Metabolic activity changes in the cervical spinal cord upon acute forepaw pain

Metabolic activity pattern in the cervical enlargement of the spinal cord has been investigated by the quantitative 14C-2-deoxyglucose technique in unanaesthetized, unrestrained rats injected with a small amount of dilute formalin (0.06 ml, 5%) in the right forepaw. Control animals were similarly handled but no injection was performed. In the Formalin group a significant increase of mean glucose utilization was observed in the dorsal horn of the injected side, both with respect to controls and to the opposite side. Analyses of spatial distribution of the isotope uptake ascertained that the superficial region, corresponding approximately to laminae I-II, and the neck (V-VI) of the dorsal horn showed the highest increase in glucose utilization. This technique appears potentially useful for investigating pain mechanisms in conscious animals