A. Hernandez et al., Lesion of the bulbospinal noradrenergic pathways blocks desipramine-induced inhibition of the C-fiber evoked nociceptive reflex in rats, NEUROSCI L, 302(1), 2001, pp. 1-4
Desipramine-induced inhibition of spinal cord nociceptive transmission was
studied in rats with or without lesion of the bulbospinal noradrenergic sys
tem by recording the C-fiber evoked nociceptive reflex from a hind limb. Bu
lbospinal noradrenergic projections were lesioned by injecting intrathecall
y 20 mug of 6-hydroxydopamine 2 weeks before the electrophysiological exper
iments. Results show that desipramine (5, 10 and 20 mg/kg intraperitoneally
) produced dose-dependent inhibition of the C reflex response duration in r
ats having intact noradrenergic bulbospinal systems. The inhibitory effect
of desipramine was reduced or even abolished in rats pre-treated with 6-hyd
roxydopamine. In addition, [H-3]-noradrenaline uptake was significantly low
er in spinal cord slices arising from 6-hydroxydopamine lesioned animals, a
s compared to that from intact rats. These observations support the notion
that the antinociceptive activity of antidepressants with noradrenergic sel
ectivity depends on a normal rate of endogenous noradrenaline released by b
ulbospinal neurons. (C) 2001 Elsevier Science ireland Ltd. All rights reser
ved.