Dopamine mediated behavior and GABA influence.

The possibility of interactions between GABA and dopaminergic central nervous mechanisms in the expression of spontaneous behavior was investigated using the behavior pattern shown by male rats in an exploratory test situation. The present study corroborates the facilitatory action of low doses of the dopamine agonist apomorphine on the investigative activity element of the male rats exploratory behavior pattern, as shown previously. In addition it was found that the GABA agonist baclofen in different doses (1.2-4.8 mg/kg IP) selectively increased this activity. Pretreatment with a submaximal dose of baclofen (1.2 mg/kg) potentiated the effect of apomorphine (25 micrograms/kg), indicating that baclofen has the same effect on behavior as presynaptically active dopamine agonists. Thus GABA mechanisms might influence dopamine mediated behavior. The investigative activity which previously has been considered to reflect the adaptive state of an animal is suggested to be influenced by a changed activity in GABA neurons, DA neurons or an interaction between these two systems in the various brain structures involved in the expression of this behavior.