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Costas-Ferreira C, Durán R, Faro LF. Neurotoxic effects of exposure to glyphosate in rat striatum: Effects and mechanisms of action on dopaminergic neurotransmission. Pestic Biochem Physiol 2023; 193:105433. [PMID: 37248010 DOI: 10.1016/j.pestbp.2023.105433] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 04/09/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023]
Abstract
The main objective of this study was to evaluate the effects and possible mechanisms of action of glyphosate and a glyphosate-based herbicide (GBH) on dopaminergic neurotransmission in the rat striatum. Acute exposure to glyphosate or GBH, administered by systemic (75 or 150 mg/kg, i.p.) or intrastriatal (1, 5, or 10 mM for 1 h) routes, produced significant concentration-dependent increases in dopamine release measured in vivo by cerebral microdialysis coupled to HPLC with electrochemical detection. Systemic administration of glyphosate also significantly impaired motor control and decreased striatal acetylcholinesterase activity and antioxidant capacity. At least two mechanisms can be proposed to explain the glyphosate-induced increases in extracellular dopamine levels: increased exocytotic dopamine release from synaptic vesicles or inhibition of dopamine transporter (DAT). Thus, we investigated the effects of intrastriatal administration of glyphosate (5 mM) in animals pretreated with tetrodotoxin (TTX) or reserpine. It was observed that TTX (10 or 20 μM) had no significant effect on glyphosate-induced dopamine release, while reserpine (10 mg/kg i.p) partially but significantly reduced the dopamine release. When glyphosate was coinfused with nomifensine (50 μM), the increase in dopamine levels was significantly higher than that observed with glyphosate or nomifensine alone. So, two possible hypotheses could explain this additive effect: both glyphosate and nomifensine act through different mechanisms at the dopaminergic terminals to increase dopamine levels; or both nomifensine and glyphosate act on DAT, with glyphosate simultaneously inhibiting reuptake and stimulating dopamine release by reversing the DAT function. Future research is needed to determine the effects of this pesticide at environmentally relevant doses.
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Affiliation(s)
- Carmen Costas-Ferreira
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain
| | - Rafael Durán
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain
| | - Lilian Ferreira Faro
- Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo, Vigo, Spain.
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Cervetto C, Venturini A, Guidolin D, Maura G, Passalacqua M, Tacchetti C, Cortelli P, Genedani S, Candiani S, Ramoino P, Pelassa S, Marcoli M, Agnati LF. Homocysteine and A2A-D2 Receptor-Receptor Interaction at Striatal Astrocyte Processes. J Mol Neurosci 2018; 65:456-466. [PMID: 30030763 DOI: 10.1007/s12031-018-1120-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/11/2018] [Indexed: 01/03/2023]
Abstract
The interaction between adenosine A2A and dopamine D2 receptors in striatal neurons is a well-established phenomenon and has opened up new perspectives on the molecular mechanisms involved in Parkinson's disease. However, it has barely been investigated in astrocytes. Here, we show by immunofluorescence that both A2A and D2 receptors are expressed in adult rat striatal astrocytes in situ, and investigate on presence, function, and interactions of the receptors in the astrocyte processes-acutely prepared from the adult rat striatum-and on the effects of homocysteine on the A2A-D2 receptor-receptor interaction. We found that A2A and D2 receptors were co-expressed on vesicular glutamate transporter-1-positive astrocyte processes, and confirmed that A2A-D2 receptor-receptor interaction controlled glutamate release-assessed by measuring the [3H]D-aspartate release-from the processes. The complexity of A2A-D2 receptor-receptor interaction is suggested by the effect of intracellular homocysteine, which reduced D2-mediated inhibition of glutamate release (homocysteine allosteric action on D2), without interfering with the A2A-mediated antagonism of the D2 effect (maintained A2A-D2 interaction). Our findings indicate the crucial integrative role of A2A-D2 molecular circuits at the plasma membrane of striatal astrocyte processes. The fact that homocysteine reduced D2-mediated inhibition of glutamate release could provide new insights into striatal astrocyte-neuron intercellular communications. As striatal astrocytes are recognized to be involved in Parkinson's pathophysiology, these findings may shed light on the pathogenic mechanisms of the disease and contribute to the development of new drugs for its treatment.
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Affiliation(s)
- Chiara Cervetto
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
| | - Arianna Venturini
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Diego Guidolin
- Department of Neuroscience, University of Padova, Padua, Italy
| | - Guido Maura
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
| | - Mario Passalacqua
- Department of Experimental Medicine, Section of Biochemistry, and Italian Institute of Biostructures and Biosystems, University of Genova, Genoa, Italy
| | - Carlo Tacchetti
- Experimental Imaging Center, Scientific Institute San Raffaele, Milan, Italy
| | - Pietro Cortelli
- Department of Biomedical and NeuroMotor Sciences (DIBINEM) Alma Mater Studiorum, University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Susanna Genedani
- Department of Diagnostic, Clinical Medicine and Public Health, University of Modena and Reggio Emilia, Modena, Italy
| | - Simona Candiani
- Department of Earth, Environmental and Life Sciences, University of Genova, Genoa, Italy
| | - Paola Ramoino
- Department of Earth, Environmental and Life Sciences, University of Genova, Genoa, Italy
| | - Simone Pelassa
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy
| | - Manuela Marcoli
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Viale Cembrano 4, 16148, Genoa, Italy. .,Centre of Excellence for Biomedical Research CEBR, University of Genova, Genoa, Italy.
| | - Luigi F Agnati
- Department of Diagnostic, Clinical Medicine and Public Health, University of Modena and Reggio Emilia, Modena, Italy.,Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Wąsik A, Romańska I, Antkiewicz-Michaluk L. Comparison of the Effects of Acute and Chronic Administration of Tetrahydroisoquinoline Amines on the In Vivo Dopamine Release: A Microdialysis Study in the Rat Striatum. Neurotox Res 2016; 30:648-57. [PMID: 27568335 DOI: 10.1007/s12640-016-9661-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/11/2016] [Accepted: 08/13/2016] [Indexed: 11/22/2022]
Abstract
The etiology of Parkinson’s disease (PD) may involve endogenous and exogenous factors. 1-Benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ), which was shown to be neurotoxic for dopaminergic neurons, is one of such factors, thus it can be used to construct an animal model of PD. In contrast, 1,2,3,4-tetrahydroisoquinoline (TIQ) and 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) produce neuroprotective effects acting as monoamino oxidase (MAO) inhibitors and free radical scavengers that reduce oxidative stress in the mammalian brain. In this study, we aimed to investigate the effects of neuroprotective compounds, TIQ and 1MeTIQ, on the dopamine release in vivo in an animal model of PD induced by chronic administration of 1BnTIQ (25 mg/kg i.p.). Using an in vivo microdialysis methodology, we measured the impact of both acute and chronic treatment with TIQ and 1MeTIQ (50 mg/kg i.p.) on 1BnTIQ-induced changes in dopamine release in the rat striatum. Additionally, the behavioral test was carried out to check the influence of repeated administrations of the investigated compounds on the locomotor activity of rats. The behavioral studies showed that the chronic administration of 1BnTIQ produced a significant elevation of exploratory locomotor activity, and both the investigated amines, TIQ and 1MeTIQ, administered together with 1BnTIQ completely prevented 1BnTIQ-produced hyperactivity. The in vivo microdialysis studies demonstrated that the chronic treatment with 1BnTIQ caused a significant and long-lasting increase in the dopamine release (approximately 300 %) to the extracellular space in the rat striatum, which was demonstrated in the basal samples 24 h after 1BnTIQ injection. The combined chronic administration of 1BnTIQ and the investigated compounds, TIQ or 1MeTIQ, completely antagonized the 1BnTIQ-induced essential disturbances of the dopamine releasing to the extracellular space in the striatum. In conclusion, we suggest that higher concentrations of 1BnTIQ in the brain produced distinct impairment in the dopamine release, whereas TIQ and 1MeTIQ (compounds with previously revealed neuroprotective properties) completely prevented 1BnTIQ-induced abnormalities in the function of dopamine neurons and restored the dopamine release to the control values.
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Lee SM, Kant A, Blake D, Murthy V, Boyd K, Wyrick SJ, Mailman RB. SKF-83959 is not a highly-biased functionally selective D1 dopamine receptor ligand with activity at phospholipase C. Neuropharmacology 2014; 86:145-54. [PMID: 24929112 DOI: 10.1016/j.neuropharm.2014.05.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 05/23/2014] [Accepted: 05/29/2014] [Indexed: 11/21/2022]
Abstract
SKF-83959 [6-chloro-7,8-dihydroxy-3-methyl-1-(3-methylphenyl)-2,3,4,5-tetrahydro-1H-3-benzazepine] is reported to be a functionally selective dopamine D1 receptor ligand with high bias for D1-mediated phospholipase C (PLC) versus D1-coupled adenylate cyclase signaling. This signaling bias is proposed to explain behavioral activity in both rat and primate Parkinson's disease models, and a D1-D2 heterodimer has been proposed as the underlying mechanism. We have conducted an in-depth pharmacological characterization of this compound in dopamine D1 and D2 receptors in both rat brain and heterologous systems expressing human D1 or D2 receptors. Contrary to common assumptions, SKF-83959 is similar to the classical, well-characterized partial agonist SKF38393 in all systems. It is a partial agonist (not an antagonist) at adenylate cyclase in vitro and ex vivo, and is a partial agonist in D1-mediated β-arrestin recruitment. Contrary to earlier reports, it does not have D1-mediated effects on PLC signaling in heterologous systems. Because drug metabolites can also contribute, its 3-N-demethylated analog also was synthesized and tested. As expected from the known structure-activity relationships of the benzazepines, this compound also had high affinity for the D1 receptor and somewhat higher intrinsic activity than the parent ligand, and also might contribute to in vivo effects of SKF-83959. Together, these data demonstrate that SKF-83959 is not a highly-biased functionally selective D1 ligand, and that its reported behavioral data can be explained solely by its partial D1 agonism in canonical signaling pathway(s). Mechanisms that have been proposed based on the purported signaling novelty of SKF-83959 at PLC should be reconsidered.
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