The researchers looked at the role of cholecystokinin (CCK)-peptides in the brain that are linked to psychiatric disorders like anxiety, depression and schizophrenia-in modulating communication between cells in the brain.
They found that CCK functions in the brain as an extremely specific switch with a highly unusual, dual action.
On the one hand, it enhances the synthesis and release of natural marijuana-like (endocannabinoid) substances from a particular class of nerve cells known to modulate neuronal excitability in brain circuits critical for cognition and mood. On the other hand, CCK robustly increases electrical activity in a different class of nerve cells that play critical roles in learning and memory.
"These results reveal a new mechanism for CCK to regulate nerve cell activity in a highly specific manner," Nature magazine quoted the study's lead author, Csaba Foldy, postdoctoral researcher in anatomy and neurobiology, as saying.
The researchers focused their study on the hippocampus, the region of the brain involved in learning, memory and emotion. Damage or alterations to the hippocampus can cause cognitive disorders, epilepsy, and mental illness.
"By linking CCK actions to endocannabinoids, the study provides novel possibilities for the future development of therapies for a number of neurological diseases. Cannabinoid compounds are interesting because they act through special receptors on nerve cells to modulate these cells' behaviour," said Ivan Soltesz, professor and chair of the Department of Anatomy and Neurobiology and senior author of the study.
"This discovery offers the potential for new drug therapies because the link between CCK and cannabinoids can now be further investigated to determine how its modulation by either pharmacological or genetic means alters excitability in the hippocampus," he added.