Depolarization-induced Suppression of Inhibition - A Note On DSE

A Note On DSE

While working with the cerebellum, Kreitzer's group also discovered that depolarization of Purkinje cells could also cause a temporary reduction in excitatory input into these cells from both climbing fibres and parallel fibres (Kreitzer et al. 2001b). This phenomenon was termed depolarization-induced suppression of excitation (DSE), and differs from DSI only by the kind of neurotransmitter whose release is reduced. In the case of DSI, the result is a reduction in inhibitory GABA release, while in DSE the effect is a reduction in excitatory glutamate release. DSE was also found to occur in other regions of the brain, however the evidence for the involvement of the endocannabinoid receptor CB1 in this process is not as solid as it is for DSI. Both DSI and DSE have been studied in the CB1 knock-out mice. Some groups show that both DSI and DSE are lacking in these mice, while others have shown that DSE, but not DSI, can still be evoked in the knock-outs (Ohno-Shosaku et al. 2002, Hajos et al. 2001). The endocannabinoids may still mediate DSE too, but by acting at an as-of-yet unknown cannabinoid receptor. Interestingly, some work has shown that anandamide can bind to the vannilloid receptor VR1, the receptor responsible for mediating the effects of capsaicin. This receptor is present in the brain, and anandamide actions at this receptor may potentially contribute to DSE (Cristino et al. 2006, Hajos et al. 2002). However DSE is currently a largely unexplored phenomenon and more research is needed to draw any firm conclusions.