Figure 7.

Partial agonist activity of mianserin at κ-opioid receptors in rat striatum. (A) Antagonism of dynorphin A 1–13 (dyn A)-stimulated [³⁵S]GTPγS binding by mianserin. Tissue membranes were incubated with increasing concentrations of dyn A without and with the indicated concentrations of mianserin (mians). The inset shows the Schild plot of mianserin antagonism. Values are the mean ± SEM of four experiments. (B–D) Mianserin antagonizes the stimulation of [³⁵S]GTPγS binding by (–) U-50 488 but not the δ-opioid agonist DPDPE and the µ-opioid agonist DAMGO. Tissue membranes were incubated in the presence of the indicated concentrations of the opioid agonists without and with 10 µM mianserin. Values are the mean ± SEM of three to four experiments.