TY - JOUR
T1 - Chronic activation of CB2 cannabinoid receptors in the hippocampus increases excitatory synaptic transmission
AU - Kim, Jimok
AU - Li, Yong
N1 - Publisher Copyright:
© 2014 The Physiological Society.
PY - 2015/2/15
Y1 - 2015/2/15
N2 - Key points: The effects of cannabinoids are primarily mediated by two types of cannabinoid receptors, CB1 receptors in the nervous system and CB2 receptors in the immune system. Recent evidence indicates that CB2 receptors are also widely expressed in the brain and involved in neuropsychiatric functions, such as schizophrenia-like behaviours, anxiety, memory, vomiting and pain. The cellular mechanisms by which CB2 receptors regulate neuronal functions are unknown. We show that chronic activation of CB2 receptors in the hippocampus for 7-10 days increases excitatory synaptic transmission, whereas short-term activation of CB2 receptors has little effect on synaptic activity. This study reveals a novel role of CB2 receptors in the brain, which is clearly distinct from that of CB1 receptors, and thus, will help us to understand better the diverse effects of cannabinoids in the nervous system. The roles of CB1 cannabinoid receptors in regulating neuronal activity have been extensively characterized. Although early studies show that CB1 receptors are present in the nervous system and CB2 cannabinoid receptors are in the immune system, recent evidence indicates that CB2 receptors are also expressed in the brain. Activation or blockade of CB2 receptors in vivo induces neuropsychiatric effects, but the cellular mechanisms of CB2 receptor function are unclear. The aim of this study is to determine how activation of CB2 receptors present in the hippocampus regulates synaptic function. Here, we show that when organotypic cultures of rodent hippocampal slices were treated with a CB2 receptor agonist (JWH133 or GP1a) for 7-10 days, quantal glutamate release became more frequent and spine density was increased via extracellular signal-regulated kinases. Chronic intraperitoneal injection of JWH133 into mice also increased excitatory synaptic transmission. These effects were blocked by a CB2 receptor antagonist (SR144528) or absent from hippocampal slices of CB2 receptor knock-out mice. This study reveals a novel cellular function of CB2 cannabinoid receptors in the hippocampus and provides insights into how cannabinoid receptor subtypes diversify the roles of cannabinoids in the brain.
AB - Key points: The effects of cannabinoids are primarily mediated by two types of cannabinoid receptors, CB1 receptors in the nervous system and CB2 receptors in the immune system. Recent evidence indicates that CB2 receptors are also widely expressed in the brain and involved in neuropsychiatric functions, such as schizophrenia-like behaviours, anxiety, memory, vomiting and pain. The cellular mechanisms by which CB2 receptors regulate neuronal functions are unknown. We show that chronic activation of CB2 receptors in the hippocampus for 7-10 days increases excitatory synaptic transmission, whereas short-term activation of CB2 receptors has little effect on synaptic activity. This study reveals a novel role of CB2 receptors in the brain, which is clearly distinct from that of CB1 receptors, and thus, will help us to understand better the diverse effects of cannabinoids in the nervous system. The roles of CB1 cannabinoid receptors in regulating neuronal activity have been extensively characterized. Although early studies show that CB1 receptors are present in the nervous system and CB2 cannabinoid receptors are in the immune system, recent evidence indicates that CB2 receptors are also expressed in the brain. Activation or blockade of CB2 receptors in vivo induces neuropsychiatric effects, but the cellular mechanisms of CB2 receptor function are unclear. The aim of this study is to determine how activation of CB2 receptors present in the hippocampus regulates synaptic function. Here, we show that when organotypic cultures of rodent hippocampal slices were treated with a CB2 receptor agonist (JWH133 or GP1a) for 7-10 days, quantal glutamate release became more frequent and spine density was increased via extracellular signal-regulated kinases. Chronic intraperitoneal injection of JWH133 into mice also increased excitatory synaptic transmission. These effects were blocked by a CB2 receptor antagonist (SR144528) or absent from hippocampal slices of CB2 receptor knock-out mice. This study reveals a novel cellular function of CB2 cannabinoid receptors in the hippocampus and provides insights into how cannabinoid receptor subtypes diversify the roles of cannabinoids in the brain.
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U2 - 10.1113/jphysiol.2014.286633
DO - 10.1113/jphysiol.2014.286633
M3 - Article
C2 - 25504573
AN - SCOPUS:84923411240
SN - 0022-3751
VL - 593
SP - 871
EP - 886
JO - Journal of Physiology
JF - Journal of Physiology
IS - 4
ER -