%0 Journal Article
%T The role of CA1 ¦Á-adrenoceptor on scopolamine induced memory impairment in male rats
%A Nasrin-Sadat Azami
%A morteza piri
%A Mehrdad Jahanshahi
%A Shahrbanoo oryan
%J Physiology and Pharmacology
%D 2010
%I Iranian Society for Physiology and Pharmacology
%X Introduction: Similarities in the memory impairment between Alzheimer patients and scopolamine treated animals have been reported. In the present study, the possible role of ¦Á-adrenergic receptors of the dorsal hippocampus on scopolamine state-dependent memory in adult male Wistar rats was evaluated. Methods: The animals were bilaterally implanted with chronic cannulae in the CA1 regions of the dorsal hippocampus, trained in a step-through type inhibitory avoidance task, and tested 24 h after training to measure stepthrough latency. Results: Post-training intra-CA1 administration of scopolamine (0.5 and 2¦Ìg/rat) dose-dependently reduced the step-through latency, showing an amnestic response. Amnesia produced by post-training scopolamine (2 ¦Ìg/rat) was reversed by pre-test administration of the scopolamine (0.5 and 2 ¦Ìg/rat) that is due to a state-dependent effect. Pre-test intra-CA1 injection of ¦Á1-adrenoceptor agonist, phenylephrine (0.25, 0.5 ¦Ìg/rat) in the dose range that we used, could not affect memory impairment induced by post-training injection of scopolamine (2 ¦Ìg/rat). However intra-CA1 pretest injection of ¦Á2-adrenoceptor agonist, clonidine (0.5 ¦Ìg/rat) improved post-training scopolamine (2 ¦Ìg/rat) intra- CA1 injection induced retrieval impairment. Furthermore, pre-test intra-CA1 microinjection of phenylephrine (0.25 and 0.5 ¦Ìg/rat) or clonidine (0.25 and 0.5 ¦Ìg/rat) with an ineffective dose of scopolamine (0.25 ¦Ìg/rat), synergistically improved memory performance impaired by post-training scopolamine (2 ¦Ìg/rat). Our results also showed that, pre-test injection of ¦Á1-receptor antagonist prazosin (1, 2 ¦Ìg/rat) or ¦Á2-receptors antagonist yohimbine (1, 2 ¦Ìg/rat) before effective dose of scopolamine (2 ¦Ìg/rat) prevented the improvement of memory by pre-test scopolamine. Conclusion: These results suggest that ¦Á1- and ¦Á2-adrenergic receptors of the dorsal hippocampal CA1 region may play an important role in scopolamine-induced amnesia and scopolamine state-dependent memory.
%K Key words: Scopolamine
%K ¦Á-adrenergic receptors
%K Dorsal hippocampus
%K Inhibitory avoidance response
%K Statedependent learning
%U http://www.phypha.ir/ppj/browse.php?a_code=A-10-380-1&slc_lang=en&sid=1