Influence of acute hyperglycaemia on the amplitude of nociceptive spinal evoked potentials in healthy rats.

To evaluate the effect of blood glucose level on the amplitude of nociceptive spinal evoked potentials in healthy rats, an acute hyperglycaemia state was induced in an experimental group of 12 rats, through the infusion of glucosade solution. A Ringer-lactate solution was administered equivolumetrically to the control group (5 rats) under the same experimental conditions. Nociceptive spinal evoked potentials were recorded every 2 min, before and during the induction of hyperglycaemia, from the left lumbar cord dorsum activated orthodromically by ipsilateral electrical stimulation of the hind paw (20 Volts, 0.5 ms, 0.2 Hertz). Acute hyperglycaemia induced an increase of amplitude in both N (+8.92%, p = .000006) and P (+10.46%, p = .000037) waves when comparing control and experimental groups or basal versus infusion values, in response to nociceptive stimuli. The present results show that acute hyperglycaemia could contribute to central nociceptive sensitization; it would be attributed to an increased synchronization of spinal dorsal horn neuronal discharges.