GABAergic neurotransmission has been implicated in many aspects oflearning and memory, as well as mood and anxiety disorders. The amygdalahas been one of the major focuses in this area, given its essential role inmodulating emotionally relevant memories. However, studies with male subjectsare still predominant in the field. Here we investigated the consequences for anaversive memory of enhancing or decreasing GABAergic transmission in thebasolateral nucleus of the amygdala (BLA). Wistar female rats were trained inthe plus-maze discriminative avoidance task, in which they had to learn to avoidone of the enclosed arms where an aversive stimulus consisting of a bright lightand a loud noise was given (day 1). Fifteen minutes before the test session (day2) animals received 0,2 μL infusions of either saline solution, the GABAergicagonist muscimol (0,05 mg/ml), or the GABAergic antagonist bicuculine (0,025mg/ml) bilaterally intra-BLA. On the test day, females in proestrous or estrouspresented adequate retrieval and did not extinguish the task, while females inmetestrous or diestrous presented impaired retrieval. In the first group,muscimol infusion impaired retrieval and bicuculline had no effect, suggestingnaturally low levels of GABAergic transmission in the BLA of proestrous andestrous females. In the second group, muscimol infusion had no effect andbicuculline reversed retrieval impairment, suggesting naturally high levels ofGABAergic transmission in the BLA of metestrous and diestous females.Additionally, proestrous and estrous females presented higher anxiety levelscompared to metestrous and diestrous females, which could explain betterperformance of this group. On the other hand, BLA GABAergic system did notinterfere with the innate fear response because drug infusions had no effect inanxiety. Thus, retrieval alterations caused by the GABAergic drugs wereprobably related specifically to memory processes
展开▼
