CENTRAL EFFECT OF THE NONSTEROID ANTIINFLAMMATORY AGENTS, INDOMETHACIN, IBUPROFEN, AND DICLOFENAC, DETERMINED IN C-FIBER-EVOKED ACTIVITY IN SINGLE NEURONS OF THE RAT THALAMUS

This study aimed to investigate if the non-steroid anti-inflammatory agents, indometacin, ibuprofen and diclofenac, are capable of depressing sensory responses of the nociceptive system by a central action. For this purpose, experiments were carried out on rats under urethane anaesthesia in which activity was elicited by electrical stimulation of afferent C fibres in the sural nerve. Recordings were made ipsi- or contralaterally from single neurones in the dorsomedial part of the ventral nucleus (VDM) of the thalamus. The 3 drugs produced a dose-dependent depression of the evoked activity which amounted to about 60% of the controls at the highest doses employed and lasted longer than 60 min. Their potency ranking, according to the ED50 values (in brackets), is: indometacin (5 mg/kg) > diclofenac (10.9 mg/kg) > ibuprofen (15.6 mg/kg). The results suggest that a central action might contribute to the analgesia produced by these non-steroid anti-inflammatory agents. © 1990.