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Young PA, Waller O, Ball K, Williams CC, Nashmi R. Phasic Stimulation of Dopaminergic Neurons of the Lateral Substantia Nigra Increases Open Field Exploratory Behaviour and Reduces Habituation Over Time. Neuroscience 2024; 551:276-289. [PMID: 38838978 DOI: 10.1016/j.neuroscience.2024.05.025] [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: 10/05/2023] [Revised: 04/09/2024] [Accepted: 05/20/2024] [Indexed: 06/07/2024]
Abstract
Transient nigrostriatal dopaminergic signalling is well known for its role in reinforcement learning and increasingly so for its role in the initiation of voluntary movement. However, how transient bursts of dopamine modulate voluntary movement remains unclear, likely due to the heterogeneity of the nigrostriatal system, the focus of optogenetic studies on locomotion at sub-sec time intervals, and the overlapping roles of phasic dopamine in behaviour and novelty signalling. In this study we investigated how phasic activity in the lateral substantia nigra pars compacta (lateral SNc) over time affects voluntary behaviours during exploration. Using a transgenic mouse model of both sexes expressing channelrhodopsin (ChR2) in dopamine transporter-expressing cells, we stimulated the lateral SNc while mice explored an open field over two consecutive days. We found that phasic activation of the lateral SNc induced an increase in exploratory behaviours including horizontal movement activity, locomotion initiation, and rearing specifically on the first open field exposure, but not on the second day. In addition, stimulated animals did not habituate to the same extent as their ChR2-negative counterparts, as indicated by a lack of decrease in baseline activity. These findings suggest that rather than prompting voluntary movement in general, phasic nigrostriatal dopamine prompts context-appropriate behaviours. In addition, dopamine signalling that modulates movement acts over longer timescales than the transient signal, affecting behaviour even after the signal has ended.
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Affiliation(s)
- Penelope A Young
- Department of Biology, University of Victoria, British Columbia V8W 2Y2, Canada; Division of Medical Sciences, University of Victoria, British Columbia V8W 2Y2, Canada
| | - Olivia Waller
- Department of Biology, University of Victoria, British Columbia V8W 2Y2, Canada
| | - Katherine Ball
- Department of Biology, University of Victoria, British Columbia V8W 2Y2, Canada
| | - Chad C Williams
- Carney Institute for Brain Science, Brown University, Providence, RI 02912, USA
| | - Raad Nashmi
- Department of Biology, University of Victoria, British Columbia V8W 2Y2, Canada; Division of Medical Sciences, University of Victoria, British Columbia V8W 2Y2, Canada.
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Donlon J, Kumari P, Varghese SP, Bai M, Florentin OD, Frost ED, Banks J, Vadlapatla N, Kam O, Shad MU, Rahman S, Abulseoud OA, Stone TW, Koola MM. Integrative Pharmacology in the Treatment of Substance Use Disorders. J Dual Diagn 2024; 20:132-177. [PMID: 38117676 DOI: 10.1080/15504263.2023.2293854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
The detrimental physical, mental, and socioeconomic effects of substance use disorders (SUDs) have been apparent to the medical community for decades. However, it has become increasingly urgent in recent years to develop novel pharmacotherapies to treat SUDs. Currently, practitioners typically rely on monotherapy. Monotherapy has been shown to be superior to no treatment at all for most substance classes. However, many randomized controlled trials (RCTs) have revealed that monotherapy leads to poorer outcomes when compared with combination treatment in all specialties of medicine. The results of RCTs suggest that monotherapy frequently fails since multiple dysregulated pathways, enzymes, neurotransmitters, and receptors are involved in the pathophysiology of SUDs. As such, research is urgently needed to determine how various neurobiological mechanisms can be targeted by novel combination treatments to create increasingly specific yet exceedingly comprehensive approaches to SUD treatment. This article aims to review the neurobiology that integrates many pathophysiologic mechanisms and discuss integrative pharmacology developments that may ultimately improve clinical outcomes for patients with SUDs. Many neurobiological mechanisms are known to be involved in SUDs including dopaminergic, nicotinic, N-methyl-D-aspartate (NMDA), and kynurenic acid (KYNA) mechanisms. Emerging evidence indicates that KYNA, a tryptophan metabolite, modulates all these major pathophysiologic mechanisms. Therefore, achieving KYNA homeostasis by harmonizing integrative pathophysiology and pharmacology could prove to be a better therapeutic approach for SUDs. We propose KYNA-NMDA-α7nAChRcentric pathophysiology, the "conductor of the orchestra," as a novel approach to treat many SUDs concurrently. KYNA-NMDA-α7nAChR pathophysiology may be the "command center" of neuropsychiatry. To date, extant RCTs have shown equivocal findings across comparison conditions, possibly because investigators targeted single pathophysiologic mechanisms, hit wrong targets in underlying pathophysiologic mechanisms, and tested inadequate monotherapy treatment. We provide examples of potential combination treatments that simultaneously target multiple pathophysiologic mechanisms in addition to KYNA. Kynurenine pathway metabolism demonstrates the greatest potential as a target for neuropsychiatric diseases. The investigational medications with the most evidence include memantine, galantamine, and N-acetylcysteine. Future RCTs are warranted with novel combination treatments for SUDs. Multicenter RCTs with integrative pharmacology offer a promising, potentially fruitful avenue to develop novel therapeutics for the treatment of SUDs.
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Affiliation(s)
- Jack Donlon
- Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Pooja Kumari
- Community Living Trent Highlands, Peterborough, Canada
| | - Sajoy P Varghese
- Addiction Recovery Treatment Services, Veterans Affairs Northern California Health Care System, University of California, Davis, Sacramento, California, USA
| | - Michael Bai
- Columbia University, New York, New York, USA
| | - Ori David Florentin
- Department of Psychiatry, Westchester Medical Center, Valhalla, New York, USA
| | - Emma D Frost
- Department of Neurology, Cooper University Health Care, Camden, New Jersey, USA
| | - John Banks
- Talkiatry Mental Health Clinic, New York, New York, USA
| | - Niyathi Vadlapatla
- Thomas Jefferson High School for Science and Technology, Alexandria, Virginia, USA
| | - Olivia Kam
- Stony Brook University Renaissance School of Medicine, Stony Brook, New York, USA
| | - Mujeeb U Shad
- Department of Psychiatry, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Shafiqur Rahman
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota, USA
| | - Osama A Abulseoud
- Department of Psychiatry and Psychology, Alix School of Medicine at Mayo Clinic, Phoenix, Arizona, USA
| | - Trevor W Stone
- Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK
| | - Maju Mathew Koola
- Department of Psychiatry and Behavioral Health, Cooper University Health Care, Cooper Medical School of Rowan University, Camden, New Jersey, USA
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Kuiper LB, Roberts JB, Estave PM, Leo D, Gainetdinov RR, Jones SR. Patterns of ethanol intake in male rats with partial dopamine transporter deficiency. GENES, BRAIN, AND BEHAVIOR 2023; 22:e12847. [PMID: 37461188 PMCID: PMC10733570 DOI: 10.1111/gbb.12847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 03/09/2023] [Accepted: 03/28/2023] [Indexed: 12/22/2023]
Abstract
Mesolimbic dopamine signaling plays a major role in alcohol and substance use disorders as well as comorbidities such as anxiety and depression. Growing evidence suggests that alcohol drinking is modulated by the function of the dopamine transporter (DAT), which tightly regulates extracellular dopamine concentrations. Adult male rats on a Wistar Han background (DAT+/+) and rats with a partial DAT deletion (DAT+/-) were used in this study. First, using fast-scan cyclic voltammetry in brain slices containing the nucleus accumbens core from ethanol-naïve subjects, we measured greater evoked dopamine concentrations and slower dopamine reuptake in DAT+/- rats, consistent with increased dopamine signaling. Next, we measured ethanol drinking using the intermittent access two-bottle choice paradigm (20% v/v ethanol vs. water) across 5 weeks. DAT+/- rats voluntarily consumed less ethanol during its initial availability (the first 30 min), especially after longer periods of deprivation. In addition, DAT+/- males consumed less ethanol that was adulterated with the bitter tastant quinine. These findings suggest that partial DAT blockade and concomitant increase in brain dopamine levels has potential to reduce drinking and ameliorate alcohol use disorder (AUD).
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Affiliation(s)
- L. B. Kuiper
- Department of Physiology and PharmacologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - J. B. Roberts
- Department of Physiology and PharmacologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - P. M. Estave
- Department of Physiology and PharmacologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
| | - D. Leo
- Department of NeurosciencesUniversity of MonsMonsBelgium
| | - R. R. Gainetdinov
- Institute of Translational BiomedicineSt. Petersburg State UniversitySt. PetersburgRussia
- St. Petersburg University HospitalSt. Petersburg State UniversitySt. PetersburgRussia
| | - S. R. Jones
- Department of Physiology and PharmacologyWake Forest School of MedicineWinston‐SalemNorth CarolinaUSA
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