Positive allosteric modulation of type 1 cannabinoid receptors reduces spike-and-wave discharges in Genetic Absence Epilepsy Rats from Strasbourg

Endocannabinoid-Mediated Control of Neural Circuit Excitability and Epileptic Seizures

“…In rats with spontaneous seizures after pilocarpine-induced SE, the number of spontaneous seizures was significantly decreased by the CB 1 receptor agonist WIN55212-2 and significantly increased by the CB 1 receptor antagonist SR141716A ( Wallace et al, 2003 ). Consistent results were obtained by using the CB 1 receptor blocker AM251 for spontaneous seizures after kainate-induced SE ( Sugaya et al, 2016 ) and by using positive allosteric modulator of CB 1 receptor for the spontaneous absence seizures in GAERS rats ( Roebuck et al, 2021 ). These results indicate that CB 1 receptor signaling in the epileptic brain suppresses the occurrence of spontaneous seizures in the SE model and the absence seizure model ( Figure 2 and Table 1 ).…”

“…WIN55212-2 injection decreased the number of spontaneous spike-and-wave discharges for 3 h in WAG/Rij rats. Interestingly, very long, sporadic trains of spike-and-wave discharges were observed in WAG/Rij rats from 3 h after WIN55212-2 injection ( van Rijn et al, 2010 ), which is in sharp contrast to the decreased duration of spike-and-wave discharges after CB 1 activation in GAERS rats ( Roebuck et al, 2021 ). These long spike-and-wave discharge trains were partially suppressed by co-administration of AM251 ( van Rijn et al, 2010 ), suggesting the involvement of CB 1 receptor signaling in these abnormal paroxysmal discharges.…”

“…Interestingly, the expression of CB 1 receptor mRNA quantified by using in situ hybridization was significantly decreased in 8 month old but not 2 month old WAG/Rij rats compared to that in age-matched ACI rats (van Rijn et al, 2010), suggesting that the change in CB 1 receptor reflects the pathological progression of absence seizures. On the other hand, the decrease in CB 1 receptor expression was observed in the cortex and the hippocampus, but not in the thalamus of GAERS rats compared to control rats (Roebuck et al, 2021). In a mouse model of Dravet syndrome wherein the mice carry a missense mutation (A1783V) in the Scn1a gene that encodes the α subunit of a voltage-gated sodium channel, decreased CB 1 but increased CB 2 receptor expression was reported in the hippocampus by western blotting analysis (Satta et al, 2020).…”

Cannabinoid receptors distribution in mouse cortical plasma membrane compartments

“…2 A, B). Previous data demonstrate that western blot detection of GPCRs, including the CB receptors, results in the detection of multiple bands corresponding to isoform variants, potential dimers, and post-translations modifications [ 49 , 51 , 57 ]. In our study, only the bands for CB1 receptor (60 kDa) and CB2 receptor (40 kDa) were quantified.…”

“…Antibodies used in these experiments were as follows: rabbit polyclonal anti-CB1 receptor antibody directed against the first 99 amino acids of the receptor (Sigma-Aldrich, IgG, Cat# C1108, lot# SLCD8394) (dilution of 1:250) [ 42 ]; rabbit polyclonal anti-CB2 receptor antibody directed against the first 32 amino acids of the receptor (Abcam, IgG, Cat# ab3561, lot# GR45436-1) (dilution of 1:50) [ 43 ]; rabbit polyclonal anti-transferrin receptor (Abcam, IgG, Cat# ab84036) (dilution of 1:1000) [ 44 ]; rabbit polyclonal anti-flotillin-1 directed against residue surrounding Ile368 of human flotillin-1 (Cell Signaling, IgG, Cat# 3253) (dilution of 1:1000) [ 45 ]; mouse monoclonal anti-cytochrome C raised against amino acids 1–104 (Santa Cruz Biotechnology, IgG, Cat# sc-13156, lot# I1516) (dilution of 1:500) [ 46 ]; mouse monoclonal anti-stearoyl-CoA desaturase-1 (SCD1) (Abcam, IgG, Cat# ab19862, lot# GR138898-1) (dilution of 1:1000) [ 47 ]; rabbit polyclonal anti-caveolin-1 (Abcam, IgG, Cat# ab2910, lot# GR3382824-4) (dilution of 1:1000); mouse monoclonal anti-PrPc raised against N-terminal domain of PrPc (Abcam, IgG, Cat# ab61409, lot#GR3368463-1) (dilution of 1:1000) [ 48 ]. Anti-CB1 receptor antibody has been previously validated in our laboratory for western blot using both serial dilution and blocking peptide approaches to confirm the antibody’s specificity in rodent cortical tissue [ 49 ]. Anti-CB2 receptor antibody has been previously validated in Huang et al [ 50 ] and Zhang et al [ 51 ] for mouse lung and brain, respectively.…”