title: Intrathecal catheterization influences tolerance to chronic morphine in rats.
abstract: We evaluated the antinociceptive effects of acute and chronic morphine administered spinally via lumbar puncture in intrathecally catheterized and sham-surgery rats. The effects of acute morphine did not differ between groups. Catheterized rats developed tolerance to chronic morphine more rapidly, compared with sham and naive rats. Therefore, catheter presence facilitated development of opioid antinociceptive tolerance. Spinal astrogliosis, determined by measurement of 3-dimensional cell volumes, was observed in catheterized rats as indicated by significantly larger cell volumes compared with surgery-naive controls. Gliosis induced by chronic intrathecal morphine administered to surgery-naive animals was comparable to that observed in saline-treated catheterized rats.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada.
authors.forename: Theresa-Alexandra
authors.initials: TA
authors.lastname: Mattioli
authors.forename: Maaja
authors.initials: M
authors.lastname: Sutak
authors.forename: Brian
authors.initials: B
authors.lastname: Milne
authors.forename: Khem
authors.initials: K
authors.lastname: Jhamandas
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Cahill
mesh_terms: D000775:Anesthesia, Spinal / Q000379:methods; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology; D002404:Catheterization / Q000379:methods; D002408:Catheters, Indwelling; D004361:Drug Tolerance / Q000502:physiology*; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D009020:Morphine