Trauma to the spinal cord causes a cascade of secondary events, such as
mitochondrial dysfunction, which disrupts cellular functions and ultimately leads to cell death.
Cyclosporin A (CsA) is a potent
immunosuppressant that promotes mitochondrial function by inhibiting mitochondrial permeability transition (mPT). Clinical trials examining CsA in
traumatic brain injury are currently under-way, but CsA is potentially neurotoxic.
NIM811 is a non-immunosuppressive CsA derivative that inhibits mPT at nanomolar concentrations and with significantly less cytotoxicity than CsA. In the present study, we investigated the effects of
NIM811 treatment on mitochondrial bioenergetics and the production of
reactive oxygen species following
spinal cord injury (SCI) in rats. Rats were pretreated with
NIM811 or vehicle, and after 15 min the rats received a "mild/moderate"
spinal cord contusion. After 24 h, the spinal cords were rapidly removed and synaptosomal mitochondria were isolated.
NIM811 pretreatment significantly improved mitochondrial respiratory control ratios, and the maximal electron transport capacity of complex I and II, as well as their
ATP-producing capacity. Consistent with the improvements in mitochondrial function,
NIM811 pretreatment significantly decreased
free radical production in isolated mitochondria. These studies are the first to demonstrate the therapeutic potential of CsA derivatives in a model of SCI, and support the need for continued investigation of compounds like
NIM811 as an acute treatment for human SCI.