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IPM
30
YEARS OLD

“School of Cognitive Sciences”

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Paper   IPM / Cognitive Sciences / 11300
School of Cognitive Sciences
  Title:   Involvement of dorsal hippocampal a-adrenergic receptors in the effect of scopolamine on memory retrieval in inhibitory avoidance task
  Author(s): 
1.  Nasrin Azami
2.  Morteza Piri
3.  Shahrbano Oryan
4.  Mehrdad Jahanshahi
5.  Vahab Babapour
6.  Mohammad Reza Zarrindast
  Status:   Published
  Journal: Neurobiology of Learning and Memory
  Vol.:  93
  Year:  2010
  Pages:   455-462
  Supported by:  IPM
  Abstract:
The present study evaluated the possible role of a-adrenergic receptors of the dorsal hippocampus on scopolamine-induced amnesia and scopolamine state-dependent memory in adult male Wistar rats. 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 step-through latency. Results indicate that post-training or pre-test intra-CA1 administration of scopolamine (1 and 2 lg/rat) dose-dependently reduced the step-through latency, showing an amnestic response. Amnesia produced by post-training scopolamine (2 lg/rat) was reversed by pre-test administration of the scopolamine that is due to a state-dependent effect. Interestingly, pre-test intra-CA1 microinjection of a1-adrenergic agonist, phenylephrine (1 and 2 lg/rat) or a2-adrenergic agonist, clonidine improved post-training scopolamine (2 lg/rat)-induced retrieval impairment. Furthermore, pre-test intra-CA1 microinjection of phenylephrine (0.25, 0.5 and 1 lg/rat) or clonidine (0.25, 0.5 and 1 lg/rat) with an ineffective dose of scopolamine (0.25 lg/rat), synergistically improved memory performance impaired by post-training scopolamine. On the other hand, pre-test injection of a1-receptors antagonist prazosin (1 and 2 lg/rat) or a2-receptors antagonist yohimbine (1 and 2 lg/rat) prevented the restoration of memory by pre-test scopolamine. It is important to note that pre-test intra-CA1 administration of the same doses of prazosin or yohimbine, alone did not affect memory retrieval. These results suggest that a1- and a2-adrenergic receptors of the dorsal hippocampal CA1 regions may play an important role in scopolamine-induced amnesia and scopolamine state-dependent memory.

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