Galanin like immunoreactivity in dorsal root ganglia and spinal cord after different degrees of chronic constriction injury

M.F. CORONEL; P.R. BRUMOVSKY; J.B. AQUINO; T. HÖKFELT; M.J. VILLAR

Orlando, USA

Congreso; Society for Neuroscience; 2002

Society for Neuroscience

Galanin (GAL) is a peptide normally expressed at low levels in dorsal root ganglia (DRG) and in local dorsal horn neurons. It is strongly upregulated after peripheral nerve lesions. In the present work we have analysed galanin immunoreactivity in DRGs and spinal cord in adult male rats with different degrees of chronic constriction injury (CCI) of the sciatic nerve. The diameter of the nerve was reduced by ligation in 10-30%, 40-60% or 70-90% of its original size. Animals subjected to peripheral axotomy were also included for comparison. After different survival times (7, 14, 30, 60 days) the ipsilateral and contralateral DRGs (L4-5), as well as the corresponding levels of the spinal cord, were removed. The tissue was processed for standard ABC immunohistochemistry using GAL antibodies. CCI induced an increase in the number of GAL immunoreactive (IR) neurons in DRGs. This increase was gradual after a 10-30% and 40-60%, reaching a peak after 70-90% compression of the nerve after survival times of 7, 14, 30 or 60 days. With all constrictions performed the highest numbers of galanin-IR neurons were reached 14 days after the constriction was made. In the dorsal horn, CCI induced a modest elevation in GAL expression. These results show that GAL expression in DRGs and spinal cord is regulated by nerve ligation, supporting the role of this neuropeptide as a mediator of antinociception.