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 micrograms) alone did not produce any significant effects on behaviors, the peptide (12.5 micrograms) 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 micrograms) were fully reversed by the opioid antagonist M(r) 2266 (10.0 mg/kg). However, dynorphin A(1-13) (3.0 or 12.5 micrograms) 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 kappa-opioid receptors.