Effect of MOG sensitization on somatosensory evoked potential in Lewis rats

Abstract

Myelin oligodendrocyte glycoprotein (MOG) is commonly used as an immunogen to induce an immune response against endogenous myelin, thereby modeling multiple sclerosis in rodents. When MOG is combined with complete Freund’s adjuvant (CFA), multifocal, multiphasic disease ensues; whereas when MOG is combined with incomplete Freund’s adjuvant (IFA), clinical disease is usually absent. MOG-IFA immunized animals can be induced to have neurological disease after intraspinal injections of cytokines and ethidium bromide (EtBr). In this study, we investigated whether MOG-IFA immunized rats exhibited subclinical injury as defined by Somatosensory Evoked Potential (SEP) recordings. The titration of Anti-MOG-125 antibodies showed robust peripheral mounting of immune response against myelin in MOG-immunized rats. However the SEP measures showed no significant change over time. Upon injecting cytokine-EtBr in the spinal cord after MOG sensitization, the SEP recordings showed reduced amplitude and prolonged latency, suggestive of axonal injury and demyelination in the dorsal column, respectively. These findings were later confirmed using T2-weighted MRI and histological hematoxilin-eosin stain of the spinal cord. This report establishes that MOG-IFA immunization alone does not alter neuronal conduction in SEP-related neural-pathways and that longitudinal in-vivo SSEP recordings provide a sensitive read-out for focal myelitis (MOG-IFA & intraspinal cytokine-EtBr) in rats.

Plasticity associated changes in cortical somatosensory evoked potentials following spinal cord injury in rats

“…Five transcranial screw electrodes were implanted on the cranium of each rat for SSEP recordings, as previously described [16][17][18][19][20]. Briefly, an incision was made along the midline of the shaved head and a dental drill was used to drill five burr holes in the exposed part of the skull corresponding to the hindlimb and forelimb regions of the S1.…”

“…For SSEP recordings, rats were anesthetized with 1.5% isoflurane and intramuscular needle electrodes were used to electrically stimulate the median and tibial nerves of the left and right limbs, as previously described [16][17][18][19][20]. An isolated constant current stimulator (Digitimer, Welwyn Garden City, Hertfordshire, UK) was used to deliver positive current pulses of 3.5 mA with 200 µs duration at 0.5 Hz to one limb at a time while concurrently recording the evoked potential responses on the cortex.…”

Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury

“…Such evoked potential studies, as performed by García-Alías et al, Lee et al, Al-Nashash et al and others are generally longitudinal; with evoked potential monitoring being performed both before and after the rat is injured (García-Alías et al, 2006;Lee et al, 2007;Onifer et al, 2007b;Agrawal et al, 2009a;Al-Nashash et al, 2009;All et al, 2009). However, these studies generally do not record evoked potentials from all four limbs and as a result do not provide a complete picture of spinal cord integrity.…”

Secreted phosphoprotein 24 kD inhibits nerve root inflammation induced by bone morphogenetic protein-2

“…It represents a combination of rat joint movements, hindlimb movements, stepping, forelimb and hindlimb coordination, trunk position and stability, paw placement, and tail position on a scale from 0 to 21 [13]. Briefly, rats were placed in an 80Â80 cm box, with 17-cm walls, lined with blue cloth.…”