Baclofen concentration-response curves differ between hippocampal subfields.
The hippocampus contains interneurons that release gamma-aminobutyric acid (GABA). GABA hyperpolarizes hippocampal CA1 and CA3 pyramidal cells through activation of GABAB postsynaptic receptors. GABAB and 5-hydroxytryptamine1A (5-HT1A) receptors share effector mechanism(s). Agonist potency and the maximal hyperpolarization produced by 5-HT1A receptor activation is different between the CA1 and CA3 subfields. We determined that baclofen, a selective GABAB agonist, was more potent and produced a greater maximal response in area CA3 than in CA1. The larger magnitude of the response can be attributed partly to the larger input resistance of CA3 neurons. GABAB receptor-effector coupling differences between area CA1 and CA3 are proposed as the mechanism underlying the baclofen response incongruities.
Beck
S G
SG
Department of Pharmacology, Loyola University Medical Center, Maywood, IL 60153, USA.
Birnstiel
S
S
Pouliot
W A
WA
Choi
K C
KC
D000818:Animals; D001418:Baclofen / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D001418:Baclofen