Dependence Is Not Addiction and “tolerance” Declares Addiction.
Dependence is not addiction and “tolerance” declares addiction.
JAMA Intern Med. 2013 Apr 8; 173(7): 595-6
Geller AS
Acute ketamine-induced neuroplasticity: ribosomal protein S6 phosphorylation expression in drug addiction-related rat brain areas.
Neuroreport. 2013 May 8; 24(7): 388-93
Tedesco V, Ravagnani C, Bertoglio D, Chiamulera C
Recent clinical studies show that a low dose of dissociative anesthetic ketamine (KET) induced a rapid antidepressant response that lasted for up to 7 days. This effect could be related to the capacity of KET to acutely induce molecular mechanisms of neuroplasticity engaged after chronic treatments. KET produces its actions by binding to the glutamate N-methyl-D-aspartic acid receptor, leading to increased activation of the mammalian target of rapamycin. Ribosomal protein S6 phosphorylation (rpS6P) is downstream to mammalian target of rapamycin and p70S6K activation, a molecular mechanism correlating synaptic protein synthesis and neuroplasticity. As neuroplasticity is also a key mechanism of addiction development, and considering the increasing abuse of KET, our aim was to examine the effect of acute KET administration on the expression of rpS6 in drug addiction-related cerebral areas. We tested in rats the effect of different KET doses (5 or 10 mg/kg, intraperitoneally) on rpS6P expression by immunolocalization in prelimbic (PRL) and infralimbic (IL) cortices, nucleus accumbens core (NAcC) and nucleus accumbens shell (NAcS), hippocampus (CA1 and CA3), and basolateral amygdala (BLA). Expression levels of rpS6 were quantified. A significant dose-related increase in rpS6P expression in PRL, IL, BLA, NAcC but not in the NAcS and hippocampus was found after acute KET. These data confirm acute KET-induced neuroplasticity effects, and extend these findings to drug addiction-related brain areas. HubMed – addiction
Reviving the ethos of scientific research in psychiatric practice.
Aust N Z J Psychiatry. 2013 Apr; 47(4): 309-11
Looi JC, Kisely SR, Merry SN, Crowe J, Hayhow BD
The clinical relevance of neuroplasticity in corticostriatal networks during operant learning.
Neurosci Biobehav Rev. 2013 Apr 5;
Andrzejewski ME, McKee BL, Baldwin AE, Burns L, Hernandez P
Dopamine and glutamate serve crucial functions in neural plasticity, learning and memory, and addiction. Contemporary theories contend that these two, widely-distributed neurotransmitter systems play an integrative role in motivational and associative information processing. Combined signaling of these systems, particularly through the dopamine (DA) D1 and glutamate (Glu) N-methyl-D-aspartate receptors (NMDAR), triggers critical intracellular signaling cascades that lead to changes in chromatin structure, gene expression, synaptic plasticity, and ultimately behavior. Addictive drugs also induce long-term neuroadaptations at the molecular and genomic levels causing structural changes that alter basic connectivity. Indeed, evidence that drugs of abuse engage D1- and NMDA-mediated neuronal cascades shared with normal reward learning provides one of the most important insights from contemporary studies on the neurobiology of addiction. Such drug-induced neuroadaptations likely contribute to abnormal information processing and behavior, resulting in the poor decision-making, loss of control, and compulsivity that characterize addiction. Such features are also common to many other neuropsychiatric disorders. Behavior problems, construed as difficulties associated with operant learning and behavior, present compelling challenges and unique opportunities for their treatment that require further study. The present review highlights the integrative work of Ann E. Kelley and colleagues, demonstrating a critical role not only for NMDAR, D1 receptors (D1R), and their associated signaling cascades, but also for other Glu receptors and protein synthesis in operant learning throughout a cortico-striatal-limbic network. Recent work has extended the impact of appetitive learning to epigenetic processes. A better understanding of these processes will likely assist in discovering therapeutics to engage neural plasticity-related processes and promote functional behavioral adaptations. HubMed – addiction