Interaction Between Testosterone and Bicuculline GABAA Antagonist in the CA1 Region of Hippocampus in Spatial Learning in Adult Male Rats

The hippocampus plays a vital role in spatial learning and memory. Testosterone appears to mediate spatial discrimination and the GABAer-gic system has also been reported to have a criti-cal role in this effect. In the present study we in-vestigated the interaction between testosterone (androgenic receptor agonist) and bicuculline (GABAA receptor antagonist) on spatial learning and memory performance in male Wistar rats. Materials and Methods: Cannulae were implanted into the CA1 of rats bilaterally and drugs were injected before daily training in the Morris water maze (MWM). In the first experiment, testosterone (0, 20, 40, 80 µg the 0.5 µl DMSO/side) was injected intra-CA1 before each session. In the second experiment, intra-CA1 injection of bicuculline (0, 1, 2, 4 µg 0.5 µl saline/side) were given before every session. In the last experiment, testosterone 80 µg, 0.5 µl and bicuculline 2 µg, 0.5 µl were injected into the CA1. Results: The results showed that testosterone 80 µg or bicuculline 2 µg, each given separately , and also microinjection of both testosterone + bicuculline increased travel distance and escape latency to find the platform, as compared to their vehicles. Conclusion: It is shown that administration of testosterone and bicuculline separately impaired spatial learning and memory. Microinjection of bicuculline after testosterone treatment did not change spatial learning impairment when com-pared to testosterone and bicuculline injected separately.