title: Clinical and Histological Effects of the Intrathecal Administration of a Single Dose of Dexmedetomidine in Rabbits.
abstract: BACKGROUND
  There is experimental evidence that dexmedetomidine has neuroprotective effects. So, it could be expected that its intrathecal or epidural administration presents no harm. However, whether dexmedetomidine is neurotoxic to the spinal cord remains to be fully elucidated.
  
  
  OBJECTIVE
  To evaluate the effect of preservative-free dexmedetomidine administered as a subarachnoid single injection on the spinal cord and meninges of rabbits.
  
  
  METHODS
  Research article.
  
  
  METHODS
  Experimental research laboratory.
  
  
  METHODS
  Twenty young adult female rabbits, each weighing between 3200 and 4900 g, and having a spine length between 36 and 40 cm, were divided by lot into 2 groups (G): 0.9% saline in G1 and preservative-free dexmedetomidine in G2 (dose of 10 µg). After intravenous anesthesia with ketamine and xylazine, the subarachnoid space was punctured at S1-S2 under ultrasound guidance, and a random 5 µl.cm-1 of spinal length (0.2 mL) of solution (saline or dexmedetomidine) was injected. The animals remained in captivity for 21 days under medical observation and were sacrificed by decapitation. The lumbosacral spinal cord portion was removed for immunohistochemistry to assess the glial fibrillary acidic protein (GFAP), and histology was assessed using hematoxylin and eosin (HE) stain.
  
  
  RESULTS
  None of the animals had impaired motor function or decreased nociception during the period of clinical observation. None of the animals from the control group showed signs of injuries to meninges. In the dexmedetomidine group, however, 9 animals presented with signs of meningeal injury. The main histological changes observed were areas with meningeal thickening and lymphoplasmocitary infiltration in the pia-mater and arachnoid. Further histological examination also revealed adherence areas among the pia and arachnoid. There was no signal of injury in neural tissue in any animal of both groups.
  
  
  CONCLUSIONS
  Evaluation of the possible analgesic effects of the intrathecal dexmedetomidine was not performed.
  
  
  CONCLUSIONS
  On the basis of the present results, dexmedetomidine administered in the subarachnoid space in a single dose of 10 µg is capable of producing histological changes over the meninges of rabbits.
authors.affiliation: Postgraduate Program in Anesthesiology, Botucatu Medical School, Unesp - Univ. Estadual Paulista, Brazil.
authors.forename: Hugh D
authors.initials: HD
authors.lastname: de Pereira Cardoso
authors.affiliation: Postgraduate Program in Anesthesiology, Botucatu Medical School, Unesp - Univ. Estadual Paulista, Brazil.
authors.forename: Natalie C
authors.initials: NC
authors.lastname: Fim
authors.affiliation: Department of Pathology, Botucatu Medical School, UNESP- Univ. Estadual Paulista, Brazil.
authors.forename: Mariangela A
authors.initials: MA
authors.lastname: Marques
authors.affiliation: Department of Dermatology, Botucatu Medical School, UNESP-Univ. Estadual Paulista, Brazil.
authors.forename: Helio
authors.initials: H
authors.lastname: Mint
authors.affiliation: Department of Dermatology, Botucatu Medical School, UNESP-Univ. Estadual Paulista, Brazil.
authors.forename: Vania M
authors.initials: VM
authors.lastname: de Vasconcelos Machado
authors.affiliation: University of Texas Medical Branch, Galveston, TX.
authors.forename: Daneshvari R
authors.initials: DR
authors.lastname: Solanki
authors.forename: Rodrigo Moreira
authors.initials: RM
authors.lastname: Lima
authors.affiliation: Postgraduate Program in Anesthesiology, Botucatu Medical School, Unesp - Univ. Estadual Paulista, Brazil.
authors.forename: Ana L
authors.initials: AL
authors.lastname: de Carvalho
authors.forename: Lais H
authors.initials: LH
authors.lastname: Navarro
authors.forename: Eliana M
authors.initials: EM
authors.lastname: Ganem
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000009:adverse effects; D000818:Animals; D020927:Dexmedetomidine / Q000008:administration & dosage* / Q000009:adverse effects; D004195:Disease Models, Animal; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry; D007278:Injections, Spinal / Q000009:adverse effects / Q000379:methods; D008578:Meninges / Q000187:drug effects; D009048:Motor Skills / Q000187:drug effects; D059225:Nociception / Q000187:drug effects; D011817:Rabbits; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013346:Subarachnoid Space / Q000187:drug effects
chemical_list: D018712:Analgesics, Non-Narcotic; D005904:Glial Fibrillary Acidic Protein; D020927:Dexmedetomidine