Background: Locomotor sensitization to repeated ethanol (EtOH) administration is proposed to play a role in early and recurring steps of addiction. The present study was designed to examine the effect of agmatine on EtOH-induced locomotor sensitization in mice.
Methods: Mice received daily single intraperitoneal injection of EtOH (2.5 g/kg, 20 v/v) for 7 consecutive days. Following a 3-day EtOH-free phase, the mice were challenged with EtOH on day 11 with a single injection of EtOH. Agmatine (10 to 40 μg/mouse), endogenous agmatine enhancers (l-arginine [80 μg/mouse], arcaine [50 μg/mouse], aminoguanidine [25 μg/mouse]), and imidazoline receptor agonist/antagonists were injected (intracerebroventricular [i.c.v.]) either daily before the injection of EtOH during the 7-day development phase or on days 8, 9, and 10 (EtOH-free phase). The horizontal locomotor activity was determined on days 1, 3, 5, 7, and 11.
Results: Agmatine (20 to 40 μg/mouse) administration for 7 days (development phase) significantly attenuated the locomotor sensitization response of EtOH challenge on day 11. Further, the agmatine administered only during EtOH-free period (days 8, 9, and 10) also inhibited the enhanced locomotor activity on the 11th day to EtOH challenge as compared to control mice indicating blockade of expression of sensitization. Daily treatment (i.c.v.) with endogenous agmatine enhancers like l-arginine (80 μg/mouse) or arcaine (50 μg/mouse) and aminoguanidine (25 μg/mouse) restrained the development as well as expression of sensitization to EtOH. Imidazoline I receptor agonist, moxonidine, and I agonist, 2-BFI, not only decreased the development and expression of locomotor sensitization but also potentiated the effect of agmatine when employed in combination. Importantly, I receptor antagonist, efaroxan, and I antagonist, idazoxan, blocked the effect of agmatine, revealing the involvement of imidazoline receptors in agmatine-mediated inhibition of EtOH sensitization.
Conclusions: Inhibition of EtOH sensitization by agmatine is mediated through imidazoline receptors and project agmatine and imidazoline agents in the pharmacotherapy of alcohol addiction.
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http://dx.doi.org/10.1111/acer.13972 | DOI Listing |
Front Mol Neurosci
December 2024
Laboratory of Neuropsychiatry, Psychiatric Centre Copenhagen, Mental Health Services in the Capital Region of Denmark and University of Copenhagen, Copenhagen, Denmark.
Objective: Acetylcholine modulates the activity of the direct and indirect pathways within the striatum through interaction with muscarinic M and M receptors. M receptors are uniquely positioned to regulate plasticity within the direct pathway and play a substantial role in reward and addiction-related behaviors. However, the role of M receptors on cholinergic neurons has been less explored.
View Article and Find Full Text PDFTransl Psychiatry
December 2024
Center for Substance Abuse Research, Temple University, Philadelphia, PA, USA.
Recent progress in psychiatric research has highlighted neuroinflammation in the pathophysiology of opioid use disorder (OUD), suggesting that heightened immune responses in the brain may exacerbate opioid-related mechanisms. However, the molecular mechanisms resulting from neuroinflammation that impact opioid-induced behaviors and transcriptional pathways remain poorly understood. In this study, we have begun to address this critical knowledge gap by exploring the intersection between neuroinflammation and exposure to the opioid heroin, utilizing lipopolysaccharide (LPS)-induced neuroinflammation, to investigate transcriptional changes in the nucleus accumbens (NAc), an essential region in the mesolimbic dopamine system that mediates opioid reward.
View Article and Find Full Text PDFPharmacol Biochem Behav
December 2024
Department of Psychology and Center for Neuroscience and Behavior, Miami University, Oxford, OH, USA. Electronic address:
Mu-opioid receptors (MORs) in the amygdala and striatum are important in addictive and rewarding behaviors. The transcription factor Foxp2 is a genetic marker of intercalated (ITC) cells in the amygdala and a subset of striatal medium spiny neurons (MSNs), both of which express MORs in wild-type mice and are neuronal subpopulations of potential relevance to alcohol-drinking behaviors. For the current series of studies, we characterized the behavior of mice with genetic deletion of the MOR gene Oprm1 in Foxp2-expressing neurons (Foxp2-Cre/Oprm1).
View Article and Find Full Text PDFNeuropharmacology
March 2025
Department of Pharmacology and Physiology, Drexel University College of Medicine, USA. Electronic address:
Psychopharmacology (Berl)
November 2024
School of Psychology, Victoria University of Wellington, Wellington, New Zealand.
Rationale: Tobacco monoamine oxidase (MAO) inhibitors have long been suspected of influencing tobacco dependence, but direct evidence of their effects has been difficult to obtain. Recently we have identified two new groups of monoamine oxidase inhibitors, hydroquinones and polyunsaturated fatty acids (linoleic and linolenic acid), abundant in tobacco smoke.
Objectives: To test, in relevant animal models, whether the combined effect of these inhibitors is sufficient to affect addictive responses to nicotine.
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