Depolarization-induced Suppression of Inhibition

Depolarization-induced Suppression Of Inhibition

Depolarization-induced suppression of inhibition (DSI) is the classical and original electrophysiological example of endocannabinoid function in the central nervous system. Prior to the demonstration that DSI was dependent on the cannabinoid CB1 receptor function, there was no way of producing an in vitro endocannabinoid mediated effect.

DSI is classically produced in a brain slice experiment (i.e. a 300-400 µm slice of brain, with intact axons and synapses) where a single neuron is "depolarized" (the normal −70 mV potential across the neuronal membrane is reduced, usually to −30 to 0 mV) for a period of 1 to 10 seconds. After the depolarization, inhibitory GABA mediated neurotransmission is reduced. This has been demonstrated to be caused by the release of endogenous cannabinoids from the depolarized neuron which diffuses to nearby neurons, and binds and activates CB1 receptors, which act presynaptically to reduce neurotransmitter release.