title: Chromaffin cell transplant in spinal cord reduces secondary allodynia induced by formalin in the rat. Role of opioid receptors and α₂-adrenoceptors.
abstract: In the present study, the effect of chromaffin cell transplant in the spinal cord was evaluated on formalin-induced mechanical secondary allodynia in the rat. Chromaffin cells were transplanted into the lumbar subarachnoid space before or after formalin injection. Subcutaneous formalin injection (50 μl, 1%) produced long-lasting secondary allodynia in the ipsilateral and contralateral hind paws. Once secondary allodynia was established, treatment with chromaffin cells produced a significant reduction in the nociceptive behavior in both hind paws. The antiallodynic effect was time-dependent since it was observed 15 days after chromaffin cell transplants but not before. On the other hand, pre-treatment with chromaffin cells prevented the expression of secondary allodynia in both hind paws in the rat. Antiallodynic effect of chromaffin cells was reverted with the non-selective opioid receptor antagonist naltrexone and the non-selective α(2)-adrenoceptor antagonist rauwolscine. Clusters of viable chromaffin cells labeled with anti-tyrosine hydroxylase antibodies were observed in the retrieved transplants 15 days after transplant. These results establish the analgesic efficacy of intrathecal chromaffin cells on formalin-induced secondary allodynia. Our data suggest that chromaffin cells release neuroactive substances including opioid peptides and adrenergic amines that reduce secondary allodynia in rats through activation of their receptors.
authors: Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico.
authors: Mónica
authors: M
authors: Ambriz-Tututi
authors: Violeta
authors: V
authors: Sánchez-González
authors: René
authors: R
authors: Drucker-Colín
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D019439:Chromaffin Cells / Q000637:transplantation*; D005260:Female; D005557:Formaldehyde / Q000009:adverse effects*; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology / Q000601:surgery*; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists; D051381:Rats; D017208:Rats, Wistar; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D009292:Narcotic Antagonists; D018341:Receptors, Adrenergic, alpha-2; D011957:Receptors, Opioid; D005557:Formaldehyde; D015016:Yohimbine; D009271:Naltrexone