title: Modulation of WIN55,212-2 state-dependent memory by α2-adrenergic receptors of the dorsal hippocampus.
abstract: BACKGROUND
  An overlapping distribution of α2-adrenergic receptors with cannabinoid receptors has been reported in certain brain structures such as the dorsal hippocampus. Thus, functional interactions between cannabinoid and α2-adrenergic systems in cognitive control seem possible. In the present study, we examine the possible role of α2-adrenergic receptors of the dorsal hippocampus on WIN55,212-2 state-dependent learning.
  
  
  METHODS
  Adult male Wistar rats were bilaterally implanted with chronic cannulae in the CA1 regions of their dorsal hippocampi trained in a step-down type inhibitory avoidance task and tested 24 hr after training, to measure step-down latency.
  
  
  RESULTS
  Post-training or pre-test intra-CA1 administration of the cannabinoid receptor agonist, WIN 55,212-2 (0.25 and 0.5 µg/rat) induced amnesia. Amnesia produced by post-training WIN55,212-2 (0.5 µg/rat) was reversed by pre-test administration of WIN55,212-2, that was due to a state-dependent effect. Pre-test intra-CA1 microinjections of clonidine (0.25, 0.5 and 1 μg/rat) or yohimbine (0.5, 0.75, and 1 μg/rat) did not affect memory retrieval per se. Pre-test intra-CA1 administration of clonidine (0.5 and 1 μg/rat) or clonidine (0.25, 0.5, and 1 μg/rat) with an ineffective dose of WIN 55,212-2 (0.25 µg/rat) reversed post-training WIN55,212-2 (0.5 µg/rat,intra-CA1) induced memory impairment. Pre-test intra-CA1 microinjection of yohimbine (1 μg/rat) before administration of WIN55,212-2 (0.5 µg/rat, intra-CA1), however, dose-dependently inhibited WIN55,212-2 state-dependent memory.
  
  
  CONCLUSIONS
  Modulation of α2-adrenergic receptors in the dorsal hippocampal CA1 regions can influence WIN55,212-2 induced amnesia and WIN55,212-2 state-dependent learning of an inhibitory avoidance task by pre- or post-synaptic mechanism(s).
authors: Department of Biology, Faculty of Basic Sciences, Islamic Azad University, Ardabil Branch, Ardabil, Iran.
authors: Morteza
authors: M
authors: Piri
authors: Mohammad-Reza
authors: MR
authors: Zarrindast
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000647:Amnesia / Q000139:chemically induced; D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects*; D048588:Benzoxazines / Q000494:pharmacology*; D056547:CA1 Region, Hippocampal / Q000502:physiology*; D063387:Cannabinoid Receptor Antagonists; D003000:Clonidine / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D009025:Morpholines / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D018709:Statistics, Nonparametric; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D048588:Benzoxazines; D063387:Cannabinoid Receptor Antagonists; D009025:Morpholines; D009281:Naphthalenes; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D003000:Clonidine