Blockade of isoproterenol-induced synaptic potentiation by tetra-9-aminoacridine in the rat amygdala.
The effects of tetrahydro-9-aminoacridine (THA) on beta-adrenoceptor activation-induced synaptic potentiation were studied in brain slices of the rat amygdala using intracellular recording techniques. To exclude the involvement of N-methyl-D-aspartate (NMDA) receptors, all the experiments were performed in the presence of NMDA receptor antagonist, D-APV (50 microM). Bath application of isoproterenol (Iso; 15 microM) results in a long-lasting enhancement of the amplitude of excitatory postsynaptic potentials (EPSPs) to 200 +/- 6% of baseline. Forskolin, which directly activates adenyl cyclase, produces a similar effect suggesting that Iso may act through a cyclic AMP-dependent mechanism. Pretreatment of the slices with THA (300 microM) completely abolishes the Iso- and forskolin-induced synaptic potentiation. We hypothesize that the locus of THA/beta-adrenoceptor interaction is presynaptic; the underlying mechanism is likely due to THA's depression of transmitter release via a presynaptic blockade of voltage-dependent Ca2+ channels.
Wang
S J
SJ
Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan.
Huang
C C
CC
Hsu
K S
KS
Tsai
J J
JJ
Huang
C C
CC
Gean
P W
PW
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000679:Amygdala / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D005576:Colforsin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009473:Neuronal Plasticity / Q000187:drug effects; D010277:Parasympathomimetics / Q000494:pharmacology*; D051381:Rats; D013569:Synapses / Q000187:drug effects*; D013570:Synaptic Membranes / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects; D013619:Tacrine / Q000494:pharmacology*
D000318:Adrenergic beta-Agonists; D010277:Parasympathomimetics; D005576:Colforsin; D013619:Tacrine; D000242:Cyclic AMP; D007545:Isoproterenol