title: Psychostimulants, antidepressants and neurokinin-1 receptor antagonists ('motor disinhibitors') have overlapping, but distinct, effects on monoamine transmission: the involvement of L-type Ca2+ channels and implications for the treatment of ADHD.
abstract: Both psychostimulants and antidepressants target monoamine transporters and, as a consequence, augment monoamine transmission. These two groups of drugs also increase motor activity in preclinical behavioural screens for antidepressants. Substance P-preferring receptor (NK1R) antagonists similarly increase both motor activity in these tests and monoamine transmission in the brain. In this article, the neurochemical and behavioural responses to these three groups of drugs are compared. It becomes evident that NK1R antagonists represent a distinct class of compounds ('motor disinhibitors') that differ substantially from both psychostimulants and antidepressants, especially during states of heightened arousal or stress. Also, all three groups of drugs influence the activation of voltage-gated Ca(v)1.2 and Ca(v)1.3 L-type channels (LTCCs) in the brain, albeit in different ways. This article discusses evidence that points to disruption of these functional interactions between NK1R and LTCCs as a contributing factor in the cognitive and behavioural abnormalities that are prominent features of Attention Deficit Hyperactivity Disorder (ADHD). Arising from this is the interesting possibility that the hyperactivity and impulsivity (as in ADHD) and psychomotor retardation (as in depression) reflect opposite poles of a behavioural continuum. A better understanding of this pharmacological network could help explain why psychostimulants augment motor behaviour during stress (e.g., in preclinical screens for antidepressants) and yet reduce locomotor activity and impulsivity in ADHD. This article is part of the Special Issue entitled 'CNS Stimulants'.
authors.affiliation: Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: c.stanford@ucl.ac.uk.
authors.forename: S Clare
authors.initials: SC
authors.lastname: Stanford
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology; D015306:Biogenic Monoamines / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D000697:Central Nervous System Stimulants / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D064729:Neurokinin-1 Receptor Antagonists / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000928:Antidepressive Agents; D015306:Biogenic Monoamines; D020746:Calcium Channels, L-Type; D000697:Central Nervous System Stimulants; D064729:Neurokinin-1 Receptor Antagonists
keywords: Antidepressant; Attention Deficit Hyperactivity Disorder (ADHD); L-type calcium channel (LTCC); Monoamine transmission; Neurokinin receptor (NK1R) antagonist; Nifedipine; Psychostimulant