title: The initial fall in arterial pressure evoked by endotoxin is mediated by the ventrolateral periaqueductal gray.
abstract: This study tested the hypothesis that the initial fall in arterial pressure evoked by lipopolysaccharide (LPS) is mediated by the ventrolateral column of the midbrain periaqueductal gray region (vlPAG). To test this hypothesis, the local anaesthetic lidocaine (2%; 0.1 μL, 0.2 μL or 1.0 μL), the delta opioid receptor antagonist naltrindole (2 nmol) or saline was microinjected into the vlPAG of isoflurane-anaesthetized rats bilaterally and LPS (1 mg/kg) or saline was administered intravenously 2 min later. Both lidocaine and naltrindole inhibited LPS-evoked hypotension significantly but did not affect arterial pressure in saline-treated control animals. Neither lidocaine nor naltrindole altered heart rate significantly in either LPS-treated or control animals. Microinjection of lidocaine or naltrindole into the dorsolateral PAG was ineffective. These data indicate that the vlPAG plays an important role in the initiation of endotoxic hypotension and further show that delta opioid receptors in the vlPAG participate in the response.
authors.affiliation: Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Millington
authors.affiliation: Department of Medical Pharmacology, Faculty of Medicine, Uludag University, Bursa, Turkey.
authors.forename: M Sertac
authors.initials: MS
authors.lastname: Yilmaz
authors.affiliation: Department of Pharmaceutical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Feleder
mesh_terms: D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects* / Q000502:physiology*; D004731:Endotoxins / Q000008:administration & dosage; D007276:Injections, Intraventricular; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D008297:Male; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004731:Endotoxins; D008070:Lipopolysaccharides
keywords: Endotoxin; delta receptor; endotoxin shock; lipopolysaccharide; opioid receptor; periaqueductal gray; preoptic area