Figure 3.

The effect of microinjection of TNFα into the caudal vlPAG. Recombinant TNFα (20 ng) or saline (vehicle) was microinjected into the vlPAG, followed 1 h later by intraperitoneal administration of naloxone (4 mg/kg, i.p.). The behavioral signs were observed for 30 min after naloxone. (a) The microinjection of TNFα into the caudal vlPAG-induced morphine withdrawal-like behavioral signs after naloxone. Single microinjection of recombinant TNFα into the vlPAG also evoked upregulation of pERK1/2 (b), expression of Fos (c), and phosphorylation of CREB (d) while naloxone was given. ^*p<0.05 vs vehicle, ^**p<0.01 vs vehicle, n=5, t-test.