Figure 3.

Effects of modulation of CB₁ and CB₂ receptor activation on cerebral infarction after MCAO. Administration of the CB₁ antagonist (SR141716, 20mg/kg, i.p.) 1 hour before MCAO significantly decreased cerebral infarction while administration of CB₂ antagonist (SR144528, 20mg/kg, i.p.) alone increased cerebral infarction compared with vehicle-treated group (A). CB₂ agonist (O-1966, 1mg/kg, i.v.) alone decreased infarct volume which was completely reversed by CB₂ antagonist; while administration of CB₂ agonist with CB₁ antagonist together dramatically further reduced cerebral infarction following MCAO (B). When the CB₂ agonist (O-1966) was administered i.p. and antagonists were given at a lower dosage at 5mg/kg i.p.1 hour before MCAO, both the CB₂ agonist and CB₁ antagonist still significantly reduced cerebral infarction, while CB₂ antagonist tended to increase the cerebral infarction although not achieving statistical significance. The combination of both CB₂ agonist (1mg/kg, i.p.) and CB₁ antagonist (5mg/kg, i.p.) dramatically reduced cerebral infarction compared to vehicle treated group (C). (n=5–8 in each group, data were expressed as Mean±SEM, *p<0.05 vs vehicle treated control group, **p<0.01 vs vehicle treated control group, ***p<0.001 vs vehicle treated control group)