Interaction of cholecystokinin and glutamate agonists within the dLGN, the dentate gyrus, and the hippocampus.
The interaction of sulfated cholecystokinin (CCK-8S) with excitatory amino acids (EAA) was studied on single units of the dorsal lateral geniculate nucleus (dLGN), the dentate gyrus, and the hippocampal CA3 region in rats anaesthetized with urethane. lontophoretic co-administration of small, individually ineffective currents of CCK-8S and kainic acid or N-methyl-D-aspartate repeatedly elicited an increase of the discharge rate in nearly all geniculate and half of the dentate neurons but not in those of the CA3 region. The effect could be reduced by the CCKB receptor antagonist PD 135,158 more often than by the CCKA antagonist KL 1001. The increased firing due to co-administration of CCK and kainate could also be suppressed by the non-NMDA antagonist CNQX but not by the NMDA antagonists CPP or AP-5, which were otherwise able to prevent the neuron from responding to co-administration of CCK and NMDA. It is suggested that in distinct brain regions the effectivity of the "low level" EAA transmission may be enhanced by small amounts of CCK-8S. This is thought to be mediated by a coactivation of CCK and EEA receptors.
Gabriel
S
S
Department of Neurophysiology, Institute of Physiology, Humboldt University Berlin, Berlin, Germany.
Grützmann
R
R
Lemke
M
M
Gabriel
H J
HJ
Henklein
P
P
Davidowa
H
H
D000818:Animals; D018891:Dentate Gyrus / Q000187:drug effects*; D004347:Drug Interactions; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005829:Geniculate Bodies / Q000187:drug effects*; D006624:Hippocampus / Q000187:drug effects*; D007478:Iontophoresis; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012844:Sincalide / Q000031:analogs & derivatives* / Q000494:pharmacology; D018709:Statistics, Nonparametric
C090019:8-sulfocholecystokinin octapeptide; D018690:Excitatory Amino Acid Agonists; D016202:N-Methylaspartate; D012844:Sincalide; D007608:Kainic Acid