Peripheral inflammation is associated with increased glutamic acid decarboxylase immunoreactivity in the rat spinal cord.

We have examined the frequency and distribution of neuron profiles immunoreactive for glutamic acid decarboxylase, a biosynthetic enzyme for the putative inhibitory neurotransmitter, gamma aminobutyric acid, in the lumbar spinal cord of colchicine-treated rats with unilateral inflammation of a hindpaw. Ipsilateral to the inflamed hindpaw, there was an apparent increase in the levels of glutamic acid decarboxylase, as indicated by significant increases in the number of visible glutamic acid decarboxylase-like immunoreactive profiles within the superficial dorsal horn, neck of the dorsal horn and the deep gray matter at L4. An increase limited to the deep gray matter at L6 was also seen. No alteration was identified at L2. These results are the first to demonstrate that peripheral inflammation is associated with altered levels of glutamic acid decarboxylase-like immunoreactivity.