Microdialysis Unveils the Role of the α₂-Adrenergic System in the Basolateral Amygdala during Acquisition of Conditioned Odor Aversion in the Rat

Abstract

Previous work has shown that β-adrenergic and GABAergic systems in the basolateral amygdala (BLA) are involved in the acquisition of conditioned odor aversion (COA) learning. The involvement of α-adrenoreceptors, however, is poorly documented. In a first experiment, male Long-Evans rats received infusions of 0.1 μg of the selective α-antagonist dexefaroxan (Dex) in the BLA before being exposed to COA learning. In a second experiment, levels of norepinephrine (NE) were analyzed following Dex retrodialysis into the BLA. While microdialysis data showed a significant enhancement of NE release in the BLA with Dex, behavioral results showed that pre-CS infusion of Dex impaired, rather than facilitated, the acquisition of COA. Our results show that the NE system in the BLA is involved in the acquisition of COA, including a strong α-receptor modulation until now unsuspected. Supported by the recent literature, the present data suggest moreover that the processes underlying this learning are probably mediated by the balanced effects of NE excitatory/inhibitory signaling in the BLA, in which interneurons are highly involved.

Improving Stereotaxic Neurosurgery Techniques and Procedures Greatly Reduces the Number of Rats Used per Experimental Group—A Practice Report

“…From 2006, anesthesia has been induced by i.p. injection of a mixture of 3/4 part of ketamine (Imalgene ® , Boerhinger, Ingelheim, France; 100 mg/kg) and ¼ part of the alpha-2 agonist xylazine hydrochloride (Rompun ® , Elanco France, La Garenne Colombes, France; 10 mg/kg) [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Anesthesia is maintained by reinjections of a half- or quarter-dose after an initial phase of 30 to 45 min.…”

A novel microemulsion-based isotonic perfusate modulated by Ringer’s solution for improved microdialysis recovery of liposoluble substances

“…After implanting a probe into the body, a micro-perfusion pump drives a perfusate flow through a dialysis membrane to dissolve small molecules around the target tissue via a concentration gradient between the inside and outside of probes, thereby enabling effective sampling from the living tissue [ 2 ]. Common perfusates include normal saline, phosphate buffer, Ringer’s solution, and citrate glucose anticoagulant solution; the composition of ion components, pH value, osmotic pressure, and ionic strength of the perfusate should be similar to those of the internal environment of the sampling site [ 3 , 4 ]. Aqueous perfusates limit microdialysis to the detection of water-soluble components.…”