Paradoxical lower sensitivity of Locus Coeruleus than Substantia Nigra pars compacta neurons to acute actions of rotenone.

Paradoxical lower sensitivity of Locus Coeruleus than Substantia Nigra pars compacta neurons to acute actions of rotenone.
Exp Neurol. 2016 Oct 19;:
Authors: Yee AG, Freestone PS, Bai JZ, Lipski J
Abstract
Parkinson's disease (PD) is not only associated with degeneration of dopaminergic (DAergic) neurons in the Substantia Nigra, but also with profound loss of noradrenergic neurons in the Locus Coeruleus (LC). Remarkably, LC degeneration may exceed, or even precede the loss of nigral DAergic neurons, suggesting that LC neurons may be more susceptible to damage by various insults. Using a combination of electrophysiology, fluorescence imaging and electrochemistry, we directly compared the responses of LC, nigral DAergic and nigral non-dopaminergic (non-DAergic) neurons in rat brain slices to acute application of rotenone, a mitochondrial toxin used to create animal and in vitro models of PD. Rotenone (0.01-5.0μM) dose-dependently inhibited the firing of all three groups of neurons, primarily by activating KATP channels. The toxin also depolarised mitochondrial potential (Ψm) and released reactive oxygen species (H2O2). When KATP channels were blocked, rotenone (1μM) increased the firing of LC neurons by activating an inward current associated with dose-dependent increase of cytosolic free Ca(2+) ([Ca(2+)]i). This effect was attenuated by blocking oxidative stress-sensitive TRPM2 channels, and by pre-treatment of slices with anti-oxi...

Source: Experimental Neurology - October 18, 2016 Category: Neurology Authors: Yee AG, Freestone PS, Bai JZ, Lipski J Tags: Exp Neurol Source Type: research