Are beta-adrenergic receptors in the hippocampal CA1 region required for retrieval of contextual fear memory?
It is well established that beta-adrenoceptors (beta-ARs) in the hippocampal CA1 region are involved in regulating synaptic plasticity and are essential for acquisition and consolidation of spatial memory and contextual fear memory. Previous studies reported that beta-ARs in the CA1 region are also involved in memory retrieval. The present study re-examined the role of hippocampal beta-ARs in retrieval of conditioned contextual fear. We bilaterally infused a high dose of the beta-AR antagonist propranolol (15mug in 1mul saline) into the CA1 region 30min before retention test and found that propranolol produced no deficit in retrieval of either 1-day or 7-day contextual fear. We then examined if beta-AR stimulation would produce a beneficial effect. The beta-AR agonist isoproterenol (10mug in 1mul saline) was infused into the CA1 region 30min before retention test. Surprisingly, isoproterenol did not enhance but severely disrupted retrieval of 7-day contextual fear memory, with no impact on retrieval of 1-day contextual fear memory. The present study argues against the previous conclusion that beta-ARs in the CA1 region play a role in memory retrieval. beta-ARs in the CA1 region may be dispensable for retrieval of conditioned contextual fear.
Qi
Xue-Lian
XL
Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Zhu
Bi
B
Zhang
Xue-Han
XH
Li
Bao-Ming
BM
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000818:Animals; D005239:Fear / Q000502:physiology* / Q000528:radiation effects; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D011433:Propranolol / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D011433:Propranolol