Antidyskinetic activity of new derivatives of inydazol-4,5-dicarbonic acid in a parkinsonism experimental model due to administration of 6-hydroxydopapine

Full Text

BACKGROUND

Parkinson’s disease (PD) has a major effect on society. For reasons that are not yet fully understood, its incidence and prevalence have increased rapidly over the past two decades, probably due to rapid population aging. PD has a huge personal burden. Levodopa replacement therapy remains the current clinical treatment of choice for patients with PD; however, levodopa-induced dyskinesia (LID) occurs in approximately 80% of patients treated for advanced PD [1, 2]. The uniqueness of this degenerative disease is related to its chronicity, that is, it can persist for decades [3, 4].

Motor symptoms include bradykinesia, muscle rigidity, resting tremors, and postural instability. Patients with PD also experience various non-motor symptoms such as sleep disturbances, dementia, sensory impairment, and autonomic dysfunction [5–7].

The typical disease course is slow progression with increasing disability. PD also places a significant burden on caregivers and an increasing socio-economic burden on society [8, 9].

The marked heterogeneity of symptoms makes PD an ideal disease for evidence-based medicine, in which treatment methods such as pharmacotherapy, neurosurgery, and rehabilitation must be individually selected in accordance with the priorities and needs of each patient and, ultimately, with his/her genetic or other specific biological characteristics. However, this important advancement toward personalized medicine should not be overstated, as patients with PD also share common pathophysiological pathways, such as neuroinflammation or mitochondrial dysfunction; thus, certain treatments can benefit many people having diseases with seemingly different forms of development [6, 10].

Role of glutamate and NMDA receptors in the pathogenesis and treatment of PD

Glutamate is the main excitatory neurotransmitter in the brain and is involved in the regulation of various neurological functions. NMDA receptors are a subtype of glutamate receptors that play important roles in synaptic plasticity, learning, and memory. In PD, growing evidence shows that the dysregulation of NMDA receptors may contribute to its pathophysiology [11, 12].

In PD, excitotoxicity is believed to be one of the main ways that involve the NMDA receptors. As dopamine levels decrease in the brain, glutamate release relatively increases, which can lead to the overstimulation of NMDA receptors and ultimately to neuronal damage. In addition to their role in excitotoxicity, NMDA receptors may be involved in the development of non-motor PD-related symptoms such as cognitive impairment and depression. Studies have shown that functions of NMDA receptors are altered in various brain regions in patients with PD and that these changes may contribute to the development of these non-motor symptoms [11, 13, 14].

While the role of glutamate in PD is still being investigated, targeting glutamate neurotransmission may represent a potentially new therapeutic approach for this disease. For example, drugs that modulate glutamate receptors or reduce glutamate release have shown promising results in preclinical studies and clinical trials [15, 16].

Effect of levodopa on the development of dyskinesias

Levodopa, prescribed in combination with carbidopa, is the most commonly used drug for PD treatment. As the disease progresses, nearly all patients with PD undergo dopamine replacement therapy using levodopa. Although levodopa is the gold standard in the treatment of PD and may alleviate PD symptoms, it has side effects with long-term use [17, 18].

LID develops in approximately 80% of patients treated for advanced PD. A deeper understanding of the pathological mechanisms of LID and possible ways to compensate for them would substantially improve the treatment outcomes of patients with PD and reduce the complexity of drug use and side effects, thereby improving the quality of life and prolonging the life cycle. In Russia, only one noncompetitive NMDA blocker (amantadine) is registered for the treatment of PD. Various NMDA receptor antagonists are undergoing preclinical and clinical trials. Currently, amantadine and other NMDA receptor ligands under evaluation are the most relevant methods to eliminate LID [1, 2, 19, 20].

The study aimed to analyze the antidyskinetic effect of new ligands of the glutamate NMDA receptor complex, namely, 1,2-substituted imidazole-4,5-dicarboxylic acids (IEM2295 and IEM2296). Based on the results of previous studies on the activity of imidazole dicarboxylic acid derivatives and given the similarity in the pharmacological action of amantadine and the studied compounds, IEM2295 and IEM2296 were assumed to demonstrate pronounced antidyskinetic activity [21–23].

MATERIALS AND METHODS

A total of 25 rats were examined, and some were excluded from the study during the experiment. The model was based on the toxic effect of 6-hydroxydopamine (6-HODA) on the rat brain tissue [24, 25]. Given that 6-HODA penetrates the blood–brain barrier poorly, the solution was injected directly into the brain tissue through a previously provided trepanation access; the surgical intervention was performed under aseptic conditions with preliminary anesthesia. Thirty minutes before the administration of 6-HODA, desipramine was injected intraperitoneally to enhance the selective toxic effect on dopamine neurons. The 6-HODA solution was injected unilaterally into the compact area of the substantia nigra according to the coordinates of the stereotaxic atlas. The neurotoxin was injected using a Hamilton syringe at a rate of 1 μL/min.

Three weeks after surgery, the animals were placed in polycarbonate boxes, and to assess the severity of the damaging effect of the neurotoxin, d-amphetamine sulfate was administered once. After 30 min, ipsilateral movements were recorded (i.e., symptoms of damage to the cells of the substantia nigra), and the rats that demonstrated symptoms were included in the experiment. The remaining animals were divided into three groups of six animals each. Group 1 (control) received injections of only levodopa and benserazide, group 2 received injections of levodopa, benserazide, and IEM2295 at (test substance) a dose of 30 mg/kg, and group 3 received injections of levodopa, benserazide, and IEM2296 (test substance) at a dose of 20 mg/kg. The doses of the studied compounds were selected from those that demonstrated the highest antiparkinsonian activity in previous experiments.

Each group was assessed according to the three criteria for motor dysfunction, namely, limb dyskinesia, axial dyskinesia, and masticatory dyskinesia.

The severity of motor functions was assessed on a scale ranging from 0 to 4 points 35, 70, 105, and 140 min after the administration of the above substances, where 0 was the absence of pathological movements, and 4 indicated the most pronounced degree of pathological movements.

Results were statistically processed using MS Excel 2010 and BioStat 2009. The normality of data distribution was determined using the Shapiro–Wilk test. The significance of the differences in values between groups was determined using the Newman–Keuls rank test.

RESULTS

When assessing limb dyskinesia (Fig. 1), statistically significant differences were revealed between the control group and the IEM2295 group at the 70^th (p = 0.028846), 105^th (p = 0.000203), and 140^th (p = 0.000195) minute and between the control group and the IEM2296 group at the 70^th (p = 0.039564), 105^th (p = 0.000208), and 140^th (p = 0.000173) minute.

 

Рис. 1. Результаты оценки дискинезии конечностей

Fig. 1. Results of the assessment of limb dyskinesia

 

In the assessment of axial dyskinesia (Fig. 2), statistically significant differences were found between the control group and group 2 at the 35^th (p = 0.027807), 105^th (p = 0.005529), and 140^th (p = 0.001275) minute and between the control group and group 3 at the 105^th (p = 0.019900) and 140^th (p = 0.001174) minute.

 

Рис. 2. Результаты оценки осевой дискинезии

Fig. 2. Results of the assessment of axial dyskinesia

 

When assessing masticatory dyskinesia (Fig. 3), statistically significant differences were found between the control group and group 2 at the 105^th (p = 0.009257) and 140^th (p = 0.000461) minute and between the control group and group 3 at the 105^th (p = 0.020323) and 140^th (p = 0.000266) minute.

 

Рис. 3. Результаты оценки жевательной дискинезии

Fig. 3. Results of the assessment of chewing dyskinesia

 

In other cases, no statistically significant differences were noted.

DISCUSSION

The results of the experiment indicated that the new ligands of the glutamate NMDA receptor complex, namely, IEM2295 and IEM2296, demonstrated antiparkinsonian and antidyskinetic activities because they reduce the severity of motor dysfunction in rats with LID in an experimental model of parkinsonism.

Analysis of the results revealed that the greatest effect on reducing the severity of limb dyskinesia, axial dyskinesia, and masticatory dyskinesia in rats was registered at the 105^th and 140^th minute after the administration of the test substances. Statistically significant differences between the control group and the test group were detected at all time points for limb dyskinesia; at the 35^th, 105^th, and 140^th minute for axial dyskinesia; and at the 105^th and 140^th minute for masticatory dyskinesia.

The main hypothesis is that the new ligands of the glutamate NMDA receptor complex, namely, 1,2-substituted imidazole-4,5-dicarboxylic acids (IEM2295 and IEM2296), have antidyskinetic activity because of their noncompetitive antagonism ability, that is, NMDA-blocking effect when interaction with hyperactive glutamate receptors of the striatum helps dispose of peak-dose dyskinesias [18, 26–28].

CONCLUSION

The studied compounds demonstrated a pronounced antidyskinetic effect on the model with the administration of 6-HODA. Considering their effect on the glutamatergic system, the most effective method might be the combination with other antiparkinsonian drugs, which will allow interaction with all pathogenetic links of PD [29].

The results indicate the prospects for the development of these substances and further search for effective and safe antiparkinsonian drugs in the range of compounds of this class.

ADDITIONAL INFORMATION

Authors contribution. Thereby, all authors made a substantial contribution to the conception of the study, acquisition, analysis, interpretation of data for the work, drafting and revising the article, final approval of the version to be published and agree to be accountable for all aspects of the study. The contribution of each author: V.D. Dergachev, E.E. Yakovleva, M.A. Brusina, E.R. Bychkov — manuscript drafting, writing and pilot data analyses; L.B. Piotrovskiy, P.D. Shabanov — general concept discussion.

Competing interests. The authors declare that they have no competing interests.

Funding source. This study was supported by State Programme FGWG-2022-0004, Ministry of Science and High Education of Russia.

About the authors

Vladimir D. Dergachev

Institute of Experimental Medicine

Email: dergachevvd@mail.ru

postgraduate student

Russian Federation, 12, Akademika Pavlova str., Saint Petersburg, 197376

Ekaterina E. Yakovleva

Institute of Experimental Medicine; St. Petersburg State Pediatric Medical University

Email: eeiakovleva@mail.ru
ORCID iD: 0000-0002-0270-0217

cand. sci. (med.), researcher

Russian Federation, 12, Akademika Pavlova str., Saint Petersburg, 197376

Maria A. Brusina

Institute of Experimental Medicine

Email: mashasemen@gmail.com
ORCID iD: 0000-0001-8433-120X
SPIN-code: 8953-8772

cand. sci. (chem.), junior researcher

Russian Federation, 12, Akademika Pavlova str., Saint Petersburg, 197376

Evgenii R. Bychkov

Institute of Experimental Medicine

Email: bychkov@mail.ru
ORCID iD: 0000-0002-8911-6805
SPIN-code: 9408-0799

cand. sci. (med.), head of the laboratory

Russian Federation, 12, Academika Pavlova st., Saint Petersburg, 197376

Levon B. Piotrovskiy

Institute of Experimental Medicine

Email: levon-piotrovsky@yandex.ru
ORCID iD: 0000-0001-8679-1365
SPIN-code: 2927-6178

dr. sci. (biol.), professor, head of the laboratory

Russian Federation, 12, Academika Pavlova str., Saint Petersburg, 197376

Petr D. Shabanov

Institute of Experimental Medicine

Author for correspondence.
Email: pdshabanov@mail.ru
ORCID iD: 0000-0003-1464-1127
SPIN-code: 8974-7477

dr. sci. (med.), professor and head of the department

Russian Federation, 12, Akademika Pavlova str., Saint Petersburg, 197376

References

Supplementary files