Concurrent reduction of inflammation and spinal Fos-LI neurons by systemic diclofenac in the rat.

Intraplantar carrageenan induced a peripheral inflammation and c-Fos like immunoreactivity (Fos-LI) in the dorsal horn, L4-L5 segments, of the rat spinal cord. The total number of control carrageenan evoked Fos-LI neurons was 126 +/- 6 per section, which were predominately located in the superficial and deep laminae (41 +/- 2% and 39 +/- 2% of the total number of Fos-LI neurons per section) of the dorsal horn. Pre-administered diclofenac (3, 6, 9 mg/kg i.v.) dose dependently reduced the number of Fos-LI neurons, with effects being strongest on the deep laminae Fos-LI neurons. The effects of diclofenac (9 mg/kg) on the number of Fos-LI neurons (68 +/- 2% reduction) and inflamed ankle (72 +/- 7% reduction) and paw (49 +/- 6% reduction) diameters, were positively correlated.