[The role of GABA-ergic transmission of caudate-putamen nucleus (CPN) in the control of conditioned behavior in rats].

Using the method of bilateral injection of GABA (100 micrograms/microliters) and muscimol (0.1 micrograms/microliters) into the caudate-putamen nucleus (CPN) we have studied the role of GABA-ergic transmission of CPN in the control of conditioned behavior. In order to compare the effects of GABA and muscimol on two behavioral paradigms, rats of either sex weighing 160-180 g were trained to perform discrimination learning and conditioned avoidance response. A tone (1 kHz, 80 dB) was used as a conditioned stimulus. After bilateral injections of GABA and muscimol into the trained rats' CPN respectively, the conditioned avoidance response was inhibited temporarily, whereas the discrimination learning remained almost unchanged. In addition, the inhibitory effect of muscimol on the conditioned avoidance response was attenuated or even abolished by following bilateral intra-CPN injection of picrotoxin (0.1 micrograms/microliters for each side). As a control, the same volume of saline was injected into CPN bilaterally, and it showed that there was no change of both the conditioned avoidance response and the discrimination learning. The results show that the GABA-ergic transmission of CPN does play a role in the control of avoidance conditioning in rats, and thus support the suggestion that GABA-ergic transmission of the caudate-globus pallidus plays an important role in the control of conditioned behavior.