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Novo JP, Muga M, Lourenço T, Sanches ES, Leitão RA, Silva AP. Dichotomous effect of methylphenidate on microglia and astrocytes: Insights from in vitro and animal studies. Toxicol Lett 2023; 389:1-10. [PMID: 37844808 DOI: 10.1016/j.toxlet.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/27/2023] [Accepted: 10/09/2023] [Indexed: 10/18/2023]
Abstract
Methylphenidate (MPH) has been used for decades to treat attention-deficit/hyperactivity disorder (ADHD) and narcolepsy. Moreover, several studies have shown that it is subject to misuse, particularly among college students and adolescents, for cognitive enhancement or as a recreational drug. This phenomenon causes concern, and it is critical to clarify better how MPH impacts brain cells. In fact, data has suggested that MPH could result in neuroinflammation and neurodegeneration across several brain regions; however, little is known about the effect of MPH on glial cells. To address this, we used microglia N9 cell line and primary cultures of cortical astrocytes that were exposed to MPH (0.01 - 2 mM), as well as Wistar Kyoto rats (WKY) chronically administered with MPH (1.5 mg/kg/day). Several parameters were analyzed, and we concluded that MPH has no significant direct effect on microglial cells, apart from cell migration impairment. On the contrary, MPH promotes astrogliosis, oxidative/nitrosative stress, and increases proinflammatory cytokine TNF levels by astrocytes, which was concordant with the results obtained in the hippocampus of WKY rats. Overall, the present results suggest that brain cells respond differently to MPH, with a more prominent direct effect on astrocytes when compared to microglia.
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Affiliation(s)
- João P Novo
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Portugal
| | - Mariana Muga
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal
| | - Teresa Lourenço
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal
| | - Eliane S Sanches
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Portugal
| | - Ricardo A Leitão
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Portugal; Clinical Academic Center of Coimbra (CACC), Coimbra, Portugal
| | - Ana Paula Silva
- Univ Coimbra, Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, and Coimbra Institute for Clinical and Biomedical Research (iCBR), Coimbra, Portugal; Univ Coimbra, Center for Innovative Biomedicine and Biotechnology (CIBB), Portugal; Clinical Academic Center of Coimbra (CACC), Coimbra, Portugal.
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Zhang X, Talpos J, Berridge MS, Apana SM, Slikker W, Wang C, Paule MG. MicroPET/CT assessment of neurochemical effects in the brain after long-term methylphenidate treatment in nonhuman primates. Neurotoxicol Teratol 2021; 87:107017. [PMID: 34265415 DOI: 10.1016/j.ntt.2021.107017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 01/23/2023]
Abstract
Methylphenidate (MPH) is a psychostimulant approved by the FDA to treatment Attention-Deficit Hyperactivity Disorder (ADHD). MPH is believed to exert its pharmacological effects via preferential blockade of the dopamine transporter (DAT) and the norepinephrine transporter (NET), resulting in increased monoamine levels in the synapse. We used a quantitative non-invasive PET imaging technique to study the effects of long-term methylphenidate use on the central nervous system (CNS). We conducted microPET/CT scans on young adult male rhesus monkeys to monitor changes in the dopaminergic system. We used [18F] AV-133, a ligand for the vesicular monoamine transporter 2 (VMAT2), and [18F]FESP a ligand for the D2 and 5HT2 receptors. In this study we evaluated the effects if chronic MPH treatment in the nonhuman primates (NHP). Two-year-old, male rhesus monkeys were orally administered MPH diluted in the electrolyte replenisher, Prang, twice a day, five days per week (M-F) over an 8-year period. The dose of MPH was gradually escalated from 0.15 mg/kg initially to 2.5 mg/kg/dose for the low dose group, and 1.5 mg/kg to 12.5 mg/kg/dose for the high dose group (Rodriguez et al., 2010). Scans were performed on Mondays, about 60 h after their last treatment, to avoid the acute effects of MPH. Tracers were injected intravenously ten minutes before microPET/CT scanning. Sessions lasted about 120 min. The Logan reference tissue model was used to determine the Binding Potential (BP) of each tracer in the striatum with the cerebellar cortex time activity curve as an input function. Both MP treatment groups had a lower [18F] AV-133 BP, although this failed to reach statistical significance. MPH treatment did not have a significant effect on The BP of [18F] FESP in the striatum. Long-term administration of MPH did not significant change any of the marker of monoamine function used here. These data suggest that, despite lingering concerns, long-term use of methylphenidate does not negatively impact monoamine function. This study also demonstrates that microPET imaging can distinguish differences in binding potentials of a variety of radiotracers in the CNS of NHPs. This approach may provide minimally-invasive biomarkers of neurochemical processes associated with chronic exposure to CNS medications. (Supported by NCTR).
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Affiliation(s)
- X Zhang
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, United States of America.
| | - J Talpos
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, United States of America
| | - M S Berridge
- 3D Imaging, LLC, Little Rock, AR 72113 and University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States of America
| | - S M Apana
- 3D Imaging, LLC, Little Rock, AR 72113 and University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States of America
| | - W Slikker
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, United States of America
| | - C Wang
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, United States of America
| | - M G Paule
- National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, United States of America
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