinemia. Nevertheless, current knowledge still lacks an accurate biochemical definition of hypoprolactinemia, since no clear PRL threshold has been established to rule in the diagnosis of PRL deficiency enabling early identification of those individual subjects with increased cardiovascular risk directly ascribable to the hormonal imbalance. The current review article focuses on the effects of hypoprolactinemia on the modulation of body weight, gluco-insulinemic and lipid profile, and provides latest knowledge about potential cardiovascular outcomes of hypoprolactinemia.

Effects of Prolactin Inhibition on Lipid Metabolism in Goats

Prolactin (PRL) has recently been found to play a role in lipid metabolism in addition to its traditional roles in lactation and reproduction. However, the effects of PRL on lipid metabolism in liver and adipose tissues are unclear. Therefore, we aimed to study the role of PRL on lipid metabolism in goats. Twenty healthy eleven-month-old Yanshan cashmere goats with similar body weights (BWs) were selected and randomly divided into a control (CON) group and a bromocriptine (BCR, a PRL inhibitor, 0.06 mg/kg, BW) group. The experiment lasted for 30 days. Blood was collected on the day before BCR treatment (day 0) and on the 15th and 30th days after BCR treatment (days 15 and 30). On day 30 of treatment, all goats were slaughtered to collect their liver, subcutaneous adipose, and perirenal adipose tissues. A portion of all collected tissues was stored in 4% paraformaldehyde for histological observation, and another portion was immediately stored in liquid nitrogen for RNA extraction. The PRL inhibition had inconclusive effects found on BW and average daily feed intake (ADFI) in goats (p > 0.05). PRL inhibition decreased the hormone-sensitive lipase (HSL) levels on day 30 (p < 0.05), but the effects were inconclusive on days 0 and 15. PRL inhibition had inconclusive effects found on total cholesterol (TCH), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), and acetyl-CoA carboxylase (ACC) on days 0, 15, and 30 (p > 0.05). Furthermore, hematoxylin-eosin (HE) staining of the liver, subcutaneous adipose, and perirenal adipose sections showed that PRL inhibition had inconclusive effects on the pathological changes in their histomorphology (p > 0.05), but measuring adipocytes showed that the area of perirenal adipocytes decreased in the BCR group (p < 0.05). The qPCR results showed that PRL inhibition increased the expression of PRL, long-form PRL receptor (LPRLR), and short-form PRL receptor (SPRLR) genes, as well as the expression of genes related to lipid metabolism, including sterol regulatory element binding transcription factor 1 (SREBF1); sterol regulatory element binding transcription factor 2 (SREBF2); acetyl-CoA carboxylase alpha (ACACA); fatty acid synthase (FASN); 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR); 7-dehydrocholesterol reductase (DHCR7); peroxisome proliferator-activated receptor gamma (PPARG); and lipase E, hormone-sensitive type (LIPE) in the liver (p < 0.05). In the subcutaneous adipose tissue, PRL inhibition increased SPRLR gene expression (p < 0.05) and decreased the expression of genes related to lipid metabolism, including SREBF1, SREBF2, ACACA, PPARG, and LIPE (p < 0.05). In the perirenal adipose tissue, the inhibition of PRL decreased the expression of the PRL, SREBF2, and HMGCR genes (p < 0.05). In conclusion, the inhibition of PRL decreases the serum HSL levels in cashmere goats; the effects of PRL on lipid metabolism are different in different tissues; and PRL affects lipid metabolic activity by regulating different PRLRs in liver and subcutaneous adipose tissues, as well as by decreasing the expression of the PRL, SREBF2, and HMGCR genes in perirenal adipose tissue.

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.

Dopamine in the regulation of glucose and lipid metabolism: a narrative review

OBJECTIVE

Owing to the global obesity epidemic, understanding the regulatory mechanisms of glucose and lipid metabolism has become increasingly important. The dopaminergic system, including dopamine, dopamine receptors, dopamine transporters, and other components, is involved in numerous physiological and pathological processes. However, the mechanism of action of the dopaminergic system in glucose and lipid metabolism is poorly understood. In this review, we examine the role of the dopaminergic system in glucose and lipid metabolism.

RESULTS

The dopaminergic system regulates glucose and lipid metabolism through several mechanisms. It regulates various activities at the central level, including appetite control and decision-making, which contribute to regulating body weight and energy metabolism. In the pituitary gland, dopamine inhibits prolactin production and promotes insulin secretion through dopamine receptor 2. Furthermore, it can influence various physiological components in the peripheral system, such as pancreatic β cells, glucagon-like peptide-1, adipocytes, hepatocytes, and muscle, by regulating insulin and glucagon secretion, glucose uptake and use, and fatty acid metabolism.

CONCLUSIONS

The role of dopamine in regulating glucose and lipid metabolism has significant implications for the physiology and pathogenesis of disease. The potential therapeutic value of dopamine lies in its effects on metabolic disorders.

Autoimmune Thyroiditis Mitigates the Effect of Metformin on Plasma Prolactin Concentration in Men with Drug-Induced Hyperprolactinemia

Metformin inhibits the secretory function of overactive anterior pituitary cells, including lactotropes. In women of childbearing age, this effect was absent if they had coexisting autoimmune (Hashimoto) thyroiditis. The current study was aimed at investigating whether autoimmune thyroiditis modulates the impact of metformin on the plasma prolactin concentration in men. This prospective cohort study included two groups of middle-aged or elderly men with drug-induced hyperprolactinemia, namely subjects with concomitant Hashimoto thyroiditis (group A) and subjects with normal thyroid function (group B), who were matched for baseline prolactin concentration and insulin sensitivity. Titers of thyroid peroxidase and thyroglobulin antibodies, levels of C-reactive protein, markers of glucose homeostasis, concentrations of pituitary hormones (prolactin, thyrotropin, gonadotropins, and adrenocorticotropic hormone), free thyroxine, free triiodothyronine, testosterone, and insulin growth factor-1 were measured before and six months after treatment with metformin. Both study groups differed in titers of both antibodies and concentrations of C-reactive protein. The drug reduced the total and monomeric prolactin concentration only in group B, and the impact on prolactin correlated with the improvement in insulin sensitivity and systemic inflammation. There were no differences between the follow-up and baseline levels of the remaining hormones. The results allow us to conclude that autoimmune thyroiditis mitigates the impact of metformin on prolactin secretion in men.

Dopamine D2 receptor antagonist counteracts hyperglycemia and insulin resistance in diet-induced obese male mice

Obesity leads to insulin resistance (IR) and type 2 diabetes. In humans, low levels of the hormone prolactin (PRL) correlate with IR, adipose tissue (AT) dysfunction, and increased prevalence of T2D. In obese rats, PRL treatment promotes insulin sensitivity and reduces visceral AT adipocyte hypertrophy. Here, we tested whether elevating PRL levels with the prokinetic and antipsychotic drug sulpiride, an antagonist of dopamine D2 receptors, improves metabolism in high fat diet (HFD)-induced obese male mice. Sulpiride treatment (30 days) reduced hyperglycemia, IR, and the serum and pancreatic levels of triglycerides in obese mice, reduced visceral and subcutaneous AT adipocyte hypertrophy, normalized markers of visceral AT function (PRL receptor, Glut4, insulin receptor and Hif-1α), and increased glycogen stores in skeletal muscle. However, the effects of sulpiride reducing hyperglycemia were also observed in obese prolactin receptor null mice. We conclude that sulpiride reduces obesity-induced hyperglycemia by mechanisms that are independent of prolactin/prolactin receptor activity. These findings support the therapeutic potential of sulpiride against metabolic dysfunction in obesity.

Metabolic and inflammatory parameters in relation to baseline characterization and treatment outcome in patients with prolactinoma: insights from a retrospective cohort study at a single tertiary center

Background

Prolactinomas (PRLs) are prevalent pituitary adenomas associated with metabolic changes and increased cardiovascular morbidity. This study examined clinical, endocrine, metabolic, and inflammatory profiles in PRL patients, aiming to identify potential prognostic markers.

Methods

The study comprised data from 59 PRL patients gathered in a registry at the University Hospital of Zurich. Diagnostic criteria included MRI findings and elevated serum prolactin levels. We assessed baseline and follow-up clinical demographics, metabolic markers, serum inflammation-based scores, and endocrine parameters. Treatment outcomes were evaluated based on prolactin normalization, tumor shrinkage, and cabergoline dosage.

Results

The PRL cohort exhibited a higher prevalence of overweight/obesity, prediabetes/diabetes mellitus, and dyslipidemia compared to the general population. Significant correlations were found between PRL characteristics and BMI, HbA1c, and fT4 levels. Follow-up data indicated decreases in tumor size, tumor volume, prolactin levels, and LDL-cholesterol, alongside increases in fT4 and sex hormones levels. No significant associations were observed between baseline parameters and tumor shrinkage at follow-up. A positive association was noted between PRL size/volume and the time to achieve prolactin normalization, and a negative association with baseline fT4 levels.

Conclusion

This study underscores the metabolic significance of PRL, with notable correlations between PRL parameters and metabolic indices. However, inflammatory markers were not significantly correlated with patient stratification or outcome prediction. These findings highlight the necessity for standardized follow-up protocols and further research into the metabolic pathogenesis in PRL patients.

Metabolic Syndrome Components in Patients with Pituitary Adenoma

Pituitary adenomas are benign tumors of the anterior portion of the pituitary gland (adenohypophysis), representing the 25% of all the tumor alterations. Pituitary adenomas are classified by the type of hormone secreted, cellularity, size, and structural alterations by the hormonal segregation. The diagnosis consists on the histopathological identification of cell types and the image-guided by magnetic resonance or tomography; the treatment can be both pharmacological and surgical. Metabolic Syndrome is the set of clinical conditions that increase the risk of cardiovascular diseases with an estimated prevalence of 25% worldwide. The alterations of metabolic syndrome are obesity, hypertension, dyslipidemia, insulin resistance, and diabetes mellitus type II. Pituitary adenomas and metabolic syndrome have an important relationship, hormone-secreting by pituitary adenomas affects a myriad of signaling pathways, which allows a favorable environment for the appearance of the metabolic syndrome. Moreover, patients with pituitary adenomas are shown to have an improvement in metabolic parameters after the medical/surgical treatment. The objective of this review is to explore the possible mechanisms through which PAs contributes to MetSx.

Low prolactin level identifies hypoactive sexual desire disorder women with a reduced inhibition profile

PURPOSE

Data on the role of prolactin (PRL) in the physiologic range in the female sexual response are scanty. We aimed at investigating the association between PRL and sexual function as assessed by the Female Sexual Function Index (FSFI). We explored the presence of a cut-off level of PRL able to identify Hypoactive Sexual Desire Disorder (HSDD).

METHODS

277 pre- and post-menopausal women consulting for Female Sexual Dysfunction (FSD) and sexually active were enrolled in an observational, retrospective study. 42 women were used as no-FSD controls. A clinical, biochemical and psychosexual evaluation was performed. The main outcome measures were: FSFI, Female Sexual Distress Scale-Revised, Middlesex Hospital Questionnaire and Sexual excitation/sexual inhibition scale (SIS/SES).

RESULTS

Normo-PRL FSD women (n = 264) showed lower FSFI Desire score than controls (n = 42), and higher than hyper-PRL FSD women (n = 13). These differences emerged both in pre-menopausal and post-menopausal subjects. In the normo-PRL FSD group, those with PRL in the higher quintile reported higher FSFI Desire scores than those with PRL in the lowest quintile. Women with HSDD presented a lower PRL level than those without (p = 0.032). A ROC curve analysis for PRL showed an accuracy of 0.610 ± 0.044 (p = 0.014) in predicting HSDD. With a threshold of < 9.83 μg/L, sensitivity and specificity for HSDD were 63% and 56%, respectively. Subjects with PRL < 9.83 μg/L also reported lower sexual inhibition (p = 0.006) and lower cortisol levels (p = 0.003) than those with PRL >  = 9.83 μg/L.

CONCLUSIONS

Hyper-PRL is associated with low desire; however, among normo-PRL FSD women, those with the lowest levels demonstrated a poorer desire than those with the highest levels. PRL < 9.83 μg/L predicted HSDD and a lower sexual inhibitory trait.

Association of prolactin with all-cause and cardiovascular mortality among patients with type 2 diabetes: a real-world study

AIMS

The association between prolactin and mortality has been less studied, and findings were inconsistent among different populations. We aimed to investigate the association between serum prolactin (PRL) and mortality among patients with type 2 diabetes.

METHODS AND RESULTS

We performed a retrospective cohort study of 10 907 patients with at least 2 prolactin measurements within 2 years since their first inpatient diagnosis of type 2 diabetes. Baseline and mean values of serum PRL were used as exposures. A multivariable-adjusted Cox proportional hazards model was used to estimate the association between PRL and mortality. During a mean follow-up of 5.34 years, 863 patients died, of whom 274 were due to cardiovascular events. Multivariable-adjusted hazard ratios (aHRs) based on different levels of baseline PRL (<100, 100-199, 200-299, and ≥300 mIU/L) were 1.00, 1.10 [95% confidence interval (CI), 0.90-1.36], 1.35 (95% CI 1.11-1.67), and 1.49 (95% CI 1.18-1.84) for all-cause mortality and 1.00, 1.24 (95% CI 0.86-1.81), 1.71 (95% CI 1.14-2.62), and 2.42 (95% CI 1.55-3.78) for cardiovascular mortality, respectively. Positive associations were also found when we used the mean values of PRL as the exposure. These associations were consistent among patients of different baseline characteristics. Further sensitivity analyses excluding patients with subclinical or clinical hypothyroidism at baseline and who died within the first 6 months since baseline demonstrated similar results.

CONCLUSIONS

A positive association between baseline PRL and mortality was observed among patients with type 2 diabetes. Prolactin may be considered a potential biomarker of mortality among patients with type 2 diabetes.

Impaired Prolactin-Lowering Effects of Metformin in Women with Polycystic Ovary Syndrome

The effect of metformin on prolactin concentration seems to be sex-dependent. The aim of this study was to determine whether the androgen status modulates the impact of metformin on plasma prolactin levels in women. This study included two matched groups of prediabetic women with hyperprolactinemia: 25 with PCOS and 25 control subjects with androgen levels within the reference range and with normal ovarian morphology. Glucose homeostasis markers, prolactin, the remaining anterior pituitary hormones, sex hormones, SHBG and IGF-1 were determined before and after six months of metformin treatment. At baseline, both groups differed in LH, LH/FSH ratio, testosterone, FAI, DHEA-S, androstenedione and estradiol. Although metformin improved insulin sensitivity and increased SHBG in both study groups, these effects were more pronounced in control subjects than in women with PCOS. In control subjects, the drug decreased total and monomeric prolactin and increased LH. In women with PCOS, metformin reduced LH, LH/FSH ratio, testosterone and FAI. In the control group, the impact on total and monomeric prolactin positively correlated with their baseline levels and with the degree of improvement in insulin sensitivity, as well as negatively correlated with testosterone and FAI. In women with PCOS, treatment-induced changes in testosterone and FAI positively correlated with the changes in LH and LH/FSH ratio. The obtained results suggest that the prolactin-lowering properties of metformin are less pronounced in women with coexisting PCOS than in women with elevated prolactin levels, probably owing to the increased production of endogenous testosterone.

Approach to the Patient With Prolactinoma

Prolactinomas are the most common pituitary tumor histotype, with microprolactinomas being prevalent in women and macroprolactinomas in men. Hyperprolactinemia is among the most common causes of hypogonadotropic hypogonadism in both sexes, prompting medical advice for hypogonadism (infertility, oligo-amenorrhea, impotence, osteoporosis/osteopenia) in both sexes, and for signs and symptoms of mass effects (hypopituitarism, visual loss, optic chiasm compression, cranial nerve deficits, headaches) predominantly in men. Diagnostic workup involves a single prolactin measurement and pituitary imaging, but some laboratory artifacts (ie, the "hook effect" and macroprolactin) can complicate or delay the diagnosis. The treatment of choice for prolactinomas is represented by dopamine agonists, mainly cabergoline, which are able to induce disease control, restore fertility in both sexes, and definitively cure one-third of patients, thus permitting treatment discontinuation. Pregnancy and menopause may promote spontaneous prolactin decline and anticipate cabergoline discontinuation in women. Surgery and/or radiotherapy are indicated in case of resistance to cabergoline not overcome by the increase in drug dose up to the maximally tolerated or the patient's personal choice of surgery. The evidence of resistance to cabergoline in invasive and proliferative tumors may indicate biological aggressiveness, thus requiring alternative therapeutic approaches mainly based on temozolomide use as monotherapy or combined with radiotherapy. In uncontrolled patients, new medical approaches (alternative hormonal treatments, cytotoxic drugs, peptide receptor radionuclide therapy, mTOR/Akt inhibitors, tyrosine kinase inhibitors, or immunotherapy) may be offered but the experience collected to date is still very scant. This article reviews different facets of prolactinomas and discusses approaches to the condition in more common clinical situations.

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.

Cardiometabolic Effects of Cabergoline and Combined Oral Contraceptive Pills in Young Women with Hyperprolactinemia: A Pilot Study

Although dopaminergic agents are the drugs of choice in treatment of prolactin excess, women who cannot be treated with these agents are recommended to receive estrogen preparations. The aim of this study was to compare cardiometabolic effects of both treatment options. The study population included three groups of young women. Subjects with mild-to-moderate hyperprolactinemia received either low-dose cabergoline or oral combined contraceptives (ethinyl estradiol plus desogestrel), while normoprolactinemic women were drug-naive. Plasma prolactin, glucose homeostasis markers, lipids, circulating levels of uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen and homocysteine, and the urinary albumin-to-creatinine ratio (UACR) were assessed at entry and six months later. Hyperprolactinemic women differed from normoprolactinemic ones in glucose homeostasis markers, high-density lipoprotein (HDL)-cholesterol, triglycerides, uric acid, hsCRP, fibrinogen, homocysteine and UACR. Cabergoline decreased total and monomeric prolactin levels, which was accompanied by normalization of glucose, insulin sensitivity, glycated hemoglobin, HDL-cholesterol, triglycerides, uric acid, hsCRP, fibrinogen, homocysteine and UACR. Despite a neutral effect on prolactin levels, combined contraceptives worsened insulin sensitivity and increased triglycerides, hsCRP, fibrinogen and UACR. At follow-up, cabergoline-treated women were characterized by a better cardiometabolic profile than women receiving ethinyl estradiol plus desogestrel. Our findings suggest that only cabergoline reduces cardiometabolic risk in young women with hyperprolactinemia.

Metabolic effects of dopamine-agonists treatment among patients with prolactinomas

PURPOSE

To evaluate the effect of cabergoline treatment on metabolic parameters including the Triglyceride-glucose (TyG) index in newly diagnosed patients with prolactinoma.

METHODS

71 consecutive nondiabetic patients with prolactinoma were enrolled. Anthropometric and laboratory tests including TyG index were measured at baseline, 3 and 6 months visits. Treatment with cabergoline at the dose of 0.25 mg twice weekly was started and increased according to prolactin levels and continued for 6 months.

RESULTS

At the baseline examination, the mean (SD) age, body mass index (BMI), waist circumference (WC), systolic blood pressure (SBP), and diastolic blood pressure (DBP) of patients were 36.2 (10.5) years, 29.2 (5.0) kg/m², 98.2 (13.7) cm, 115.3 (13.3) mmHg, and 71.4 (8.1) mmHg, respectively. Forty-one (57.7%) of patients were women and 46 (64.8%) had microadenoma. Cabergoline treatment significantly improved anthropometric and metabolic measures including BMI, WC, fasting plasma glucose, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, uric acid (only among women), TyG index, and hypogonadism. Blood pressure (both systolic and diastolic) levels remained steady except for a significant decrease in DBP after 6 months of treatment only among women. A declining trend in MetS prevalence was found from baseline to a 3-month evaluation in both genders which was statistically significant among men.

CONCLUSION

Short-term treatment with cabergoline can significantly improve cardiovascular risk factors except for blood pressure. Moreover, the TyG index as a surrogate marker of insulin resistance decreased significantly after the reduction of prolactin by treatment. Generally, results were similar among both genders.

Impaired Cardiometabolic Effects of Bromocriptine in Men With Early-Onset Androgenic Alopecia

Both hyperprolactinemia and early-onset androgenic alopecia are associated with increased cardiometabolic risk. The aim of this study was to assess whether early-onset male-pattern baldness modifies cardiometabolic effects of bromocriptine in men with prolactin excess. The study included 2 groups of men with prolactin excess: individuals with early-onset androgenic alopecia (group 1) and individuals with normal hair growth (group 2). Both groups were matched for age, smoking habits, body mass index, blood pressure, and prolactin levels. Over the entire study period (4 months), all participants were treated with bromocriptine (7.5 mg daily). Plasma levels of hormones (prolactin, total testosterone, and bioavailable testosterone), glucose homeostasis markers, lipids, uric acid, high-sensitivity C-reactive protein (hsCRP), fibrinogen, homocysteine, and the urinary albumin-to-creatinine ratio (UACR) were measured at the beginning and at the end of the study period. The two groups differed in total testosterone, bioavailable testosterone, insulin sensitivity, high-density lipoprotein (HDL) cholesterol, triglycerides, uric acid, hsCRP, fibrinogen, homocysteine, and UACR. In both groups, bromocriptine reduced prolactin, increased total and bioavailable testosterone, improved insulin sensitivity, and decreased uric acid, hsCRP, and homocysteine. The impact on prolactin, insulin sensitivity, uric acid, hsCRP, and homocysteine was stronger in group 2 than in group 1. Only in group 2 did the drug increase HDL cholesterol and decrease triglycerides, fibrinogen, and UACR. The impact on cardiometabolic risk factors correlated with a reduction in prolactin levels and an improvement in insulin sensitivity, and, in group 1, inversely correlated with testosterone levels. The obtained results suggest that men with early-onset androgenic alopecia are partially resistant to the cardiometabolic effects of bromocriptine.

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.

Epidemiological and clinical profiles of Saudi patients with hyperprolactinemia in a single tertiary care center

BACKGROUND

Prolactin is a hormone of the pituitary gland whose main function is the production of milk. Hyperprolactinemia is defined as an increase in prolactin levels above 25 μg/L in women and 20 μg/L in men. Causes of hyperprolactinemia include pituitary tumors, especially prolactinomas. Hyperprolactinemia can manifest clinically with a variety of symptoms, including galactorrhea and menstrual irregularities in women and erectile dysfunction in men. There are limited data on the epidemiology of hyperprolactinemia in the Middle East region.

OBJECTIVES

Description of the epidemiology and clinical features of hyperprolactinemia in a cohort from Saudi Arabia.

DESIGN

Medical record review SETTING: Tertiary medical center in Riyadh PATIENTS AND METHODS: The study included adult patients with hyperprolactinemia in King Abdulaziz Medical City in Riyadh. The patients were treated in endocrinology clinics from 2015 to 2019. Patients of both sexes older than 14 years were enrolled in the study. Patients with insufficient follow-up were excluded. Data were collected on demographic characteristics, symptoms, prolactin level, cause of high prolactin level, and treatment.

MAIN OUTCOME MEASURES

The frequency of different etiologies and symptoms in patients with hyperprolactinemia.

SAMPLE SIZE

295 patients RESULTS: The majority of patients with hyperprolactinemia were female 256 (86.8%). Hyperprolactinemia was diagnosed more frequently in patients in the age groups 21-30 years (42.6%) and 31-40 years (24.1%). The majority of the study population was obese or overweight: 136 (46.3%) and 74 (25.2%), respectively. Most of the cases were symptomatic (192, 65.1%). In women, the most common symptom was oligomenorrhea (35%). In men, infertility and erectile dysfunction were the most common clinical symptoms (50% and 44.7%, respectively). Idiopathic causes were the most common etiology (108, 36.6%), followed by pituitary adenomas (81, 27.5%). The majority of patients were treated (184,62.4%), with cabergoline being the most commonly used medication (173, 94.0%).

CONCLUSION

The demographic and clinical presentations and causes of hyperprolactinemia in male and female Saudi patients were similar to that in studies in other populations.

LIMITATIONS

Single-center retrospective chart review study.

CONFLICT OF INTEREST

None.

The Gender-Specific Association of DRD2 Polymorphism with Metabolic Syndrome in Patients with Schizophrenia

Background: Metabolic syndrome is widespread in patients with schizophrenia receiving long-term antipsychotic therapy. Dopamine D2 receptors play an important role in mediating both the therapeutic actions of antipsychotics and their side effects. The present study examined the association of two polymorphisms of the DRD2 gene with metabolic syndrome in patients with schizophrenia. Methods: We examined 517 patients from several regions of Siberia (Russia) with a clinical diagnosis of schizophrenia. Genotyping of two single nucleotide polymorphisms rs1799732 and rs4436578 of the dopamine D2 receptor gene (DRD2) was performed in a population of 471 patients. The results were analyzed using chi-square tests. Results: Functional polymorphism rs1799732 of the DRD2 gene is associated with drug-induced metabolic syndrome in women with schizophrenia. Conclusions: Our results show that the DRD2 gene may be involved in the pathogenesis of metabolic disorders in patients with schizophrenia. Further analysis of possible genetic markers will allow for personalized treatment with minimal side effects and optimal efficacy. This which seems relevant in light of the recent focus on improving the quality of life and ensuring a high level of social adaptation of patients with schizophrenia.

Recent findings on hyperprolactinemia and its pathological implications: a literature review

The prolactin hormone (PRL) is often secreted by lactotrophic cells of the anterior pituitary and has been shown to play a role in various biological processes, including breast feeding and reproduction. The predominant form of this hormone is the 23 kDa form and acts through its receptor (PRLR) on the cell membrane. This receptor is a member of the superfamily of hematopoietic/cytokine receptors. PRL also has a 16 kDa subunit with anti-angiogenic, proapoptotic, and anti-inflammatory effects which is produced by the proteolytic breakdown of this hormone under oxidative stress. Although the common side effects of hyperprolactinemia are exerted on the reproductive system, new studies have shown that hyperprolactinemia has a wide variety of effects, including playing a role in the development of autoimmune diseases and increasing the risk of cardiovascular disease, peripartum cardiomyopathy, and diabetes among others. The range of PRL functions is increasing with the discovery of multiple sites of PRL secretion as well as PRLR expression in various tissues. This review summarizes current knowledge of the biology of PRL and its receptor, as well as the role of PRL in human pathophysiology.

Association of Serum Prolactin With Type 2 Diabetes Mellitus: A Comparative Cross-Sectional Study From South India

BACKGROUND

 The association of serum prolactin (PRL) with diabetes is still uncertain, with a paucity of data in the south Indian population. This study aims to compare the serum PRL levels between type 2 diabetes mellitus (T2DM) patients and normoglycaemic volunteers and correlate the serum PRL level with fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated haemoglobin (HbA1c) levels, and the lipid profile in the study population.

METHODS

 This was a comparative cross-sectional study among 112 T2DM participants and 112 healthy volunteers in a tertiary care centre in India. All participants were tested for FPG, PPG, HbA1c, fasting serum lipid profile, and serum PRL, which were compared between T2DM patients and healthy volunteers.

RESULTS

 The serum PRL in T2DM patients was significantly lower compared to healthy volunteers (8.67 ± 4.37 vs. 13.76 ± 6.55 ng/ml, P < 0.001). FPG, PPG, and HbA1c correlated inversely with serum PRL in our study population. On multivariable logistic regression adjusted for age and sex, a higher serum PRL level within the physiological range was protective for T2DM (adjusted odds ratio: 0.83, 95% CI: 0.77-0.90, P < 0.001). Serum PRL levels were inversely correlated with serum total cholesterol, low-density lipoprotein cholesterol, and triglycerides, but not with high-density lipoprotein cholesterol.

CONCLUSIONS

A high serum PRL within the physiological range was inversely associated with the prevalence of T2DM in the south Indian population. Serum PRL also correlated inversely with glycaemic and blood lipid parameters. Larger longitudinal studies are required to further validate the association of serum PRL with various components of metabolic syndrome in the south Indian population.

Influence of antipsychotics on metabolic syndrome risk in patients with schizophrenia

OBJECTIVE

Many studies so far have shown that antipsychotic therapy may have an effect on the development of metabolic syndrome in patients diagnosed with schizophrenia. Our goal was to determine whether our respondents are at risk for developing metabolic syndrome and who is more predisposed to it.

METHODS

In a stable phase, 60 patients diagnosed with schizophrenia were equally divided into three groups according to the drug (risperidone, clozapine, and aripiprazole monotherapy). Control group had 20 healthy examinees. Patients were evaluated first using The Positive and Negative Syndrome Scale (PANSS). Prolactin, lipid status, glycemia, insulin, cytokine values (IL-33, TGF-β, and TNF-α) and C-reactive protein (CRP) were measured. Also, Body mass index (BMI), Homeostatic Model Assesment for Insulin Resistance (HOMA index), waist and hip circumference (WHR) and blood pressure (TA) measurement were performed in the study.

RESULTS

Patients treated with risperidone compared to healthy control subjects and aripiprazol group of patients had statistically significant difference in prolactin levels. In clozapine group compared to healthy control group values of HDL cholesterol and glucose level were statistically significant different. In aripiprazole group compared to healthy control group value of BMI was statistically significant different. Statistically significant correlations were found in TNF-α with glucose and HOMA index in risperidone treated patients and with BMI in clozapine group of patients; IL-33 with glucose in risperidone and with BMI in clozapine group of patients and TGF-β with glucose in risperidone group, with insulin and HOMA index in clozapine group and statistically significant negative correlation with LDL cholesterol in aripiprazole group of patients.

CONCLUSION

Patients on risperidone and clozapine therapy may be at greater risk of developing metabolic syndrome than patients treated with aripiprazole. Statistically significant difference in concentration of TNF-α and TGF-β was in the group of patients treated with risperidone compared to healthy control group.

J-Shaped Relationship Between Serum Prolactin and Metabolic-Associated Fatty Liver Disease in Female Patients With Type 2 Diabetes

BACKGROUND

Metabolic-associated fatty liver disease (MAFLD) has become a worldwide epidemic. Prolactin (PRL), a pituitary hormone, has been linked to MAFLD. As a result, we set out to look into the relationship between serum PRL and the risk of MAFLD in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 724 adults with T2DM were enrolled and categorized as MAFLD and non-MAFLD groups. Anthropometric data, biochemical parameters, and serum PRL levels were collected. Liver steatosis and fibrosis were assessed using FibroScan. Patients were stratified into normal PRL (NP) and high PRL (HP) groups and divided into four groups based on serum PRL quartiles. Multivariate logistic regression analysis was performed to evaluate the association between serum PRL and MAFLD risk.

RESULTS

Female but not male patients with MAFLD, liver steatosis, and fibrosis had significantly lower PRL levels in the NP group but higher PRL levels in the HP group than their counterparts. The proportions of MAFLD, liver steatosis, and fibrosis were significantly decreased in the NP group but increased in the HP group across the PRL quartiles in females but not in males. After multivariate adjustment, the adjusted ORs (AORs) and 95% CI for MAFLD among females were 18.165 (3.425-96.336), 1.784 (0.658-5.002), 1.744 (0.608-4.832), and 1.00 (reference) in the NP group (Q1-Q4, P-trend < 0.001) and 1.00 (reference), 11.098 (1.819-110.356), 15.225 (1.996-116.112), and 18.211 (2.579-128.568) in the HP group (Q1-Q4, P-trend = 0.020). Such associations were also found between serum PRL and liver fibrosis in females but not in males.

CONCLUSION

We observed a J-shaped association between serum PRL and the risk of MAFLD and liver fibrosis in females but not in males with T2DM, indicating that PRL may be relevant to MAFLD and its progression in a gender-specific manner.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry, number ChiCTR-OCS-12002381.

Metabolic effects of prolactin

Over the last years, the metabolic role of PRL has emerged. PRL excess is known to promote weight gain, obesity, metabolic syndrome, and impairment in gluco-insulinemic and lipid profiles, likely due to the suppression of physiologic dopaminergic tone. Prolactin receptors and dopamine receptors type 2 have been demonstrated to be expressed on both human pancreatic β- cell and adipocytes, supporting a key role of prolactin and dopamine in peripheral metabolic regulation. Medical treatment with the dopamine agonists bromocriptine and cabergoline has been demonstrated to decrease the prevalence of metabolic syndrome and obesity, and significantly improve gluco-insulinemic and lipid profiles. In hyperprolactinemic men with concomitant hypogonadism, correction of hyperprolactinaemia and testosterone replacement has been proven to restore metabolic impairment. In turn, low prolactin levels have also been demonstrated to exert a detrimental effect on weight gain, glucose and lipid metabolism, thus leading to an increased prevalence of metabolic syndrome. Therefore, PRL values ranging from 25 to 100 mg/L, in absence of other recognizable pathological causes, have been proposed to represent a physiological response to the request for an increase in metabolic activity, and nowadays classify the so-called HomeoFIT- PRL as a promoter of metabolic homeostasis. The current review focuses mainly on the effects of hyperprolactinemia and its control by medical treatment with DAs on the modulation of food intake, body weight, gluco-insulinemic and lipid profile. Furthermore, it provides the latest knowledge about the metabolic impact of hypoprolactinemia.

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.

Metabolic Effects of Clozapine Administration Based on Sex Differences and the Relationships Between Dosage and Prolactin Levels: An Observational Study

OBJECTIVE

Clozapine is the second-generation antipsychotic that induces the largest metabolic disorders. However, evidence is limited to the liabilities based on sex differences. This study aimed to investigate the effects of clozapine treatment on metabolic and neuroendocrine parameters, and the relationships between prescribed clozapine dosage and prolactin levels that may be associated with plasma clozapine concentrations, in 24 female and 24 male Japanese schizophrenia inpatients switched to clozapine.

METHODS

Within female and male subjects, sequential changes in 7 items of metabolic parameters, including anthropometric measurements, fasting serum lipid components and glucose levels, and estimated insulin resistance at 2 months were evaluated and analyzed against clozapine dosages and prolactin levels at 2 months.

RESULTS

Triglyceride levels, triglyceride to high-density lipoprotein ratios reflecting insulin resistance and glucose levels increased in female and male subjects. High-density lipoprotein cholesterol levels decreased in female and male subjects. High-density lipoprotein cholesterol levels were negatively correlated with prolactin levels in female subjects, and glucose levels were positively correlated with prolactin levels in male subjects, although clozapine doses showed no such correlations.

CONCLUSIONS

Clozapine administration developed sex-neutral metabolic disorders in the study subjects. Higher prolactin levels seemed to increase the risk of dyslipidemia and hyperglycemia with sex differences, which suggested that serum prolactin levels other than clozapine doses might be useful to predict sex-specific metabolic disorders. Further prospective studies, combining measurement of metabolic hormones and plasma concentrations of clozapine and its metabolites, will help to confirm our findings.

Prolactinomas

Hyperprolactinemia, defined by a level of serum prolactin above the standard upper limit of normal range, is a common finding in clinical practice and prolactinomas are the main pathological cause. Prolactinomas lead to signs and symptoms of hormone oversecretion, such as galactorrhea and hypogonadism, as well as symptoms of mass effect, including visual impairment, headaches and intracranial hypertension. Diagnosis involves prolactin measurement and sellar imaging, but several pitfalls are involved in this evaluation, which may difficult the proper management. Treatment is medical in the majority of cases, consisting of dopamine agonists, which present high response rates, with a very favorable safety profile. Major adverse effects that should be monitored consist of cardiac valvulopathy and impulse control disorders. Other treatment options include surgery and radiotherapy. Temozolomide may be used for aggressive or malignant carcinomas. Finally, pregnancy outcomes are similar to general population even when dopamine agonist treatment is maintained.

Hyperprolactinemia after menopause: Diagnosis and management

Most prolactinomas are diagnosed in women of reproductive age and are generally microadenomas. Prolactinomas diagnosed in postmenopausal women are less common and are not usually associated with the typical syndrome induced by prolactin excess, including infertility and oligo-amenorrhea. This implies that the diagnosis of prolactinomas after menopause may be delayed and require greater clinical effort. Limited data are available on the management and prognosis of prolactinomas in postmenopausal women. However, the physiologic decline of prolactin levels during menopause and the lack of fertility concerns, which represent specific indications for medical treatment with dopamine agonists, might require a careful reassessment of therapeutic management in such patients. Postmenopausal women with microprolactinoma may be successfully withdrawn from medical therapy with dopamine agonists, whereas in those with macroprolactinomas greater caution is advisable before dopamine agonists are discontinued, considering the potential, although rare, tumor enlargement. This review focuses on the diagnostic challenges and therapeutic management of prolactinomas in postmenopausal women.

Time-of-Day-Dependent Effects of Bromocriptine to Ameliorate Vascular Pathology and Metabolic Syndrome in SHR Rats Held on High Fat Diet

The treatment of type 2 diabetes patients with bromocriptine-QR, a unique, quick release micronized formulation of bromocriptine, improves glycemic control and reduces adverse cardiovascular events. While the improvement of glycemic control is largely the result of improved postprandial hepatic glucose metabolism and insulin action, the mechanisms underlying the drug's cardioprotective effects are less well defined. Bromocriptine is a sympatholytic dopamine agonist and reduces the elevated sympathetic tone, characteristic of metabolic syndrome and type 2 diabetes, which potentiates elevations of vascular oxidative/nitrosative stress, known to precipitate cardiovascular disease. Therefore, this study investigated the impact of bromocriptine treatment upon biomarkers of vascular oxidative/nitrosative stress (including the pro-oxidative/nitrosative stress enzymes of NADPH oxidase 4, inducible nitric oxide (iNOS), uncoupled endothelial nitric oxide synthase (eNOS), the pro-inflammatory/pro-oxidative marker GTP cyclohydrolase 1 (GTPCH 1), and the pro-vascular health enzyme, soluble guanylate cyclase (sGC) as well as the plasma level of thiobarbituric acid reactive substances (TBARS), a circulating marker of systemic oxidative stress), in hypertensive SHR rats held on a high fat diet to induce metabolic syndrome. Inasmuch as the central nervous system (CNS) dopaminergic activities both regulate and are regulated by CNS circadian pacemaker circuitry, this study also investigated the time-of-day-dependent effects of bromocriptine treatment (10 mg/kg/day at either 13 or 19 h after the onset of light (at the natural waking time or late during the activity period, respectively) among animals held on 14 h daily photoperiods for 16 days upon such vascular biomarkers of vascular redox state, several metabolic syndrome parameters, and mediobasal hypothalamic (MBH) mRNA expression levels of neuropeptides neuropeptide Y (NPY) and agouti-related protein (AgRP) which regulate the peripheral fuel metabolism and of mRNA expression of other MBH glial and neuronal cell genes that support such metabolism regulating neurons in this model system. Such bromocriptine treatment at ZT 13 improved (reduced) biomarkers of vascular oxidative/nitrosative stress including plasma TBARS level, aortic NADPH oxidase 4, iNOS and GTPCH 1 levels, and improved other markers of coupled eNOS function, including increased sGC protein level, relative to controls. However, bromocriptine treatment at ZT 19 produced no improvement in either coupled eNOS function or sGC protein level. Moreover, such ZT 13 bromocriptine treatment reduced several metabolic syndrome parameters including fasting insulin and leptin levels, as well as elevated systolic and diastolic blood pressure, insulin resistance, body fat store levels and liver fat content, however, such effects of ZT 19 bromocriptine treatment were largely absent versus control. Finally, ZT 13 bromocriptine treatment reduced MBH NPY and AgRP mRNA levels and mRNA levels of several MBH glial cell/neuronal genes that code for neuronal support/plasticity proteins (suggesting a shift in neuronal structure/function to a new metabolic control state) while ZT 19 treatment reduced only AgRP, not NPY, and was with very little effect on such MBH glial cell genes expression. These findings indicate that circadian-timed bromocriptine administration at the natural circadian peak of CNS dopaminergic activity (that is diminished in insulin resistant states), but not outside this daily time window when such CNS dopaminergic activity is naturally low, produces widespread improvements in biomarkers of vascular oxidative stress that are associated with the amelioration of metabolic syndrome and reductions in MBH neuropeptides and gene expressions known to facilitate metabolic syndrome. These results of such circadian-timed bromocriptine treatment upon vascular pathology provide potential mechanisms for the observed marked reductions in adverse cardiovascular events with circadian-timed bromocriptine-QR therapy (similarly timed to the onset of daily waking as in this study) of type 2 diabetes subjects and warrant further investigations into related mechanisms and the potential application of such intervention to prediabetes and metabolic syndrome patients as well.

Effects of Pituitary Surgery and High-Dose Cabergoline Therapy on Metabolic Profile in Patients With Prolactinoma Resistant to Conventional Cabergoline Treatment

OBJECTIVE

Control of prolactin excess is associated with the improvement in gluco-insulinemic and lipid profile. The current study aimed at investigating the effects of pituitary surgery and medical therapy with high dose cabergoline (≥2mg/week) on metabolic profile in patients with prolactinoma resistant to cabergoline conventional doses (<2mg/week).

DESIGN

Thirty-four patients (22 men, 12 women, aged 33.9 ± 12.5 years) with prolactinoma (4 microadenomas and 30 macroadenomas) were included in the present study. Among them 17 (50%) received pituitary surgery (PS, Group1) and 17 (50%) medical therapy with high dose cabergoline (Group 2).

METHODS

In the whole patient cohort, anthropometric (weight, BMI) and biochemical (fasting glucose and insulin, triglycerides, total, HDL and LDL-cholesterol, HOMA-IR, HOMA-β and ISI0) parameters were evaluated before and within 12 months after treatment.

RESULTS

In Group 1, prolactin (p=0.002), total cholesterol (p=0.012), and triglycerides (p=0.030) significantly decreased after pituitary surgery compared to the baseline. Prolactin significantly correlated with fasting glucose (r=0.056, p=0.025). In Group 2, fasting insulin (p=0.033), HOMA-β (p=0.011) and ISI0 (p=0.011) significantly improved compared to baseline. Postoperative cabergoline dose significantly correlated with Δfasting glucose (r=-0.556, p=0.039) and ΔLDL cholesterol (r=- 0.521, p=0.046), and was the best predictor of ΔLDL cholesterol (r^{2 =} 0.59, p=0.002) in Group 1.

CONCLUSIONS

The rapid decrease in PRL levels induced by PS might improve lipid metabolism, whereas HD-CAB might exert a beneficial impact on both insulin secretion and peripheral sensitivity, thus inducing a global metabolic improvement.

Comparative analysis of the influence of a high-fat/high-carbohydrate diet on the level of anxiety and neuromotor and cognitive functions in Wistar and DAT-KO rats

We compared anxiety, neuromotor, and cognitive functions in mutant rats with different allelic variants of dopamine transporter DAT knockout receiving balanced or excess in fat and fructose diet. The experiments were performed in DAT-/- homozygotes, DAT+/- heterozygotes, and DAT+/+ wild type rats. The genotype of DAT-KO rats was confirmed by restriction analysis of DAT gene compared to behavioral responses in the open field test (OF). Animals in the first groups of each strain were fed a balanced AIN93M diet; and those in the second groups with a high-fat/high-fructose diet. Neuromotor function was studied as grip strength, and behavioral responses were assessed in the elevated plus maze and conditioned passive avoidance response tests. The mass of the internal organs and white and brown fat, as well as selected lipid and nitrogen metabolism parameters in blood plasma were determined at the end of the experiment. DAT-/- had the highest specific grip strength, and showed an increase in initial exploratory activity in comparison with DAT+/- and DAT +/+. The exploratory activity was significantly reduced in the second test compared to the first one in DAT-/- and DAT+/- of first but not second group. Anxiety decreased with age in the second groups of DAT+/- and DAT+/+ (but not in DAT-/-) and was higher in DAT+/+ than in DAT+/- and DAT-/-. Excess fat and fructose resulted in the deterioration of short-term memory in DAT+/+. Lipidomic indices of blood plasma were less responsive to diet in DAT-/- and DAT-/+ in comparison to DAT+/+. The increased AsAT/AlAT activity ratio in DAT-/- compared with those in DAT+/+ suggests the activation of catabolism activity in the mutants. The consumption of excess fat and fructose significantly modified the effects produced by DAT gene allelic variants presumably due to the influence on the processes of dopamine metabolism.