Figure 9.

Quantitative analysis of the ratio and density of CB₁-positive inhibitory axon terminals in the inner molecular layer of the human dentate gyrus. A–D, The ratio and density of inhibitory axon terminals either positive or negative for CB₁ cannabinoid receptor were established in a manner similar to that detailed in Figure 7 for excitatory terminals. A, Altogether, 1092 disector pairs were analyzed, which resulted in 102 inhibitory terminals in control, 85 terminals in nonsclerotic epileptic, and 107 terminals in sclerotic epileptic patients. The number of CB₁-positive terminals forming symmetric synapses was 68 terminals in control subjects, and 60 or 77 terminals in the nonsclerotic or sclerotic epileptic samples, respectively. The number of CB₁-negative terminals was 34 terminals in control subjects, and 25 or 30 terminals in nonsclerotic or sclerotic epileptic samples, respectively. B, The ratio of CB₁-positive GABAergic axon terminals versus all GABAergic axon terminals was 67.8 ± 2.7% in control, 71.5 ± 1.3% in nonsclerotic epileptic, and 72.9 ± 3.3% in sclerotic epileptic samples (mean ± SEM). The difference between control and epileptic samples was not significant (χ² test, p = 0.698). C, The estimated numerical density of CB₁-positive inhibitory axon terminals in the inner molecular layer of the dentate gyrus of control subjects (0.16 ± 0.02/μm³) was similar in nonsclerotic epileptic patients (0.15 ± 0.01/μm³) and in sclerotic epileptic patients (0.19 ± 0.02/μm³) (ANOVA, p = 0.114). D, The estimated numerical density of CB₁-negative inhibitory axon terminals was comparable in the three groups (density in control samples, 0.08 ± 0.01/μm³; in nonsclerotic samples, 0.06 ± 0.01/μm³; and in sclerotic samples, 0.07 ± 0.01/μm³; ANOVA, p = 0.458).