Classical dopamine agonists.

The pioneering work of Arvid Carlsson has laid the foundation for a number of innovative therapies for severe central nervous system (CNS) diseases. He was awarded the Nobel Price for the discovery of the crucial role of dopamine (DA) as a neurotransmitter in the CNS, thereby forming the basis for the symptomatic therapy of Parkinson's disease (PD) with L-DOPA and subsequently dopaminergic drugs. Parenteral apomorphine has a short lasting effect in PD, bromocriptine can be administered orally and has a long-lasting effects but is poorly tolerated. Lisuride on the other hand has a high affinity to DA receptors and can be administered orally, parenterally or via the transdermal route of administration. Last but not least Carlsson developed the concepts of presynaptic effects of DA agonists as well as DA partial agonism potentially innovative mechanisms for treatment of PD and schizophrenia.

Dopamine Agonists: From the 1970s to Today.

The discovery of dopamine inhibitory effects on prolactin secretion has led to an era of successful dopaminergic therapy for prolactinomas. Herein we provide an overview of the evolution of dopamine agonists and their use in patients with PRL-secreting pituitary tumors, starting from the 1970s up to today, highlighting that normalization of PRL levels, restoration of eugonadism, and reduction of tumor mass can be achieved in the majority of patients by treatment with dopamine agonists.

Designing lisuride intranasal nanocarrier system for reduction of oxidative damage with enhanced dopamine level in brain for Parkinsonism.

In the present study, nanoemulsion (NE) loaded with lisuride were formulated for delivering drug to brain via intranasal route. Dopamine levels, pharmacokinetic, and antioxidant activity were estimated. Antioxidant effect of lisuride NE was assessed in-vivo using oxidative stress models revealing symptoms like those of Parkinson's disease. Intranasally administered lisuride NE-treated group revealed a greater number of antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione (GSH) as compared to the intravenously administered lisuride suspension in haloperidol rat model. Additionally, it was observed that lisuride NE can decrease dopamine loss. When lisuride NE was administered intranasally resulted in considerably higher dopamine concentrations (17.48 ± 0.05 ng/mL) in comparison to rats receiving haloperidol (7.28 ± 0.02 ng/mL). From study, it is suggested that NE is a possible strategy to deliver lisuride intranasally to lower free radical damage and prevent the biochemical alterations associated with Parkinson's disease.

Rearing behaviour in the mouse behavioural pattern monitor distinguishes the effects of psychedelics from those of lisuride and TBG.

Psychedelics alter consciousness and may have potential for drug development. As psychedelics are likely therapeutically active, it is important to study their effects and mechanisms using preclinical models. Here, we examined the effects of phenylalkylamine and indoleamine psychedelics on locomotor activity and exploratory behaviour using the mouse Behavioural Pattern Monitor (BPM). DOM, mescaline, and psilocin reduced locomotor activity at high doses and influenced rearings, an exploratory behaviour, in a characteristic inverted U-shaped dose-response function. Pretreatment with the selective 5-HT2A antagonist M100907 reversed the drug-induced alterations in locomotor activity, rearings, and jumps after systemic administration of DOM at low doses. However, holepoking at the full range of doses tested was not blocked by M100907. Administration of the hallucinogenic 5-HT2A agonist 25CN-NBOH induced striking similarities in response to that to psychedelics; these alterations were significantly diminished by M100907, whereas the putatively non-hallucinogenic 5-HT2A agonist TBG did not affect locomotor activity, rearings, or jumps at the most effective doses. The nonhallucinogenic 5-HT2A agonist lisuride failed to increase rearing. The results of these experiments provide strong evidence that DOM-elicited increases in rearing are due to mediation by the 5-HT2A receptor. Finally, discriminant analysis was able to distinguish all four psychedelics from lisuride and TBG based on behavioural performance alone. Thus, increased rearing in mice could provide additional evidence of behavioural differences between hallucinogenic and nonhallucinogenic 5-HT2A agonists.

The G protein biased serotonin 5-HT 2A receptor agonist lisuride exerts anti-depressant drug-like activities in mice.

There is now evidence from multiple Phase II clinical trials that psychedelic drugs can exert longlasting anxiolytic, anti-depressant, and anti-drug abuse (nicotine and ethanol) effects in patients. Despite these benefits, the hallucinogenic actions of these drugs at the serotonin 2A receptor (5-HT2AR) limit their clinical use in diverse settings. Activation of the 5-HT2AR can stimulate both G protein and ß-arrestin (ßArr) -mediated signaling. Lisuride is a G protein biased agonist at the 5-HT2AR and, unlike the structurally-related LSD, the drug does not typically produce hallucinations in normal subjects at routine doses. Here, we examined behavioral responses to lisuride, in wild-type (WT), ßArr1-KO, and ßArr2-KO mice. In the open field, lisuride reduced locomotor and rearing activities, but produced a U-shaped function for stereotypies in both ßArr lines of mice. Locomotion was decreased overall in ßArr1-KOs and ßArr2-KOs, relative to WT controls. Incidences of head twitches and retrograde walking to lisuride were low in all genotypes. Grooming was depressed in ßArr1 mice, but was increased then decreased in ßArr2 animals with lisuride. Prepulse inhibition (PPI) was unaffected in ßArr2 mice, whereas 0.5 mg/kg lisuride disrupted PPI in ßArr1 animals. The 5-HT2AR antagonist MDL100907 failed to restore PPI in ßArr1 mice, whereas the dopamine D2/D3 antagonist raclopride normalized PPI in WTs but not in ßArr1-KOs. Using vesicular monoamine transporter 2 mice, lisuride reduced immobility times in tail suspension and promoted a preference for sucrose that lasted up to 2 days. Together, it appears ßArr1 and ßArr2 play minor roles in lisuride's actions on many behaviors, while this drug exerts anti-depressant drug-like responses without hallucinogenic-like activities.

The G protein biased serotonin 5-HT2A receptor agonist lisuride exerts anti-depressant drug-like activities in mice.

There is now evidence from multiple Phase II clinical trials that psychedelic drugs can exert long-lasting anxiolytic, anti-depressant, and anti-drug abuse (nicotine and ethanol) effects in patients. Despite these benefits, the hallucinogenic actions of these drugs at the serotonin 2A receptor (5-HT2AR) limit their clinical use in diverse settings. Activation of the 5-HT2AR can stimulate both G protein and ß-arrestin (ßArr) -mediated signaling. Lisuride is a G protein biased agonist at the 5-HT2AR and, unlike the structurally-related lysergic acid diethylamide (LSD), the drug does not typically produce hallucinations in normal subjects at routine doses. Here, we examined behavioral responses to lisuride, in wild-type (WT), ßArr1-knockout (KO), and ßArr2-KO mice. In the open field, lisuride reduced locomotor and rearing activities, but produced a U-shaped function for stereotypies in both ßArr lines of mice. Locomotion was decreased overall in ßArr1-KOs and ßArr2-KOs relative to wild-type controls. Incidences of head twitches and retrograde walking to lisuride were low in all genotypes. Grooming was decreased in ßArr1 mice, but was increased then decreased in ßArr2 animals with lisuride. Serotonin syndrome-associated responses were present at all lisuride doses in WTs, but they were reduced especially in ßArr2-KO mice. Prepulse inhibition (PPI) was unaffected in ßArr2 mice, whereas 0.5 mg/kg lisuride disrupted PPI in ßArr1 animals. The 5-HT2AR antagonist MDL100907 failed to restore PPI in ßArr1 mice, whereas the dopamine D2/D3 antagonist raclopride normalized PPI in WTs but not in ßArr1-KOs. Clozapine, SCH23390, and GR127935 restored PPI in both ßArr1 genotypes. Using vesicular monoamine transporter 2 mice, lisuride reduced immobility times in tail suspension and promoted a preference for sucrose that lasted up to 2 days. Together, it appears ßArr1 and ßArr2 play minor roles in lisuride's actions on many behaviors, while this drug exerts anti-depressant drug-like responses without hallucinogenic-like activities.

Effects of Tiliroside and Lisuride Co-Treatment on the PI3K/Akt Signal Pathway: Modulating Neuroinflammation and Apoptosis in Parkinson's Disease.

Researchers are actively exploring potential bioactive compounds to enhance the effectiveness of Lisuride (Lis) in treating Parkinson's disease (PD) over the long term, aiming to mitigate the serious side effects associated with its extended use. A recent study found that combining the dietary flavonoid Tiliroside (Til) with Lis has potential anti-Parkinson's benefits. The study showed significant improvements in PD symptoms induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) when Til and Lis were given together, based on various behavioral tests. This combined treatment significantly improved motor function and protected dopaminergic neurons in rats with PD induced by MPTP. It also activated important molecular pathways related to cell survival and apoptosis control, as indicated by the increased pAkt/Akt ratio. Til and Lis together increased B-cell lymphoma 2 (Bcl-2), decreased caspase 3 activity, and prevented brain cell decay. Co-administration also reduced tumor necrosis factor alpha (TNF-α) and Interleukin-1 (IL-1). Antioxidant markers such as superoxide dismutase (SOD), catalase, and reduced glutathione significantly improved compared to the MPTP-induced control group. This study shows that using Til and Lis together effectively treats MPTP-induced PD in rats, yielding results comparable to an 8 mg/kg dose of levodopa, highlighting their potential as promising Parkinson's treatments.

Contrasting effects of DOI and lisuride on impulsive decision-making in delay discounting task.

RATIONALE: The 5-HT2A receptor is the major target of classic hallucinogens. Both DOI (2,5-dimethoxy-4-iodoamphetamine) and lisuride act at 5-HT2A receptors, and lisuride shares comparable affinity with DOI and acts as a partial agonist at 5-HT2A receptors. However, not like DOI, lisuride lacks hallucinogenic properties. Impulsive decision-making refers to the preference for an immediate small reinforcer (SR) over a delayed large reinforcer (LR). OBJECTIVES: The current study aims to compare the effects of DOI and lisuride on impulsive decision-making and further to investigate the possible receptor mechanisms responsible for the actions of the two drugs. METHODS: Impulsive decision-making was evaluated in male Sprague-Dawley rats by the percentage of choice for the LR in delay discounting task (DDT). Delay to the LR changed in an ascending order (0, 4, 8, 16, and 32 s) across one session. RESULTS: DOI (0.5 and 1.0 mg/kg) increased impulsive decision-making, and the effects of DOI (1.0 mg/kg) were blocked by the 5-HT2A receptor antagonist ketanserin (1.0 mg/kg) rather than the 5-HT2C receptor antagonist SB-242084 (1.0 mg/kg). Contrarily, lisuride (0.1, 0.3, and 0.5 mg/kg) decreased impulsive decision-making. The effects of lisuride (0.3 mg/kg) were not antagonized by ketanserin (1.0 mg/kg), selective 5-HT1A antagonist WAY-100635 (1.0 mg/kg), or selective dopamine D4 receptor antagonist L-745870 (1.0 mg/kg) but were attenuated by the selective dopamine D2/D3 receptor antagonist tiapride (40 mg/kg). CONCLUSIONS: DOI and lisuride have contrasting effects on impulsive decision-making via distinct receptors. DOI-induced increase of impulsivity is mediated by the 5-HT2A receptor, while lisuride-induced inhibition of impulsivity is regulated by the dopamine D2/D3 receptor.

Tolerance and Cross-Tolerance among Psychedelic and Nonpsychedelic 5-HT2A Receptor Agonists in Mice.

Classical psychedelics represent a subgroup of serotonergic psychoactive substances characterized by their distinct subjective effects on the human psyche. Another unique attribute of this drug class is that such effects become less apparent after repeated exposure within a short time span. The classification of psychedelics as a subgroup within the serotonergic drug family and the tolerance to their effects are replicated by the murine head twitch response (HTR) behavioral paradigm. Here, we aimed to assess tolerance and cross-tolerance to HTR elicited by psychedelic and nonpsychedelic serotonin 2A receptor (5-HT2AR) agonists in mice. We show that repeated (4 days) administration of the psychedelic 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) induced a progressive decrease in HTR behavior. Tolerance to DOI-induced HTR was also observed 24 h after a single administration of this psychedelic. Pretreatment with the 5-HT2AR antagonist M100907 reduced not only the acute manifestation of DOI-induced HTR, but also the development of tolerance to HTR. Additionally, cross-tolerance became apparent between the psychedelics DOI and lysergic acid diethylamide (LSD), whereas repeated administration of the nonpsychedelic 5-HT2AR agonist lisuride did not affect the ability of these two psychedelics to induce HTR. At the molecular level, DOI administration led to down-regulation of 5-HT2AR density in mouse frontal cortex membrane preparations. However, development of tolerance to the effect of DOI on HTR remained unchanged in ß-arrestin-2 knockout mice. Together, these data suggest that tolerance to HTR induced by psychedelics involves activation of the 5-HT2AR, is not observable upon repeated administration of nonpsychedelic 5-HT2AR agonists, and occurs via a signaling mechanism independent of ß-arrestin-2.

Contrasting effects of DOM and lisuride on impul-sive decision-making in delay discounting task / 中国药理学与毒理学杂志

OBJECTIVE The 5-HT2A receptor is the major target of classic hallucinogens.Both DOM(2,5-dimethoxy-4-methylamphetamine)and lisuride act at 5-HT2A receptors,and lisuride shares comparable affinity with DOM and acts as a partial agonist at 5-HT2A recep-tors.However,not like DOM,lisuride lacks hallucinogenic properties.Impulsive decision-making refers to the prefer-ence for an immediate small reinforcer(SR)over a delayed large reinforcer(LR).The current study aims to compare the effects of DOM and lisuride on impulsive decision-making and further to investigate the possible receptor mechanisms responsible for the actions of the two drugs.METHODS Impulsive decision-making was evaluated in male Sprague-Dawley rats by the percent-age of choice for the LR in delay discounting task(DDT).Delay to the LR changed in an ascending order(0,4,8,16,and 32 s)across one session.RESULTS DOM(0.3 and 0.5 mg·kg-1)increased impulsive decision-making,and the effects of DOM(0.5 mg·kg-1)was blocked by the 5-HT2A receptor antagonist ketanserin(1.0 mg·kg-1)rather than the 5-HT2C receptor antagonist SB-242084(1.0 mg·kg-1).Contrarily,lisuride(0.1,0.3 and 0.5 mg·kg-1)decreased impulsive decision-making.The effects of lisu-ride(0.3 mg·kg-1)were not antagonized by ketanserin(1.0 mg·kg-1),selective 5-HT1A antagonist WAY-100635(1.0 mg·kg-1)or selective dopamine D4 receptor antagonist L-745870(1.0 mg·kg-1),but were attenuated by the selec-tive dopamine D2/D3 receptor antagonist tiapride(40 mg·kg-1).CONCLUSION DOM and lisuride have contrasting effects on impulsive decision-making via distinct recep-tors.DOM-induced increase of impulsivity is mediated by the 5-HT2A receptor,while lisuride-induced inhibition of impulsivity is regulated by the dopamine D2/D3 receptor.

Effect of Hallucinogens on Unconditioned Behavior.

Because of the ethical and regulatory hurdles associated with human studies, much of what is known about the psychopharmacology of hallucinogens has been derived from animal models. However, developing reliable animal models has proven to be a challenging task due to the complexity and variability of hallucinogen effects in humans. This chapter focuses on three animal models that are frequently used to test the effects of hallucinogens on unconditioned behavior: head twitch response (HTR), prepulse inhibition of startle (PPI), and exploratory behavior. The HTR has demonstrated considerable utility in the neurochemical actions of hallucinogens. However, the latter two models have clearer conceptual bridges to human phenomenology. Consistent with the known mechanism of action of hallucinogens in humans, the behavioral effects of hallucinogens in rodents are mediated primarily by activation of 5-HT2A receptors. There is evidence, however, that other receptors may play secondary roles. The structure-activity relationships (SAR) of hallucinogens are reviewed in relation to each model, with a focus on the HTR in rats and mice.

Dopamine D3 receptor-modulated neuroprotective effects of lisuride.

Dopamine (DA) contributes to the regulation of voluntary movement, and a deficiency in DAergic neurons leads to movement disorders. The objective of this study was to examine the neuroprotective effect of DA D2-like receptor agonist, lisuride, and the role of DA receptors in this protection. Treatment with lisuride alleviated loss of tyrosine hydroxylase (TH) both direct and intraperitoneal injection in 6-hydroxydopamine (6-OHDA) mouse model. Similar results were obtained in primary neuronal cultures treated with lisuride. Lisuride protected TH expression against 6-OHDA-induced cytotoxicity in a concentration-dependent manner. Then, we evaluated the role of DA D2 and D3 receptor in neuroprotective effect of lisuride. Treatment of neuronal cultures with L-741,626, a DA D2 receptor-selective antagonist, did not alter neuroprotective effect of lisuride. However, protective effect of lisuride on TH expression was abolished when cells were treated with GR103691, a D3 receptor selective antagonist. Furthermore, whether lisuride can alleviate mitochondrial damage of DAergic neurons induced by 6-OHDA, we investigated the expression of the mitochondrial regulatory protein, paraplegin, and changes in mitochondria morphology. Treatment with lisuride countered a 6-OHDA-induced reduction in paraplegin and TH expression, and co-treatment with GR103691 blocked this effect of lisuride. Transmission electron microscopy confirmed the lisuride mitigation of 6-OHDA-induced damage to the mitochondrial membrane and cristae. These results suggest that the DA D3 receptor mediates the neuroprotective effects of lisuride by preventing mitochondrial damage.

Lisuride toxicity in a pediatric patient.

Lisuride Maleate (Dopergin) is semi synthetic ergot alkaloid used for a variety of medical conditions. It is licensed for use in Canada, EU and Middle East countries and is marketed by various drug companies. There are no reported cases of lisuride toxicity in the literature on Google Search or Pub med Search. Herein, we present a case of accidental overdose of lisuride maleate in a 21-month-old Saudi male and further clinical course and management. The aim of this report was to document the unusual features of lisuride toxicity in pediatric patients and to guide physicians for its management.