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.

Successful medical treatment of an Aspergillus terreus mycetoma of the nostril/lip in a 16-year-old Fjord pony gelding with pituitary pars intermedia dysfunction.

BACKGROUND: Mycetoma is a chronic, proliferative lesion of cutaneous/subcutaneous tissue characterized by draining tracts and granules in the discharge caused by actinomycetes (actinomycetoma) or filamentous fungi (eumycotic mycetoma). OBJECTIVES: This case report describes the unusual finding of a cutaneous mycetoma of the lateral wing of the right nostril in a gelding. ANIMAL: A 16-year-old Fjord gelding with suspected pituitary pars intermedia dysfunction (PPID) was presented for evaluation of a nonpainful, firm and raised mass involving the lateral wing of the right nostril and the lip. METHODS AND RESULTS: Cytological examination of the mass showed marked pyogranulomatous inflammation and histopathological examination revealed a fungal mycetoma. Fungal culture identified the causative organism as Aspergillus terreus, which is not known for its propensity to cause either dermal granulomas or mycetoma in domestic animals. Further investigation, including a TRH stimulation test, led to a diagnosis of PPID (Cushing's disease), which may have led to immunosuppression of the animal and increased susceptibility to infection. CONCLUSIONS AND CLINICAL IMPORTANCE: The horse was treated medically with pergolide for the PPID and oral potassium iodide for the fungal infection, with good therapeutic response and no relapse after five months. Surgical debridement or excision was not performed. To the best of the authors' knowledge, this is the first case report of a cutaneous mycetoma caused by A. terreus in a horse.

Pharmacokinetic and pharmacodynamic properties of pergolide mesylate following long-term administration to horses with pituitary pars intermedia dysfunction.

The objective of this study was to gain an understanding of the pharmacokinetic and pharmacodynamic properties of pergolide in horses with PPID after of long-term oral administration. Six horses with confirmed PPID were treated with pergolide (Prascend® ) at 1 mg/horse po q24 h for 2 months, followed by 2 mg/horse po q24 h for 4 months. Following the last dose, plasma samples were collected for measurement of pergolide using an LC/MS/MS method and ACTH measurement using a chemiluminescent immunoassay. Noncompartmental and compartmental pharmacokinetic analyses were performed, as well as pharmacodynamic assessment of the effect of plasma pergolide concentrations on plasma ACTH concentrations. Pergolide effectively decreased plasma ACTH concentration in aged horses with PPID, with similar pharmacokinetic properties as reported in young horses, including an approximate terminal half-life of 24 h. Plasma ACTH concentration increased by 50% in 3/6 horses at 2 days and 6/6 horses 10 days after discontinuing drug administration. Pergolide was quantified in all horses at 2 days and in none at 10 days after last dose. In summary, after discontinuing pergolide treatment, plasma ACTH concentration increased while pergolide was still quantifiable in some horses. Once-daily dosing of pergolide is likely appropriate in most horses with PPID for regulating the plasma ACTH concentration.

Therapeutics for Equine Endocrine Disorders.

Equine endocrine disease is commonly encountered by equine practitioners. Pituitary pars intermedia dysfunction (PPID) and equine metabolic syndrome (EMS) predominate. The most logical therapeutic approach in PPID uses dopamine agonists; pergolide mesylate is the most common. Bromocryptine and cabergoline are alternative drugs with similar actions. Drugs from other classes have a poor evidence basis, although cyproheptadine and trilostane might be considered. EMS requires management changes as the primary approach; reasonable justification for use of drugs such as levothyroxine and metformin may apply. Therapeutic options exist in rare cases of diabetes mellitus, diabetes insipidus, hyperthyroidism, and critical illness-related corticosteroid insufficiency.

Effectiveness of risk minimization measures for cabergoline-induced cardiac valve fibrosis in clinical practice in Italy.

On June 2008, the European Medicines Agency (EMA) introduced changes to the Summary of Product Characteristics (SPC) for cabergoline and pergolide, to reduce the risk of cardiac valvulopathy in users of these drugs. To assess the effectiveness of EMA recommendations in Italian clinical practice, we retrospectively reviewed medical charts of patients with degenerative Parkinsonism treated with cabergoline in three large Italian clinics between January 2006 and June 2012. The prevalence and the severity of cardiac valve regurgitation were assessed in patients who stopped cabergoline therapy prior to June 2008 or continued therapy after that date. In addition, the proportion of patients undergoing echocardiographic examination in each cohort was evaluated. A total of 61 patients were available for evaluation. The proportion of patients who underwent a baseline echocardiographic examination increased from 64 % in the period before the 2008 SPC changes to 71 % among those who continued treatment after that date. However, only 18 and 29 % of patients underwent at least two echocardiographic examinations during the pre-SPC and cross-SPC change period, respectively. No severe cardiac valve regurgitation was documented in any of the study patients using cabergoline either prior or after 26th June 2008. Our findings show that the 2008 changes to the SPC resulted in an increase in physicians' awareness of cabergoline-induced valvulopathy risk in Italy. However, only a small percentage of patients underwent serial echocardiography. Further efforts are needed to achieve better compliance with the prescribing guidelines for cabergoline treated patients in clinical practice.

[Severe punding in Parkinson's disease]. / Punding sévère au cours d'une maladie de Parkinson.

BACKGROUND: Punding is a stereotypical behavior characterized by an intense fascination with repetitive handling and examining of mechanical devices or arranging common objects. This condition, which is different from both obsessive-compulsive disorder and mania, is still underestimated in patients with Parkinson's disease and may have deleterious social consequences on patients and their families. CASE REPORT: We report the case of severe punding in a 23-year-old parkinsonian woman, who presented, a few days following a rise in the dose of pergolide up to 2,5 mg/(d), frequent and daily unusual repetitive behavior, characterized by ceaseless sewing, disassembly and reassembly of phones, and coloring of drawings. These behaviors were associated with a common peak of dose dyskinesia and were responsible for a considerable reduction in duration of sleep with negative impact on the quality of life of her parents. These symptoms significantly improved immediately after switching pergolide to an equivalent dose of ropinirole (12 mg/(d). DISCUSSION: Punding has only recently come to the attention of physicians through the first report in a parkinsonian patient, triggered by dopaminergic replacement therapy. The phenomenon was thought to be related to excessive dopaminergic stimulation of the limbic and associative pathways. The current mainstay of treatment is the reduction in the dose of dopaminergic medication or changing the presumed responsible drug, often a dopaminergic agonist. In this article, the authors review the epidemiology, pathophysiology and management of this curious phenomenon.

BEVA primary care clinical guidelines: Diagnosis and management of equine pituitary pars intermedia dysfunction.

BACKGROUND: Pituitary pars intermedia dysfunction (PPID) is a prevalent, age-related chronic disorder in equids. Diagnosis of PPID can be challenging because of its broad spectrum of clinical presentations and disparate published diagnostic criteria, and there are limited available treatment options. OBJECTIVES: To develop evidence-based primary care guidelines for the diagnosis and treatment of equine PPID based on the available literature. STUDY DESIGN: Evidence-based clinical guideline using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. METHODS: Research questions were proposed by a panel of veterinarians and developed into PICO or another structured format. VetSRev and Veterinary Evidence were searched for evidence summaries, and systematic searches of the NCBI PubMed and CAB Direct databases were conducted using keyword searches in July 2022 and updated in January 2023. The evidence was evaluated using the GRADE framework. RESULTS AND RECOMMENDATIONS: The research questions were categorised into four areas: (A) Case selection for diagnostic testing, pre-test probability and diagnostic test accuracy, (B) interpretation of test results, (C) pharmacological treatments and other treatment/management options and (D) monitoring treated cases. Relevant veterinary publications were identified and assessed using the GRADE criteria. The results were developed into recommendations: (A) Case selection for diagnostic testing and diagnostic test accuracy: (i) The prevalence of PPID in equids aged ≥15 years is between 21% and 27%; (ii) hypertrichosis or delayed/incomplete hair coat shedding provides a high index of clinical suspicion for PPID; (iii) the combination of clinical signs and age informs the index of clinical suspicion prior to diagnostic testing; (iv) estimated pre-test probability of PPID should be considered in interpretation of diagnostic test results; (v) pre-test probability of PPID is low in equids aged <10 years; (vi) both pre-test probability of disease and season of testing have strong influence on the ability to diagnose PPID using basal adrenocorticotropic hormone (ACTH) or ACTH after thyrotropin-releasing hormone (TRH) stimulation. The overall diagnostic accuracy of basal ACTH concentrations for diagnosing PPID ranged between 88% and 92% in the autumn and 70% and 86% in the non-autumn, depending on the pre-test probability. Based on a single study, the overall diagnostic accuracy of ACTH concentrations in response to TRH after 30 minutes for diagnosing PPID ranged between 92% and 98% in the autumn and 90% and 94% in the non-autumn, depending on the pre-test probability. Thus, it should be remembered that the risk of a false positive result increases in situations where there is a low pre-test probability, which could mean that treatment is initiated for PPID without checking for a more likely alternative diagnosis. This could compromise horse welfare due to the commencement of lifelong therapy and/or failing to identify and treat an alternative potentially life-threatening condition. (B) Interpretation of diagnostic tests: (i) There is a significant effect of breed on plasma ACTH concentration, particularly in the autumn with markedly higher ACTH concentrations in some but not all 'thrifty' breeds; (ii) basal and/or post-TRH ACTH concentrations may also be affected by latitude/location, diet/feeding, coat colour, critical illness and trailer transport; (iii) mild pain is unlikely to have a large effect on basal ACTH, but caution may be required for more severe pain; (iv) determining diagnostic thresholds that allow for all possible contributory factors is not practical; therefore, the use of equivocal ranges is supported; (v) dynamic insulin testing and TRH stimulation testing may be combined, but TRH stimulation testing should not immediately follow an oral sugar test; (vi) equids with PPID and hyperinsulinaemia appear to be at higher risk of laminitis, but ACTH is not an independent predictor of laminitis risk. (C) Pharmacologic treatments and other treatment/management options: (i) Pergolide improves most clinical signs associated with PPID in the majority of affected animals; (ii) Pergolide treatment lowers basal ACTH concentrations and improves the ACTH response to TRH in many animals, but measures of insulin dysregulation (ID) are not altered in most cases; (iii) chasteberry has no effect on ACTH concentrations and there is no benefit to adding chasteberry to pergolide therapy; (iv) combination of cyproheptadine with pergolide is not superior to pergolide alone; (v) there is no evidence that pergolide has adverse cardiac effects in horses; (vi) Pergolide does not affect insulin sensitivity. (D) Monitoring pergolide-treated cases: (i) Hormone assays provide a crude indication of pituitary control in response to pergolide therapy, however it is unknown whether monitoring of ACTH concentrations and titrating of pergolide doses accordingly is associated with improved endocrinological or clinical outcome; (ii) it is unknown whether monitoring the ACTH response to TRH or clinical signs is associated with an improved outcome; (iii) there is very weak evidence to suggest that increasing pergolide dose in autumn months may be beneficial; (iv) there is little advantage in waiting for more than a month to perform follow-up endocrine testing following initiation of pergolide therapy; there may be merit in performing repeat tests sooner; (v) timing of sampling in relation to pergolide dosing does not confound measurement of ACTH concentration; (vi) there is no evidence that making changes after interpretation of ACTH concentrations measured at certain times of the year is associated with improved outcomes; (vii) evidence is very limited, however, compliance with PPID treatment appears to be poor and it is unclear whether this influences clinical outcome; (viii) evidence is very limited, but horses with clinical signs of PPID are likely to shed more nematode eggs than horses without clinical signs of PPID; it is unclear whether this results in an increased risk of parasitic disease or whether there is a need for more frequent assessment of faecal worm egg counts. MAIN LIMITATIONS: Limited relevant publications in the veterinary scientific literature. CONCLUSIONS: These findings should be used to inform decision-making in equine primary care practice.

Risk of thromboembolic events in patients with prolactinomas compared with patients with nonfunctional pituitary adenomas.

Prolactin has been proposed as a potent coactivator of platelet aggregation, possibly contributing to thromboembolic events. The objective of the study was to evaluate the relationship between prolactinoma and deep vein thrombosis (DVT), pulmonary embolism (PE), and cerebrovascular accident (CVA). Subjects were identified from a prospectively maintained pituitary database at the Cleveland Clinic. We retrospectively reviewed the charts of 544 subjects: 347 patients with prolactinomas (prolactinoma group) and 197 patients with nonfunctional pituitary adenomas (control group). Main outcome measures were DVT, PE and CVA. We found that 19 (5.5%) patients in the prolactinoma group and five (2.5%) patients in the control group had documented DVT, PE, or CVA, but this difference was not significant (p = 0.109). However, the mean initial prolactin level was higher at the time of diagnosis among prolactinoma patients than among controls (815.23 ng/ml vs. 15.90 ng/ml; p < 0.001). Among prolactinoma patients, 15 (5.5%) of 275 patients who underwent medical treatment (with cabergoline, bromocriptine, pergolide and/or other drug) and 4 (5.6%) of 72 patients who underwent transsphenoidal surgery had documented DVT, PE, or CVA, which suggests that dopaminergic therapy did not influence the risk of thromboembolic events. Hyperprolactinemia per se does not appear to predispose to a hypercoagulable state.

The effect of dopamine agonists on cognitive functions in non-demented early-mild Parkinson's disease patients.

The effect of dopamine agonists (DAs) on cognition in Parkinson's disease (PD) is not yet completely established. Previous papers reported a worsening effect on some cognitive functions with some DAs, but not with others, suggesting that DAs may differently affect cognition in PD patients according to their pharmacological characteristics. We set out to test the effect of rotigotine and cabergoline on cognitive functions in a group of forty non-demented early-mild PD patients (H &Y <2). Subjects were randomly divided into two groups and evaluated in a randomized cross-over study using neuropsychological tests; at the same time, motor function was monitored under three different treatment conditions: DA (rotigotine or cabergoline), L-dopa, and off therapy. Rotigotine and cabergoline were chosen because while they share a mixed D1 and D2 receptor profile, the former is non-ergolinic and the latter ergolinic. No significant differences were found in cognitive function between the basal condition and the DA treatments. On the basis of the present data, which we compare with previous findings regarding pramipexole IR and pergolide, we hypothesize that combined stimulation of both dopamine receptor families, as occurs with rotigotine, cabergoline, L-dopa and pergolide, may preserve cognitive functions more than pure D2 family stimulation.

Comparison of hair follicle histology between horses with pituitary pars intermedia dysfunction and excessive hair growth and normal aged horses.

BACKGROUND: Pituitary pars intermedia dysfunction (PPID) in older equids is commonly recognized by a long hair coat that fails to shed. OBJECTIVE: The aim of this study was to compare hair follicle stages in PPID-affected horses with excessively long hair coats with the stages of normal aged horses (controls) and to compare hair follicle stages in PPID-affected horses after 6 months of treatment with pergolide mesylate with those of control horses. ANIMALS: Eight PPID-affected horses and four normal, age-matched, control horses. METHODS: Skin biopsies were collected from the neck and rump of PPID-affected and control horses. A diagnosis of PPID was established based on hair coat changes and supportive overnight dexamethasone suppression test results. Skin biopsies were repeated after 6 months of treatment with pergolide. The number of hair follicles in anagen (A) or telogen (T) was counted for each skin biopsy using transverse sections. RESULTS: Pretreatment biopsies had a greater percentage of A follicles (neck 96%, rump 95%) and a lower percentage of T follicles (neck 4%, rump 5%) in PPID-affected horses than in control horses (A, neck 15%, rump 25%; and T, neck 85%, rump 75%). After treatment with pergolide, all PPID-affected horses had improved shedding, and the percentages of A follicles (neck 69%, rump 70%) and T follicles (neck 31%, rump 30%) were not different from untreated control horses (A, neck 68%, rump 82%; and T, neck 32%, rump 18%). CONCLUSIONS: These findings document that excessive hair growth (hypertrichosis) in PPID-affected horses is due to persistence of hair follicles in A. Furthermore, treatment with pergolide improved shedding and reduced the percentage of A follicles in PPID-affected horses.

Valvular heart disease in patients exposed to pergolide: insights from the clinical presentation.

PURPOSE: The aim of this study was to determine whether the presence of symptoms would aid in the detection of valvular heart disease (VHD) in those exposed to pergolide. METHODS: Utilizing a prospective, cross-sectional study design, patients with an exposure to pergolide were asked regarding the presence or absence of chest pain, shortness of breath or lower extremity edema through a questionnaire. Echocardiograms were obtained on the same day as the questionnaire and were blinded to all staff involved in the study. The sensitivity, specificity, positive and negative predictive value of the reported symptoms towards the outcome moderate or severe valvular regurgitation were obtained. Using the area under the receiver-operating characteristic curve, we also ascertained whether a relationship existed between symptoms, pergolide dose and presence of VHD. To understand the associations between symptoms and echocardiographic covariates, a logistic regression analysis was performed adjusted for age and gender. RESULTS: The sensitivity, specificity, positive and negative predictive value of symptom presentation and total dose was sufficiently low that it did not aid in the determination whether significant valvular regurgitation was present. Multivariable analysis noted a significant association with indexed left atrial volume (p = 0.011), estimated pulmonary artery pressure (p = 0.047) and shortness of breath. CONCLUSIONS: The presence or absence of symptoms does not help guide whether valvular regurgitation is present or absent in individuals exposed to pergolide. Therefore, echocardiography is needed to confirm or refute pergolide-associated VHD.

The effect of pergolide mesylate on adrenocorticotrophic hormone responses to exogenous thyrotropin releasing hormone in horses.

Thyrotropin releasing hormone (TRH) stimulation testing is often used to support a diagnosis of pituitary pars intermedia dysfunction (PPID) in horses although it is unclear whether or not repeat TRH stimulation testing post-treatment is a valid means of assessing response to medical therapy. Laboratory submissions from 64 suspected equine PPID cases were examined including the initial pre-treatment TRH stimulation test and a follow up test within 100 days of starting medical therapy with pergolide. In a subset of cases, further follow-up tests were examined beyond 100 days of starting treatment. Results from tests conducted between 1 July and 30 November were excluded. Significant improvements were seen in both the baseline and TRH-stimulated adrenocorticotrophic hormone (ACTH) concentrations within 100 days with no further improvements seen in the subset of cases examined thereafter. Although 88% (n = 56/64) of all cases showed a decreased response to TRH post-treatment, only 24% (n = 9/38) of horses with positive pre-treatment TRH stimulation tests normalised following treatment, with a further 34% (n = 13/38) improving into an equivocal test outcome category. Most commonly (42%; n = 16/38), horses with positive pre-treatment TRH stimulation tests remained positive following treatment, although 75% (n = 12/16) of these showed a numerically lower post-treatment response to TRH. These results will help inform practitioners of expected changes in TRH stimulation test results when assessing response of horses with PPID to medical therapy with pergolide.

Use of the SGLT2 inhibitor canagliflozin for control of refractory equine hyperinsulinemia and laminitis.

Background: Hyperinsulinemia associated with pituitary pars intermedia dysfunction (PPID) and/or equine metabolic syndrome is well documented to put horses at high risk of laminitis. While dietary control of simple sugars and starch is the most effective therapy to control hyperinsulinemia, some horses fail to respond. Case Descriptions: Ten horses with hyperinsulinemia refractory to diet control, metformin, levothyroxine, and pergolide (if diagnosed with PPID) were treated with sodium-glucose cotransporter-2 inhibitor canagliflozin (Invokana®). Nine horses were hyperglycemic (>5.5 mmol/l) or had a history of hyperglycemia. Before instituting therapy, renal function was assessed by determining serum creatinine and blood urea nitrogen concentrations. Canagliflozin was administered orally once a day, with food. Dipstick urinalysis was performed every 2 weeks to confirm glucosuria and screen for proteinuria. Owners were also instructed regarding clinical signs consistent with urinary tract infection. All horses responded with a substantial decrease in serum insulin concentrations to normal or near normal values. Laminitis pain resolved in all cases, with regression of fat deposits. Owner satisfaction with outcomes was 100%. Conclusion: Once daily administration of the SGLT2 inhibitor canagliflozin corrected hyperglycemia, reduced insulin to normal or near normal levels, and was 100% effective in reversing or reducing abnormal fat pads and eliminating laminitis pain in horses with refractory hyperinsulinemia and laminitis. The core aspects of therapy-diet control, exercise when possible, and adequate treatment of PPID-must also be maintained if using canagliflozin. Canagliflozin should be reserved for refractory cases. Further controlled trials to investigate canagliflozin pharmacokinetics, pharmacodynamics, efficacy, and safety are needed.

Dopamine agonists for restless legs syndrome.

BACKGROUND: According to clinical guidelines, dopamine agonists are the first-line treatment of restless legs syndrome (RLS). OBJECTIVES: To evaluate efficacy and safety of dopamine agonists for RLS. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2008, Issue 4), MEDLINE, EMBASE, PsycINFO and CINAHL, from January 1985 to December 2008, plus reference lists of articles. We contacted pharmaceutical companies. SELECTION CRITERIA: We included double-blind randomised controlled trials (RCTs) of dopamine agonist treatment versus placebo or other treatment for a period of at least seven days in patients with RLS (≥ 18 years). Outcomes included the International RLS Severity Rating Scale (IRLS), Clinical Global Impressions (CGI-I), polysomnography and self rated sleep quality, quality of life, daytime functioning, and safety parameters. DATA COLLECTION AND ANALYSIS: Two reviewers extracted data separately; assessed risk of bias; and contacted pharmaceutical companies and authors for additional information. We collected dropout rates due to adverse events and experience of adverse events. MAIN RESULTS: We included 35 placebo controlled and three active controlled RCTs (N = 7365). The mean reduction on the IRLS was -5.7 points lower in dopamine agonist treatment compared to placebo (95% confidence interval (CI) -6.7 to -4.7). Periodic limb movements in sleep per hour of sleep (PLMS-Index; PLMSI) were -22.4/h lower than in placebo (95% CI -27.8 to -16.9). Self rated quality of sleep and disease specific quality of life were improved by a standardised mean difference (SMD) of 0.40 (95% CI 0.33 to 0.47) and 0.34 (95% CI 0.23 to 0.44), respectively. Patients were more likely to drop out (odds ratio (OR) 1.82, 95% CI 1.35 to 2.45) and experienced more adverse events under dopamine agonist treatment than with placebo (OR 1.82, 95% CI 1.59 to 2.08). Visual inspection of forest plots showed the highest efficacy in three studies investigating cabergoline and pergolide (N = 3). Active controlled trials investigated effects of cabergoline, pergolide, and pramipexole in a number of outcomes. The IRLS score was lower with cabergoline and pramipexole compared to levodopa (MD -5.3, 95% CI -8.4 to -2.1). Only four studies investigated treatment efficacy up to seven months. The most severe side effect, augmentation, was not assessed reliably. AUTHORS' CONCLUSIONS: The meta-analyses show the superiority of dopamine agonists over placebo in RCTs up to seven months. Cabergoline and pramipexole showed larger efficacy compared to levodopa in some but not all outcomes.

Increased plasma arginine vasopressin levels in dopamine agonist-treated Parkinson's disease patients.

OBJECTIVE: Several cases of syndrome of inappropriate antidiuresis induced by antiparkinson agents have been previously reported. However, the effect of antiparkinson agents on plasma arginine vasopressin (AVP) levels remains unknown in Parkinson's disease (PD) patients. The aim of the present study is to determine plasma AVP levels in PD patients and the effects of antiparkinson agents on these levels. METHODS: PD patients who visited our clinic between November 2008 and September 2009 were included in this study. Patients were excluded if they had at least one condition that could be associated with high AVP levels. PD patients who had been treated with antiparkinson agents participated in this study (treated PD group, n=76). De novo PD patients were also included (n=25). RESULTS: Mean plasma AVP levels were significantly higher in treated PD patients than those in treatment-naïve patients. Neither disease severity nor L-dopa dosage correlated with plasma AVP levels. Multiple linear regression analysis identified the male gender and pergolide dosage as weak independent predictors of high plasma AVP levels. While no difference in plasma AVP levels between genders in treatment-naïve patients was observed, mean plasma AVP levels were significantly higher in male patients than in female patients administered antiparkinson agents. Mean plasma AVP levels in pergolide users were significantly higher than those in dopamine agonist nonusers with corresponding disease duration and L-dopa/carbidopa dosage. In some patients, plasma AVP levels appeared to be dependent on pramipexole dosage. CONCLUSION: Dopamine agonists may cause increased plasma AVP levels in some PD patients.

Equine pituitary pars intermedia dysfunction.

Equine pituitary pars intermedia dysfunction (PPID), also known as equine Cushing's syndrome, is a widely recognized disease of aged horses. Over the past two decades, the aged horse population has expanded significantly and in addition, client awareness of PPID has increased. As a result, there has been an increase in both diagnostic testing and treatment of the disease. This review focuses on the pathophysiology and clinical syndrome, as well as advances in diagnostic testing and treatment of PPID, with an emphasis on those findings that are new since the excellent comprehensive review by Schott in 2002.

Markers of muscle atrophy and impact of treatment with pergolide in horses with pituitary pars intermedia dysfunction and muscle atrophy.

Pituitary pars intermedia dysfunction (PPID) is a common endocrine disorder of aged horses, with muscle atrophy as one of the clinical signs. We sought to compare muscle mass and regulation of skeletal muscle proteolysis between horses with PPID and muscle atrophy to older horses without PPID, and to assess the impact of treatment with pergolide (dopaminergic agonist) on PPID horses. We hypothesized that PPID-associated muscle atrophy is a result of increased proteolysis, and that markers of muscle atrophy and proteolysis would improve over time with pergolide treatment. Markers of muscle atrophy, adiposity, insulin regulation, skeletal muscle composition, and proteolysis (muscle atrophy F- box/atrogin 1 [MAFbx1], muscle RING finger 1 [MuRF1], Bcl2/adenovirus EIV 19kD interacting protein 3 [Bnip3], and microtubule-associated light chain 3 [LC3]) were compared between PPID and control horses. PPID horses were treated for 12 weeks with either pergolide or placebo. Dose of pergolide was adjusted based upon monthly measurement of adrenocorticotropin, and markers of muscle atrophy, adiposity, insulin regulation, skeletal muscle composition, and proteolysis were compared after 12 weeks of treatment. Horses with PPID exhibited increased transcript abundance of MuRF1 (P= 0.04) compared to control. However, no difference was observed in transcript abundance of markers of proteolysis with treatment (P ≥ 0.25). Pergolide treated horses lost weight (P = 0.02) and improved fasting insulin (P = 0.02), while placebo treated horses gained weight and rump fat thickness (P = 0.02). Findings from this study suggest that treatment with pergolide may promote weight loss and improve insulin regulation in horses with PPID, but does not impact muscle mass or markers of muscle proteolysis.

Effects of pituitary pars intermedia dysfunction and Prascend (pergolide tablets) treatment on endocrine and immune function in horses.

It remains unclear how pituitary pars intermedia dysfunction (PPID) and pergolide treatment (Prascend [pergolide tablets]) affect endocrine and immune function in horses. To evaluate these effects, blood was collected regularly from 28 university-owned horses (10 Non-PPID, 9 PPID control [PC], and 9 PPID treatment [PT]) over approximately 15 mo. Pergolide treatment was initiated after Day 0 collections. Analyses included ACTH, insulin, total cortisol, free cortisol, complete blood counts, plasma myeloperoxidase, and cytokine/receptor gene expression in basal whole blood and in vitro stimulations (PMA/ionomycin, heat-inactivated Rhodococcus equi, and heat-inactivated Escherichia coli) of whole blood and peripheral blood mononuclear cells (PBMCs). The results were analyzed using a linear mixed model (SAS 9.4) with significance set at P < 0.05. Significant group (P = 0.0014) and group-by-time (P = 0.0004) effects were observed in resting ACTH such that PT horses differed from Non-PPID horses only at Day 0. PT horses had significantly lower changes in ACTH responses to thyrotropin-releasing hormone stimulation tests than PC horses at non-fall time points only, mid-late February 2018 (P = 0.016) and early April 2018 (P = 0.0172). When PT and PC horses did not differ, they were combined before comparison to Non-PPID horses. No significant group or group-by-time effects were seen in resting insulin, total cortisol, or free cortisol; however, significant time effects were observed in these measures. PPID horses had lower absolute lymphocyte (P = 0.028) and red blood cell (P = 0.0203) counts than Non-PPID horses. In unstimulated whole blood, PPID horses had increased IL-8 expression compared with Non-PPID horses (P = 0.0102). In addition, PPID horses had decreased interferon γ production from PBMCs after stimulation with R. equi (P = 0.0063) and E. coli (P = 0.0057) and showed increased transforming growth factor ß expression after E. coli stimulation (P = 0.0399). The main limitations of this study were a limited sample size and an inability to truly randomize the PPID horses into treatment groups. Resting ACTH is likely the best choice for determining successful responses to pergolide. Neither PPID nor pergolide appears to influence insulin, total cortisol, and free cortisol. As measured, systemic immune function was altered in PPID horses, and it is likely that these horses are indeed at increased risk of opportunistic infection. Despite reducing ACTH, pergolide treatment did not appear to influence immune function.

Resistance to Dopamine Agonists in Pituitary Tumors: Molecular Mechanisms.

Pituitary neuroendocrine tumors (PitNET) are commonly benign tumors accounting for 10-25% of intracranial tumors. Prolactin-secreting adenomas represent the most predominant type of all PitNET and for this subtype of tumors, the medical therapy relies on the use of dopamine agonists (DAs). DAs yield an excellent therapeutic response in reducing tumor size and hormonal secretion targeting the dopamine receptor type 2 (D2DR) whose higher expression in prolactin-secreting adenomas compared to other PitNET is now well established. Moreover, although DAs therapy does not represent the first-line therapy for other PitNET, off-label use of DAs is considered in PitNET expressing D2DR. Nevertheless, DAs primary or secondary resistance, occurring in a subset of patients, may involve several molecular mechanisms, presently not fully elucidated. Dopamine receptors (DRs) expression is a prerequisite for a proper DA function in PitNET and several molecular events may negatively modify DR membrane expression, through the DRs down-regulation and intracellular trafficking, and DR signal transduction pathway. The current mini-review will summarise the presently known molecular events that underpin the unsuccessful therapy with DAs.

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.