Differential effects of desipramine on direct- and sensory-evoked noradrenaline release in thalamic locus coeruleus terminals.
The effects of desipramine on sensory-evoked (sciatic nerve stimulation) activation of locus coeruleus neurones were investigated in vivo by using treated carbon-fibre electrodes in conjunction with either differential normal pulse voltammetry or differential pulse amperometry. Firstly, the amplitude of the sensory-evoked increase in extracellular noradrenaline, monitored in thalamic locus coeruleus terminals, was not modified by desipramine (10 mg/kg), whereas that evoked by direct activation of locus coeruleus neurones was greatly increased: +143% for dorsal noradrenergic bundle stimulation and +761% for glutamate ejection in the locus coeruleus. Secondly, desipramine administered at the same dose significantly reduced (-48%) the activation of locus coeruleus neurones (monitored at the somato-dendritic level) evoked by prolonged sciatic nerve stimulation. Our results indicate that acute treatment with desipramine does not potentiate overall noradrenergic transmission by locus coeruleus neurones during sensory stimulation.
Brun
P
P
INSERM U 171, Centre Hospitalier Lyon-Sud, Pierre Bénite, France.
Suaud-Chagny
M F
MF
Gonon
F
F
Buda
M
M
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D003891:Desipramine / Q000008:administration & dosage / Q000494:pharmacology*; D004558:Electric Stimulation; D004566:Electrodes; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D008125:Locus Coeruleus / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve; D013787:Thalamic Nuclei / Q000187:drug effects* / Q000502:physiology
D005971:Glutamates; D015102:3,4-Dihydroxyphenylacetic Acid; D018698:Glutamic Acid; D003891:Desipramine; D009638:Norepinephrine