Modulation of alpha 1-and alpha 2-adrenoceptor binding sites in the brain of audiogenic seizure susceptible mice (DBA/2J).

The binding of [3H]dihydroalprenolol ([3H]DHA), [3H]prazosin and [3H]clonidine was assayed in whole brain and various brain regions of audiogenic seizure (AS) susceptible DBA/2J (D2) mice aged 10, 24 and 50 days (i.e. before, during and after their period of AS susceptibility, respectively) and in age-matched C57BL/6J (B6) controls. In whole brain, at 24 days, [3H]DHA binding was similar in the two strains, while the binding of [3H]prazosin and [3H]clonidine was significantly lowered in D2 mice. No difference could be detected in 10 and 50 day old mice with any of the ligands. Regional studies indicated an involvement of the cerebral cortex, the olfactory bulbs and the brain-stem. alpha- (but not beta-)adrenoceptor changes were concomitant with the AS susceptibility period. These changes were unevenly distributed in the brain of D2 mice; they suggest that alpha 1- and alpha 2-adrenoceptor subtypes might play different roles in the AS of the D2 mouse strain.