Effects of chronic intrathecal infusion of a ∂ opioid agonist in dogs

Kjersti Horais, Victor J Hruby, Steven Rossi, Dasa Cizkova, Carol Meschter, Robert T Dorr, Tony L. Yaksh

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

To define the effects of chronic spinal exposure to a highly selective ∂ opioid agonist c[DPen2, DPen5]enkephalin (DPDPE), adult beagles were prepared with chronic lumbar intrathecal catheters. Groups of dogs received intrathecal infusions (100 μl/h) of saline (vehicle), DPDPE 3 mg/ml or 6 mg/ml for 28 days. Over the 28-day period, saline or 3 mg/ml showed minimal changes in neurological function, whereas in the 6 mg/ml animals, prominent hind limb dysfunction evolved over the 28-day interval. Histopathology in control animals displayed a modest pericatheter reaction considered normal for this model. Dogs receiving DPDPE (three of four at 6 mg/ml and one of four at 3 mg/ml) but not saline (zero of four) developed large inflammatory masses (granulomas) in the intrathecal space located proximal to the catheter tip. In these masses, severe chronic inflammatory changes in combination with necrosis and fibrosis was detected. Occasional focal destruction of neuropil was detected also in the adjacent spinal cord parenchyma. These masses contained extensive accumulation of mouse antihuman macrophages (MAC)-positive inflammatory cells expressing tumor necrosis factor-α (TNF-α), revealing infiltration of macrophages, granulocytes, and monocytes. In separate animals, prepared with dual intrathecal catheters, lumbar CSF was sampled at specified time points following intrathecal bolus (3 mg/ml) and 24 h DPDPE infusion (3 mg/ml and 6 mg/ml). Steady-state cerebrospinal fluid (CSF) DPDPE levels were 18.6 ± 1.0 and 22.6 ± 4.0 μg/ml for 3 mg/ml and 6 mg/ml infusions respectively. These results indicate that this ∂ opioid agonist DPDPE produces a concentration and time-dependent formation of an intrathecal inflammatory mass.

Original languageEnglish (US)
Pages (from-to)263-275
Number of pages13
JournalToxicological Sciences
Volume71
Issue number2
DOIs
StatePublished - Feb 1 2003

Fingerprint

Enkephalins
Opioid Analgesics
Dogs
Catheters
Cerebrospinal fluid
Animals
Macrophages
Cerebrospinal Fluid
Neuropil
Granuloma
Infiltration
Granulocytes
Monocytes
Spinal Cord
Fibrosis
Necrosis
Extremities
Tumor Necrosis Factor-alpha
Cells

Keywords

  • ∂ opioid agonist
  • Dog
  • DPDPE
  • Granuloma
  • Intrathecal

ASJC Scopus subject areas

  • Toxicology

Cite this

Effects of chronic intrathecal infusion of a ∂ opioid agonist in dogs. / Horais, Kjersti; Hruby, Victor J; Rossi, Steven; Cizkova, Dasa; Meschter, Carol; Dorr, Robert T; Yaksh, Tony L.

In: Toxicological Sciences, Vol. 71, No. 2, 01.02.2003, p. 263-275.

Research output: Contribution to journalArticle

Horais, Kjersti ; Hruby, Victor J ; Rossi, Steven ; Cizkova, Dasa ; Meschter, Carol ; Dorr, Robert T ; Yaksh, Tony L. / Effects of chronic intrathecal infusion of a ∂ opioid agonist in dogs. In: Toxicological Sciences. 2003 ; Vol. 71, No. 2. pp. 263-275.
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