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Azizifar N, Mohaddes G, Keyhanmanesh R, Athari SZ, Alimohammadi S, Farajdokht F. Intranasal AdipoRon Mitigated Anxiety and Depression-Like Behaviors in 6-OHDA-Induced Parkinson 's Disease Rat Model: Going Beyond Motor Symptoms. Neurochem Res 2024:10.1007/s11064-024-04223-8. [PMID: 39096412 DOI: 10.1007/s11064-024-04223-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 07/02/2024] [Accepted: 07/29/2024] [Indexed: 08/05/2024]
Abstract
Depression and anxiety are prevalent neuropsychiatric conditions among patients with Parkinson's disease (PD), which may manifest prior to motor symptoms. As levodopa, a prominent treatment for PD motor symptoms, provides few benefits for mood-related abnormalities, tackling non-motor symptoms is particularly important. AdipoRon (Ad), an adiponectin agonist, has demonstrated neuroprotective effects by suppressing neuroinflammatory responses and activating the AMPK/Sirt-1 signaling pathway. This study looked at the potential advantages and underlying mechanisms of intranasal Ad in a rat model of PD induced by 6-hydroxydopamine (6-OHDA). We found that Ad at doses of 1 and 10 µg for 21 days exhibited anxiolytic- and antidepressant effects in the open field (OF) test, elevated plus maze (EPM), sucrose splash test, and forced swimming test in a PD model caused by a unilateral 6-OHDA injection into the medial forebrain bundle (MFB). The Ad also lowered the levels of corticosterone in the blood, decreased inflammasome components (NLRP3, caspase 1, and IL-1β), and increased Sirt-1 protein levels in the prefrontal cortex (PFC) of PD rats. We conclude that Ad ameliorates anxious and depressive-like behaviors in the PD rat model through stimulating the AMPK/Sirt-1 signaling and blocking the NLRP3 inflammasome pathways in the PFC.
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Affiliation(s)
- Negin Azizifar
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Gisou Mohaddes
- Department of Biomedical Education, College of Osteopathic Medicine, California Health Sciences University, Clovis, CA, USA
| | - Rana Keyhanmanesh
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Seyed Zanyar Athari
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Soraya Alimohammadi
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Fereshteh Farajdokht
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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Zanella CA, Marques N, Junqueira S, Prediger RD, Tasca CI, Cimarosti HI. Guanosine increases global SUMO1-ylation in the hippocampus of young and aged mice and improves the short-term memory of young mice. J Neurochem 2024; 168:1503-1513. [PMID: 37491912 DOI: 10.1111/jnc.15920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/27/2023]
Abstract
The nucleoside guanosine is an endogenous neuromodulator associated with neuroprotection. The roles of guanosine during aging are still not fully elucidated. Guanosine modulates SUMOylation in neurons and astrocytes in vitro, but it is not known whether guanosine can modulate SUMOylation in vivo and improve cognitive functions during aging. SUMOylation is a post-translational protein modification with potential neuroprotective roles. In this follow-up study, we investigated whether guanosine could modulate SUMOylation in vivo and behavior in young and aged mice. Young (3-month-old) and aged (24-month-old) C57BL/6 mice were treated with guanosine (8 mg/kg intraperitoneal) daily for 14 days. Starting on day 8 of treatment, the following behavioral tests were performed: open field, novel object location, Y-maze, sucrose splash test, and tail suspension test. Treatment with guanosine did not change the locomotor activity of young or aged mice in the open-field test. Treatment with guanosine improved short-term memory only for young mice but did not change the working memory of either young or aged mice, as evaluated using object recognition and the Y-maze tests, respectively. Depressive-like behaviors, such as impaired grooming evaluated through the splash test, did not change in either young or aged mice. However, young mice treated with guanosine increased their immobility time in the tail suspension test, suggesting an effect on behavioral coping strategies. Global SUMO1-ylation was significantly increased in the hippocampus of young and aged mice after 14 days of treatment with guanosine, whereas no changes were detected in the cerebral cortex of either young or aged mice. Our findings demonstrate that guanosine also targets hippocampal SUMOylation in vivo, thereby contributing to a deeper understanding of its mechanisms of action. This highlights the involvement of SUMOylation in guanosine's modulatory and neuroprotective effects.
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Affiliation(s)
- Camila A Zanella
- Pharmacology Department, Pharmacology Postgraduate Program, Biological Sciences Center (CCB), Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
| | - Naiani Marques
- Biochemistry Department, Biochemistry Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
| | - Stella Junqueira
- Neuroscience Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
| | - Rui D Prediger
- Pharmacology Department, Pharmacology Postgraduate Program, Biological Sciences Center (CCB), Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
- Neuroscience Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
| | - Carla I Tasca
- Biochemistry Department, Biochemistry Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
- Neuroscience Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
| | - Helena I Cimarosti
- Pharmacology Department, Pharmacology Postgraduate Program, Biological Sciences Center (CCB), Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
- Neuroscience Postgraduate Program, CCB, UFSC, Florianópolis, Brazil
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Boi L, Fisone G. Investigating affective neuropsychiatric symptoms in rodent models of Parkinson's disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 174:119-186. [PMID: 38341228 DOI: 10.1016/bs.irn.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Affective neuropsychiatric disorders such as depression, anxiety and apathy are among the most frequent non-motor symptoms observed in people with Parkinson's disease (PD). These conditions often emerge during the prodromal phase of the disease and are generally considered to result from neurodegenerative processes in meso-corticolimbic structures, occurring in parallel to the loss of nigrostriatal dopaminergic neurons. Depression, anxiety, and apathy are often treated with conventional medications, including selective serotonin reuptake inhibitors, tricyclic antidepressants, and dopaminergic agonists. The ability of these pharmacological interventions to consistently counteract such neuropsychiatric symptoms in PD is still relatively limited and the development of reliable experimental models represents an important tool to identify more effective treatments. This chapter provides information on rodent models of PD utilized to study these affective neuropsychiatric symptoms. Neurotoxin-based and genetic models are discussed, together with the main behavioral tests utilized to identify depression- and anxiety-like behaviors, anhedonia, and apathy. The ability of various therapeutic approaches to counteract the symptoms observed in the various models is also reviewed.
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Affiliation(s)
- Laura Boi
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Gilberto Fisone
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Camargo A, Bettio LEB, Rosa PB, Rosa JM, Altê GA, Rodrigues ALS. The antidepressant-like effect of guanosine involves the modulation of adenosine A 1 and A 2A receptors. Purinergic Signal 2022:10.1007/s11302-022-09898-8. [PMID: 36166131 DOI: 10.1007/s11302-022-09898-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/13/2022] [Indexed: 11/25/2022] Open
Abstract
Guanosine has been considered a promising candidate for antidepressant responses, but if this nucleoside could modulate adenosine A1 (A1R) and A2A (A2AR) receptors to exert antidepressant-like actions remains to be elucidated. This study investigated the role of A1R and A2AR in the antidepressant-like response of guanosine in the mouse tail suspension test and molecular interactions between guanosine and A1R and A2AR by docking analysis. The acute (60 min) administration of guanosine (0.05 mg/kg, p.o.) significantly decreased the immobility time in the tail suspension test, without affecting the locomotor performance in the open-field test, suggesting an antidepressant-like effect. This behavioral response was paralleled with increased A1R and reduced A2AR immunocontent in the hippocampus, but not in the prefrontal cortex, of mice. Guanosine-mediated antidepressant-like effect was not altered by the pretreatment with caffeine (3 mg/kg, i.p., a non-selective adenosine A1R/A2AR antagonist), 8-cyclopentyl-1,3-dipropylxanthine (DPCPX - 2 mg/kg, i.p., a selective adenosine A1R antagonist), or 4-(2-[7-amino-2-{2-furyl}{1,2,4}triazolo-{2,3-a}{1,3,5}triazin-5-yl-amino]ethyl)-phenol (ZM241385 - 1 mg/kg, i.p., a selective adenosine A2AR antagonist). However, the antidepressant-like response of guanosine was completely abolished by adenosine (0.5 mg/kg, i.p., a non-selective adenosine A1R/A2AR agonist), N-6-cyclohexyladenosine (CHA - 0.05 mg/kg, i.p., a selective adenosine A1 receptor agonist), and N-6-[2-(3,5-dimethoxyphenyl)-2-(methylphenyl)ethyl]adenosine (DPMA - 0.1 mg/kg, i.p., a selective adenosine A2A receptor agonist). Finally, docking analysis also indicated that guanosine might interact with A1R and A2AR at the adenosine binding site. Overall, this study reinforces the antidepressant-like of guanosine and unveils a previously unexplored modulation of the modulation of A1R and A2AR in its antidepressant-like effect.
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Affiliation(s)
- Anderson Camargo
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil
| | - Luis E B Bettio
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil
| | - Priscila B Rosa
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil
| | - Julia M Rosa
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil
| | - Glorister A Altê
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil
| | - Ana Lúcia S Rodrigues
- Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, FlorianopolisSanta Catarina, 88040-900, Brazil.
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Guanosine as a promising target for fast-acting antidepressant responses. Pharmacol Biochem Behav 2022; 218:173422. [PMID: 35732211 DOI: 10.1016/j.pbb.2022.173422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/24/2022] [Accepted: 06/16/2022] [Indexed: 02/07/2023]
Abstract
Although the rapid-onset and sustained antidepressant responses elicited by ketamine have gained considerable attention in recent years, it has some knock-on effects that limit its widespread clinical use. Therefore, ketamine is considered the prototype for the new generation of glutamate-based rapid-acting antidepressants. Within this context, it has been demonstrated that guanosine, an endogenous guanine-based purine, has overlapping mechanisms of action with ketamine and is effective in eliciting fast antidepressant-like responses and even potentiating ketamine's actions in preclinical studies. Here, we review the recent findings regarding the ability of guanosine to produce rapid-acting antidepressant-like effects and we provide an overview of the molecular mechanisms underlying its antidepressant-like actions. Moreover, the neurobiological mechanisms underpinning the ability of guanosine in boosting the antidepressant-like and pro-synaptogenic effects elicited by ketamine are also reported. Taken together, this review opens perspectives for the use of guanosine alone or in combination with ketamine for the management of treatment-resistant depression.
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Mou YK, Guan LN, Yao XY, Wang JH, Song XY, Ji YQ, Ren C, Wei SZ. Application of Neurotoxin-Induced Animal Models in the Study of Parkinson's Disease-Related Depression: Profile and Proposal. Front Aging Neurosci 2022; 14:890512. [PMID: 35645772 PMCID: PMC9136050 DOI: 10.3389/fnagi.2022.890512] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 04/27/2022] [Indexed: 01/17/2023] Open
Abstract
Depression can be a non-motor symptom, a risk factor, and even a co-morbidity of Parkinson's disease (PD). In either case, depression seriously affects the quality of life of PD patients. Unfortunately, at present, a large number of clinical and basic studies focused on the pathophysiological mechanism of PD and the prevention and treatment of motor symptoms. Although there has been increasing attention to PD-related depression, it is difficult to achieve early detection and early intervention, because the clinical guidelines mostly refer to depression developed after or accompanied by motor impairments. Why is there such a dilemma? This is because there has been no suitable preclinical animal model for studying the relationship between depression and PD, and the assessment of depressive behavior in PD preclinical models is as well a very challenging task since it is not free from the confounding from the motor impairment. As a common method to simulate PD symptoms, neurotoxin-induced PD models have been widely used. Studies have found that neurotoxin-induced PD model animals could exhibit depression-like behaviors, which sometimes manifested earlier than motor impairments. Therefore, there have been attempts to establish the PD-related depression model by neurotoxin induction. However, due to a lack of unified protocol, the reported results were diverse. For the purpose of further promoting the improvement and optimization of the animal models and the study of PD-related depression, we reviewed the establishment and evaluation strategies of the current animal models of PD-related depression based on both the existing literature and our own research experience, and discussed the possible mechanism and interventions, in order to provide a reference for future research in this area.
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Affiliation(s)
- Ya-Kui Mou
- Department of Otolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Li-Na Guan
- Department of Neurosurgical Intensive Care Unit, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Xiao-Yan Yao
- Department of Neurology, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Jia-Hui Wang
- Department of Central Laboratory, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Xiao-Yu Song
- Department of Otolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Yong-Qiang Ji
- Department of Nephrology, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Chao Ren
- Department of Otolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
- Department of Neurology, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
| | - Shi-Zhuang Wei
- Department of Otolaryngology, Head and Neck Surgery, Yantai Yuhuangding Hospital, Qingdao University, Yantai, China
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The α7 nAChR allosteric modulator PNU-120596 amends neuroinflammatory and motor consequences of parkinsonism in rats: Role of JAK2/NF-κB/GSk3β/ TNF-α pathway. Biomed Pharmacother 2022; 148:112776. [PMID: 35272136 DOI: 10.1016/j.biopha.2022.112776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 02/01/2022] [Accepted: 02/27/2022] [Indexed: 11/20/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disorder and a leading cause of disability. The current gold standard for PD treatment, L-Dopa, has limited clinical efficacy and multiple side effects. Evidence suggests that activation of α7 nicotinic acetylcholine receptors (α7nAChRs) abrogates neuronal and inflammatory insults. Here we tested whether PNU-120596 (PNU), a type II positive allosteric modulator of α7 nAChR, has a critical role in regulating motor dysfunction and neuroinflammation correlated with the associated PD dysfunction. Neuroprotective mechanisms were investigated through neurobehavioral, molecular, histopathological, and immunohistochemical studies. PNU reversed motor incoordination and hypokinesia induced via the intrastriatal injection of 6-hydroxydopamine and manifested by lower falling latency in the rotarod test, short ambulation time and low rearing incidence in open field test. Tyrosine hydroxylase immunostaining showed a significant restoration of dopaminergic neurons following PNU treatment, in addition to histopathological restoration in nigrostriatal tissues. PNU halted striatal neuroinflammation manifested as a suppressed expression of JAK2/NF-κB/GSk3β accompanied by a parallel decline in the protein expression of TNF-α in nigrostriatal tissue denoting the modulator anti-inflammatory capacity. Moreover, the protective effects of PNU were partially reversed by the α7 nAChR antagonist, methyllycaconitine, indicating the role of α7 nAChR modulation in the mechanism of action of PNU. This is the first study to reveal the positive effects of PNU-120596 on motor derangements of PD via JAK2/NF-κB/GSk3β/ TNF-α neuroinflammatory pathways, which could offer a potential therapeutic strategy for PD.
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Massari CM, Zuccarini M, Di Iorio P, Tasca CI. Guanosine Mechanisms of Action: Toward Molecular Targets. Front Pharmacol 2021; 12:653146. [PMID: 33867993 PMCID: PMC8044438 DOI: 10.3389/fphar.2021.653146] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/26/2021] [Indexed: 01/02/2023] Open
Affiliation(s)
- Caio M Massari
- Laboratório De Neuroquímica-4, Departamento De Bioquímica, Centro De Ciências Biológicas, Universidade Federal De Santa Catarina, Florianópolis, Brazil
| | - Mariachiara Zuccarini
- Department of Biomedical Sciences, University G. D'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Patrizia Di Iorio
- Department of Biomedical Sciences, University G. D'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Carla I Tasca
- Laboratório De Neuroquímica-4, Departamento De Bioquímica, Centro De Ciências Biológicas, Universidade Federal De Santa Catarina, Florianópolis, Brazil
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Johnson A, Rainville JR, Rivero-Ballon GN, Dhimitri K, Hodes GE. Testing the Limits of Sex Differences Using Variable Stress. Neuroscience 2020; 454:72-84. [PMID: 31917340 DOI: 10.1016/j.neuroscience.2019.12.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 02/07/2023]
Abstract
Depression is a chronic disease that affects nearly twice as many women as men, and symptoms can differ by sex. Preclinical models disproportionately use male subjects and test a single behavioral endpoint immediately at the cessation of stress. We conducted variable stress in male and female mice for 6, 28, and 56 days, and measured behavior with a battery chosen to match research domain criteria. To examine individual differences, we generated a composite z score to measure stress susceptibility across behavioral tests. We also tested behavior following a 30-day recovery period to evaluate the duration of the stress effects. Females, but not males, were susceptible to 6 days of variable stress when behavioral testing started 24 h later. If behavioral testing was conducted 30 days later both males and females expressed stress related behaviors. Males and females were stress susceptible to 28 days of variable stress and effects were long lasting. Both sexes habituated to 56 days of variable stress, but anxiety associated measures still showed persistence. Performance on specific behavioral tests was often different between individuals and between sexes, and not all stressed animals were susceptible to all tested behaviors. These studies confirm that behavioral sex differences are detected in response to variable stress, and reveal information about individual differences. Use of a test battery that measures varying endophenotypes can be combined into a single stress susceptibility score as a tool similar to the scales/inventories used for the study of depression in humans. We present these data with the goal of furthering the field's understanding sex differences and how they shape the biology of mood disorders.
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Affiliation(s)
- Alyssa Johnson
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Jennifer R Rainville
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - G Nicole Rivero-Ballon
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Katerina Dhimitri
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Georgia E Hodes
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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Influence of intranasal exposure of MPTP in multiple doses on liver functions and transition from non-motor to motor symptoms in a rat PD model. Naunyn Schmiedebergs Arch Pharmacol 2019; 393:147-165. [PMID: 31468077 DOI: 10.1007/s00210-019-01715-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/15/2019] [Indexed: 12/14/2022]
Abstract
Besides the effects on the striatum, the impairment of visceral organs including liver functions has been reported in Parkinson's disease (PD) patients. However, it is yet unclear if liver functions are affected in the early stage of the disease before the motor phase has appeared. The aim of our present study was thus to assess the effect of intranasal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in different doses on striatum and liver functions. Deterioration of non-motor activities appeared on single exposure to MPTP along with rise in striatum oxidative stress and decline in antioxidant levels. Decreases in dopamine, noradrenaline, and GABA and increase in serotonin were detected in striatum. Motor coordination was impaired with a single dose of MPTP, and with repeated MPTP exposure, there was further significant impairment. Locomotor activity was affected from second exposure of MPTP, and the impairment increased with third MPTP exposure. Impairment of liver function through increase in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels was observed after first MPTP insult, and it worsened with second and third administrations. First administration of MPTP triggered systemic inflammation showing significant increase in inflammatory markers in the liver. Our data shows for the first time that an intranasal route of entry of MPTP affects liver from the non-motor phase of PD itself, occurring concomitantly with the reduction of striatal dopamine. It also suggests that a single dose is not enough to bring about progression of the disease from non-motor to locomotor deficiency, and a repeated dose is needed to establish the motor severity phase in the rat intranasal MPTP model.
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