In vivo measurement of noradrenaline in the locus coeruleus of rats during the formalin test: a microdialysis study.
The locus coeruleus is involved in the regulation of the sense of pain. To demonstrate the changes in noradrenaline level in the locus coeruleus during the formalin test, a microdialysis probe was implanted into the left locus coeruleus of rats. Formalin was subcutaneously injected into the plantar surface of the right hind paw and pain ratings were recorded. The concentrations of noradrenaline and its metabolite 3-methoxy-4-hydroxyphenylethylenglycol (MHPG) were measured. The results showed an almost four-fold elevation in noradrenaline release in the early phase of the formalin test; levels return to baseline in the late phase. Levels of MHPG changed in a similar fashion.
Sajedianfard
Javad
J
Department of Physiology, Tarbiat Modarres University, P.O. Box 14155-4838, Tehran, Iran.
Khatami
Shohreh
S
Semnanian
Saeed
S
Naghdi
Naser
N
Jorjani
Masomeh
M
D000818:Animals; D005557:Formaldehyde; D008125:Locus Coeruleus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000378:metabolism; D017551:Microdialysis; D009638:Norepinephrine / Q000378:metabolism*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D005557:Formaldehyde; D008734:Methoxyhydroxyphenylglycol; D009638:Norepinephrine