title: Prostanoids modulate opioid cerebrovascular responses in newborn pigs.
abstract: The influences of opioids on pial arteriolar diameter and cortical periarachnoid cerebrospinal fluid prostanoid concentration were investigated in piglets with closed cranial windows. Methionine enkephalin (10(-12)-10(-6) M) increased pial arteriolar diameter (139 +/- 4, 149 +/- 3, 178 +/- 3 microns, for control, 10(-12), and 10(-6) M, respectively). Leucine enkephalin produced similar pial arteriolar dilation. In contrast, dynorphin elicited dilation during normotension and constriction during hypotension. beta-Endorphin (10(-12)-10(-6) M) decreased pial arteriolar diameter (137 +/- 6, 128 +/- 6, 92 +/- 7 microns, for control, 10(-12) and 10(-6) M, respectively). All four opioids increased cerebrospinal fluid 6-keto-prostaglandin (PG)F1 alpha, PGE2, PGF2 alpha and thromboxane B2. Indomethacin (5 mg/kg i.v.) blocked methionine and leucine enkephalin and dynorphin-induced pial arteriolar dilation, but potentiated beta-endorphin-induced constriction and the constriction caused by dynorphin in hypotensive piglets. These data indicate that prostanoids modulate opioid effects on the cerebral vasculature.
authors.affiliation: Laboratory for Research in Neonatal Physiology, University of Tennessee, Memphis.
authors.forename: W M
authors.initials: WM
authors.lastname: Armstead
authors.forename: R
authors.initials: R
authors.lastname: Mirro
authors.forename: D W
authors.initials: DW
authors.lastname: Busija
authors.forename: C W
authors.initials: CW
authors.lastname: Leffler
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001099:Arachnoid / Q000098:blood supply; D001160:Arterioles / Q000033:anatomy & histology / Q000187:drug effects; D001784:Blood Gas Analysis; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004399:Dynorphins / Q000008:administration & dosage / Q000494:pharmacology; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000008:administration & dosage / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D010841:Pia Mater / Q000098:blood supply; D011453:Prostaglandins / Q000096:biosynthesis / Q000134:cerebrospinal fluid / Q000502:physiology*; D013552:Swine; D014664:Vasodilation / Q000187:drug effects; D001615:beta-Endorphin / Q000494:pharmacology
chemical_list: D004723:Endorphins; D011453:Prostaglandins; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D004399:Dynorphins; D007213:Indomethacin