در آزمون فرمالين با استفاده از روش ميكرودياليز LOCUS C؟RULEUS اندازه گيري غلظت نور آدرنالين در

Measurement of noradrenalin concentration in locus ceruleus: a microdialysis analysis following formalin test

Noradrenalin (NA) concentration was measured in locus ceruleus (LC) of male Wistar rats (280-320 g) following formalin test. For this purpose, the rats were anesthetized with sodium pentobarbital (50 mg/kg, i.p.), a microdialysis probe was implanted into the left LC, and the microdialysis experiments were carried out 24 h after the implantation of the probe. The probes were perfused with artificial cerebrospinal fluid (ACSF) at a flow rate of 2 gllmin and fractions were collected at 15-min intervals. The animals were divided into two groups. In the control group, normal saline and in the test group, 50 t1 of 2.5% formalin was subcutaneously injected into the plantar surface of the right hindpaw and pain scores were visually recorded. The samples were quantified by HPLC-ECD for determining the concentration of noradrenalin (NA) and its metabolite 4-hydroxy-3-methoxy phenyl glycol (MHPG). The results showed that an almost four-fold elevation in NA release at the early phase of formalin test occurs in the test group which returned to baseline in the late phase of the test. In addition, MHPG had a similar elevation in the test group which returned to baseline in the late phase of the test.