Boden P R, Hill R G
Parke-Davis Research Unit, New Addenbrookes Hospital Site, Cambridge, England.
Neuropeptides. 1988 Aug-Sep;12(2):95-103. doi: 10.1016/0143-4179(88)90037-6.
Extracellular and intracellular recordings from CA1 neurones of rat hippocampal slices were undertaken to assess the relative potencies of cholecystokinin fragments. The CCK peptides displayed a large variability in their effects on extracellularly recorded population spikes. Intracellular recordings from CA1 neurones revealed a more consistent excitant action of these compounds. The C-terminal octapeptide CCK-8S, the tetrapeptide CCK-4 and pentagastrin were all found to be agonists when applied to hippocampal CA1 neurones maintained in vitro. Repeated application of the peptide fragments to the same cell resulted in a loss of activity. Neurones pre-treated with a CCK peptide showed no response to an application of a second, different, CCK fragment indicative of receptor cross-desensitization. Depolarisations induced by the excitatory amino acid L-glutamate remained unaffected by peptide application. These data suggest that the CCK fragments are agonists at rat CA1 neurones and share a common mode of action distinct from that of the excitatory amino acid L-glutamate.
