Table 2.
[3H]SR141716A Bmax values and % down-regulation in membranes from various brain regions in vehicle- and THC-treated adolescent and adult rats of both sexes
| Female adolescents | Female adults | Male adolescents | Male adults | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Brain region | Veh | THC | % DR | Veh | THC | % DR | Veh | THC | % DR | Veh | THC | % DR |
| Prefrontal Cortex | 4.5 | 3.4 | 23% | 2.3 | 1.7 | 23% | 4.8 | 3.8 | 20% | 2.4 | 1.8 | 26% |
| (0.15) | (0.18) | (5.8) | (0.13) | (0.09) | (6.5) | (0.11) | (0.14) | (3.2) | (0.09) | (0.17) | (5.0) | |
| Striatum | 3.4 | 2.8 | 17% | 1.8 | 1.5 | 16% | 4.1 | 3.4 | 18% | 2.0 | 1.6 | 20% |
| (0.12) | (0.06) | (3.8) | (0.05) | (0.03) | (3.8) | (0.08) | (0.24) | (4.6) | (0.04) | (0.07) | (4.5) | |
| Hypothalamus | 5.5 | 2.9 | 47% | 3.8 | 1.9 | 50% | 5.4 | 3.0 | 44% | 2.7 | 1.5 | 45% |
| (0.12) | (0.06) | (1.4) | (0.10) | (0.08) | (2.2) | (0.15) | (0.06) | (1.5) | (0.09) | (0.06) | (3.8) | |
| Ventral midbrain | 4.1 | 2.9 | 30% | 2.9 | 2.1 | 29% | 5.2 | 3.7 | 28% | 3.7 | 2.6 | 29% |
| (0.08) | (0.08) | (2.5) | (0.04) | (0.05) | (2.3) | (0.19) | (0.15) | (3.6) | (0.14) | (0.09) | (2.9) | |
Each value in columns labelled ‘Veh’ and ‘THC’ represents mean Bmax value (SEM), expressed in pmol per mg of membrane protein. % DR = % down-regulation =Bmax value of THC-treated rats expressed as a percent of maximal CB1 receptor binding (Bmax) of vehicle-treated rats of corresponding age and sex. Age × sex × treatment anovas followed by Tukey post hoc tests revealed that Bmax values for adolescents were significantly higher than those for adults, regardless of treatment, with age-treatment interaction terms (and associated probability levels) for each region as follows: [prefrontal cortex F(1,40) = 5.5, P= 0.02], [striatum F(1,40) = 4.5, P= 0.04], [hypothalamus F(1,40) = 9.4, P= 0.004], [ventral midbrain F(1,40) = 6.0, P= 0.02]. In addition, the main effects for treatment were significant, indicating that THC treatment decreased Bmax values in each region. In contrast, percent down-regulation for each region did not differ across age and sex.