Influence of naloxone pretreatment on the [3H]ketanserin binding and on 5-HT levels in the rat brain
| 5HT2Characteristics | ||||
|---|---|---|---|---|
| Cortex | Pons | |||
| Bmax | Kd | Bmax | Kd | |
| fmol mg/prot | nM | fmol mg/prot | nM | |
| SAL + VEH | 257.4 ± 10.5 | 1.35 ± 0.05 | 33.4 ± 3.8 | 1.34 ± 0.05 |
| NAL + VEH | 259.2 ± 10.3 | 1.54 ± 0.10 | 35.4 ± 3.3 | 1.35 ± 0.07 |
| SAL + PARA | 182.2 ± 15.6* | 1.62 ± 0.05 | 37.5 ± 1.2 | 1.25 ± 0.05 |
| NAL + PARA | 257.2 ± 12.2** | 1.27 ± 0.07 | 38.7 ± 2.9 | 1.36 ± 0.07 |
| SAL + MORP | 184.4 ± 9.6* | 1.13 ± 0.04 | 38.1 ± 2.3 | 1.30 ± 0.04 |
| NAL + MORP | 231.2 ± 10.1** | 1.23 ± 0.07 | 36.3 ± 2.1 | 1.32 ± 0.06 |
Naloxone (NAL; 1 mg/kg) or saline (SAL) were injected i.p.; PARA (400 mg/kg i.p.), MORP (8 mg/kg s.c.) or vehicle (VEH) were administered 30 min after the pretreatment. Rats were sacrificed 90 min after PARA or 30 min after MORP administration, and their brains were dissected for binding assay in pons and cerebral cortex. B max(maximum binding capacity) and K d (equilibrium dissociation constant) values were derived by the Rosenthal plot. Values are means ± S.E. of eight rats.
* P < .05 vs. SAL + VEH (ANOVA followed by Student-Newman-Keuls test).
** P < .05 vs. SAL + PARA or SAL + MORP (ANOVA followed by Student-Newman-Keuls test).