Aromatase inhibitors as a therapeutic strategy for male prolactinoma resistant to dopamine agonists: a retrospective cohort study and literature review

PURPOSE

To assess the effect of letrozole, an aromatase inhibitor (AI), in patients with resistant prolactinoma that presented an increase in serum prolactin (PRL) levels during testosterone replacement therapy (TRT).

METHODS

A retrospective cohort study in a single tertiary care center. From March 2012 to July 2023, 53 male patients over 18 years with prolactinoma were followed in our Neuroendocrine Unit. Of those, 90.6% presented macroadenomas, 41% of them were resistant to cabergoline and 25% presented persistent hypogonadism to whom TRT was indicated. Among them, five presented a significant increase in PRL levels and AI was initiated. All five patients had resistant prolactinomas. One of them was excluded due to tumor aggressiveness and concomitant use of temozolomide during AI therapy.

RESULTS

Four patients were included in the analysis, with a mean age of 28.5 (± 7.5) years, median prolactin of 1060 (600 to 6700) ng/mL and median of the largest tumor diameter of 3.6 (1.5 to 5) cm at the time of prolactinoma diagnosis. On TRT, all presented an increase in serum PRL levels (231 to 396%), with a subsequent decrease (61 to 93%) after adding AI. During AI treatment for a median time of 60.5 (21 to 120) months, tumor shrinkage was observed in two cases (-8 and -3 mm in the maximum diameter) and tumor stability in the other two. No major side effects occurred and AI was well tolerated.

CONCLUSION

AI might be an option for men with resistant prolactinoma who have an increase in PRL levels on TRT. Nevertheless, prospective randomized clinical trials are needed to ensure efficacy and security for this approach.

Impulse control disorders in patients with dopamine agonist-treated pituitary adenomas: a cross-sectional multicenter study

BACKGROUND

Impulse control disorders (ICDs) have been described as underrecognized side effects of dopamine agonists (DAs) in neurological disorders but are not sufficiently understood in endocrine conditions.

OBJECTIVE

To identify the prevalence of DAs induced ICDs and determine potential risk factors related to these disorders in patients with prolactinoma and non-function pituitary adenomas (NFPAs).

METHODS

This is a cross-sectional multicenter study involving 200 patients with prolactinoma and NFPAs, who received follow-ups in tertiary referral centers. DA-induced ICDs were assessed using ICD questionnaires modified from prior studies.

RESULT

At least one ICD was reported by 52% of participants, among whom 28.5% mentioned compulsive shopping, 24.5% punding, and 24.5% hypersexuality. Furthermore, 33% of the patients reported the presence of one type of ICD behavior, while 12% specified two and 7% had three types of such behavior. The multivariable logistic regression showed that the significant risk factors of ICD were younger age (adjusted odds ratio [AOR]: 0.92, 95% confidence interval [CI]: 0.88-0.97, p 0.001), being single (AOR: 0.15, 95%CI: 0.03-0.84, p 0.03), and a positive history of psychiatric illness (AOR: 7.67, 95% CI: 1.37-42.97, p 0.021).

CONCLUSION

ICDs with a broad range of psychiatric symptoms are common in individuals with DA-treated prolactinoma and NFPAs. Endocrinologists should be aware of this potential side effect, particularly in patients with a personal history of psychiatric disorder.

Selective attention towards infants in nulliparous women across the menstrual cycle

Research in women showed that testosterone is associated with decreased selective attention towards infant stimuli, which can be compensated for by oxytocin administration. In theory, caregiving behavior is thought to be mediated by oxytocin. Oxytocin binds to dopaminergic neurons and thus supposedly motivates aspects of caregiving through its influence on dopaminergic transmission. Most previous studies on caregiving behaviors were thereby performed in women under hormonal contraception to avoid hormonal fluctuations. However, recent studies repeatedly demonstrated decisive influences of the hormonal changes across the female menstrual cycle on dopamine-mediated behaviors, suggesting that estradiol acts as dopamine agonist in the follicular phase and progesterone as dopamine antagonist in the luteal phase. In the present study, we investigated selective attention towards infants as one central aspect of caregiving behavior over the natural menstrual cycle and in relation to interindividual differences of estradiol and progesterone. As expected, we found that women with higher estradiol in the follicular phase also showed higher selective attention towards infant faces among adult distractors, whereas the correlation disappeared in the luteal phase. In contrast, progesterone did not correlate with selective attention towards infants. The present findings collectively support the assumption that estradiol may act as dopamine agonist in the follicular phase, thereby supposedly promoting an important aspect of caretaking behavior.

Long-term dopamine agonist treatment fails to restore altered central sensory processing in restless legs syndrome: Evidence from current perception threshold measurements

OBJECTIVES

Although some studies have examined the impact of short-term dopamine agonist treatment on altered central sensory processing in patients with restless legs syndrome (RLS), there is a scarcity of research investigating the effect of long-term treatment with these drugs. The aim of this study is to investigate the long-term impact of dopamine agonist treatment on altered central sensory processing in RLS patients using current perception threshold (CPT) testing.

METHODS

We conducted a study of 24 RLS patients, measuring their CPT values before and after dopamine agonist treatment for at least 2 months. Patients were classified as responders or non-responders based on their decrease in International Restless Legs Syndrome (IRLS) score. Clinical parameters were collected and compared pre- and post-treatment.

RESULTS

The mean duration of treatment with dopamine agonist was 13.6 ± 11.0 months. Our results showed that dopamine agonist treatment significantly improved clinical parameters, including the IRLS score, Visual Analogue Scale, and RLS Quality of Life questionnaire. However, CPT values did not show significant changes for all stimulus frequencies after treatment. Furthermore, we did not find any difference in CPT values before and after treatment in both responders and non-responders.

CONCLUSIONS

Our study demonstrated that long-term treatment with dopamine agonists effectively reduces RLS symptoms, but does not reverse the altered central sensory processing observed on CPT testing in RLS patients. These results support the notion that the pathophysiology of RLS is multifactorial and not solely driven by dopaminergic dysfunction.

Prolactinomas Resistant to Dopamine Agonists: Pathophysiology and Treatment

Prolactinomas are the most common functional pituitary tumors, accounting for 40% of all pituitary adenomas. Medical treatment with dopamine agonists (DA), mainly cabergoline, is considered the primary therapy for these patients. Prolactin normalization is achieved in 80-90% of prolactinomas treated with cabergoline. Patients resistant to the standard dose can escalate the dose of cabergoline up to the maximum tolerated dose. The expression of dopamine (D2) receptors and dopamine affinity is decreased in aggressive and resistant prolactinomas. Patients with aggressive and DA-resistant adenomas or with rare PRL-secreting carcinomas can be treated off-label with temozolomide (TMZ), a DNA alkylating agent. TMZ is effective in 40-50% of treated lactotroph tumors showing at least a partial response. However, patients tend to escape from the effect of TMZ after a limited time of response. Other therapeutic options include aromatase inhibitors, the somatostatin receptor ligand pasireotide, peptide receptor radionuclide therapy (PRRT), immune-checkpoint inhibitors, tyrosine-kinase inhibitors, or everolimus, the mammalian target of rapamycin inhibitor. These experimental treatments were effective in some patients carrying refractory prolactinomas showing usually partial tumor control. However, the number of treated patients with any of these new therapeutic options is very limited and treatment results are inconsistent, thus additional experience with more patients is required.

Impulse Control Disorders in Patients with Pituitary Tumors Treated with Dopamine Agonists: A Systematic Review

BACKGROUND

The increased prevalence of Impulse Control Disorders (ICDs) in dopamine agonist (DA) treated patients with Parkinson's disease is well described. Despite the frequent use of DAs in the management of pituitary tumors, the relationship between DAs and prevalence of ICDs in patients with pituitary tumours is unclear.

AIMS

To establish the prevalence of ICDs in patients with prolactinoma or acromegaly and determine whether prevalence differs in those on DAs to those treated without.

METHODS

Systematic review of the literature (registered a priori) reporting prevalence of ICDs in patients with prolactinoma or acromegaly (conducted June 2023). A narrative synthesis describing prevalence of ICDs according to assessment method was performed. Prevalence comparisons between patients with prolactinoma or acromegaly treated with DAs, to patients treated without, were summarised.

RESULTS

Studies were largely retrospective, observational and heterogenous, with few patients with prolactinoma and acromegaly treated without DA. Prevalence of ICDs varied between 0-60% in patients with prolactinoma, and from 5-23% in studies with at least five patients with acromegaly. In most studies comparing DA exposed to non-DA exposed cases, DA use was not associated with ICDs.

CONCLUSIONS

Reported prevalence of ICDs in patients with prolactinoma and acromegaly varies considerably. Given ICDs were reported to be highly prevalent in some studies, clinicians should be mindful of these potentially serious disorders. ICD screening tools validated for use in patients with pituitary tumors combined with prospective studies including appropriate controls, are necessary to accurately establish prevalence of ICDs and true impact of DAs in their development.

Efficacy and Safety of Endoscopic Transsphenoidal Resection for Prolactinoma: A Retrospective Multicenter Case-series

BACKGROUND

Endoscopic transsphenoidal surgery (ETSS) for prolactinoma is reserved for dopamine agonist (DA) resistance, intolerance, or apoplexy. High remission (overall 67%, microprolactinoma up to 90%), low recurrence (5-20%) rates highlighted that surgery might be first-line treatment.

AIMS

To report on outcomes of ETSS in a cohort of prolactinomas.

METHODS

Multicenter retrospective cohort of 137 prolactinoma patients (age 38.2 ± 13.7 years; 61.3% female, median follow-up 28.0 [15.0-55.5] months) operated between 2010-2019 with histopathological confirmation.

RESULTS

Median preoperative prolactin levels were 166 (98-837 µg/L; males 996 [159-2145 µg/L] vs. females 129 [84-223 µg/L], p <0.001). 56 (40.9%) microprolactinomas, 69 (50.4%) macroprolactinomas, and 7 (5.1%) giant prolactinomas were included, whereas no adenoma was detected in 5 (3.6%) patients. Males had larger tumors (macroprolactinomas: 38, 71.7%) vs. 31 (36.9%), p <0.001; giant prolactinomas: 7 (13.2%) vs. 0 (0.0%), (p <0.001). Prolactinomas were graded as KNOSP-3 in 15 (11.5%), and KNOSP-4 in 20 (15.3%) patients. Primary indication was DA intolerance (59, 43.1%); males 14 (26.4%) vs. females 45 (53.6%), p = 0.006. Long-term remission (i.e., DA-free prolactin level <1xULN) was achieved in 87 (63.5%) patients, being higher in intended complete resection (69/92 [75.0%]), and lower in males (25 [47.2%] vs. 62 females [73.8%], p = 0.002). Transient DI (n = 29, 21.2%) was the most frequent complication.

CONCLUSIONS

Despite high proportions of macroprolactinoma and KNOSP 3-4, long-term remission rates were 63.5% overall, and 83.3% in microprolactinoma patients. Males had less favorable remission rate compared to females. These findings highlight that ETSS may be a safe and efficacious treatment to manage prolactinoma.

Exploring the prescribing trends and factors affecting initial anti-parkinsonian drug selection in Korea: A nationwide population-based cohort study

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disorder typically treated with dopamine replacement therapy and dopamine agonists (DAs) to alleviate symptoms and minimize dyskinesia. Optimal treatment strategies for patients newly diagnosed with PD have been a topic of debate for many years.

METHODS

We conducted a 10-year descriptive study of drug prescription trends and factors affecting prescription choices for newly diagnosed drug-naïve PD patients using data from the National Health Insurance program in Korea. To identify statistically significant differences in yearly trends, we employed the Cochran-Armitage trend test. Additionally, we utilized multiple logistic regression analysis to investigate the factors associated with the selection of levodopa and DAs as initial anti-parkinsonian drugs.

RESULTS

A total of 99,118 patients with PD who were prescribed levodopa or DAs alone as initial anti-parkinsonian drugs between 2011 and 2020 were eligible for inclusion in the analysis. The prescription rate of DAs increased until 2012, and then steadily decreased annually. The likelihood of levodopa prescription increased with age and at higher-level hospitals. In terms of comorbidities, patients with Alzheimer's disease and cerebrovascular diseases were more likely to be prescribed levodopa than those with peptic ulcer disease and dyslipidemia.

CONCLUSION

The decline in levodopa prescriptions was reversed in 2012, and the prescription rate has continued to increase until recently. The odds ratio of levodopa prescription increased in elderly patients with Alzheimer's disease and decreased in patients with Medical aid insurance and peptic ulcer disease.

Surgical Treatment of Prolactinomas: Potential Role as a First-Line Treatment Modality

PURPOSE

Treatment with dopamine agonists (DAs) has been the first-line standard treatment for prolactinoma, and surgery has been reserved for drug intolerance and resistance for several decades. We evaluated whether surgery plays a primary role in prolactinoma management.

MATERIALS AND METHODS

We conducted a retrospective study of 210 prolactinoma patients who had received surgical treatment at our institution. We analyzed the treatment outcomes according to tumor extent, sex, and preoperative DA medication.

RESULTS

Overall hormonal remission was achieved in 164 patients (78.1%), and complete removal was achieved in 194 patients (92.4%). When the tumors were completely removed, the remission rate increased to 84.5%. Anterior pituitary function was normalized or improved in 94.6% of patients, whereas only 4.1% of patients showed worsening of hormone control. Hormonal remission was higher in patients who had not received DA preoperatively than in those who had received preoperative DA treatment. Smaller tumor size (<1 cm), no invasion into the cavernous sinus, and female sex were predictors of good surgical outcomes.

CONCLUSION

Although DAs remain the first-line standard treatment for prolactinomas, surgery can be an excellent option and should be considered as an alternative primary treatment modality when patients are predicted to achieve a good surgical outcome.

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.

Dopamine agonist therapy in Parkinson's disease: Spanish expert consensus on its use in different clinical situations

BACKGROUND

Different types of therapies were proven effective for the medical management of motor and non-motor symptoms in Parkinson's disease (PD). We aimed to gain consensus on the Dopamine agonist (DA) therapy use in different clinical scenarios of Parkinson's disease (PD) patients.

METHODS

This consensus study was based on the nominal group technique. Initially, a Consensus Group comprising 12 expert neurologists in the PD field identified the topics to be addressed and elaborated different evidence-based preliminary statements. Next, a panel of 48 Spanish neurologists expressed their opinion on an internet-based systematic voting program. Finally, initial ideas were reviewed and rewritten according to panel contribution and were ranked by the Consensus group using a Likert-type scale. The analysis of data was carried out by using a combination of both qualitative and quantitative methods. The consensus was achieved if the statement reached ≥3,5 points on the voting process.

RESULTS

The Consensus Group produced 76 real-world recommendations. The topics addressed included 12 statements related to DA therapy in early PD, 20 statements concerning DA treatment strategy in patients with motor complications, 11 statements associated with DA drugs and their side effects, and 33 statements regarding DA therapy in specific clinical scenarios. The Consensus Group did not reach a consensus on 15 statements.

CONCLUSION

The findings from this consensus method represent an exploratory step to help clinicians and patients in the appropriate use of DA in different stages and clinical situations of PD.

Safety review of current pharmacotherapies for levodopa-treated patients with Parkinson's disease

INTRODUCTION

Levodopa remains the gold standard for treatment of Parkinson's disease (PD). Patients develop complications with disease progression, necessitating adjunctive therapy to control fluctuations in motor and non-motor symptoms and dyskinesia. Knowledge of medication safety and tolerability is critical to ascertain the benefit-risk ratio and select an adjunctive therapy that provides the highest chance for medication adherence. Posing a challenge are the sheer abundance of options, stemming from the development of several new drugs in recent years, as well as differences in commercial drug availability worldwide.

AREAS COVERED

This review evaluates the efficacy, safety, and tolerability of current US FDA-approved pharmacotherapies for levodopa-treated PD patients, including dopamine agonists, monoamine oxidase type-B inhibitors, catechol-O-methyltransferase inhibitors, the N-methyl-D-aspartate receptor antagonist amantadine, and the adenosine receptor antagonist istradefylline. Data were taken from pivotal phase III randomized controlled and post-surveillance studies, when available, that directly led to FDA-approval.

EXPERT OPINION

No strong evidence exists to support use of a specific adjunctive treatment for improving Off time. Only one medication has demonstrated improvement in dyskinesia in levodopa-treated PD patients; however, every patient cannot tolerate it and therefore adjunctive therapy should be tailored to an individual's symptoms and risk for specific adverse effects.

Role of Immediate Postoperative Prolactin Measurement in Female Prolactinoma Patients: Predicting Long-Term Remission After Complete Tumor Removal

BACKGROUND

Transsphenoidal surgery is one of the important treatment options in the management of prolactinomas; however, complete resection of the tumor does not always lead to endocrinological remission. While many studies have investigated preoperative factors associated with surgical outcome, little has been known about the relationship between postoperative factors and long-term surgical outcomes; moreover, there is no consistency in results. The aim of this study was to demonstrate the reliability of immediate postoperative prolactin levels as predictors of long-term outcomes.

METHODS

A total of 105 female patients who underwent complete removal of their histologically confirmed prolactinomas were included, and their medical records were retrospectively reviewed. To evaluate the predictability of immediate postoperative prolactin levels for long-term remission, prolactin levels were measured at 2, 6, 12, 18, 24, 48, and 72 h after surgery.

RESULTS

From the 105 included patients, 95 (90.5%) and 10 (9.5%) belonged to the remission and non-remission groups, respectively. A significant difference was observed in the prolactin level measured 6 h after surgery between the remission and non-remission groups, and this difference stayed apparent until 72 h after surgery. We derived a cut-off value for every postoperative time point that showed a significant relationship with disease remission.

CONCLUSION

Our study suggests that immediate postoperative measurement of prolactin levels is a reliable predictor of long-term remission and can contribute to early identification of patients who require adjuvant treatment after surgery.

Dopamine agonists versus levodopa monotherapy in early Parkinson's disease for the potential risks of motor complications: A network meta-analysis

BACKGROUND

Compared with levodopa, dopamine agonists (DAs) as initial treatment are associated with lower incidences of motor complications in early Parkinson's disease (PD). There is no strong evidence that a given DA is more potent in lower incidences of motor complications than another.

OBJECTIVE

We performed a network meta-analysis of levodopa versus DAs as monotherapy in early PD to access the risk of motor complications.

METHODS

Databases were searched up to June 2022 for eligible RCTs. Levodopa and four DAs (pramipexole, ropinirole, bromocriptine and pergolide) were investigated. The incidences of motor complications and efficacy, tolerability and safety outcomes were analyzed.

RESULTS

Nine RCTs (2112 patients) were included in the current study. The surface under the cumulative ranking curve (SUCRA) indicated that levodopa ranked first in the incidence of dyskinesia (0.988), followed by pergolide, pramipexole, ropinirole, and bromocriptine (0.704, 0.408, 0.240, 0.160). Pramipexole was least prone to wearing-off (0.109) and on-off fluctuation (0.041). Levodopa performed best in improvements of UPDRS-II, UPDRS-III, and UPDRS-II + III (0.925, 0.952, 0.934). Bromocriptine ranked first in total withdrawals and withdrawals due to adverse events (0.736, 0.751). Four DAs showed different adverse events profiles.

CONCLUSION

In the two non-ergot DAs, ropinirole is associated with a lower risk of dyskinesia while pramipexole is associated with lower risks of wearing-off and on-off fluctuations. Our research may facilitate head-to-head research, larger sample sizes, long following-up time RCTs to confirm the findings of this network meta-analysis.

How to manage intolerance to dopamine agonist in patients with prolactinoma

PURPOSE

Dopamine agonists (DA) are the gold-standard for prolactinoma and hyperprolactinemia treatment. Intolerance to DA leading to drug drop out occurs in 3 to 12% of cases. We provide here a review of published data about DA intolerance and present a case report concerning the use of intravaginal cabergoline.

METHODS

We review the literature on the definition, the pathogenesis, frequency and management of DA intolerance. In addition, the review provides strategies to enhance tolerability and avoid precocious clinical treatment withdrawal.

RESULTS

Cabergoline is often cited as the most tolerable DA and its side effects tend to ameliorate within days to weeks. Restarting the same drug at a lower dose or switching to another DA can be used in cases of intolerance. The vaginal route can be tried specifically if there are gastrointestinal side effects in the oral administration. Symptomatic treatment could be attempted, although mainly based on a strategy used in other diseases.

CONCLUSIONS

Due to limited data, no guidelines have been developed for the management of intolerance in DA treatment. The most frequent management is to perform transsphenoidal surgery. Nevertheless, this manuscript provides data derived from published literature and expert opinion, suggesting new approaches to this clinical issue.

The effect of levodopa treatment on vascular endothelial function in Parkinson's disease

OBJECTIVE

There has been increasing awareness that micro-vascular alteration or vascular inflammation has been associated with levodopa-induced dyskinesia in PD. Vascular endothelial function assessed by flow mediated dilation (FMD) is known to reflect early microvascular change. We compare the impact of levodopa or dopamine agonist treatment on the change of FMD in de novo PD patients.

METHODS

This retrospective study used a selected sample from registry. We identified de-novo PD patients who underwent FMD at baseline, and follow-up FMD after 1 year (± 2 month) of levodopa (n = 18) or dopamine agonist (n = 18) treatment.

RESULTS

FMD decreased after levodopa (8.60 ± 0.46 to 7.21 ± 0.4, p = 0.002) but there were no significant changes after DA treatment (8.33 ± 0.38 to 8.22 ± 0.33, p = 0.26). Homocysteine rose (11.52 ± 0.45 to 14.33 ± 0.68, p < 0.05) during levodopa treatment, but dopamine agonist had no effect (10.59 ± 0.38 to 11.38 ± 0.67, p = 0.184). Correlation analysis revealed that the changes in homocysteine level had non-significant correlation with FMD change (r =  - 0.30, p = 0.06). FMD change was not associated with age (p = 0.47), disease duration (p = 0.81), baseline motor UPDRS (p = 0.43), motor UPDRS change (p = 0.64), levodopa equivalent dose change (p = 0.65).

CONCLUSIONS

We found that 1-year levodopa treatment may adversely affect vascular endothelial function in de novo PD. Further studies are needed to clarify the exact pathogenesis and clinical implication of levodopa-induced endothelial dysfunction in PD.

DRD2 expression based on 18F-fallypride PET/MR predicts the dopamine agonist resistance of prolactinomas: a pilot study

PURPOSE

The dopamine agonists (DA) have been used widely to treat prolactinomas. However, it is difficult to predict whether the patient will be responsive to DA treatment.

METHODS

We aimed to investigate whether the in vivo expression of DRD2 based on ¹⁸F-fallypride PET/MR could predict the therapeutic effect of DA on prolactinomas. Seven patients with prolactinomas completed ¹⁸F-fallypride PET/MR. Among them, three patients underwent surgery and further tumor immunohistochemistry. Imaging findings and immunohistochemical staining were compared with treatment outcomes.

RESULTS

¹⁸F-fallypride PET/MR was visually positive in 7 of 7 patients, and DRD2 target specificity could be confirmed by immunohistochemical staining. A significantly lower tracer standard uptake value (SUV) could be detected in the resistant patients (n = 3) than in the sensitive patients (n = 4; SUV_mean, 4.67 ± 1.32 vs. 13.57 ± 2.42, p < 0.05). DRD2 expression determined by ¹⁸F-fallypride PET/MR corresponded with the DA treatment response.

CONCLUSION

¹⁸F-fallypride PET/MR may be a promising technique for predicting DA response in patients with prolactinoma.

Distinctive Effects of D1 and D2 Receptor Agonists on Cortico-Basal Ganglia Oscillations in a Rodent Model of L-DOPA-Induced Dyskinesia

L-DOPA-induced dyskinesia (LID) in Parkinson's disease has been linked to oscillatory neuronal activities in the cortico-basal ganglia network. We set out to examine the pattern of cortico-basal ganglia oscillations induced by selective agonists of D1 and D2 receptors in a rat model of LID. Local field potentials were recorded in freely moving rats using large-scale electrodes targeting three motor cortical regions, dorsomedial and dorsolateral striatum, external globus pallidus, and substantial nigra pars reticulata. Abnormal involuntary movements were elicited by the D1 agonist SKF82958 or the D2 agonist sumanirole, while overall motor activity was quantified using video analysis (DeepLabCut). Both SKF82958 and sumanirole induced dyskinesia, although with significant differences in temporal course, overall severity, and body distribution. The D1 agonist induced prominent narrowband oscillations in the high gamma range (70-110 Hz) in all recorded structures except for the nigra reticulata. Additionally, the D1 agonist induced strong functional connectivity between the recorded structures and the phase analysis revealed that the primary motor cortex (forelimb area) was leading a supplementary motor area and striatum. Following treatment with the D2 agonist, narrowband gamma oscillations were detected only in forelimb motor cortex and dorsolateral striatum, while prominent oscillations in the theta band occurred in the globus pallidus and nigra reticulata. Our results reveal that the dyskinetic effects of D1 and D2 receptor agonists are associated with distinct patterns of cortico-basal ganglia oscillations, suggesting a recruitment of partially distinct networks.

Brain monoamine vesicular transport disease caused by homozygous SLC18A2 variants: A study in 42 affected individuals

PURPOSE

Brain monoamine vesicular transport disease is an infantile-onset movement disorder that mimics cerebral palsy. In 2013, the homozygous SLC18A2 variant, p.Pro387Leu, was first reported as a cause of this rare disorder, and dopamine agonists were efficient for treating affected individuals from a single large family. To date, only 6 variants have been reported. In this study, we evaluated genotype-phenotype correlations in individuals with biallelic SLC18A2 variants.

METHODS

A total of 42 affected individuals with homozygous SLC18A2 variant alleles were identified. We evaluated genotype-phenotype correlations and the missense variants in the affected individuals based on the structural modeling of rat VMAT2 encoded by Slc18a2, with cytoplasm- and lumen-facing conformations. A Caenorhabditis elegans model was created for functional studies.

RESULTS

A total of 19 homozygous SLC18A2 variants, including 3 recurrent variants, were identified using exome sequencing. The affected individuals typically showed global developmental delay, hypotonia, dystonia, oculogyric crisis, and autonomic nervous system involvement (temperature dysregulation/sweating, hypersalivation, and gastrointestinal dysmotility). Among the 58 affected individuals described to date, 16 (28%) died before the age of 13 years. Of the 17 patients with p.Pro237His, 9 died, whereas all 14 patients with p.Pro387Leu survived. Although a dopamine agonist mildly improved the disease symptoms in 18 of 21 patients (86%), some affected individuals with p.Ile43Phe and p.Pro387Leu showed milder phenotypes and presented prolonged survival even without treatment. The C. elegans model showed behavioral abnormalities.

CONCLUSION

These data expand the phenotypic and genotypic spectra of SLC18A2-related disorders.

Dopamine agonist monotherapy utilization in patients with Parkinson's disease

Objectives

To characterize patients with Parkinson's disease (PD) who initiated dopamine agonist (DA) monotherapy, describe medication utilization and provider types, and estimate medication adherence and discontinuation rates.

Methods

Retrospective study identified patients with PD in the Optum Research Database and included those with ≥1 claim for DA or levodopa between 09/01/2012 and 12/31/2018, ≥2 PD diagnoses, commercial or Medicare Advantage Part D (MAPD) insurance, ≥40 years old, and continuous medical and pharmacy coverage ≥12 months before and after index date. A subset of patients receiving DA monotherapy was selected for this analysis. Variables were analyzed descriptively. Adherence was measured with medication possession ratio (MPR) and proportion of days covered (PDC); defined as ≥0.80.

Results

Patients (N = 642) had mean (SD) age of 70.2 (9.9) years, 70.6 % had MAPD coverage, and 61.7 % were male. Neurologists prescribed 64.6 % of DA monotherapy, and 56.9 % of patients had ≥2 PD diagnoses before or on the index date. Index therapy was discontinued by 44.1 % of patients, and 55.9 % persisted for 12 months without change. Mean (SD) time to discontinuation was 102 (79) days. Mean (SD) MPR for patients (n = 562) with ≥2 fills was 0.84 (0.2); 70.3 % were MPR adherent. Mean (SD) PDC for all 642 patients was 0.66 (0.3); 50.5 % were PDC adherent.

Conclusion

Adherence and continuation of therapy were suboptimal, which could translate into poor patient outcomes. Future studies could provide insights on the impact of low adherence and persistence with DA monotherapy.

A Genetic Assessment of Dopamine Agonist-Induced Impulse Control Disorder in Patients with Prolactinoma

CONTEXT

Dopamine agonist-induced (DA-induced) impulse control disorder (ICD) represents a group of behavioral disorders that are increasingly recognized in patients with prolactinoma.

OBJECTIVE

We aimed to examine the genetic component of the underlying mechanism of DA-induced ICD.

METHODS

Prolactinoma patients receiving dopamine agonist (cabergoline) treatment were included in the study. These patients were divided into two groups: patients who developed ICD due to DA and patients who did not. Patients were evaluated for polymorphisms of the DRD1, DRD3, COMT, DDC, GRIN2B, TPH2, OPRK1, OPRM1, SLC6A4, SLC6A3, HTR2A genes.

RESULTS

Of the 72 prolactinoma patients using cabergoline, 20 were diagnosed with ICD. When patients with and without ICD were compared according to genotype frequencies; OPRK1/rs702764, DRD3/rs6280, HTR2A/rs6313, SLC6A4/rs7224199, GRIN2B/rs7301328, TPH2/rs7305115, COMT/rs4680, DRD1/rs4532 polymorphisms significantly increased in patients with DA-induced ICD.

CONCLUSION

Our results show that multiple neurotransmission systems affect DA-induced ICD in patients with prolactinoma.

Pituitary acting drugs: cabergoline and pasireotide

First-line treatment for Cushing´s disease is transsphenoidal surgery. But in cases of persistent or recurrent disease after surgery, contraindications to surgery, severe hypercortisolism control before surgery, or for patients waiting for radiotherapy effects, medical therapy may be indicated. Pituitary-directed agents include cabergoline and pasireotide. Both drugs present similar potential for biochemical control and pasireotide has additionally been proved to reduce tumor volume. Moreover, pasireotide was evaluated in high quality studies. In respect to safety, both drugs are well tolerated and safe, but special attention should be given for cardiac valve disease and psychiatric disorder for cabergoline, and hyperglycemia for pasireotide.

Impairment of endothelial function in Parkinson's disease

OBJECTIVE

There are conflicting data regarding the relationship between Parkinson's disease (PD) and the atherosclerotic process. This study aimed to compare endothelial function in patients with PD and matched controls. In PD subjects, we searched for factors contributing to endothelial dysfunction as well. Traditional vascular risk factors, PD characteristics, and PD medication were considered.

RESULTS

We prospectively enrolled 41 patients with PD and 41 controls matched for age, sex, body mass index, and vascular risk factors. Endothelial function (EF) was assessed using peripheral arterial tonometry (EndoPAT 2000 device) and expressed as reperfusion hyperemia index (RHI). Clinical characteristics including PD medication were recorded. RHI was non-significantly lower in the PD group than in controls (1.8 ± 0.5 vs. 1.9 ± 0.5, p = 0.478). In PD patients, in linear regression analysis, smoking (beta = -0.453, p = 0.008) and use of dopamine agonists (beta = -0.365, p = 0.030) were significant contributors in a model predicting RHI. Despite non-significant differences in endothelial dysfunction between PD patients and controls, our results suggest an association between smoking, dopamine agonists, and impaired EF in PD patients. The small sample size, as well as the absence of an extended search for traditional and non-traditional vascular risk factors, are the most important factors limiting the interpretation of the current results.

Outcome of Dopamine Agonist Therapy Withdrawal in Children with Prolactinomas

BACKGROUND

Prolactinomas are rare in children and adolescents. As in adults, dopamine agonists (DAs) are the treatment of choice in the majority of patients. However, at what point children should be taken off of therapy and what the recurrence risk of hyperprolactinemia is following treatment withdrawal is not well described.

OBJECTIVE

Our objective was to systematically review our experience with DA treatment withdrawal in children and adolescents with prolactinomas.

METHODS

A retrospective review of patients followed for prolactinomas during the last 12 years was conducted. Variables analyzed included age, gender, initial serum prolactin levels, tumor characteristics, cabergoline dose, and results of treatment withdrawal. Clinical characteristics of patients who met eligibility criteria for DA withdrawal were compared with those who did not. Patients who underwent surgery were excluded.

RESULTS

Of 47 patients identified, 42 were included in the study. Of those, DA withdrawal was attempted in 13 (31%) and was initially successful in 3 (21%). Patients who did not meet eligibility criteria for treatment withdrawal had higher baseline prolactin levels (p = 0.018) as well as larger (p = 0.03) and more invasive (p = 0.002) tumors.

CONCLUSIONS

Less than half of our patients were eligible for DA treatment withdrawal and less than one-fourth achieved remission of hyperprolactinemia following cessation of therapy. This suggests that the overall recurrence rate of prolactinomas in pediatric patients may be higher than has been reported in adults.

Proportion and predictors of Hypogonadism Recovery in Men with Macroprolactinomas treated with dopamine agonists

INTRODUCTION

Hypogonadism is the most common form of hypopituitarism in men with macroprolactinoma. However, evidence on factors related to hypogonadism recovery is limited.

OBJECTIVES

We estimated the proportion of hypogonadism in men with macroprolactinoma exclusively treated with dopamine agonists, and we assessed the factors predicting hypogonadism recovery.

PATIENTS AND METHODS

This was a multicenter retrospective study of men with macroprolactinoma identified using ICD 9 and 10 codes and treated between 2009 and 2019 in five centers in the United Arab Emirates and Saudi Arabia. We evaluated hypogonadism, defined as low total testosterone (TT) level with normal or low gonadotropins on presentation and during the last clinic visit.

RESULTS

A total of 79 patients (median age 32 years) were included in the study. The most common symptoms at presentation were headache (73.7%), erectile dysfunction (55.4%), and low libido (54.3%). The median tumor size was 2.9 cm (1.0-9.7) at diagnosis. Sixty-three patients (79.7%) had hypogonadism at baseline. Growth hormone deficiency (GHD) and hypothyroidism were present in 34.4% and 32.9% of patients, respectively. The median serum prolactin (PRL) level was 20,175 (min-max 2254 - 500,000) mIU/l with a median serum TT of 4.5 (min-max 0.4-28.2) nmol/l. Most patients were treated with cabergoline (n = 77, 97.5%) with a median of 6 (min-max 0.6-22) years. At follow-up, 65% of patients recovered their pituitary-testicular axis. Patients with recovered hypogonadism had smaller median tumor size (2.4 [1-5.4] vs. 4.3 [1.6-9.7], p = 0.003), lower PRL level (18, 277 [2254 - 274, 250] vs. 63,703 [ 3,365-500,000], p = 0.008 ), higher TT level (4.6 [0.6-9.2] vs. 2.3 [0.5-7.3], p = 0.008), lower PRL normalization time on medical therapy (8 months (0.7-72) vs. 24 (3-120), p = 0.009) as well as lower frequency of GHD (17.1% vs. 60%, p = 0.006) and secondary hypothyroidism (17.9% vs. 57.1%, p = 0.003) compared with those with persistent hypogonadism respectively. Age at diagnosis, presenting symptoms and duration of medical therapy did not predict hypogonadism recovery.

CONCLUSIONS

About two-thirds of men with macroprolactinoma recover from hypogonadism, mostly with 24 months of therapy. Smaller adenoma size, lower prolactin level, earlier prolactin normalization, and higher testosterone patients were related to testosterone normalization.

Resistant prolactinomas: a case series of 26 patients

PURPOSE

Prolactin (PRL)-secreting tumors are the most common functional pituitary adenomas. They usually respond to dopamine agonist (DA) treatment, with PRL normalization and adenoma shrinkage. Our aim was to characterize patients with prolactinoma resistant to DA treatment.

METHODS

This retrospective case series included patients diagnosed with DA-resistant prolactinomas between 1993-2017 in three medical centers. Resistance was defined as PRL levels above three times the upper limit of normal (ULN) despite a weekly dose of ≥2 mg cabergoline (CAB). Clinical and biochemical information, and response to treatment, were retrieved from medical records.

RESULTS

Twenty-six patients were identified; 20 males. Of 25 macroadenomas, three were giant tumors (>40 mm) and 15 (57.7%) were invasive. The mean age at diagnosis was 31.8 ± 14.9 years (range: 13-62). The median maximal CAB dose was 3.5 mg/week (IQR, 2.5-5). Half the patients received only CAB in escalating doses, nine received CAB and underwent transsphenoidal surgery, and four underwent surgery and radiotherapy in addition to CAB treatment. PRL levels at baseline between patients treated only with CAB and those operated were (91.6 [51.1-296.7] vs. 73.1 [22.6-170.9] XULN p = 0.355), and under maximal CAB dose PRL levels between patients treated only with CAB and those operated were similar (5.77 [1.27-11.27] vs 5.27 (2.9-26) XULN p = 0.317). At the last visit patients who received combined therapy achieved lower PRL levels than those treated with DA only (5.22 [1.7-21.6] vs 1.1 [0.44-3.99] XULN p = 0.017) PRL normalization was attained in seven patients and levels below 3 × ULN in fourteen patients; the overall response was 56%.

CONCLUSIONS

Resistant prolactinomas usually require a multi-modal treatment strategy. We were able to control 14/25 (56%) of resistant tumors.

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.

Dopamine agonist for the rapid improvement of visual field defects in giant and macro-prolactinomas

PURPOSE

To evaluate effect of first-line dopamine agonist (DA) therapy as an alternative to surgery for visual field defect (VFD) recovery in giant and macro-prolactinoma.

METHODS

In this retrospective study, 125 patients with giant and macro-prolactinoma, except those with a history of previous surgery or radiotherapy, were evaluated. Those who underwent visual field examinations using the Humphrey Visual Field analyser upon initial assessment and after treatment were included for analysis. Twelve patients with VFD were included. The effects of DA therapy on both VFD and tumor size were evaluated within the first three months.

RESULTS

There were twelve patients analysed: three females and nine males, five giant and seven macroprolactinomas; eight patients received cabergoline (CAB) and four patients received bromocriptine (BRC). The mean adenoma diameter was 35±13mm (range 15-60), and the mean PRL level was 3,523ng/dL (range 312-11,703). Eight patients (67%) complained of blurred vision, while four patients (33%) reported no visual symptoms. After a median duration of three weeks, the VFD completely resolved in ten patients (83%) but only partially improved in two (17%). The mean initial doses of CAB and BRC that provided VFD improvement were 0.5±0.2mg/week and 6.3±1.4mg/day, respectively. After a mean duration of 2.2±0.9months, the mean decrease in adenoma size was 43.6±24.5% (range 10-95%).

CONCLUSION

The use of DA as a first-line treatment for at least one month before deciding on surgery is recommended in giant and macro-prolactinomas with VFD. Surgery should be considered only in cases with DA resistance or persistent visual impairment despite medical therapy.

Effects of dietary and milking frequency changes and administration of cabergoline on clinical udder characteristics in dairy cows during dry-off

We investigated the effects of 2 diet energy densities [normal lactation diet (NORM) vs. energy-reduced diet (REDU), both fed for ad libitum intake] and 2 daily milking frequencies [twice (2×) vs. once (1×)] during 1 week before the dry-off day, as well as effects of an injection of either a dopamine agonist [cabergoline (CAB); Velactis, Ceva Santé Animale, Libourne, France; labelled for use only with abrupt dry-off, e.g. no reduction in diet energy density or milking frequency before the last milking] or saline (SAL) following the last milking, on clinical udder characteristics of Holstein cows. During a week before and after the last milking, the following measures were recorded: palpation-based udder firmness and soreness; image-based hock-hock distance; responsiveness to mechanical udder stimulation and degree of udder fill measured with a dynamometer. Before the last milking, REDU cows displayed lower odds of having a firm udder and lower degree of udder fill, as well as lower responsiveness to mechanical udder stimulation, than NORM cows. After the last milking, REDU cows displayed shorter hock-hock distance compared with NORM cows. The effects of milking frequency on the clinical udder characteristics were unclear. Within 24 h following injection, CAB cows showed lower odds of having a firm udder, shorter hock-hock distance, and lower degree of udder fill than SAL cows, irrespective of treatment group before dry-off. In this study, reducing diet energy density prior to dry-off, and to some extent administering the dopamine agonist cabergoline after the last milking, resulted in fewest clinical udder changes.

The role of MAPK11/12/13/14 (p38 MAPK) protein in dopamine agonist-resistant prolactinomas

BACKGROUND

Prolactinoma is a functional pituitary adenoma that secretes excessive prolactin. Dopamine agonists (DAs) such as bromocriptine (BRC) are the first-line treatment for prolactinomas, but the resistance rate is increasing year by year, creating a clinical challenge. Therefore, it is urgent to explore the molecular mechanism of bromocriptine resistance in prolactinomas. Activation of the P38 MAPK pathway affects multidrug resistance in tumours. Our previous studies have demonstrated that inhibiting MAPK14 can suppress the occurrence of prolactinoma, but the role of MAPK11/12/13/14 (p38 MAPK) signalling in dopamine agonist-resistant prolactinomas is still unclear.

METHODS

A prolactinoma rat model was established to determine the effect of bromocriptine on MAPK11/12/13/14 signalling. DA-resistant GH3 cells and DA-sensitive MMQ cells were used, and the role of MAPK11/12/13/14 in bromocriptine-resistant prolactinomas was preliminarily verified by western blot, RT-qPCR, ELISA, flow cytometry and CCK-8 experiments. The effects of MAPK11 or MAPK14 on bromocriptine-resistant prolactinomas were further verified by siRNA transfection experiments.

RESULTS

Bromocriptine was used to treat rat prolactinoma by upregulating DRD2 expression and downregulating the expression level of MAPK11/12/13/14 in vivo experiments. The in vitro experiments showed that GH3 cells are resistant to bromocriptine and that MMQ cells are sensitive to bromocriptine. Bromocriptine could significantly reduce the expression of MAPK12 and MAPK13 in GH3 cells and MMQ cells. Bromocriptine could significantly reduce the expression of MAPK11, MAPK14, NF-κB p65 and Bcl2 in MMQ but had no effect on MAPK11, MAPK14, NF-κB p65 and Bcl2 in GH3 cells. In addition, knockdown of MAPK11 and MAPK14 in GH3 cells by siRNA transfection reversed the resistance of GH3 cells to bromocriptine, and haloperidol (HAL) blocked the inhibitory effect of bromocriptine on MAPK14, MAPK11, and PRL in MMQ cells. Our findings show that MAPK11 and MAPK14 proteins are involved in bromocriptine resistance in prolactinomas.

CONCLUSION

Bromocriptine reduces the expression of MAPK11/12/13/14 in prolactinomas, and MAPK11 and MAPK14 are involved in bromocriptine resistance in prolactinomas by regulating apoptosis. Reducing the expression of MAPK11 or MAPK14 can reverse bromocriptine resistance in prolactinomas.

The recurrence of prolactinoma after withdrawal of dopamine agonist: a systematic review and meta-analysis

BACKGROUND

Prolactinoma is the major cause of hyperprolactinemia, and dopamine agonists (DAs) are generally the first-line treatment for them. Several studies have reviewed the recurrent rate of hyperprolactinemia after DAs withdrawal. However, few of them have concerned the recurrence risk of prolactinoma following the withdrawal of DAs.

METHODS

Three medical databases, PubMed, EMBASE and Cochrane library, were retrieved up to February, 14, 2021 to identify studies related to recurrence of prolactinoma and withdrawal of DAs. Statistical analyses including meta-analysis, sensitivity analysis, meta-regression, funnel plot and Egger test were performed through software R.

RESULTS

A total of 3225 studies were retrieved from the three data bases, and 13 studies consisted of 616 patients and 19 arms were finally included in this systematic analysis. There was no significant heterogeneity among the included studies, and fixed effect model was thus used. The pooled recurrence proportion of prolactinoma after withdrawal of DA was 2% with a 95% confidence interval (CI) of 1-3%.

CONCLUSION

Our study showed a very low recurrent rate of prolactinomas after DAs withdrawal. Much more prospective studies with larger cases and longer follow-up period are encouraged to confirm our finding.

TRIAL REGISTRATION

Registration number CRD42021245888 (PROSPERO).

Effects of bromocriptine in peripartum cardiomyopathy: a systematic review and meta-analysis

Peripartum cardiomyopathy (PPCM) is a rare but potentially life-threatening form of heart failure (HF). Bromocriptine, a dopamine D2 agonist, has been used as an adjunctive treatment for PPCM with controversial benefits. A comprehensive literature search was conducted through June 2021. We included studies comparing the outcomes of PPCM with or without bromocriptine use. Pooled risk ratio (RR) with 95% confidence intervals (CI) and I² statistics were calculated. Composite major adverse outcomes were defined by a composite of death, need for advanced HF therapies, persistent New York Heart Association (NYHA) functional class III/V, or left ventricular ejection fraction (LVEF) ≤ 35% at 6-month follow-up. LVEF recovery was defined by improvement of LVEF to more than 50%. Eight studies (two randomized-controlled, six observational) involving 593 PPCM patients were included. Bromocriptine use was associated with significantly higher survival (91.6% vs. 83.9%, RR 1.11 p = 0.02). Baseline LVEF was not significantly different between the groups. LVEF at follow-up was significantly higher in the bromocriptine group (53.3% vs. 41.8%, p < 0.001). There was no significant association between bromocriptine use and lower composite major adverse outcomes (13.7% vs. 33.3%, RR 0.60 p = 0.54) or LVEF recovery (46.9% vs. 46.8%, RR 0.94 p = 0.74). In conclusion, the addition of bromocriptine to standard HF treatment in PPCM was associated with significantly higher survival and higher LVEF improvement. No association with lower composite adverse clinical outcomes or LVEF recovery was seen. The findings, although encouraging, warrant larger randomized-controlled studies.

Dopamine genetic risk score predicts impulse control behaviors in Parkinson's disease

INTRODUCTION

Up to 40% of Parkinson's disease patients taking dopamine agonist medication develop impulse control behaviors which can have severe negative consequences. The current study aimed to utilize dopamine genetics to identify patients most at risk of developing these behaviors.

METHODS

Demographic, clinical, and genetic data were obtained from the Parkinson's Progression Markers Initiative for de novo patients (n = 327), patients taking dopamine agonists (n = 146), and healthy controls (n = 160). Impulsive behaviors were identified using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease. A dopamine genetic risk score was calculated for each patient according to polymorphisms in genes coding for dopamine D1, D2 and D3 receptors, and catechol-O-methyltransferase. A higher score reflected higher central dopamine neurotransmission.

RESULTS

Patients on agonists with a low dopamine genetic risk score were over 18 times more likely to have an impulsive behavior compared to higher scores (p = 0.04). The 38% of patients taking agonists who had at least one impulsive behavior were more likely to be male and report higher Unified Parkinson's Disease Rating Scale I&II scores. With increasing time on dopamine agonists (range 92-2283 days, mean 798 ± 565 standard deviation), only patients with a high dopamine genetic risk score showed an increase in number of impulsive behaviors (p = 0.033). Predictive effects of the gene score were not present in de novo or healthy control.

CONCLUSIONS

A dopamine genetic risk score can identify patients most at risk of developing impulsive behaviors on dopamine agonist medication and predict how these behaviors may worsen over time.

An assessment of Parkinson's disease medication treatment patterns in the Medicaid population

INTRODUCTION

Most Parkinson's disease (PD) medication adherence studies have focused on patients with commercial or Medicare health insurance coverage. However, less is known regarding medication treatment patterns within the Medicaid population.

METHODS

This retrospective cohort study utilized 2011-2019 administrative healthcare claims from 7 state Medicaid programs. We compared newly diagnosed patients with PD started on either levodopa or a dopamine agonist (DA). Baseline comorbidities were compared. Outcomes were assessed during a 12-month post-index observation period, and included total medication days, proportion of days covered (PDC), adherence status, persistence to initiating PD medication, and time to non-persistence of initiating PD medication.

RESULTS

Our study sample of 805 Medicaid patients had an average age of 54.1 years, with 52.0% being female. Levodopa was the predominant PD medication at initiation (75.4%). Roughly half of patients had a baseline depressive disorder and nearly 40% had an anxiety disorder. Levodopa patients had a significantly higher PDC compared to DA patients (0.621 vs. 0.546, p = 0.007). An adjusted logistic regression model showed no significant difference in the number of adherent patients between the two groups (p = 0.058). An adjusted Cox proportional hazards model controlling for demographic and baseline variables showed a 26% lower risk of non-persistence for levodopa patients versus DA patients (HR 0.740, CI 0.597-0.917, p = 0.006).

CONCLUSIONS

Adherence and persistence rates were suboptimal following initiation of either levodopa or DA medication for patients with PD in Medicaid programs, though rates were better for those initiated on levodopa.

The PRolaCT studies - a study protocol for a combined randomised clinical trial and observational cohort study design in prolactinoma

Background

First-line treatment for prolactinomas is a medical treatment with dopamine agonists (DAs), which effectively control hyperprolactinaemia in most patients, although post-withdrawal remission rates are approximately 34%. Therefore, many patients require prolonged DA treatment, while side effects negatively impact health-related quality of life (HRQoL). Endoscopic transsphenoidal resection is reserved for patients with severe side effects, or with DA-resistant prolactinoma. Surgery has a good safety profile and high probability of remission and may thus deserve a more prominent place in prolactinoma treatment. The hypothesis for this study is that early or upfront surgical resection is superior to DA treatment both in terms of HRQoL and remission rate in patients with a non-invasive prolactinoma of limited size.

Methods

We present a combined randomised clinical trial and observational cohort study design, which comprises three unblinded randomised controlled trials (RCTs; PRolaCT-1, PRolaCT-2, PRolaCT-3), and an observational study arm (PRolaCT-O) that compare neurosurgical counselling, and potential subsequent endoscopic transsphenoidal adenoma resection, with current standard care. Patients with a non-invasive prolactinoma (< 25 mm) will be eligible for one of three RCTs based on the duration of pre-treatment with DAs: PRolaCT-1: newly diagnosed, treatment-naïve patients; PRolaCT-2: patients with limited duration of DA treatment (4–6 months); and PRolaCT-3: patients with persisting prolactinoma after DA treatment for > 2 years. PRolaCT-O will include patients who decline randomisation, due to e.g. a clear treatment preference. Primary outcomes are disease remission after 36 months and HRQoL after 12 months.

Discussion

Early or upfront surgical resection for patients with a limited-sized prolactinoma may be a reasonable alternative to the current standard practice of DA treatment, which we will investigate in three RCTs and an observational cohort study. Within the three RCTs, patients will be randomised between neurosurgical counselling and standard care. The observational study arm will recruit patients who refuse randomisation and have a pronounced treatment preference. PRolaCT will collect randomised and observational data, which may facilitate a more individually tailored practice of evidence-based medicine.

Trial registration

US National Library of Medicine registry (ClinicalTrials.gov) NCT04107480. Registered on 27 September 2019, registered retrospectively (by 2 months).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05604-y.

Tumor stem-like cells isolated from MMQ cells resist to dopamine agonist treatment

Although tumor stem-like cells (TSLCs) have been studied in a range of malignant tumors, evidence for the presence of these cells in pituitary adenomas needs further exploration. Here, we identified a small subset of sphere-forming cells possess tumor stem-like cell properties in rat prolactinoma MMQ cells, which resist to dopamine agonist treatment. Comparing to MMQ cells, sphere-forming cells showed higher cell viability after dopamine agonist (DA) treatment. Furthermore, the cells showed lower expression of prolactin (PRL) and dopamine 2 receptor (D2R). On the contrary, the daughter tumor cells differentiated from these cells restored the sensitivity to DA and showed high expression of PRL and D2R. The lower D2R expression and DA resistance might be due to DNA hypermethylation of D2R promoter. Our study demonstrates that the sphere-forming cells isolated from MMQ cells possess the trait of TSLCs and resist to DA treatment, which offers the opportunity to further investigate the mechanisms underlying tumor recurrence based on TSLCs.

Current profile controlled transdermal delivery of pramipexole from an iontophoretic patch system in vitro and in vivo

The objective was to evaluate the transdermal iontophoretic delivery of pramipexole using constant and complex multi-phasic current profiles from an iontophoretic patch system in vitro and in vivo. Preliminary in vitro experiments were performed to optimize iontophoretic patch design and configuration. "Single" compartment systems containing only pramipexole dihydrochloride, and designed to maximize delivery efficiency, suffered from an insufficiency of chloride ions with anodal electrochemistry passing from an Ag/AgCl couple to an Ag dissolution electrode. Addition of NaCl to provide more chloride ions decreased pramipexole delivery efficiency due to competition between pramipexole and sodium cations. A "two-compartment" iontophoretic patch where the drug reservoir was separated from the anodal compartment, which now included NaCl, was shown to be a good compromise since it ensured Ag/AgCl electrochemistry at the anode and an acceptable delivery efficiency. In vivo studies using this iontophoretic patch demonstrated that the plasma concentration of pramipexole closely followed the variation of the applied continuous and multi-phasic current profiles and underlined the control provided by iontophoresis and its unique ability to rapidly change drug input rates. The applied current density and duration of current application were also shown to modulate pramipexole delivery to the brain and CSF.

Impact of primary medical or surgical therapy on prolactinoma patients' BMI and metabolic profile over the long-term

•

High prolactin (PRL) levels are associated with weight gain and impaired metabolic profiles.

•

Long-term control of hyperprolactinemia can be attained by first-line surgery and medical therapy.

•

Normalization of PRL improves patients’ BMI and fasting glucose levels.

•

Marginal changes in patients’ metabolic profiles are noted regardless of the primary therapy.

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Not dopamine agonists per se, but rather the control of hyperprolactinemia plays a role in metabolic profile alterations.

Objectives

High prolactin levels have been associated with weight gain and impaired metabolic profiles. While treatment with dopamine agonists (DAs) has been shown to improve these parameters, there is a lack of surgical series on its comparative effect in prolactinoma patients.

Methods

In this retrospective, comparative study, consecutive patients with a prolactinoma were enrolled if treated with first-line transsphenoidal surgery (TSS) or with DAs. Patients with prolactinomas of Knosp grade >2 and those with a follow-up <24 months were excluded, as were patients with missing laboratory metabolic parameters at baseline and over the long-term. Effects of either treatment on BMI and the metabolic profile were analyzed, and independent risk factors for long-term obesity were calculated.

Results

Primary treatment was TSS for 12 patients (40%) and DAs for 18 patients (60%). At diagnosis, no significant differences between the two cohorts were observed with regard to adenoma size, Knosp grading, baseline prolactin (PRL) levels, prevalence of hypogonadism, or laboratory metabolic parameters. Mean follow-up was 51.9 months (range, 24–158). Over the long-term, both TSS and DAs led to the control of hyperprolactinemia (92% vs. 72%) and hypogonadism (78% vs. 83%) in the majority of patients. While a significant decrease in patients’ BMI and fasting glucose were observed, changes in the lipid profile were marginal and independent of the treatment modality. At baseline, increased BMI—but not the primary treatment strategy—was an independent predictor of long-term obesity.

Conclusions

Over the long-term, patients’ BMI and FG improve, but changes in the metabolic profile are marginal and independent of the primary treatment. It is presumable that not DAs per se, but rather the control of hyperprolactinemia plays a role in patients’ metabolic profile alterations.

Revisiting canine pseudocyesis

Canine (Canis familiaris) pseudocyesis, pseudopregnancy, false pregnancy or nervous lactation is a frequent syndrome observed in non-pregnant, late diestrous or early anestrous females that is characterized by different degrees of mammary gland enlargement, maternal behavior and lactation. Further education about this frequent canine physiological event is still necessary to ensure optimal diagnosis and treatment strategies. Thus, the aim of this article was to review and update the physiopathology, physical and behavioral signs, diagnosis, treatment and prevention of pseudocyesis in bitches in which it is a clinical problem.

Impact of behavioral side effects on the management of Parkinson patients treated with dopamine agonists

Dopamine agonists are one of the main stay of treatment option for Parkinson disease (PD). Side effects that develop from their use are generally categorized into behavioral and non-behavioral. Behavioral side effects include: impulse control behavior disorder (ICD), psychosis and cognitive impairment. Non-behavioral side effects include: nausea/vomiting, "sleep attacks", leg swelling, weight gain and orthostasis. The aim of this study is to evaluate the clinicians' response to PD patients who developed behavioral side effects from dopamine agonists, in comparison to those patients who developed only non-behavioral side effects. We performed a retrospective chart review of all patients diagnosed with PD over a two year period. Among 313 patients who were on a dopamine agonist, 156 reported side effects. Sixty-five patients reported behavioral (with or without non-behavioral) side effects, while 91 experienced only non-behavioral side effects. Forty-nine out of the 65 patients (75.3%) who experienced behavioral side effects had their dopamine agonist dose decreased compared to 53 out of 91patients (58.2%) who experienced only non-behavioral side effects (Chi square = 4.92, p < 0.05). Patients with behavioral side effects were 3 times more likely have their dose decreased (OR = 3.3; 95%CI = 1.442-7.551; P = 0.005). However, neither taper speed nor the occurrence of dopamine agonist withdrawal syndrome (DAWS) differed between the two groups. Amongst PD patients treated with dopamine agonists, the presence of behavioral side effects independently increased the chance of dopamine agonist dose reduction. Prospective studies are needed to confirm these findings.

Social listening - revealing Parkinson's disease over day and night

Background

Nocturnal symptoms in Parkinson’s disease are often treated after management of daytime manifestations. In order to better understand the unmet needs of nocturnal symptoms management, we analyzed the characteristics and burden of nocturnal symptoms from patients’ perspectives and explored their changes over time. Overall symptoms (occurring at day or night) were collected to compare whether the unmet needs related to nocturnal symptoms and to overall symptoms are different.

Methods

We used a Social Listening big-data technique to analyze large amounts of Parkinson’s disease symptoms in dialogues available from social media platforms in 2016 to 2018. These symptoms were classified as either overall symptoms or nocturnal symptoms. We used share of voice (SOV) of symptoms as a proportion of total dialogues per year to reflect the characteristics of symptoms. Negative sentiment score of symptoms was analyzed to find out their related burden.

Results

We found the SOV for overall motor symptoms was 79% and had not increased between 2016 and 2018 (79%, p = 0.5). The SOV for non-motor symptoms was 69% and had grown by 7% in 2018 (p <  0.01). The SOV for motor complications was 9% and had increased by 6% in 2018 (p <  0.01). The SOV of motor symptoms was larger than non-motor symptoms and motor complications (p <  0.01). The SOV of non-motor symptoms was larger than motor complications (p <  0.01). For nocturnal symptoms, 45% of the analyzed PD population reported nocturnal symptoms in 2018, growing by 6% (p <  0.01). The SOV for nocturnal-occurring motor symptoms was higher than most non-motor symptoms. However, non-motor symptoms had the higher increases and evoked higher negative sentiment regardless of whether they occurred during the day or night. For symptoms that can occur at either day or night, each nocturnal symptom was rated with a higher negative sentiment score than the same symptom during the day.

Conclusions

The growing SOV and the greater negative sentiment of nocturnal symptoms suggest management of nocturnal symptoms is an unmet need of patients. A greater emphasis on detecting and treating nocturnal symptoms with 24-h care is encouraged.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-020-02024-4.

Restless Legs Syndrome: Contemporary Diagnosis and Treatment

Restless legs syndrome (RLS) is characterized by an uncomfortable urge to move the legs while at rest, relief upon movement or getting up to walk, and worsened symptom severity at night. RLS may be primary (idiopathic) or secondary to pregnancy or a variety of systemic disorders, especially iron deficiency, and chronic renal insufficiency. Genetic predisposition with a family history is common. The pathogenesis of RLS remains unclear but is likely to involve central nervous system dopaminergic dysfunction, as well as other, undefined contributing mechanisms. Evaluation begins with a thorough history and examination, and iron measures, including ferritin and transferrin saturation, should be checked at presentation and with worsened symptoms, especially when augmentation develops. Augmentation is characterized by more intense symptom severity, earlier symptom occurrence, and often, symptom spread from the legs to the arms or other body regions. Some people with RLS have adequate symptom control with non-pharmacological measures such as massage or temperate baths. First-line management options include iron-replacement therapy in those with evidence for reduced body-iron stores or, alternatively, with prescribed gabapentin or pregabalin, and dopamine agonists such as pramipexole, ropinirole, and rotigotine. Second-line therapies include intravenous iron infusion in those who are intolerant of oral iron and/or those having augmentation with intense, severe RLS symptoms, and opioids including tramadol, oxycodone, and methadone. RLS significantly impacts patients' quality of life and remains a therapeutic area sorely in need of innovation and a further pipeline of new, biologically informed therapies.

Patients with acromegaly might not be at higher risk for dopamine agonist-induced impulse control disorders than those with prolactinomas

OBJECTIVE

To evaluate the prevalence of impulse control disorders (ICD) and psychiatric symptoms in patients with acromegaly receiving dopamine agonists (DA) in comparison with those with prolactinoma, nonfunctioning pituitary adenomas (NFA), and healthy controls (HC).

DESIGN

Forty patients with acromegaly, 40 with prolactinoma, 38 with NFA, and 32 HCs were included. All patients and controls were evaluated using the revised version of the Minnesota Impulsive Disorders Interview (MIDI-R), Symptom Check List (SCL-90-R) questionnaire, Barratt Impulsiveness Scale (BIS-11), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI).

RESULTS

We detected ICD associated with DAs in two patients with acromegaly (5%) and three patients (7.5%) with prolactinoma. All patients' symptoms resolved after discontinuation of the drug. While the mean DA dose was higher in patients with acromegaly than prolactinomas (p < 0.05), no difference was detected in terms of ICD prevalence between two groups (p > 0.05). SCL-90 depression and interpersonal sensitivity subscale positivity was higher in patients with NFA than HCs. Patients with prolactinoma had higher obsession and interpersonal sensitivity positivity and those with NFA had higher somatization, interpersonal sensitivity, and depression positivity as compared to patients with acromegaly (p < 0.05 for all).

CONCLUSIONS

Although DA dose was significantly higher in patients with acromegaly, there was no significant difference in the prevalence of DA-related ICD. The higher prevalence of positive screening in SCL-90 in patients with NFA in comparison to HCs supports the hypothesis that the presence of a pituitary adenoma per se might cause significant psychiatric symptoms.

The long noncoding RNA-H19/miRNA-93a/ATG7 axis regulates the sensitivity of pituitary adenomas to dopamine agonists

Dopamine agonists (DAs), such as cabergoline and bromocriptine, are the first-line clinical treatment for prolactinomas. Our previous study demonstrated that long noncoding RNA H19 expression is frequently downregulated in human primary pituitary adenomas and is negatively correlated with tumor progression. However, the significance and mechanism of H19 in the DA treatment of prolactinomas are still unknown. In this study, we reported that H19 had a synergistic effect with DA treatment on prolactinomas in vitro and in vivo. Mechanistically, H19 promoted ATG7 expression in pituitary tumor cells by inhibiting miR-93a expression. In addition, a potential binding site between miR-93 and H19 was confirmed, and low expression of miR-93 was previously found in DA-resistant prolactinomas. Furthermore, we showed that miR-93a regulates ATG7 expression by targeting ATG7 mRNA. In conclusion, our study has identified the role of the H19-miR-93-ATG7 axis in DA treatment of prolactinomas, which may be a potential therapeutic target for human prolactinomas.

Efficacy of pergolide for the management of equine pituitary pars intermedia dysfunction: A systematic review

Pergolide, a dopamine agonist, is commonly administered to manage pituitary pars intermedia dysfunction (PPID), a progressive neurodegenerative disease prevalent in aged horses. However, available evidence regarding pergolide's efficacy in improving clinical and endocrine parameters is limited. The aim of this systematic review was to assess published literature and evaluate evidence regarding whether pergolide treatment results in improvement of clinical signs and/or adrenocorticotrophic hormone (ACTH) concentration compared to no treatment or other unlicensed treatments. Systematic searches of electronic databases were undertaken in April 2019, repeated in August and October 2019, and updated in July 2020. English language publications published prior to these dates were included. Screening, data extraction and quality assessment of publications was undertaken individually by the authors using predefined criteria and subsequently cross-checked. Modified critically appraised topic data collection forms were used to extract data. Due to marked between-study variations, meta-analysis was not undertaken. After removal of duplicate records; 612 publications were identified, of which 129 abstracts were screened for eligibility and 28 publications met criteria for inclusion in the review. Most studies were descriptive case series, cohort studies or non-randomised, uncontrolled field trials. Despite marked variation in study populations, case selection, diagnostic protocols, pergolide dose, follow-up period and outcome measures, in the vast majority of the included studies, pergolide was reported to provide overall clinical improvement in >75% of cases. However, reported improvements in individual clinical signs varied widely. A reduction in plasma ACTH concentrations was reported in 44-74% of cases, while normalisation to within reported reference intervals occurred in 28-74% of cases.

Restoring pars intermedia dopamine concentrations and tyrosine hydroxylase expression levels with pergolide: evidence from horses with pituitary pars intermedia dysfunction

Background

Pituitary pars intermedia dysfunction (PPID) develops slowly in aged horses as degeneration of hypothalamic dopaminergic neurons leads to proliferation of pars intermedia (PI) melanotropes through hyperplasia and adenoma formation. Dopamine (DA) concentrations and tyrosine hydroxylase (TH) immunoreactivity are markedly reduced in PI tissue of PPID-affected equids and treatment with the DA receptor agonist pergolide results in notable clinical improvement. Thus, we hypothesized that pergolide treatment of PPID-affected horses would result in greater DA and TH levels in PI tissue collected from PPID-affected horses versus untreated PPID-affected horses.

To test this hypothesis, pituitary glands were removed from 18 horses: four untreated PPID-affected horses, four aged and four young horses without signs of PPID, and six PPID-affected horses that had been treated with pergolide at 2 µg/kg orally once daily for 6 months. DA concentrations and TH expression levels in PI tissues were determined by high performance liquid chromatography with electrochemical detection and Western blot analyses, respectively.

Results

DA and TH levels were lowest in PI collected from untreated PPID-affected horses while levels in the pergolide treated horses were similar to those of aged horses without signs of PPID.

Conclusions

These findings provide evidence of restoration of DA and TH levels following treatment with pergolide. Equine PPID is a potential animal model of dopaminergic neurodegeneration, which could provide insight into human neurodegenerative diseases.

The multifunctional dopamine D2/D3 receptor agonists also possess inhibitory activity against the full-length tau441 protein aggregation

Neurodegeneration leads to variety of diseases which are linked to aberrant protein or peptide aggregation, as a one possible mechanism. Hence, small drug molecules targeting aggregation are of interest. Tau protein aggregation is one of the biomarkers of neurodegenerative diseases and is a viable drug target. Toward multifunctional inhibitors, we aim to incorporate structural elements in a potential drug in order to preserve dopamine agonist activity, which elevates disease symptoms associated with motor skills, and promote inhibitory activity against aggregation of the full-length tau (2N4R, tau441) protein. In our design, we introduced various moieties (catechol, non-catechol, biphenyl, piperazine, and thiazole) to determine which functional group leads to the greatest aggregation inhibition of tau. In vitro, tau aggregation was induced by heparin and monitored by using fluorescence aggregation assay, transmission electron microscopy and 4,4'-Dianilino-1,1'-binaphthyl-5,5'-disulfonic acid dipotassium salt (Bis-ANS) fluorescence spectroscopy. The catechol containing compounds, D-519 and D-520, prevented aggregation of tau. By contrast, non-catechol and thiazole containing compounds (D-264 and D-636) were poor inhibitors. The Bis-ANS studies revealed that the potent inhibitors bound solvent-exposed hydrophobic sites. Based on the density functional theory calculations on inhibitors tested, the compounds characterized with the high polarity and polarizability were more effective aggregation inhibitors. These findings could lead to the development of small multifunctional drug inhibitors for the treatment of tau-associated neurodegeneration.

Classics in Chemical Neuroscience: Pramipexole

Pramipexole was first manufactured by Pharmacia and Upjohn in July 1997 under the United States brand names of Mirapex and Mirapex ER. Pramipexole is classified as a nonergoline aminobenzothiazole compound that selectively agonizes the dopamine D₂-like receptor subfamily, which includes the D₂, D₃, and D₄ receptor subtypes. Pramipexole is a unique compound in its therapeutic potential because it has D₃-preferring properties. The D₃ receptor target has implications in both motor and psychiatric symptoms of Parkinson's disease, restless leg syndrome, and bipolar and unipolar depression. Currently, pramipexole is approved to treat signs and symptoms of idiopathic Parkinson's disease and moderate to severe symptoms of primary restless leg syndrome. Parkinson's disease is characterized by tremor, bradykinesia, rigidity, gait disorders, and a disturbance of posture due to a decrease in dopamine stores in the substantia nigra with the consequent presence of Lewy bodies. Restless leg syndrome is a neurologic sensorimotor disorder characterized by a compelling urge to move the body/limb to relieve this uncomfortable sensation. In this Review, we will discuss the synthesis, drug metabolism, pharmacology, adverse effects, history, and the importance of pramipexole to neuroscience and describe its role in therapy.

Classics in Chemical Neuroscience: Pramipexole

Pramipexole was first manufactured by Pharmacia and Upjohn in July 1997 under the United States brand names of Mirapex and Mirapex ER. Pramipexole is classified as a nonergoline aminobenzothiazole compound that selectively agonizes the dopamine D₂-like receptor subfamily, which includes the D₂, D₃, and D₄ receptor subtypes. Pramipexole is a unique compound in its therapeutic potential because it has D₃-preferring properties. The D₃ receptor target has implications in both motor and psychiatric symptoms of Parkinson's disease, restless leg syndrome, and bipolar and unipolar depression. Currently, pramipexole is approved to treat signs and symptoms of idiopathic Parkinson's disease and moderate to severe symptoms of primary restless leg syndrome. Parkinson's disease is characterized by tremor, bradykinesia, rigidity, gait disorders, and a disturbance of posture due to a decrease in dopamine stores in the substantia nigra with the consequent presence of Lewy bodies. Restless leg syndrome is a neurologic sensorimotor disorder characterized by a compelling urge to move the body/limb to relieve this uncomfortable sensation. In this Review, we will discuss the synthesis, drug metabolism, pharmacology, adverse effects, history, and the importance of pramipexole to neuroscience and describe its role in therapy.

The Role of Dopamine Agonists in Pituitary Adenomas

Dopamine agonist therapy is the primary therapy for prolactin-secreting adenomas and usually results in normoprolactinemia, eugonadism, and tumor reduction. Cabergoline is superior to bromocriptine with regard to efficacy and tolerance. Withdrawal of cabergoline can be attempted in patients with normal prolactin levels on low doses of medication and evidence of radiographic tumor involution. Dopamine agonists have been used off label in patients with acromegaly, Cushing disease, and nonfunctioning adenomas. A trial of cabergoline monotherapy can be effective in patients with biochemically mild acromegaly. Cabergoline combination with somatostatin receptor ligands or pegvisomant improves insulin-like growth factor level 1 in majority of patients.