Activation of beta- and alpha-2-adrenoceptors in the basolateral amygdala has opposing effects on hippocampal-prefrontal long-term potentiation.
Noradrenaline (NA), released by the locus coeruleus (LC), plays a key role in mediating the effects of stress on memory functions. The LC provides diffuse projections to many forebrain nuclei including the hippocampus, the prefrontal cortex (PFC), and the basolateral amygdala (BLA). These three structures are intricately interlinked. The hippocampal-prefrontal (H-PFC) pathway is involved in various cognitive functions. The first aim of this study was to examine the role of BLA in H-PFC plasticity by infusion of drugs to activate and inactivate the BLA and studying the effects on H-PFC long-term potentiation (LTP) in the rat in vivo. Activation of the BLA with glutamate impaired, while inactivation with muscimol augmented, H-PFC LTP. This study also aimed to demonstrate how directly applying noradrenaline and other noradrenergic agents in the BLA can affect H-PFC LTP. Noradrenaline at 1μg/0.2μl enhanced H-PFC LTP. Stimulating alpha-2-adrenoceptors in the BLA with clonidine enhanced LTP while blocking alpha-2 adrenoceptors with idazoxan impaired it. Propranolol, a non-selective beta antagonist, enhanced H-PFC LTP while isoprenaline, a non-selective beta agonist, decreased H-PFC LTP. These results suggest that the BLA regulates H-PFC plasticity negatively and also provide a mechanism by which noradrenaline in the BLA can affect H-PFC plasticity via alpha-2 and beta adrenoceptors.
['Lim|Ee Peng|EP|', 'Dawe|Gavin S|GS|', 'Jay|Thérèse M|TM|']
D058647:Adrenergic alpha-2 Receptor Agonists D058669:Adrenergic alpha-2 Receptor Antagonists D000318:Adrenergic beta-Agonists D000319:Adrenergic beta-Antagonists D000818:Animals D066272:Basolateral Nuclear Complex D003000:Clonidine D006624:Hippocampus D019329:Idazoxan D007545:Isoproterenol D017774:Long-Term Potentiation D008297:Male D009638:Norepinephrine D017397:Prefrontal Cortex D011433:Propranolol D051381:Rats D017207:Rats, Sprague-Dawley
Basolateral amygdala Long-term potentiation Noradrenaline Hippocampus Prefrontal cortex