Release of immunoreactive brain-derived neurotrophic factor in the spinal cord of the rat following sciatic nerve transection.

Using the antibody microprobe method, the sites of spinal release of immuno reactive brain-derived neurotrophic factor (BDNF) was studied in normal rat s, and rats with prior sciatic nerve transection. In normal rats, a signifi cant basal release of immunoreactive BDNF was found in the superficial dors al horn. Following sciatic nerve transection (performed 14 days previously) , release of BDNF was found throughout the whole of the dorsal hem. extendi ng into deeper laminae. Electrical stimulation of the ipsilateral sciatic n erve at a strength adequate to excite either A fibres (20 Hz at 2xthreshold voltage) or A and C fibres (20 Hz at 20xthreshold voltage) did not alter t he basal release of immunoreactive BDNF in normal or in nerve-injured rats. The results suggest that BDNF is released from the central terminals of pr imary afferent fibres, but such release is not solely dependent upon action potential invasion of these terminals. The increased extent of release fol lowing nerve transection is consistent with the hypothesis that BDNF plays a role in the central response to peripheral nerve injury. (C) 2001 Publish ed by Elsevier Science B.V.