Bromocriptine (Ergoset) reduces body weight and improves glucose tolerance in obese subjects

A Combination of a Dopamine Receptor 2 Agonist and a Kappa Opioid Receptor Antagonist Synergistically Reduces Weight in Diet-Induced Obese Rodents

As the global obesity rate increases, so does the urgency to find effective anti-obesity drugs. In the search for therapeutic targets, central nervous system (CNS) mechanisms engaged in the regulation of energy expenditure and food intake, such as the opioid and dopamine systems, are crucial. In this study, we examined the effect on body weight of two drugs: bromocriptine (BC), a D2R receptor agonist, and PF-04455242, a selective κ opioid receptor (KOR) antagonist. Using diet-induced obese (DIO) rats, we aimed to ascertain whether the administration of BC and PF-04455242, independently or in combination, could enhance body weight loss. Furthermore, the present work demonstrates that the peripheral coadministration of BC and PF-04455242 enhances the reduction of weight in DIO rats and leads to a decrease in adiposity in a food-intake-independent manner. These effects were based on heightened energy expenditure, particularly through the activation of brown adipose tissue (BAT) thermogenesis. Overall, our findings indicate that the combination of BC and PF-04455242 effectively induces body weight loss through increased energy expenditure by increasing thermogenic activity and highlight the importance of the combined use of drugs to combat obesity.

Effectiveness of pharmacotherapies for diabetes on nicotine, food, and water intake in insulin-resistant rats

The intersectionality between diabetes medications and nicotine consumption was assessed in female and male rats. Briefly, the rats were fed a high-fat diet (HFD) or regular diet (RD) for 4 weeks. Then separate groups received vehicle or a low dose of streptozotocin (STZ; 25 mg/kg). Three days later, insulin resistance was assessed by measuring plasma glucose levels for 180 min following an injection of insulin (0.75 U/kg). The rats were then prepared with jugular catheters, and they were given 23 h access to nicotine intravenous self-administration (IVSA) in 4 days cycles with 3 days of forced abstinence in their home cages where they consumed their respective diet. During the IVSA sessions, operant responses for food and water and changes in body weight were recorded. Prior to administration of the pharmacotherapies, the rats were given access to two doses of nicotine (0.015 then 0.03 mg/kg for the remainder of the study). Then, daily injections of the pharmacotherapies were given at the onset of dark cycle (6 p.m.) in the following order: 1) dapagliflozin (3.0 then 10.0 mg/kg), 2) insulin (0.75 U/kg twice), and 3) bromocriptine (3.0 then 10.0 mg/kg). The results suggest that our HFD+STZ regiment induced insulin resistance in female and male rats. Also, the HFD-fed rats displayed higher nicotine intake than RD controls, regardless of sex. Administration of insulin, but not dapagliflozin or bromocriptine, normalized nicotine intake in HFD-fed rats to control levels. These results have clinical implications regarding the potential efficacy of insulin to control excessive nicotine intake in persons with diabetes.

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.

Effect of bromocriptine on glycemic control, risk of cardiovascular diseases and weight in patients with type 2 diabetes: a systematic review

BACKGROUND

Type 2 diabetes (T2DM) patients, including those in good glycemic control, have an increased risk of cardiovascular disease (CVD). Maintaining good glycemic control with drugs may reduce long-term CVD risk. Bromocriptine has been in clinical use for over 30 years, but the utility of bromocriptine in the treatment of diabetes patients has been proposed more recently.

OBJECTIVE

To summarize the available data regarding the effect of bromocriptine in T2DM management.

METHOD

A systematic literature search was conducted in the electronic databases, including Google Scholar, PubMed, Medline, and Science Direct, to locate studies that meet the objectives of this systematic review. Additional articles were included by conducting direct Google searches of the references cited by eligible articles located by the database search. The following search terms were used on PubMed "bromocriptine OR dopamine agonist AND diabetes mellitus OR hyperglycemia OR obese".

RESULT

Eight studies were included in the final analysis. 6210 of the 9391 study participants received bromocriptine treatment, while 3183 received a placebo. The studies demonstrated that patients who took bromocriptine treatment had significantly reduced blood glucose and BMI, which is the main cardiovascular risk factor in T2DM patients.

CONCLUSION

Based on this systematic review, bromocriptine may be used for T2DM treatment for its cardiovascular risk reduction effect, especially body weight reduction. However, advanced study designs might be warranted.

Ectopic lipid metabolism in anterior pituitary dysfunction

Over the past decades, adapted lifestyle and dietary habits in industrialized countries have led to a progress of obesity and associated metabolic disorders. Concomitant insulin resistance and derangements in lipid metabolism foster the deposition of excess lipids in organs and tissues with limited capacity of physiologic lipid storage. In organs pivotal for systemic metabolic homeostasis, this ectopic lipid content disturbs metabolic action, thereby promotes the progression of metabolic disease, and inherits a risk for cardiometabolic complications. Pituitary hormone syndromes are commonly associated with metabolic diseases. However, the impact on subcutaneous, visceral, and ectopic fat stores between disorders and their underlying hormonal axes is rather different, and the underlying pathophysiological pathways remain largely unknown. Pituitary disorders might influence ectopic lipid deposition indirectly by modulating lipid metabolism and insulin sensitivity, but also directly by organ specific hormonal effects on energy metabolism. In this review, we aim to I) provide information about the impact of pituitary disorders on ectopic fat stores, II) and to present up-to-date knowledge on potential pathophysiological mechanisms of hormone action in ectopic lipid metabolism.

AGA Clinical Practice Guideline on Pharmacological Interventions for Adults With Obesity

BACKGROUND & AIMS

Pharmacological management of obesity improves outcomes and decreases the risk of obesity-related complications. This American Gastroenterological Association guideline is intended to support practitioners in decisions about pharmacological interventions for overweight and obesity.

METHODS

A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation framework to prioritize clinical questions, identify patient-centered outcomes, and conduct an evidence synthesis of the following agents: semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate extended-release (ER), naltrexone-bupropion ER, orlistat, phentermine, diethylpropion, and Gelesis100 oral superabsorbent hydrogel. The guideline panel used the evidence-to-decision framework to develop recommendations for the pharmacological management of obesity and provided implementation considerations for clinical practice.

RESULTS

The guideline panel made 9 recommendations. The panel strongly recommended the use of pharmacotherapy in addition to lifestyle intervention in adults with overweight and obesity (body mass index ≥30 kg/m2, or ≥27 kg/m2 with weight-related complications) who have an inadequate response to lifestyle interventions. The panel suggested the use of semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate ER, and naltrexone-bupropion ER (based on moderate certainty evidence), and phentermine and diethylpropion (based on low certainty evidence), for long-term management of overweight and obesity. The guideline panel suggested against the use of orlistat. The panel identified the use of Gelesis100 oral superabsorbent hydrogel as a knowledge gap.

CONCLUSIONS

In adults with overweight and obesity who have an inadequate response to lifestyle interventions alone, long-term pharmacological therapy is recommended, with multiple effective and safe treatment options.

Therapeutic potential of dopamine agonists in the treatment of type 2 diabetes mellitus

Diabetes is a global health concern that has affected almost 415 million people globally. Bromocriptine is a dopamine D2 agonist, which is a Food and Drug Administration (FDA)-approved drug to treat type 2 diabetes mellitus (T2DM) patients. However, it is considered that a novel treatment therapy is required which can be used in the treatment of diabetes with or without other antidiabetic agents. Dopamine agonists are usually used in neurological disorders like Parkinson's disease (PD), restless leg syndrome, and hyperprolactinemia. However, dopamine agonists including bromocriptine and cabergoline are also effective in reducing the glycemic level in T2DM patients. Bromocriptine was formerly used for the treatment of PD, hyperprolactinemia, and restless leg syndrome, but now it is used for improving glycemic levels as well as reducing free fatty acids and triglycerides. In addition, cabergoline has been found to be effective in glycemic control, but this drug is yet to be approved by the FDA due to its limitations and lack of study. Findings of the clinical trials of bromocriptine have suggested that it reduces almost 0.4-0.8% glycated hemoglobin and cardiovascular risk by 40% in insulin-resistant patients. Moreover, the safe use of bromocriptine in obese T2DM patients makes it a more attractive option as it causes weight loss. Indeed, bromocriptine is a novel therapy for T2DM patients, as its mechanism of action is unique in T2DM patients with minimal adverse effects. This review summarizes the potential of dopamine agonists in the treatment of T2DM.

Diabetes mellitus and Parkinson's disease: dangerous liaisons between insulin and dopamine

The relationship between diabetes mellitus and Parkinson's disease has been described in several epidemiological studies over the 1960s to date. Molecular studies have shown the possible functional link between insulin and dopamine, as there is strong evidence demonstrating the action of dopamine in pancreatic islets, as well as the insulin effects on feeding and cognition through central nervous system mechanism, largely independent of glucose utilization. Therapies used for the treatment of type 2 diabetes mellitus appear to be promising candidates for symptomatic and/or disease-modifying action in neurodegenerative diseases including Parkinson's disease, while an old dopamine agonist, bromocriptine, has been repositioned for the type 2 diabetes mellitus treatment. This review will aim at reappraising the different studies that have highlighted the dangerous liaisons between diabetes mellitus and Parkinson's disease.

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.

Whole-brain activation signatures of weight-lowering drugs

OBJECTIVE

The development of effective anti-obesity therapeutics relies heavily on the ability to target specific brain homeostatic and hedonic mechanisms controlling body weight. To obtain further insight into neurocircuits recruited by anti-obesity drug treatment, the present study aimed to determine whole-brain activation signatures of six different weight-lowering drug classes.

METHODS

Chow-fed C57BL/6J mice (n = 8 per group) received acute treatment with lorcaserin (7 mg/kg; i.p.), rimonabant (10 mg/kg; i.p.), bromocriptine (10 mg/kg; i.p.), sibutramine (10 mg/kg; p.o.), semaglutide (0.04 mg/kg; s.c.) or setmelanotide (4 mg/kg; s.c.). Brains were sampled two hours post-dosing and whole-brain neuronal activation patterns were analysed at single-cell resolution using c-Fos immunohistochemistry and automated quantitative three-dimensional (3D) imaging.

RESULTS

The whole-brain analysis comprised 308 atlas-defined mouse brain areas. To enable fast and efficient data mining, a web-based 3D imaging data viewer was developed. All weight-lowering drugs demonstrated brain-wide responses with notable similarities in c-Fos expression signatures. Overlapping c-Fos responses were detected in discrete homeostatic and non-homeostatic feeding centres located in the dorsal vagal complex and hypothalamus with concurrent activation of several limbic structures as well as the dopaminergic system.

CONCLUSIONS

Whole-brain c-Fos expression signatures of various weight-lowering drug classes point to a discrete set of brain regions and neurocircuits which could represent key neuroanatomical targets for future anti-obesity therapeutics.

Association Between Prolactinoma and Body Mass Index

OBJECTIVE

Obesity is increasing worldwide, and certain endocrine disorders may contribute to weight gain. While several studies have examined the association between weight gain and prolactinomas, the results are conflicting. Therefore, this study aimed to determine if body mass index (BMI) is higher among those with prolactinomas than those without.

METHODS

We identified patients ≥18 years of age referred to an endocrine clinic between 2008 and 2018 with newly diagnosed prolactinomas. We extracted the relevant information, and comparative data was obtained from the 2015-2016 National Health and Nutrition Examination Survey.

RESULTS

In total, 34 cases met the inclusion criteria. One third of the patients described weight gain at presentation. Those with prolactinomas had a significantly higher BMI than the National Health and Nutrition Examination Survey population (median BMI, 29.8 kg/m² vs 28.3 kg/m², P = .0048). When stratified by sex, only men with prolactinomas had an increased BMI compared with the controls. Moreover, those with prolactinomas had a higher prevalence of class II obesity (BMI ≥ 35 kg/m²) than the survey population (35% vs 18%, P = .01). Among the prolactinoma patients, a correlation was observed between BMI and log-transformed prolactin levels (R² = 0.4, P = .0002).

CONCLUSION

Weight gain can be a presenting symptom for patients with newly diagnosed prolactinomas. Those with prolactinomas have a higher BMI and an increased prevalence of class II obesity. These findings suggest that patients should be counseled regarding weight issues related to prolactinomas at presentation and should be a consideration in the investigative and treatment algorithm of prolactinomas.

Impact of Brain Insulin Signaling on Dopamine Function, Food Intake, Reward, and Emotional Behavior

PURPOSE OF REVIEW

Dietary obesity is primarily attributed to an imbalance between food intake and energy expenditure. Adherence to lifestyle interventions reducing weight is typically low. As a result, obesity becomes a chronic state with increased co-morbidities such as insulin resistance and diabetes. We review the effects of brain insulin action and dopaminergic signal transmission on food intake, reward, and mood as well as potential modulations of these systems to counteract the obesity epidemic.

RECENT FINDINGS

Central insulin and dopamine action are interlinked and impact on food intake, reward, and mood. Brain insulin resistance causes hyperphagia, anxiety, and depressive-like behavior and compromises the dopaminergic system. Such effects can induce reduced compliance to medical treatment. Insulin receptor sensitization and dopamine receptor agonists show attenuation of obesity and improvement of mental health in rodents and humans. Modulating brain insulin and dopamine signaling in obese patients can potentially improve therapeutic outcomes.

Dopamine D2 receptor signaling modulates pancreatic beta cell circadian rhythms

Antipsychotic drugs (APD) have clinically important, adverse effects on metabolism that limit their therapeutic utility. Pancreatic beta cells produce dopamine and express the D₂ dopamine receptor (D2R). As D2R antagonists, APDs alter glucose-stimulated insulin secretion, indicating that dopamine likely plays a role in APD-induced metabolic dysfunction. Insulin secretion from beta cells is also modulated by the circadian clock. Disturbed circadian rhythms cause metabolic disturbances similar to those observed in APD-treated subjects. Given the importance of dopamine and circadian rhythms for beta cells, we hypothesized that the beta cell dopamine system and circadian clock interact and dually regulate insulin secretion, and that circadian manipulations may alter the metabolic impact of APDs. We measured circadian rhythms, insulin release, and the impact of dopamine upon these processes in beta cells using bioluminescent reporters. We then assessed the impact of circadian timing on weight gain and metabolic outcomes in mice treated with the APD sulpiride at the onset of light or dark. We found that molecular components of the dopamine system were rhythmically expressed in beta cells. D2R stimulation by endogenous dopamine or the agonist bromocriptine reduced circadian rhythm amplitude, and altered the temporal profile of insulin secretion. Sulpiride caused greater weight gain and hyperinsulinemia in mice when given in the dark phase compared to the light phase. D2R-acting drugs affect circadian-dopamine interactions and modulate beta cell metabolic function. These findings identify circadian timing as a novel and important mechanism underlying APD-induced metabolic dysfunction, offering new possibilities for therapeutic interventions.

Bromocriptine improves glucose tolerance independent of circadian timing, prolactin, or the melanocortin-4 receptor

Bromocriptine, a dopamine D2 receptor agonist originally used for the treatment of hyperprolactinemia, is largely successful in reducing hyperglycemia and improving glucose tolerance in type 2 diabetics. However, the mechanism behind bromocriptine's effect on glucose intolerance is unclear. Here, we tested three hypotheses, that bromocriptine may exert its effects on glucose metabolism by 1) decreasing prolactin secretion, 2) indirectly increasing activity of key melanocortin receptors in the central nervous system, or 3) improving/restoring circadian rhythms. Using a diet-induced obese (DIO) mouse model, we established that a 2-wk treatment of bromocriptine is robustly effective at improving glucose tolerance. We then demonstrated that bromocriptine is effective at improving the glucose tolerance of both DIO prolactin-deficient and melanocortin-4 receptor (MC4R)-deficient mice, pointing to bromocriptine's ability to affect glucose tolerance independently of prolactin or MC4R signaling. Finally, we tested bromocriptine's dependence on the circadian system by testing its effectiveness in environmental (e.g., repeated shifts to the light-dark cycle) and genetic (e.g., the Clock mutant mouse) models of circadian disruption. In both models of circadian disruption, bromocriptine was effective at improving glucose tolerance, indicating that a functional or well-aligned endogenous clock is not necessary for bromocriptine's effects on glucose metabolism. Taken together, these results do not support the role of prolactin, MC4R, or the circadian clock as integral to bromocriptine's underlying mechanism. Instead, we find that bromocriptine is a robust diabetic treatment and resilient to genetically induced obesity, diabetes, and circadian disruption.

Food Addiction: Implications for the Diagnosis and Treatment of Overeating

With the obesity epidemic being largely attributed to overeating, much research has been aimed at understanding the psychological causes of overeating and using this knowledge to develop targeted interventions. Here, we review this literature under a model of food addiction and present evidence according to the fifth edition of the Diagnostic and Statistical Manual (DSM-5) criteria for substance use disorders. We review several innovative treatments related to a food addiction model ranging from cognitive intervention tasks to neuromodulation techniques. We conclude that there is evidence to suggest that, for some individuals, food can induce addictive-type behaviours similar to those seen with other addictive substances. However, with several DSM-5 criteria having limited application to overeating, the term 'food addiction' is likely to apply only in a minority of cases. Nevertheless, research investigating the underlying psychological causes of overeating within the context of food addiction has led to some novel and potentially effective interventions. Understanding the similarities and differences between the addictive characteristics of food and illicit substances should prove fruitful in further developing these interventions.

Hypothalamic dopamine signaling regulates brown fat thermogenesis

Dopamine signaling is a crucial part of the brain reward system and can affect feeding behavior. Dopamine receptors are also expressed in the hypothalamus, which is known to control energy metabolism in peripheral tissues. Here we show that pharmacological or chemogenetic stimulation of dopamine receptor 2 (D2R) expressing cells in the lateral hypothalamic area (LHA) and the zona incerta (ZI) decreases body weight and stimulates brown fat activity in rodents in a feeding-independent manner. LHA/ZI D2R stimulation requires an intact sympathetic nervous system and orexin system to exert its action and involves inhibition of PI3K in the LHA/ZI. We further demonstrate that, as early as 3 months after onset of treatment, patients treated with the D2R agonist cabergoline experience an increase in energy expenditure that persists for one year, leading to total body weight and fat loss through a prolactin-independent mechanism. Our results may provide a mechanistic explanation for how clinically used D2R agonists act in the CNS to regulate energy balance.

Glucose Abnormalities Associated to Prolactin Secreting Pituitary Adenomas

The pathogenesis of obesity and alterations in glucose profile have been linked to PRL excess, as it is reportedly associated with metabolic syndrome in thereabout one third of patients. In vitro exposure of pancreatic islet to PRL is known to stimulate insulin secretion and β-cell proliferation, and in turn overexpression of PRL in β-cells increases insulin release and β-cell replication. PRL excess has been found to worsen glucose profile because it reduces glucose tolerance and induces insulin resistance either in obese and non-obese patients. To note, pancreatic β-cells and adipocytes widely express dopamine receptors type 2, and dopamine has been hypothesized to play a key role as modulator of insulin and adipose functions. The dopamine agonists bromocriptine and cabergoline significantly improve abnormalities in glucose profile and reduce the prevalence of metabolic syndrome in a remarkable proportion of patients, regardless of whether body weight and PRL status may change. However, in men with hyperprolactinemia complicated by hypogonadism, testosterone replacement can ameliorate insulin resistance and abnormalities in glucose metabolism. Therefore, in patients with PRL-secreting pituitary adenomas control of PRL excess by dopamine agonists is mandatory to improve glucose and insulin abnormalities.

Repurposing of Bromocriptine for Cancer Therapy

Bromocriptine is an ergot alkaloid and dopamine D₂ receptor agonist used to treat Parkinson's disease, acromegaly, hyperprolactinemia, and galactorrhea, and more recently diabetes mellitus. The drug is also active against pituitary hormone-dependent tumors (prolactinomas and growth-hormone producing adenomas). We investigated, whether bromocriptine also inhibits hormone-independent and multidrug-resistant (MDR) tumors. We found that bromocriptine was cytotoxic towards drug-sensitive CCRF-CEM, multidrug-resistant CEM/ADR5000 leukemic cells as well as wild-type or multidrug-resistant ABCB5-transfected HEK293 cell lines, but not sensitive or BCRP-transfected multidrug-resistant MDA-MB-231 breast cancer cells. Bromocriptine strongly bound to NF-κB pathway proteins as shown by molecular docking and interacted more strongly with DNA-bound NF-κB than free NF-κB, indicating that bromocriptine may inhibit NF-κB binding to DNA. Furthermore, bromocriptine decreased NF-κB activity by a SEAP-driven NF-κB reporter cell assay. The expression of MDR-conferring ABC-transporters (ABCB1, ABCB5, ABCC1, and ABCG2) and other resistance-mediating factors (EGFR, mutated TP53, and IκB) did not correlate with cellular response to bromocriptine in a panel of 60 NCI cell lines. There was no correlation between cellular response to bromocriptine and anticancer drugs usually involved in MDR (e.g., anthracyclines, Vinca alkaloids, taxanes, epipodophyllotoxins, and others). COMPARE analysis of microarray-based mRNA expression in these cell lines revealed that genes from various functional groups such as ribosomal proteins, transcription, translation, DNA repair, DNA damage, protein folding, mitochondrial respiratory chain, and chemokines correlated with cellular response to bromocriptine. Our results indicate that bromocriptine inhibited drug-resistant tumor cells with different resistance mechanisms in a hormone-independent manner. As refractory and otherwise drug-resistant tumors represent a major challenge to successful cancer chemotherapy, bromocriptine may be considered for repurposing in cancer therapy.

Pharmaceutical interventions for weight-loss maintenance: no effect from cabergoline

BACKGROUND

Weight regain is a major limitation to successful weight maintenance following weight loss. Observational studies suggest that stimulation of dopamine receptors in the central nervous system is associated with weight loss and inhibition of weight gain. Our objective was to test the hypothesis that dopamine agonist treatment would prevent weight regain following acute weight loss in individuals with obesity.

METHODS

We conducted a 2-year double blind randomised controlled trial comparing the effect of a dopamine agonist, cabergoline, with placebo on weight regain in obese individuals who had lost at least 5% of their body weight using an 800 kcal/day commercial meal replacement programme. The primary outcome measure was the difference in mean weight between the treatment and control groups over the 2-year period following randomisation.

RESULTS

At 24 months, there was no difference in body weight between cabergoline and placebo treatment after adjustment for age, gender and baseline values (0.6 kg (95% CI: -1.5, 2.6), p = 0.58). The mean (±SD) baseline body weight of the randomised participants was 101.8 kg, the mean (±SD) weight loss with the 800 kcal/day diet was 7.1 ± 1.8 kg and the mean (±SD) weight regain at 24 months was 5.1 ± 7.5 kg. There were no significant differences in BMI, percent weight loss, waist circumference, resting energy expenditure, blood pressure or metabolic parameters at 24 months between the two groups.

CONCLUSIONS

Treatment with the dopamine agonist cabergoline does not prevent weight regain in obese individuals following weight loss.

The effects of hyperprolactinemia and its control on metabolic diseases

INTRODUCTION

Hyperprolactinaemia has been implicated in the pathogenesis of obesity and glucose intolerance and is reportedly associated with impaired metabolic profile and metabolic syndrome in approximately one third of patients.

AREAS COVERED

Suppression of dopaminergic tone has been proposed as a potential mechanism responsible for weight gain and metabolic abnormalities in such patients. Dopamine receptor type 2 (D₂R) is abundantly expressed on human pancreatic β-cell and adipocytes, suggesting a regulatory role for peripheral dopamine in insulin and adipose functions. Medical treatment with the dopamine-agonists bromocriptine and cabergoline has been shown to significantly improve gluco-insulinemic and lipid profile, also reducing the prevalence of metabolic syndrome. In patients with concomitant hypogonadism, simultaneous correction of both PRL excess and testosterone deficiency is mandatory to improve insulin resistance and metabolic abnormalities.

EXPERT COMMENTARY

Hyperprolactinemia promotes metabolic alterations. Control of PRL excess by dopamine agonists is mandatory to induce weight loss and to improve metabolic profile, and replacement treatment for concomitant hypogonadism effectively ameliorates insulin resistance and metabolic syndrome.

Neuropsychiatric and metabolic aspects of dopaminergic therapy: perspectives from an endocrinologist and a psychiatrist

The dopaminergic treatment represents the primary treatment in prolactinomas, which are the most common pituitary adenomas and account for about 40% of all pituitary tumours with an annual incidence of six to ten cases per million population. The dopaminergic treatment includes ergot and non-ergot derivatives with high affinity for the dopamine receptors D1 or/and D2. Through the activation of the dopaminergic pathway on pituitary lactotrophs, the dopamine agonists inhibit the prolactin synthesis and secretion, therefore normalizing the prolactin levels and restoring eugonadism, but they also lead to tumour shrinkage. Treatment with dopamine agonists has been associated - apart from the common side effects such as gastrointestinal symptoms, dizziness and hypotension - with neuropsychiatric side effects such as impulse control disorders (e.g. pathological gambling, compulsive shopping, hypersexuality and binge eating) and also with behavioral changes from low mood, irritability and verbal aggressiveness up to psychotic and manic symptoms and paranoid delusions not only in patients with prolactinomas but also in patients with Parkinson's disease and restless leg syndrome. They usually have de novo onset after initiation of the dopaminergic treatment and have been mainly reported in patients with Parkinson's disease, who are being treated with higher doses of dopamine agonists. Moreover, dopamine and prolactin seem to play an essential role in the metabolic pathway. Patients with hyperprolactinemia tend to have increased body weight and an altered metabolic profile with hyperinsulinemia and increased prevalence of diabetes mellitus in comparison to healthy individuals and patients with non-functioning pituitary adenomas. Treatment with dopamine agonists in these patients in short-term studies seems to lead to weight loss and amelioration of the metabolic changes. Together these observations provide evidence that dopamine and prolactin have a crucial role both in the regard and metabolic system, findings that merit further investigation in long-term studies.

Obesity: Current and potential pharmacotherapeutics and targets

Obesity is a global epidemic that contributes to a number of health complications including cardiovascular disease, type 2 diabetes, cancer and neuropsychiatric disorders. Pharmacotherapeutic strategies to treat obesity are urgently needed. Research over the past two decades has increased substantially our knowledge of central and peripheral mechanisms underlying homeostatic energy balance. Homeostatic mechanisms involve multiple components including neuronal circuits, some originating in hypothalamus and brain stem, as well as peripherally-derived satiety, hunger and adiposity signals that modulate neural activity and regulate eating behavior. Dysregulation of one or more of these homeostatic components results in obesity. Coincident with obesity, reward mechanisms that regulate hedonic aspects of food intake override the homeostatic regulation of eating. In addition to functional interactions between homeostatic and reward systems in the regulation of food intake, homeostatic signals have the ability to alter vulnerability to drug abuse. Regarding the treatment of obesity, pharmacological monotherapies primarily focus on a single protein target. FDA-approved monotherapy options include phentermine (Adipex-P®), orlistat (Xenical®), lorcaserin (Belviq®) and liraglutide (Saxenda®). However, monotherapies have limited efficacy, in part due to the recruitment of alternate and counter-regulatory pathways. Consequently, a multi-target approach may provide greater benefit. Recently, two combination products have been approved by the FDA to treat obesity, including phentermine/topiramate (Qsymia®) and naltrexone/bupropion (Contrave®). The current review provides an overview of homeostatic and reward mechanisms that regulate energy balance, potential therapeutic targets for obesity and current treatment options, including some candidate therapeutics in clinical development. Finally, challenges in anti-obesity drug development are discussed.

Bromocriptine and insulin sensitivity in lean and obese subjects

Bromocriptine is a glucose-lowering drug, which was shown to be effective in obese subjects with insulin resistance. It is usually administered in the morning. The exact working mechanism of bromocriptine still has to be elucidated. Therefore, in this open-label randomized prospective cross-over mechanistic study, we assessed whether the timing of bromocriptine administration (morning vs evening) results in different effects and whether these effects differ between lean and obese subjects. We studied the effect of bromocriptine on insulin sensitivity in 8 lean and 8 overweight subjects using an oral glucose tolerance test. The subjects used bromocriptine in randomized cross-over order for 2 weeks in the morning and 2 weeks in the evening. We found that in lean subjects, bromocriptine administration in the evening resulted in a significantly higher post-prandial insulin sensitivity as compared with the pre-exposure visit (glucose area under the curve (AUC) 742 mmol/L * 120 min (695-818) vs 641 (504-750), P = 0.036, AUC for insulin did not change, P = 0.575). In obese subjects, both morning and evening administration of bromocriptine resulted in a significantly higher insulin sensitivity: morning administration in obese: insulin AUC (55,900 mmol/L * 120 min (43,236-96,831) vs 36,448 (25,213-57,711), P = 0.012) and glucose AUC P = 0.069; evening administration in obese: glucose AUC (735 mmol/L * 120 min (614-988) vs 644 (568-829), P = 0.017) and insulin AUC, P = 0.208. In conclusion, bromocriptine increases insulin sensitivity in both lean and obese subjects. In lean subjects, this effect only occurred when bromocriptine was administrated in the evening, whereas in the obese, insulin sensitivity increased independent of the timing of bromocriptine administration.

Evidence-based practice use of quick-release bromocriptine across the natural history of type 2 diabetes mellitus

OBJECTIVES

To provide an evidence-based practice overview on the clinical use of bromocriptine-quick release (QR) across the natural history of type 2 diabetes mellitus (T2DM).

METHODS

Articles for inclusion were selected after a comprehensive literature search of English-language PubMed articles and identification of other relevant references through other sources. Inclusion criteria were animal studies examining the mechanism of action and efficacy of bromocriptine, and clinical studies examining the safety and efficacy of bromocriptine-QR in patients with T2DM, without a time limitation.

RESULTS

The brain plays a key role in total body metabolism, in particular ensuring that sufficient levels of glucose are available for proper neural functioning. The hypothalamic suprachiasmatic nucleus (SCN), the body's biological clock, plays a key role in the regulation of seasonal and diurnal variations of insulin sensitivity. A daily surge of dopaminergic activity in the SCN upon waking enables insulin sensitivity throughout the day. When this is disrupted (e.g. by a high fat/sugar diet, stress, altered [diminished] exercise, altered sleep/wake cycle, diabetes), insulin resistance persists throughout the day and overnight. Improving the morning surge in dopaminergic activity with the short-acting dopamine D2 receptor agonist bromocriptine-QR can safely and effectively improve glycemic control, while improving cardiovascular disease risk factors and related adverse events, and reducing sympathetic tone, as demonstrated by 5 reports of the Cycloset Safety Trial and 3 additional clinical studies of bromocriptine-QR.

CONCLUSIONS

In patients with T2DM, the dopamine D2 receptor agonist bromocriptine-QR has been shown to be well tolerated, efficacious, and a logical treatment option.

Development of a Rapid Insulin Assay by Homogenous Time-Resolved Fluorescence

Direct measurement of insulin is critical for basic and clinical studies of insulin secretion. However, current methods are expensive and time-consuming. We developed an insulin assay based on homogenous time-resolved fluorescence that is significantly more rapid and cost-effective than current commonly used approaches. This assay was applied effectively to an insulin secreting cell line, INS-1E cells, as well as pancreatic islets, allowing us to validate the assay by elucidating mechanisms by which dopamine regulates insulin release. We found that dopamine functioned as a significant negative modulator of glucose-stimulated insulin secretion. Further, we showed that bromocriptine, a known dopamine D2/D3 receptor agonist and newly approved drug used for treatment of type II diabetes mellitus, also decreased glucose-stimulated insulin secretion in islets to levels comparable to those caused by dopamine treatment.

Enhanced vulnerability to tobacco use in persons with diabetes: A behavioral and neurobiological framework

Tobacco use significantly magnifies the negative health complications associated with diabetes. Although tobacco use is strongly discouraged in persons with diabetes, clinical evidence suggests that they often continue to smoke and have more difficulty quitting despite serious contraindications. Here, we suggest that a potential reason for enhanced vulnerability to tobacco use in persons with diabetes is greater rewarding effects of nicotine. This review summarizes pre-clinical evidence indicating that the rewarding effects of nicotine are enhanced in rodent models of type 1 and type 2 diabetes. We also provide a framework of neurobiological mechanisms that are posited to promote tobacco use in persons with diabetes. This framework suggests that diabetes induces a disruption in insulin signaling that leads to a suppression of dopamine systems in the mesolimbic reward pathway. Lastly, we consider the clinical implications of enhanced rewarding effects of nicotine that may promote tobacco use in persons with diabetes. The clinical efficacy of smoking cessation medications that enhance dopamine are important to consider, given that persons with diabetes may display disrupted dopaminergic mechanisms. Future work is needed to better understand the complex interaction of dopamine and insulin in order to develop better smoking cessation medications for persons with diabetes.

A review of dopamine agonist therapy in type 2 diabetes and effects on cardio-metabolic parameters

Dopamine action appears to play a role in changes that are seen in obesity, metabolic syndrome and type 2 diabetes mellitus. Bromocriptine-QR (Quick Release), a dopamine agonist, is approved for use in treatment of type 2 diabetes. It has demonstrated modest improvement in glycemic parameters, cholesterol and weight in certain cohorts. Limited data using cabergoline, a long-acting dopamine agonist, also demonstrate glycemic efficacy. Additionally, bromocriptine-QR appears to have a favorable cardiovascular risk reduction. The direct mechanism by which bromocriptine-QR, or central dopamine agonism, achieves modest glycemic control and favorable cardio-metabolic profile is unclear. This relationship appears to be more complex than the historical explanation of "resetting" the circadian clock and may further be elucidated using data in individuals with hyperprolactinemia and prolactinoma.

Pharmacologic treatment of type 2 diabetes: oral medications

OBJECTIVE

To review the oral and injectable pharmacologic treatment options for type 2 diabetes.

DATA SOURCES

A literature search was conducted using PubMed electronic database for studies published in English between 1993 and September 2014. Search terms included diabetes mellitus, type 2 diabetes, and the individual name for each antidiabetic medication reviewed. In addition, manual searches were performed for cross-references from publications. Package inserts, United States Food and Drug Administration (FDA) Web site, Institute for Safe Medication Practices Web site, American Diabetes Association Web site and scientific session poster presentations, and individual drug company Web pages were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

This review focused on information elucidated over the past 10 years to assist prescribers in choosing optimal therapy based on individual patient characteristics. Studies leading to the approval of or raising safety concerns for the antidiabetic medications reviewed in this article were included.

DATA SYNTHESIS

In the past 10 years, there have been 4 novel oral antidiabetic medication classes and 9 new injectable agents and insulin products approved by the FDA for the treatment of type 2 diabetes as well as new information regarding the safety and use of several older antidiabetic medication classes. The distinctions were reviewed for each individual agent, and a comparison was completed if there was more than one agent in a particular therapeutic class. Using current information available, select investigational agents in phase III trials or those with a pending new drug application were highlighted.

CONCLUSION

There are now 9 distinct oral pharmacologic classes and a variety of insulin and noninsulin injectable medications available for the treatment of type 2 diabetes. Metformin remains the first-line treatment option for most patients. When considering options for alternative or additional treatment, prescribers must weigh the benefits and risks using individual patient characteristics.

Effect of chronic cabergoline treatment and testosterone replacement on metabolism in male patients with prolactinomas

INTRODUCTION

Hyperprolactinemia and hypogonadism are reportedly associated with an impaired metabolic profile. The current study aimed at investigating the effects of testosterone replacement and cabergoline (CAB) treatment on the metabolic profile in male hyperprolactinemic patients.

PATIENTS AND METHODS

Thirty-two men with prolactinomas, including 22 with total testosterone (TT) <8 nmol/l (HG, 69%) and 10 with TT >8 nmol/l (non-HG, 31%), were entered in the study. In all patients, metabolic parameters were assessed at diagnosis and after 12- and 24-month treatment.

RESULTS

Compared to non-HG patients, at baseline the HG patients had higher waist circumference (WC). TT significantly correlated with body mass index (BMI). Twelve-month CAB induced PRL normalization in 84%. HG prevalence significantly decreased (28%) and non-HG prevalence significantly increased (72%). Anthropometric and lipid parameters, fasting insulin (FI), insulin sensitivity index (ISI0), homeostatic model assessment of insulin secretion (HOMA-β) and homeostatic model assessment of insulin resistance (HOMA-IR) significantly improved compared to baseline. TT was the best predictor for FI. Percent change (Δ) of TT significantly correlated with ΔCholesterol, ΔWeight and ΔBMI. Compared to non-HG patients, the HG patients had a higher weight, BMI, WC and HOMA-β. In HG, testosterone replacement was started. After 24 months, PRL normalized in 97%. HG prevalence significantly decreased (6%) and non-HG prevalence significantly increased (94%). Anthropometric and lipid parameters, FI, ISI0, HOMA-β and HOMA-IR significantly improved compared to baseline, with FI, ISI0, HOMA-β and HOMA-IR further ameliorating compared to the 12-month evaluation. Compared to non-HG patients, the HG patients still had a higher weight, BMI and WC.

CONCLUSIONS

In hyperprolactinemic hypogonal men, proper testosterone replacement induces a significant improvement in the metabolic profile, even though the amelioration in the lipid profile might reflect the direct action of CAB.

Efficacy and safety of add on therapy of bromocriptine with metformin in Indian patients with type 2 diabetes mellitus: a randomized open labeled phase IV clinical trial

Objective:

To compare the effectiveness and safety of add on therapy of bromocriptine with metformin in type 2 diabetes mellitus (DM) patients.

Material and Methods:

Adult type 2 DM patients fulfilling the inclusion criteria were randomized in three groups. Group A received metformin (1000 mg/ day), while group B patients were treated with metformin (1000 mg/day) plus bromocriptine (0.8 mg/day) and group C received metformin (1000 mg/day) plus bromocriptine (1.6 mg/day) for 12 weeks. Fasting plasma glucose (FPG), postprandial plasma glucose (PPPG), and body weight were measured at week 4, 8, and 12 visits and glycosylated hemoglobin (HbA_1C) at week 12 visit.

Results:

Metformin alone and in combination with bromocriptine in escalating dose (0.8 mg/day and 1.6 mg/day) significantly (P < 0.05) decreased FPG and PPPG levels at weeks 4, 8, and 12 compared with pretreatment values. HbA_1C level in all three treatment groups significantly (P < 0.05) decreased at week 12 as compared with pretreatment baseline value. HbA_1C level in groups B and C significantly (P < 0.05) decreased as compared with group A at week 12. Addition of bromocriptine to metformin also significantly (P < 0.05) decreased FPG and PPPG levels in a dose-dependent manner as compared with metformin alone. Intergroup analysis did not show any statistically significant change in weight of study subjects at different intervals.

Conclusion:

The combination of bromocriptine with metformin significantly decreased FPG, PPPG, and HbA_1C compared with metformin alone in type 2 DM patients in a dose-dependent manner.

A randomized crossover, pilot study examining the effects of a normal protein vs. high protein breakfast on food cravings and reward signals in overweight/obese "breakfast skipping", late-adolescent girls

Background

This pilot study examined whether the addition of a normal protein (NP) vs. high protein (HP) breakfast leads to alterations in food cravings and plasma homovanillic acid (HVA), which is an index of central dopamine production, in overweight/obese ‘breakfast skipping’ late-adolescent young women.

Methods

A randomized crossover design was incorporated in which 20 girls (age 19 ± 1 y; BMI 28.6 ± 0.7 kg/m²) consumed 350 kcal NP (13 g protein) breakfast meals, 350 kcal HP (35 g protein) breakfast meals, or continued breakfast skipping (BS) for 6 consecutive days/pattern. On day 7 of each pattern, a 4 h testing day was completed including the consumption of breakfast (or no breakfast) followed by food craving questionnaires and blood sampling for HVA concentrations throughout the morning.

Results

Both breakfast meals reduced post-meal cravings for sweet and savory foods and increased HVA concentrations vs. BS (all, p < 0.05). Between breakfast meals, the HP breakfast tended to elicit greater reductions in post-meal savory cravings vs. NP (p = 0.08) and tended to elicit sustained increases in HVA concentrations prior to lunch vs. NP (p = 0.09). Lastly, HVA concentrations were positively correlated with the protein content at breakfast (r: 0.340; p < 0.03).

Conclusions

Collectively, these findings suggest that the addition of breakfast reduces post-meal food cravings and increases homovanillic acid concentrations in overweight/obese young people with higher protein versions eliciting greater responses.

The effect of the ANKK1/DRD2 Taq1A polymorphism on weight changes of dopaminergic treatment in prolactinomas

Treatment with dopamine agonists in patients with prolactinomas has been associated with weight loss in short term studies. However, long-term studies on weight changes are lacking. Taq1A is a restriction fragment length polymorphism considered as a gene marker for the DRD2 gene. The presence of at least one A1 allele is linked to reduced brain dopaminergic activity due to reduced receptor binding and lower density of the dopamine 2 receptor. We aimed at testing the hypothesis that the dopaminergic treatment in prolactinoma patients leads to sustained weight loss and that the presence of diminished weight loss response under dopamine agonists is associated with the minor A1 allele of Taq1A.We included n = 44 patients (17 male and 27 female, 26 macroadenomas and 18 microadenomas) with prolactinomas treated with dopamine agonists. Outcome measures were weight and body mass index (BMI) change under dopaminergic treatment after 2 years with regard to Taq1A status and sex. We observed that the dopaminergic treatment leads to a significant mean weight loss of 3.1 ± 6.25 kg after 2 years. Regarding Taq1A polymorphisms, 21 patients were carriers of at least one A1 allele and 23 patients had a genotype of A2/A2. However, the presence of the A1 allele was neither associated with the mean BMI at baseline nor with an altered weight loss response under dopamine agonist therapy. Our results implicate that the dopaminergic treatment leads to a sustained weight loss in patients with prolactinomas after 2 years. However, there was no association to the A1 allele of Taq1A, observation that needs to be analysed in larger cohorts.

Age-dependent association of serum prolactin with glycaemia and insulin sensitivity in humans

The dopamine agonist bromocriptine has been approved for the treatment of type 2 diabetes in the United States. Bromocriptine inhibits prolactin secretion, and patients with hyperprolactinaemia display impaired insulin sensitivity. We therefore hypothesized that low prolactin levels are associated with lower glycaemia and higher insulin sensitivity in healthy subjects. Prolactin levels were determined from fasting serum in participants without diabetes from the cross-sectional Tübingen family study for type 2 diabetes (m/f = 562/1,121, age = 40 ± 13 years, BMI = 30 ± 9 kg/m(2)). A 75 g oral glucose tolerance test was performed, and the area under the glucose curve (AUC(0-120)Glucose) and insulin sensitivity index were calculated. A subgroup (n = 494) underwent hyperinsulinaemic-euglycaemic clamp tests. Prolactin associated positively with insulin sensitivity (p = 0.001, adjusted for gender, age, and BMI). Age strongly interacted (p < 0.0001) with the effect of prolactin on insulin sensitivity, inverting the positive relationship to a negative one in younger participants. Glycated haemoglobin (HbA1c) and AUC(0-120)Glucose correlated negatively with prolactin, and an interaction with age was found as well. Higher prolactin levels are associated with improved insulin sensitivity and lower glucose in individuals without diabetes. This relationship turns to its opposite in younger persons. As prolactin is a proxy for the dopaminergic tone in the central nervous system, these associations may indicate an age-dependent influence of the brain on peripheral insulin sensitivity.

Neuroendocrine and metabolic components of dopamine agonist amelioration of metabolic syndrome in SHR rats

BACKGROUND

The hypertensive, pro-inflammatory, obese state is strongly coupled to peripheral and hepatic insulin resistance (in composite termed metabolic syndrome [MS]). Hepatic pro-inflammatory pathways have been demonstrated to initiate or exacerbate hepatic insulin resistance and contribute to fatty liver, a correlate of MS. Previous studies in seasonally obese animals have implicated an important role for circadian phase-dependent increases in hypothalamic dopaminergic tone in the maintenance of the lean, insulin sensitive condition. However, mechanisms driving this dopaminergic effect have not been fully delineated and the impact of such dopaminergic function upon the above mentioned parameters of MS, particularly upon key intra-hepatic regulators of liver inflammation and lipid and glucose metabolism have never been investigated.

OBJECTIVE

This study therefore investigated the effects of timed daily administration of bromocriptine, a potent dopamine D2 receptor agonist, on a) ventromedial hypothalamic catecholamine activity, b) MS and c) hepatic protein levels of key regulators of liver inflammation and glucose and lipid metabolism in a non-seasonal model of MS - the hypertensive, obese SHR rat.

METHODS

Sixteen week old SHR rats maintained on 14 hour daily photoperiods were treated daily for 16 days with bromocriptine (10 mg/kg, i.p.) or vehicle at 1 hour before light offset and, subsequent to blood pressure recordings on day 14, were then utilized for in vivo microdialysis of ventromedial hypothalamic catecholamine activity or sacrificed for the analyses of MS factors and regulators of hepatic metabolism. Normal Wistar rats served as wild-type controls for hypothalamic activity, body fat levels, and insulin sensitivity.

RESULTS

Bromocriptine treatment significantly reduced ventromedial hypothalamic norepinephrine and serotonin levels to the normal range and systolic and diastolic blood pressures, retroperitoneal body fat level, plasma insulin and glucose levels and HOMA-IR relative to vehicle treated SHR controls. Such treatment also reduced plasma levels of C-reactive protein, leptin, and norepinephrine and increased that of plasma adiponectin significantly relative to SHR controls. Finally, bromocriptine treatment significantly reduced hepatic levels of several pro-inflammatory pathway proteins and of the master transcriptional activators of lipogenesis, gluconeogenesis, and free fatty acid oxidation versus control SHR rats.

CONCLUSION

These findings indicate that in SHR rats, timed daily dopamine agonist treatment improves hypothalamic and neuroendocrine pathologies associated with MS and such neuroendocrine events are coupled to a transformation of liver metabolism potentiating a reduction of elevated lipogenic and gluconeogenic capacity. This liver effect may be driven in part by concurrent reductions in hyperinsulinemia and sympathetic tone as well as by reductions in intra-hepatic inflammation.

Higher doses of cabergoline further improve metabolic parameters in patients with prolactinoma regardless of the degree of reduction in prolactin levels

OBJECTIVE

Currently available studies that fully analyse the metabolic parameters in patients with prolactinoma are scarce and discordant. The aim of this study was to evaluate the metabolic effects of cabergoline (CAB) treatment in patients with newly diagnosed prolactinoma in relation to disease control and CAB dosage.

DESIGN

This is a retrospective clinical-based therapy analysis.

PATIENTS

Forty-three patients with prolactinoma (eight men, 35 women), aged 33·65 ± 11·23 years, were evaluated metabolically at baseline and after 12 months of CAB treatment.

MEASUREMENTS

Body mass index (BMI), systolic and diastolic blood pressure, waist circumference (WC), lipid profile, haemoglobinA1c (HbA1c), glucose and insulin levels (and their areas under the curve, AUC) after an oral glucose tolerance test, homoeostasis model assessment of insulin resistance (Homa-IR) index, insulin sensitivity index (ISI) Matsuda, oral disposition index (DIo) and visceral adiposity index (VAI) were measured at baseline and after 12 months of treatment.

RESULTS

Twelve months of CAB reduced WC (P < 0·001), total (P = 0·001) and low-density lipoprotein \terol (P < 0·001), triglycerides (P = 0·024), fasting insulin (P < 0·001), AUCINSULIN (P < 0·001), HbA1c (P = 0·022), Homa-IR (P < 0·001) and VAI (P < 0·001), with a concomitant increase in high-density lipoprotein cholesterol (P < 0·001) and in ISI Matsuda (P < 0·001), regardless of the degree of reduction in prolactin levels. The patients receiving higher doses (>0·50 mg/week) of CAB showed lower BMI (P = 0·009), fasting insulin (P = 0·001), Homa-IR (P < 0·001) and VAI (P = 0·018) and higher ISI Matsuda (P = 0·002) and DIo (P = 0·011), compared with those on lower doses.

CONCLUSIONS

A significant metabolic improvement was observed in patients with prolactinoma after 12 months of CAB treatment, especially when higher doses were used, highlighting the importance of considering the metabolic profile in these patients and the role of active treatment with high CAB doses.

Bromocriptine, a Dopamine (d2) Receptor Agonist, Used Alone and in Combination with Glipizide in Sub-Therapeutic Doses to Ameliorate Hyperglycaemia

INTRODUCTION

Bromocriptine, an ergot derivative, is an agonist at the dopamine 2 receptor and a sympatholytic. It is a well established drug in Parkinsonism, hyperprolactinaemia and acromegaly and it has various other clinical indications like induction of ovulation in female infertility. Bromocriptine has been evaluated in alloxan induced diabetic rats for its anti-hyperglycaemic effect with and without simultaneous use of glipizide.

METHODS

Diabetes was induced in albino rats by giving a single subcutaneous injection of alloxan in a dose of 150 mg/kg body weight. After 72 hours of giving alloxan injection, depending upon their blood glucose levels (350mg/dl and above), the rats were included into the study and they were divided into four groups, each comprising of 6 rats (n=24): Group 1 which was taken as control was given distilled water. Group 2 was treated with glipizide, a standard drug. Group 3 was treated with the test drug, bromocriptine and Group 4 was treated with sub therapeutic doses of test and standard drugs. The drugs were given to the diabetic rats once daily by oral route for 30 consecutive days, in order to assess their effects in terms of reduction in blood glucose levels. Blood glucose was estimated on 0(th), 10(th), 20(th), and 30(th) days of the study at fixed time intervals.

RESULTS AND CONCLUSION

Bromocriptine, which was used alone, lowered the blood glucose levels appreciably; whereas the concomitant administration of bromocriptine and glipizide in sub therapeutic doses produced a much more appreciable reduction. The results which were obtained in the group which received simultaneous administration of test and standard drugs in sub therapeutic doses were comparable to those of the group which received reference drug, glipizide. Hence, it can be concluded that bromocriptine may serve as a valuable adjunct to available anti-diabetic medication.

Review of insulin-dependent and insulin-independent agents for treating patients with type 2 diabetes mellitus and potential role for sodium-glucose co-transporter 2 inhibitors

Diabetes, especially type 2 diabetes mellitus (T2DM), continues to be a global health care problem. Although the beneficial effects of glycemic control are well established, in the United States, > 40% of adults with diabetes fail to achieve target glycated hemoglobin levels. Antidiabetic drug classes vary with respect to their mechanisms of action, glucose-lowering potential, and safety and tolerability profiles. Antidiabetic drug classes include some agents that depend on the presence or action of insulin for their therapeutic effect. As the disease state of T2DM progresses, patient pancreatic β-cell function declines, and therapies that stimulate insulin secretion or improve insulin sensitivity become less effective for this population. Therefore, the development of additional antidiabetic agents with novel mechanisms of action that can be used alone or in combination with currently approved medications may help patients achieve glycemic control. Agents that have comparable glucose-lowering capabilities but different mechanisms of action may fill treatment gaps or meet the needs of patient subpopulations. For example, inhibitors of sodium-glucose co-transporter 2 (SGLT2) represent an emerging class of glucose-lowering agents. The SGLT2 inhibitors reduce glucose reabsorption by the kidney, leading to increased urinary glucose excretion and caloric loss. In clinical trials, these agents have been shown to improve glycemic control and to reduce body weight in patients with T2DM. Additionally, SGLT2 inhibitors pose a low risk for hypoglycemia and are generally well tolerated; however, their use has been associated with an increase in the frequency of genital infections and, in some studies, urinary tract infections. Sodium-glucose co-transporter 2 inhibitors may provide an alternative or an addition to existing therapies for the treatment of patients with T2DM.

Novel therapies for the management of type 2 diabetes mellitus: part 1. pramlintide and bromocriptine-QR

Several classes of antidiabetic agents have been introduced into the market place over the past dozen years. As our understanding of the underlying pathophysiology of type 2 diabetes has advanced, attempts have been made to address these defects specifically. This brief review focuses on our experience with two such pharmacological approaches: (i) a synthetic amylin analog addressing amylin deficiency; and (ii) a dopaminergic agonist, focused on enhancing the lowered dopaminergic tone in patients with type 2 diabetes. Importantly, the use of these agents is not associated with hypoglycemia or weight gain.

Effect of cabergoline on metabolism in prolactinomas

INTRODUCTION

Hyperprolactinemia has been implicated in the pathogenesis of obesity and glucose intolerance and is reportedly associated with an impaired metabolic profile. The current study aimed at investigating the effects of 12- and 60-month treatment with cabergoline (CAB) on metabolic syndrome (MetS) in patients with prolactinomas.

PATIENTS AND METHODS

61 patients with prolactinomas (13 men, 48 women, 41 with microadenoma, 20 with macroadenoma), aged 34.4 ± 10.3 years, entered the study. In all patients, prolactin (PRL) and metabolic parameters were assessed at diagnosis and after 12 and 60 months of continuous CAB treatment. MetS was diagnosed according to NCEP-ATP III criteria.

RESULTS

Compared to baseline, CAB induced a significant decrease in PRL with complete normalization in 93% of patients after the 60-month treatment. At baseline, MetS prevalence was significantly higher in patients with PRL above (34.5%) than in those with PRL lower (12.5%) than the median (129 μg/l, p = 0.03). MetS prevalence significantly decreased after 12 (11.5%, p = 0.039) and 60 (5.0%, p = 0.001) months compared to baseline (28.0%). At both evaluations the lipid profile significantly improved compared to baseline. Fasting insulin and homeostatic model assessment of insulin resistance significantly decreased after 1 year of CAB (p = 0.012 and p = 0.002, respectively) and further improved after 60 months (p = 0.000). The visceral adiposity index significantly decreased after the 60-month treatment (p = 0.000) compared to baseline. At the 5-year evaluation CAB dose was the best predictor of percent decrease in fasting insulin (t = 2.35, p = 0.022).

CONCLUSIONS

CAB significantly reduces MetS prevalence and improves the adipose tissue dysfunction index. The improvement in PRL, insulin sensitivity and other metabolic parameters might reflect the direct effect of CAB.

Obesity in bipolar disorder: an overview

Bipolar disorder (BD) is associated with obesity, overweight, and abdominal obesity, and BD individuals with obesity have a greater illness burden. Factors related to BD, its treatment, and the individual may all contribute to BD's association with obesity. Management strategies for the obese BD patient include use of medications with better metabolic profiles, lifestyle interventions, and adjunctive pharmacotherapy for weight loss. Obesity-related psychiatric and medical comorbidities should also be assessed and managed. Bariatric surgery may be an option for carefully selected patients. Greater research into the theoretical underpinnings and clinical management of the BD-obesity connection is needed.

Adiposopathy, diabetes mellitus, and primary prevention of atherosclerotic coronary artery disease: treating "sick fat" through improving fat function with antidiabetes therapies

Both obesity and type 2 diabetes mellitus (DM) are worldwide epidemics, an association that is neither incidental nor coincidental. Adipose tissue is as an active endocrine and immune organ whose dysfunction (adiposopathy or "sick fat") is promoted by excessive caloric balance in genetically and environmentally susceptible patients. The resultant adiposopathic responses directly and indirectly contribute to pathologies leading to hyperglycemia, high blood pressure, and dyslipidemia--all major cardiovascular risk factors--as well as to cardiovascular disease (CVD) itself. Toward the goal of primary prevention of CVD among DM patients, clinical trial outcomes evidence support the use of antihypertensive agents, lipid-altering drugs, and antiplatelet agents. Some of the most proactive measures to reduce the onset of cardiovascular risk factors and potentially prevent the onset of DM are early and aggressive nutritional, physical activity, and lifestyle interventions. Such measures improve the functionality of adipose tissue, reduce adiposopathic responses, and thus improve glycemic, blood pressure, and lipid parameters--all of which would be expected to reduce CVD risk. Finally, if nutritional, physical activity, and lifestyle interventions are not successful, and if DM pharmacologic therapies are indicated, then the choice of anti-DM medications should take into consideration the effects of such agents on adipose tissue function and dysfunction, which in turn, affects major CVD risk factors and CVD.

Circulating dopamine and C-peptide levels in fasting nondiabetic hypertensive patients: the Graz Endocrine Causes of Hypertension study

OBJECTIVE

Accumulating evidence supports a potential role for dopamine in the regulation of insulin secretion. We examined the association between circulating dopamine and C-peptide concentrations using data from the Graz Endocrine Causes of Hypertension (GECOH) study.

RESEARCH DESIGN AND METHODS

After 12 h of fasting, we measured plasma dopamine and serum C-peptide levels and established determining factors of insulin secretion in 201 nondiabetic hypertensive patients (mean age 48.1 ± 16.0 years; 61.7% women).

RESULTS

Mean dopamine and C-peptide concentration were 33.4 ± 38.6 pg/mL and 3.1 ± 2.7 ng/mL, respectively. A strong and inverse correlation was observed between dopamine and C-peptide levels (r = -0.423, P < 0.001). There was no significant relationship between C-peptide, plasma epinephrine, and norepinephrine. C-peptide levels decreased steadily and significantly from tertile 1 of dopamine (3.6 ng/mL [95% CI 2.9-4.1]) to tertile 3 (1.6 ng/mL [1.5-2.7], P < 0.001) after multivariate adjustment.

CONCLUSIONS

The inverse association between dopamine and C-peptide highlights the need to evaluate whether dopamine could be effective for modulating endocrine pancreatic function.

Randomized pilot study of cabergoline, a dopamine receptor agonist: effects on body weight and glucose tolerance in obese adults

AIM

Dopaminergic hypofunction and hyperprolactinaemia have been implicated in the pathogenesis of obesity and glucose intolerance. The aim of this pilot study was to determine the efficacy of cabergoline, a dopamine receptor agonist, on body weight and glucose tolerance in obese non-diabetic persons with normal plasma prolactin levels.

METHODS

This 16-week double blind, placebo-controlled pilot study randomized non-diabetic obese adults (body mass index 30-42 kg/m(2) ) to placebo or cabergoline (0.25 mg twice weekly for 4 weeks followed by 0.5 mg twice weekly for the next 12 weeks). Of 40 subjects enrolled, 29 completed 16 weeks: 16 randomized to placebo and 13 to cabergoline. All subjects were counselled on a 500 kcal/day calorie deficit diet. A 75-g oral glucose tolerance test was performed at baseline and at 16 weeks.

RESULTS

As expected, prolactin levels decreased after cabergoline (p < 0.001). Weight loss was similar after placebo compared with cabergoline treatment: 1.0 vs. 1.2% body weight, respectively. Fasting glucose levels did not differ between groups after treatment, however, 90-min postprandial glucose and insulin decreased in the cabergoline group only (p = 0.029). HOMA-IR (homeostasis model of assessment) increased by 40% after placebo and 1.5% after cabergoline treatment.

CONCLUSIONS

This pilot study suggests that cabergoline therapy may improve glucose tolerance independent of weight loss, however, a larger, longer term study of dopamine receptor agonist therapy in obese individuals is warranted to confirm this finding.

Clinical review: Regulation of food intake, energy balance, and body fat mass: implications for the pathogenesis and treatment of obesity

CONTEXT

Obesity has emerged as one of the leading medical challenges of the 21st century. The resistance of this disorder to effective, long-term treatment can be traced to the fact that body fat stores are subject to homeostatic regulation in obese individuals, just as in lean individuals. Because the growing obesity epidemic is linked to a substantial increase in daily energy intake, a key priority is to delineate how mechanisms governing food intake and body fat content are altered in an obesogenic environment.

EVIDENCE ACQUISITION

We considered all relevant published research and cited references that represented the highest quality evidence available. Where space permitted, primary references were cited.

EVIDENCE SYNTHESIS

The increase of energy intake that has fueled the U.S. obesity epidemic is linked to greater availability of highly rewarding/palatable and energy-dense food. Obesity occurs in genetically susceptible individuals and involves the biological defense of an elevated body fat mass, which may result in part from interactions between brain reward and homeostatic circuits. Inflammatory signaling, accumulation of lipid metabolites, or other mechanisms that impair hypothalamic neurons may also contribute to the development of obesity and offer a plausible mechanism to explain the biological defense of elevated body fat mass.

CONCLUSIONS

Despite steady research progress, mechanisms underlying the resistance to fat loss once obesity is established remain incompletely understood. Breakthroughs in this area may be required for the development of effective new obesity prevention and treatment strategies.

Bromocriptine for diabetes mellitus type II

A quick-release formulation of bromocriptine is the latest drug approved by the US Food and Drug Administration for the treatment of type 2 diabetes mellitus. Most interestingly, the development of this drug stems from studies of hibernation in rodents. This article will review the physiology that led to the development of this new drug, as well as its indications, clinical use, benefits, and contraindications.