Alfentanil-induced hypermetabolism, seizure, and histopathology in rat brain.
We evaluated the effect of alfentanil on hippocampal glucose utilization and histopathology associated with alfentanil-induced seizures. Three separate experiments were performed. First, anesthetized, paralyzed Long-Evans rats (n = 15; 5 rats per group) were mechanically ventilated and randomly assigned to three groups: (a) control, 70% N2O and 30% O2 continued for 1 h; (b) low-dose alfentanil (150 micrograms/kg i.v. bolus), followed by infusion at 15 micrograms.kg-1 x min-1 for 1 h without N2O; or (c) high-dose alfentanil (1000 micrograms/kg i.v. bolus), followed by infusion at 100 micrograms.kg-1 x min-1 for 1 h without N2O. After 1 h, [6-14C]glucose was injected intravenously for autoradiography. With high-dose alfentanil, there was increased glucose utilization in the ventral hippocampus and the lateral septal nucleus. In the second experiment, anesthetized, paralyzed Sprague-Dawley rats (n = 12; 4 rats per group) were mechanically ventilated, underwent insertion of hippocampal depth electrodes, and were randomly assigned to three groups: (a) control, 70% N2O and 30% O2; (b) low-dose alfentanil (150 micrograms/kg i.v. bolus), with 70% N2O and 30% O2; or (c) high-dose alfentanil (1000 micrograms/kg i.v. bolus), with 70% N2O and 30% O2. An epileptiform pattern was observed on hippocampal and subdermal electroencephalographic recordings in both alfentanil groups. In the third experiment, anesthetized, paralyzed Sprague-Dawley rats (n = 20) were mechanically ventilated and assigned to two groups: (a) control, 70% N2O and 30% O2 (n = 5) or 100% O2 (n = 5) continued for 1 h; or (b) alfentanil (2000 micrograms/kg i.v. bolus), followed by infusion at 33.3 micrograms.kg-1 x min-1 for 1 h with 100% O2. After tracheal extubation, the rats recovered overnight. Light-microscopic evaluation revealed hippocampal or amygdaloid damage in 6 of the 10 alfentanil-treated rats. High doses of alfentanil administered to rats can produce limbic system seizure activity with hypermetabolism associated with neuropathologic lesions.
Kofke
W A
WA
Department of Anesthesiology and Critical Care Medicine, University of Pittsburgh School of Medicine, PA 15261.
Garman
R H
RH
Tom
W C
WC
Rose
M E
ME
Hawkins
R A
RA
D015760:Alfentanil / Q000633:toxicity*; D000679:Amygdala / Q000473:pathology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002540:Cerebral Cortex / Q000473:pathology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced* / Q000473:pathology; D013788:Thalamus / Q000473:pathology
D001786:Blood Glucose; D015760:Alfentanil