Release of immunoreactive galanin in the spinal cord of rats with ankle inflammation: Studies with antibody microprobes

Antibody microprobes bearing antibodies to the carboxy-terminus of rat galanin were inserted into the spinal cords of anaesthetized normal rats and those in which ankle inflammation had been induced by the unilateral subcutaneous injection of Freund's adjuvant four to six days previously. In normal rats, a basal presence of immunoreactive galanin was detected in the dorsal horn. Similar levels of immunoreactive galanin were found in the dorsal horn of both sides of the spinal cord in animals with unilateral ankle inflammation. Flexing the ankle or compressing the foot in normal rats failed to alter levels of immunoreactive galanin detected by microprobes. In animals with ankle inflammation, prolonged periods of ankle flexion did release immunoreactive galanin in the ipsilateral dorsal horn. Subsequent noxious ankle compression in these animals did not increase but rather decreased immunoreactive galanin in the dorsal horn to below basal levels. The reason for this decrease is unknown but it may represent an inhibition of release or a depletion of spinal stores of galanin.