Dose-dependent inhibition of sensory nerve activity in the feline dental pulp by anti-inflammatory drugs.

The aim of the present study was to investigate whether substances known to antagonize algogenic agents can block an experimentally induced increased sensory nerve activity in the dental pulp of the cat. Increased neural activity following repeated brief head stimulation has been shown to be characteristic of the individual cat and can be utilized for intraindividual comparative studies on such increased activity. When indomethacin, diclofenac sodium or naproxen were given intravenously as a pretreatment prior to stimulation, a consistent blocking effect on expected impulse activity as compared to the impulse activity in the control teeth was produced. Indomethacin produced a dose-dependent inhibition (ID50 0.04--0.2 mg/kg). Diclofenac sodium (5 mg/kg) inhibited nerve activity by 51--91% and naproxen (15 mg/kg) by 92--95%. Methylsergide (0.02--0.08 mg/kg) did not show such blocking effect. When the drugs were administered during a state of established increased neural activity no effect on the current impulse activity was obtained. The present results suggest that prostaglandins may be involved in certain stages of heat induced pulp inflammation and act as mediators of increased intradental sensory nerve excitability.