Intra-CA1 administration of FK-506 (tacrolimus) in rat impairs learning and memory in an inhibitory avoidance paradigm

These findings suggest that the FK-506 selectively interferes with acquisition, retention, and retrieval of information processing in CA1 of hippocampus. Given the crucial role of CN in common signaling pathway of higher functions such as memory performance and cognition, in future it would be a probable therapeutic target in the treatment of a wide verity of neurological conditions involving memory.

Using different doses of FK-506 (0.5, 5, and 50 nM) in the CA1 of hippocampus at different times (before, after the training and also before the test), the effect of drug was evaluated in a step-through inhibitory avoidance paradigm. The latency of entering to the dark compartment was considered as a criterion for memory.

The pre-training intra-CA1 injections of FK-506 impaired inhibitory avoidance (IA) learning acquisition. In addition, the post-training intra-CA1 injections of FK-506 at 1, 2, and 3 hr relative to training impaired memory consolidation. Moreover, the pre-test intra-CA1 injections of FK-506 impaired memory retrieval.