Different drug-susceptibilities of long-term potentiation in three input systems to the CA3 region of the guinea pig hippocampus in vitro.
The susceptibilities to several drugs of long-term potentiations in the three input systems (mossy, commissural/associational and fimbrial fibres) to CA3 pyramidal neurones were investigated in hippocampal slices from the guinea pig. D-2-Amino-5-phosphonovalerate (D-APV), a selective antagonist at N-methyl-D-aspartate (NMDA) receptors, blocked the long-term potentiations in the commissural/associational fibre- and fimbrial fibre-CA3 systems, but did not significantly affect that in the mossy fibre-CA3 system. The latter was suppressed by kynurenate, a non-selective glutamate receptor antagonist. On the other hand, naloxone, an opioid antagonist, inhibited and bifemelane, which improves metabolism in brain and has an anti-amnesic action, augmented long-term potentiation in mossy fibre-CA3 system but did not influence those in commissural/associational fibre- and fimbrial fibre-CA3 systems. These findings suggest that the mechanisms, relevant to production of long-term potentiation in the mossy fibre-CA3 system, are different from those in the commissural/associational fibre- and fimbrial fibre-CA3 systems. N-Methyl-D-aspartate receptors are involved in the latter systems, while non-NMDA receptors for L-glutamate and opioid receptors are involved in the former. Further, the mossy fibre-CA3 system is more susceptible to a drug, having an anti-amnesic action, than are the other two systems.
Ishihara
K
K
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
Katsuki
H
H
Sugimura
M
M
Kaneko
S
S
Satoh
M
M
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D001559:Benzhydryl Compounds / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology
D001559:Benzhydryl Compounds; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D009270:Naloxone; D015763:2-Amino-5-phosphonovalerate; C031906:bifemelane