Effects of long-term treatment with lithium and antidepressants on [3H]forskolin binding to rat cerebral cortical membranes.

1. The characteristics of [3H]forskolin binding in rat cerebral cortical membranes and the effects of long-term treatment with lithium, desipramine and tranylcypromine on the binding were investigated. 2. Specific binding of [3H]forskolin (10 nM) was augmented by the addition of magnesium, and in the presence of 5 mM MgCl2, sodium fluoride (NaF) increased further the specific binding in a concentration-dependent manner. 3. Guanyl-5'-ylimidodiphosphate (Gpp(NH)p) increased the specific binding only in the presence of 100 mM MgCl2. 4. Long-term treatment with lithium, desipramine or tranylcypromine altered neither the specific binding of [3H]forskolin nor the augmentation by MgCl2, NaF, or Gpp(NH)p. 5. The results indicate that these preparations alter neither the catalytic subunit of adenylate cyclase nor the activation of stimulatory guanine nucleotide-binding regulatory proteins (Gs).