Cholecystokinin-Like Bioactivity in Rat Cerebral Cortex

Abstract

Cholecystokinin (CCK)-like bioactivity was studied in extracts of rat cerebral cortex by three different bioassays. Positive results were obtained by all procedures used. A fairly good quantitative correlation was found when testing the same extracts by two of the methods. A considerable amount of CCK-like activity was demonstrated in the various subcellular fractions (synaptic membranes, synaptic vesicles, and synaptic fragments) corresponding to synaptic structures. The results are in accordance with the findings of several authors who demonstrated CCK-like immunoreactivity in the brain, especially in the cortex. The use of three different bioassays in three species (rabbit, rat, dog) seems to prove that some bioactive molecular form of CCK exists in the brain, mainly in the cortical area. The finding that subcellular elements of the synaptic structures contain relatively high concentrations of CCK raises the question of the possible role of CCK in the neuronal transmission.

Key-words:

• Bioassays of CCK
• cholecystokinin-cerebral cortex
• synaptic regions