Glucocorticoid regulation of motoneuronal parameters in rats with spinal cord injury

GONZALEZ SL; SARAVIA FE; GONZALEZ DENISELLE MC; LIMA ANALÍA; DE NICOLA A. F.

CELLULAR AND MOLECULAR NEUROBIOLOGY.

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 1999 vol. 19 p. 597 - 611

0272-4340

Glucocorticoids exert beneficial effects after acute CNS injury in humans andexperimental animals. To elucidate potential mechanisms of glucocorticoid action in thelesioned spinal cord, we have studied if treatment with dexamethasone (DEX) modulatedthe neurotrophin binding receptor p75 (p75NTR) and choline acetyltransferase (ChAT), amarker of neuronal functional viability.2. Rats with a sham operation or with spinal cord transection at the thoracic levelreceived vehicle or DEX several times postlesion and were sacrificed 48 hr after surgery.The lumbar region caudal to the lesion was processed for p75NTR and ChAT immunoreactivity (IR) using quantitative densitometric analysis.3. We observed that p75NTR-IR was absent from ventral horn motoneurons of shamoperated rats, in contrast to strong staining of neuronal perikaryon inTRXrats. Administration of DEX to TRX rats had no effect on the number of neuronal cell bodies expressing p75NTR-IR but significantly increased the number and length of immunostained neuronal processes.4. Furthermore, spinal cord transection reduced ChAT immunostaining of motoneuronsby 50%, whereas DEXtreatment reverted this pattern to cells with a strong immunoreactionintensity in perikaryon and cell processes.5. It is hypothesized that increased expression of p75NTR in cell processes and ofChAT in motoneurons may be part of a mechanism by which glucocorticoids affordneuroprotection, in addition to their known antiinflammatory effects.