Dynorphin A(1–13) preferentially inhibits behaviors induced by the D2 dopamine agonist RU 24213 but not by the D1 dopamine agonist SK&F 38393

The effects of dynorphin A(1–13) on the D1 dopamine agonist SK&F 38393- and the D2 dopamine agonist RU 24213-induced behavioral alterations in the mouse were determined by using multidimensional behavioral analyses based upon a capacitance system. Although dynorphin A(1–13) (3.0 or 12.5 μg) alone did not produce any significant effects on behaviors, the peptide (12.5 μg) caused an inhibitory effect on the RU 24213 (3.0 mg/kg)-induced increase in behavioral patterns such as linear locomotion and circling except rearing and grooming behaviors. The antagonistic effects of dynorphin A(1–313) (12.5 μg) were fully reversed by the opioid antagonist Mr 2266 (10.0 mg/kg). However, dynorphin A(1–13) (3.0 or 12.5 μg) failed to affect behaviors elicited by SK&F 38393 (10.0 mg/kg). These results suggest that dynorphin A(1–13) plays an inhibitory role in behaviors induced by the D2 dopamine agonist but not by the D1 dopamine agonist, possibly through the mediation of κ-opioid receptors.