Cabergoline

Lysergol exerts potent antiviral activity against the emerging Oropouche virus in vitro

Oropouche virus (OROV) has caused a new outbreak, with thousands of cases of febrile disease in South and Central America, including regions where the virus was not detected before. Oropouche fever is a neglected mosquito-borne disease that still lacks options for antiviral treatment. We developed a high-throughput screening phenotypic assay using human hepatocyte-derived HuH-7.0 cells to screen over 7700 compounds against OROV infection. We identified 13 hit compounds that were protective against OROV-induced cytopathic effect in cell culture, of which 3 were confirmed: lysergol, amiloride hydrochloride, and pyridostatin TFA, with EC50 values below 2 μM. Orthogonal assays indicate that both lysergol and pyridostatin present antiviral activity against OROV in HuH-7.0 and T24 cell lines, but lysergol is far more potent, causing up to a 100,000-fold reduction in viral load in the low micromolar range. Mechanistic studies indicate that the antiviral effect of lysergol affects early stages of viral replication, and that lysergol is also active against a recently isolated OROV strain. In conclusion, our phenotypical screening campaign led to the identification of a first-in-class compound with potent antiviral activity against the emerging OROV in cell culture. We conclude that high-throughput screening assays can be implemented in response to the emergence of arboviruses and accelerate the discovery of candidate treatments.

Indole Derivatives: A Versatile Scaffold in Modern Drug Discovery-An Updated Review on Their Multifaceted Therapeutic Applications (2020-2024)

Indole derivatives have become an important class of compounds in medicinal chemistry, recognized for their wide-ranging biological activities and therapeutic potential. This review provides a comprehensive overview of recent advances in the evaluation of indole-based compounds in the last five years, highlighting their roles in cancer treatment, infectious disease management, anti-inflammatory therapies, metabolic disorder interventions, and neurodegenerative disease management. Indole derivatives have shown significant efficacy in targeting diverse biological pathways, making them valuable scaffolds in designing new drugs. Notably, these compounds have demonstrated the ability to combat drug-resistant cancer cells and pathogens, a significant breakthrough in the field, and offer promising therapeutic options for chronic diseases such as diabetes and hypertension. By summarizing recent key findings and exploring the underlying biological mechanisms, this review underscores the potential of indole derivatives in addressing major healthcare challenges, thereby instilling hope and optimism in the field of modern medicine.

Retrospective assessment of the use of extended-release cabergoline in the management of equine pituitary pars intermedia dysfunction

Introduction

Dopaminergic agonists are accepted as the most effective treatment for pituitary pars intermedia dysfunction. However, some horses are refractory to daily oral pergolide, the recommended registered treatment. Extended-release cabergoline (ERC) injection may offer an alternative. The objective of this retrospective case series was to describe clinical and endocrinological responses to ERC.

Methods

Medical records of horses treated with weekly intramuscular injections of ERC (5 mg/mL, BOVA Aus) at either 0.01 mg/kg (high dose, HD) (n = 10) or 0.005 mg/kg (low dose, LD) (n = 30) were reviewed. Short-term ACTH responses were assessed at 5-8 days using a Wilcoxon signed ranked test. Longer-term ACTH responses (30 to 365 days) were assessed using generalised estimating equations.

Results

Five to eight days after the first dose of LDERC, median adrenocorticotropic hormone (ACTH) concentration was lower (p = 0.001), changing from 153 pg/mL (IQR: 78, 331) to 57 pg/mL (IQR: 30, 102). With HDERC, median ACTH concentration was also 153 pg/mL (IQR: 96, 185) before and then 56 pg/mL (IQR: 29, 86) after 5-8 days of treatment (p = 0.047). Over 12 months of treatment, ACTH concentration ranged from 14 to >1,250 pg/mL (median: 51 pg/mL) in horses treated with LDERC and 20 to 472 pg/mL (median: 50 pg/mL) in horses treated with HDERC. Measurements remained above the seasonal reference range in 39.3 and 52.3% of horses treated with LDERC and HDERC, respectively. Clinical improvement was reported by owners in 78.3 and 100% of horses treated with LDERC and HDERC, respectively. Partial, self-limiting inappetence was reported in 30.0% of LDERC and 60% HDERC cases. Seven horses exhibited lethargy (5 LDERC, 2 HDERC). Insulin concentrations measured 30 days post-ERC treatment were no different from baseline.

Discussion

Clinical and endocrinological responses were consistent with results of previous reports of oral pergolide treatment. Weekly injection of ERC may be an effective alternative to pergolide; the 0.005 mg/kg dose appeared to be as effective, with less risk of inappetence, than the 0.01 mg/kg dose that has been reported previously.

Antiangiogenic Effect of Dopamine and Dopaminergic Agonists as an Adjuvant Therapeutic Option in the Treatment of Cancer, Endometriosis, and Osteoarthritis

Dopamine (DA) and dopamine agonists (DA-Ag) have shown antiangiogenic potential through the vascular endothelial growth factor (VEGF) pathway. They inhibit VEGF and VEGF receptor 2 (VEGFR 2) functions through the dopamine receptor D2 (D2R), preventing important angiogenesis-related processes such as proliferation, migration, and vascular permeability. However, few studies have demonstrated the antiangiogenic mechanism and efficacy of DA and DA-Ag in diseases such as cancer, endometriosis, and osteoarthritis (OA). Therefore, the objective of this review was to describe the mechanisms of the antiangiogenic action of the DA-D2R/VEGF-VEGFR 2 system and to compile related findings from experimental studies and clinical trials on cancer, endometriosis, and OA. Advanced searches were performed in PubMed, Web of Science, SciFinder, ProQuest, EBSCO, Scopus, Science Direct, Google Scholar, PubChem, NCBI Bookshelf, DrugBank, livertox, and Clinical Trials. Articles explaining the antiangiogenic effect of DA and DA-Ag in research articles, meta-analyses, books, reviews, databases, and clinical trials were considered. DA and DA-Ag have an antiangiogenic effect that could reinforce the treatment of diseases that do not yet have a fully curative treatment, such as cancer, endometriosis, and OA. In addition, DA and DA-Ag could present advantages over other angiogenic inhibitors, such as monoclonal antibodies.

Therapeutic Potential of Dopamine and Related Drugs as Anti-Inflammatories and Antioxidants in Neuronal and Non-Neuronal Pathologies

Dopamine (DA), its derivatives, and dopaminergic drugs are compounds widely used in the management of diseases related to the nervous system. However, DA receptors have been identified in nonneuronal tissues, which has been related to their therapeutic potential in pathologies such as sepsis or septic shock, blood pressure, renal failure, diabetes, and obesity, among others. In addition, DA and dopaminergic drugs have shown anti-inflammatory and antioxidant properties in different kinds of cells.

AIM

To compile the mechanism of action of DA and the main dopaminergic drugs and show the findings that support the therapeutic potential of these molecules for the treatment of neurological and non-neurological diseases considering their antioxidant and anti-inflammatory actions.

METHOD

We performed a review article. An exhaustive search for information was carried out in specialized databases such as PubMed, PubChem, ProQuest, EBSCO, Scopus, Science Direct, Web of Science, Bookshelf, DrugBank, Livertox, and Clinical Trials.

RESULTS

We showed that DA and dopaminergic drugs have emerged for the management of neuronal and nonneuronal diseases with important therapeutic potential as anti-inflammatories and antioxidants.

CONCLUSIONS

DA and DA derivatives can be an attractive treatment strategy and a promising approach to slowing the progression of disorders through repositioning.

Effect of Cabergoline on Cognitive Impairments in Transgenic Drosophila Model of Parkinson’s Disease

Background:

Parkinson’s disease is a common neurodegenerative disorder characterized by selective loss of dopaminergic neurons in the substantia nigra pars compacta.

Introduction:

The effects of alpha synuclein, parkin mutation and pharmacological agents have been studied in the Drosophila model.

Methods:

The effect of cabergoline was studied on the cognitive impairments exhibited by the transgenic Drosophila expressing human alpha-synuclein in the neurons. The PD flies were allowed to feed on the diet having 0.5, 1 and 1.5 μM of cabergoline.

Results and Discussion:

The exposure of cabergoline not only showed a dose-dependent significant delay in the cognitive impairments but also prevented the loss of dopaminergic neurons. Molecular docking studies showed the positive interaction between cabergoline and alpha-synuclein.

Conclusion:

The results suggest a protective effect of cabergoline against the cognitive impairments.

[The effect of the dopamine D2 receptor agonist cabergoline on the content of catecholamines and expression of BDNF mRNA in the rat midbrain and hypothalamus]

AIM

To study an effect of cabergoline on dopamine and noradrenaline concentration and BDNF mRNA level in the rat midbrain and hypothalamus.

MATERIAL AND METHODS

Twenty adult male Wistar rats were used in a single treatment paradigm: animals of the treatment group (n=10) received cabergoline (i.p., 0.5 mg/kg) and the control group (n=10) received an equivalent volume of the solvent. Quantitative analysis for the dopamine (DA) and noradrenaline (NA) was carried out using high-performance liquid chromatography (HPLC) coupled with electrochemical detection. BDNF mRNA levels were studied using quantitative RT-PCR.

RESULTS AND CONCLUSION

Cabergoline significantly increases NA concentration in the midbrain 24 hours after injection: 639.2±64.5 ng/g in the treatment group versus 398.0±66.0 ng/g in the control group (p<0.05), while mean content of DA is not significantly changed (211.4±16.3 ng/g vs 169.7±54.6 ng/g, respectively). Cabergoline does not affect hypothalamic DA and NA levels. The drug increases BDNF mRNA levels by 2-times in the midbrain, but not in the hypothalamus, 24 hours after injection.

Recent progress in ergot alkaloid research

Ergot alkaloids are a class of indole derivatives produced by the genera of Ascomycota includingClaviceps,Aspergillus,Penicillium, andEpichloë.

Prolactin is related to individual differences in parental behavior and reproductive success in a biparental passerine, the zebra finch (Taeniopygia guttata)

Variation in parental care can lead to important fitness consequences. The endocrine system is known to regulate physiological and behavioral reproductive traits that are important contributors to lifetime reproductive success. However, the hormonal basis of variation in avian parental care is still not well understood. Plasma prolactin (PRL) concentrations are generally high during post-hatch parental care in birds, and may be a candidate mechanism that regulates variation in parental care and other reproductive success outcomes. Here we analyze the relationship between PRL, parental behavior (chick brooding and feeding) and reproductive success outcomes (clutch size, number of chicks hatched, and chick survival) for the first time in the zebra finch (Taeniopygia guttata). Birds were given cabergoline, a dopamine agonist traditionally used to lower prolactin in mammals, or vehicle in their food. Cabergoline had no effect on prolactin concentrations, but across both groups we found that PRL is positively correlated with parental behavior, number of chicks hatched, and chick survival, but not clutch size. Results from this study will inform hypotheses and predictions for future manipulation studies which test for a causal role for PRL in parental traits.

Cabergoline, dopamine D2 receptor agonist, prevents neuronal cell death under oxidative stress via reducing excitotoxicity

Several lines of evidence demonstrate that oxidative stress is involved in the pathogenesis of neurodegenerative diseases, including Parkinson's disease. Potent antioxidants may therefore be effective in the treatment of such diseases. Cabergoline, a dopamine D2 receptor agonist and antiparkinson drug, has been studied using several cell types including mesencephalic neurons, and is recognized as a potent radical scavenger. Here, we examined whether cabergoline exerts neuroprotective effects against oxidative stress through a receptor-mediated mechanism in cultured cortical neurons. We found that neuronal death induced by H₂O₂ exposure was inhibited by pretreatment with cabergoline, while this protective effect was eliminated in the presence of a dopamine D₂ receptor inhibitor, spiperone. Activation of ERK1/2 by H₂O₂ was suppressed by cabergoline, and an ERK signaling pathway inhibitor, U0126, similarly protected cortical neurons from cell death. This suggested the ERK signaling pathway has a critical role in cabergoline-mediated neuroprotection. Furthermore, increased extracellular levels of glutamate induced by H₂O₂, which might contribute to ERK activation, were reduced by cabergoline, while inhibitors for NMDA receptor or L-type Ca²⁺ channel demonstrated a survival effect against H₂O₂. Interestingly, we found that cabergoline increased expression levels of glutamate transporters such as EAAC1. Taken together, these results suggest that cabergoline has a protective effect on cortical neurons via a receptor-mediated mechanism including repression of ERK1/2 activation and extracellular glutamate accumulation induced by H₂O₂.

Opposing effects on the phrenic motor pathway attributed to dopamine-D1 and -D3/D2 receptor activation

Previous in vivo studies revealed that dopamine-D1-agonists elevate excitability of ventral respiratory column (VRC) neurons and increase discharge activity in the phrenic motor output through actions in the brainstem. In this in vivo study performed on pentobarbital-anesthetized cats, we show that D1-agonists (SKF-38393, dihydrexidine) given intravenously enhanced discharge activity in VRC inspiratory neurons and the phrenic nerve in two stages; discharge intensity first increased to a peak and then discharge duration increased. Cross-correlation analysis of VRC inspiratory neuron and phrenic nerve discharges showed that both stages increased strength of coupling between medullary inspiratory neurons and the phrenic motoneuron output. Intracellular recording and microiontophoresis experiments indicated that D1-agonists produced their stimulatory effects indirectly through actions on synaptic inputs to VRC inspiratory neurons. Because other laboratories have provided evidence that dopamine acting on other types of receptors depresses respiratory neuron excitability we tested the effects of piribedil, an agonist that activates receptors of the generally depressant D3/D2-dopamine receptor family, on phrenic nerve activity. Piribedil depressed phrenic nerve inspiratory discharge intensity, prolonged discharge duration, slowed burst frequency and slowed rate of action potential augmentation. The effects of piribedil were partially counteracted by intravenous injection of dihydrexidine. We propose that under normal, steady state conditions, D1-receptor-mediated excitatory modulation of phrenic motor output overrides D3/D2-receptor mediated inhibition.

Induction and expression of abnormal involuntary movements is related to the duration of dopaminergic stimulation in 6-OHDA-lesioned rats

Dyskinesia induction in Parkinson's disease (PD) appears less marked with long-acting dopamine agonists than with short-acting L-Dopa, but the relationship to duration of drug action is unknown. It is also unclear whether the duration of drug action affects the expression of established dyskinesia. This study compared the ability of L-Dopa and four dopamine agonists of different duration of action to induce abnormal involuntary movements (AIMs) in 6-hydroxydopamine (6-OHDA)-lesioned rats, and their ability to express established AIMs following prior exposure to L-Dopa. 6-OHDA-lesioned rats were treated with saline, L-Dopa/benserazide, apomorphine, ropinirole, pramipexole or pergolide once daily for 15 days. Repeated administration of the short-acting dopamine agonists, apomorphine (duration 80 min) and ropinirole (duration 90 min) induced marked axial, limb and orolingual AIMs at peak effect. L-Dopa (duration 100 min) produced moderate AIMs at peak effect, while administration of the long-acting dopamine agonists, pramipexole (duration 150 min) and pergolide (duration 240 min) resulted in mild AIMs. In rats primed to exhibit severe AIMs following repeated L-Dopa administration, acute administration of apomorphine, ropinirole and L-Dopa induced severe AIMs. By contrast, pramipexole and pergolide evoked only mild-moderate AIMs. Again, there was a negative correlation between duration of effect and the severity of AIMs expressed. These studies show that both the induction and expression of AIMs in 6-OHDA-lesioned rats are related to the duration of action of dopaminergic drugs. These findings suggest that continuous dopaminergic stimulation could be used both to avoid dyskinesia induction and to improve motor function in late-stage PD when troublesome dyskinesia is evident.

Dopamine receptor agonists for the treatment of early or advanced Parkinson's disease

Dopamine receptor agonists are indicated for the symptomatic treatment of early, moderate or advanced Parkinson's disease as well as for the reduction of levodopa-related motor complications. Ergolinic dopamine agonists, such as bromocriptine or pergolide, were initially developed and marketed, and then non-ergolinic dopamine agonists, such as pramipexole and ropinirole, were introduced, reducing the risk of drug-induced fibrotic reactions. Once-daily, controlled-release oral and transdermal formulations have been developed aiming at providing more stable 24-hour plasma drug concentrations and more convenient administration. A disease-modifying effect of dopamine agonists has not been demonstrated clinically. As with any other drug, dopamine agonists can also cause adverse drug reactions, which can be related or unrelated to dopaminergic hyperactivation. Dopaminergic reactions include nausea, hallucinations, confusion and orthostatic hypotension, among others, which were readily identified in pre-marketing clinical trials. During post-marketing surveillance, important adverse reactions were identified, such as daytime somnolence, impulse-control disorders and heart valve fibrosis. Other issues, including the efficacy of dopamine agonists for the treatment of non-motor symptoms, remain under evaluation.

Pharmacologic Management of Parkinson Disease: Choice of Initial Therapy in Early Disease

The most efficacious symptomatic agent for Parkinson's disease is levodopa; however, the development of motor complications with long-term therapy is concerning. In the modern day treatment of Parkinson's disease, non-levodopa agents (eg, dopamine agonists, monoamine oxidase type B inhibitors) should be considered as appropriate initial treatments. In early Parkinson's disease, dopamine agonists provide effective symptomatic therapy, reduce the risk for motor complications, and delay the need to initiate levodopa. However, the dopamine agonists are associated with impulse control disorders and behaviors that are concerning. Monoamine oxidase type B inhibitors are also effective as monotherapy for early stage Parkinson's disease. Clinical data demonstrate that early initiation of rasagiline (in the absence of functional impairment) is associated with improved outcomes as opposed to delayed initiation. Selegiline can delay the need for levodopa, albeit its clinical effectiveness as monotherapy is equivocal. When selecting initial therapy for early Parkinson's disease, clinicians must consider both short-term and long-term benefits and risks.

Novel insights in dopamine receptor physiology

The dopaminergic system has a pivotal role in the central nervous system but also plays important roles in the periphery, mainly in the endocrine system. Dopamine exerts its functions via five different receptors, named D(1)-D(5), belonging to the category of G protein coupled membrane receptors. Dopamine receptors are heterogeneously expressed in different cells, tissues and organs, where they stimulate or inhibit different functions, including neurotransmission and hormone synthesis and secretion. In particular, the dopamineric system has a pivotal role in the physiological regulation of the hypothalamus-pituitary-adrenal axis. Recent data have demonstrated the expression and function of dopamine receptors not only in endocrine organs but also in endocrine tumors, mainly those belonging to the hypothalamus-pituitary-adrenal axis, and also in the so-called 'neuroendocrine' tumors. These data confirm the important role of the dopaminergic system in this endocrine axis, as well as in the neuroendocrine system. This review summarizes the main structural and functional characteristics of dopamine receptors, emphasizing the most recent novelties, and focused on the physiological and pathological regulation of the hypothalamus-pituitary-adrenal axis by the dopaminergic system. In addition, the recent findings on the relationship between dopamine receptors and neuroendocrine tumors are summarized.

Efficacy and tolerability of entacapone versus cabergoline in parkinsonian patients suffering from wearing-off

In this 12-wk, multi-center, randomized, open-label, rater-blinded study, efficacy and tolerability of Entacapone (ENT) or Cabergoline (CBG) in conjunction with levodopa were compared in 161 older Parkinson's disease patients with wearing-off. Patients received either ENT, 3 to 5 times daily, or CBG, titrated according to requirements to a maximum of 6 mg/d. A significant decrease of nearly 2 hours in the daily OFF-time (primary efficacy variable) was recorded in both treatment groups. The non-inferiority test failed despite a trend in favor of ENT. Reduction in OFF-time occurred faster in the ENT compared to the CBG treated patients. A decrease of approximately 20% was detected in parts II and III of the UPDRS, with no differences between the groups. Forty-three percent of the patients in the ENT group reported dyskinesias at baseline, and 35% at the final visit. The corresponding figures in the CBG group were 46% and 43%. Quality of life, measured by PDQ-39, increased substantially with both ENT and CBG. The mean daily dosage at the final visit was 698 mg for ENT (plus 447 mg levodopa) and 3.45 mg for CBG (plus 475 mg levodopa). Adverse events (AE), leading to discontinuation, were reported in 8.5% of the ENT and 13.9% of the CBG treated patients. Nausea was the most common AE in each group, corresponding figures being 7.3% with ENT and 25.3% with CBG (P=0.0024). A probable or possible causal relationship with ENT was reported in 41% and with CBG in 64% of the AE. Among these, only one serious AE (dehydration) was recorded with each treatment group. ENT and CBG reduced the patient's motor complications effectively and to a similar degree. The clinical benefit was more quickly apparent with ENT, which also showed a more favorable AE profile than CBG.

Mitral heart disease due to cabergoline

The case of a restrictive valve disease associated with cabergoline, an ergot alkaloid agonist used in the treatment of Parkinson's disease, is described. Cardiovascular and periodical follow-up assessment may be required when these drugs are prescribed.

Tonic dopaminergic stimulation impairs associative learning in healthy subjects

Endogenous dopamine plays a central role in salience coding during associative learning. Administration of the dopamine precursor levodopa enhances learning in healthy subjects and stroke patients. Because levodopa increases both phasic and tonic dopaminergic neurotransmission, the critical mechanism mediating the enhancement of learning is unresolved. We here probed how selective tonic dopaminergic stimulation affects associative learning. Forty healthy subjects were trained in a novel vocabulary of 45 concrete nouns over the course of 5 consecutive training days in a prospective, randomized, double-blind, placebo-controlled design. Subjects received the tonically stimulating dopamine-receptor agonist pergolide (0.1 mg) vs placebo 120 min before training on each training day. The dopamine agonist significantly impaired novel word learning compared to placebo. This learning decrement persisted up to the last follow-up 4 weeks post-training. Subjects treated with pergolide also showed restricted emotional responses compared to the PLACEBO group. The extent of 'flattened' affect with pergolide was related to the degree of learning inhibition. These findings suggest that tonic occupation of dopamine receptors impairs learning by competition with phasic dopamine signals. Thus, phasic signaling seems to be the critical mechanism by which dopamine enhances associative learning in healthy subjects and stroke patients.

Novel pharmacological strategies for motor complications in Parkinson’s disease

In advanced Parkinson's disease, the combination of disease progression and levodopa therapy leads to the development of motor problems complicating the therapeutic response, known as motor response complications. The nonphysiological, pulsatile stimulation produced by most currently available dopaminergic therapies triggers a complicated series of responses resulting in the dysregulation of glutamate receptors and many other neurotransmitter systems on striatal neurons. Although a number of novel compounds that provide a more continuous dopaminergic stimulation are becoming available, no practical way to accomplish this in a truly physiological manner currently exists. Novel strategies for pharmacological intervention with the use of nondopaminergic treatments, with drugs targeting selected transmitter receptors expressed on striatal neurons appear more promising. These include NMDA or AMPA antagonists, or drugs acting on 5-hydroxytryptamine subtype 2A, alpha2-adrenergic, adenosine A2A and cannabinoid CB1 receptors. Future strategies may also target pre- and postsynaptic components that regulate firing pattern, like synaptic vesicle proteins, or nonsynaptic gap junction communication mechanisms, or drugs with actions at the signal transduction systems that modulate the phosphorylation state of NMDA receptors. These new therapeutic strategies, alone or in combination, hold the promise of providing effective control or reversal of motor response complications.