The Cannabis Papers: A citizen’s guide to cannabinoids (2011)
By Publius 

The CS World Cup: Goaltender Edition
Today, tending to the goals of mediating Alzheimer’s and preventing carcinogenesis, Publius spotlights two June abstracts from PubMed on the homeostatic cannabinoid system (CS). For Alzheimer’s disease it is CSmodulation of cognitive decline; for preventing carcinogenesis the findings unveil a previously unknown CS signaling platform: CB2-GPR55 receptor heteromers.
 
I. CS Mediates Cognitive Decline In Alzheimer’s Disease
 “It has been widely reported that β-amyloid peptide (Aβ) blocks long-term potentiation (LTP) of hippocampal synapses. Here, we show evidence that Aβ more potently blocks the potentiation of excitatory postsynaptic potential (EPSP)-spike coupling (E-S potentiation). This occurs, not by direct effect on excitatory synapses or postsynaptic neurons, but rather through an indirect mechanism: reduction of endocannabinoid-mediated peritetanic disinhibition.”
Setting: “During high-frequency (tetanic) stimulation, somatic synaptic inhibition is suppressed by endocannabinoids. We find that Aβ prevents this endocannabinoid-mediated disinhibition, thus leaving synaptic inhibition more intact during tetanic stimulation.”

Science: “This intact inhibition opposes the normal depolarization of hippocampal pyramidal neurons that occurs during tetanus, thus opposing the induction of synaptic plasticity. Thus, a pathway through which Aβ can act to modulate neural activity is identified, relevant to learning and memory and how it may mediate aspects of the cognitive decline seen in Alzheimer’s disease.”
β-Amyloid Inhibits E-S Potentiation through Suppression of Cannabinoid Receptor 1-Dependent Synaptic Disinhibition.
Orr AL, Hanson JE, Li D, Klotz A, Wright S, Schenk D, Seubert P, Madison DV.
Neuron. 2014 Jun 18;82(6):1334-45. doi: 10.1016/j.neuron.2014.04.039.
PMID: 24945775 [PubMed – in process]
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II. CS Oncology Signaling Unveiled: Evidence of Previously Unknown Platforms
 Set: “The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. As a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells.”
Setting: “Here, we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo.”
Science: “These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology.”
Targeting CB2-GPR55 Receptor Heteromers Modulates Cancer Cell Signaling.
Moreno E, Andradas C, Medrano M, Caffarel MM, Pérez-Gómez E, Blasco-Benito S, Gómez-Cañas M, Pazos MR, Irving AJ, Lluís C, Canela EI, Fernández-Ruiz J, Guzmán M, McCormick PJ, Sánchez C.
J Biol Chem. 2014 Jun 18. pii: jbc.M114.561761. [Epub ahead of print]
PMID: 24942731 [PubMed – as supplied by publisher] Free Article
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