The combined neuroprotective effects of lidocaine and dexmedetomidine after transient forebrain ischemia in rats.
BACKGROUND
We investigated whether coadministration of lidocaine and dexmedetomidine would reduce brain injury following transient forebrain ischemia in rats to a greater extent than either drug alone.


METHODS
Adult male Sprague-Dawley rats were anesthetized with halothane to maintain normocapnia and normoxia. Rats received subcutaneous injection of saline 1 ml/kg, lidocaine 10 mg/kg, dexmedetomidine 3 microg/kg, or lidocaine 10 mg/kg plus dexmedetomidine 3 microg/kg. Thirty minutes after the drug injection, forebrain ischemia was induced by hemorrhagic hypotension and occlusion of the bilateral carotid arteries, and was confirmed by isoelectric EEG. At the end of 10-min ischemia, rats were reperfused. The same dose of drugs was administered 3, 24, and 48 h after ischemia. Neurological examination was done at 1, 2, and 7 days after ischemia. Seven days after ischemia, the brain was stained with hematoxylin and eosin. We counted ischemic cells in the CA1 hippocampal region, striatum, and cerebral cortex. We also measured extracellular glutamate and norepinephrine concentration in hippocampal CA1 in the four groups.


RESULTS
As compared with saline-treated rats, rats receiving dexmedetomidine plus lidocaine showed less than neurological deficit scores at 2 and 7 days after ischemia, and had less ischemic cells in the CA1 region. However, administration of dexmedetomidine plus lidocaine did not alter the area under the glutamate concentration curve and norepinephrine concentration during ischemia in the CA1 region, compared with saline-treated rats.


CONCLUSIONS
Our results suggest coadministration of lidocaine and dexmedetomidine improves the neurological outcome without alteration of glutamate and norepinephrine concentrations during forebrain ischemia in rats.
Goyagi
T
T
Department of Anesthesia and Intensive Care Medicine, Akita University School of Medicine, Akita, Japan. tgoyagi@doc.med.akita-u.ac.jp
Nishikawa
T
T
Tobe
Y
Y
Masaki
Y
Y
D000779:Anesthetics, Local / Q000627:therapeutic use*; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D020927:Dexmedetomidine / Q000627:therapeutic use*; D004338:Drug Combinations; D018698:Glutamic Acid / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006993:Hypnotics and Sedatives / Q000627:therapeutic use*; D002546:Ischemic Attack, Transient / Q000188:drug therapy*; D008012:Lidocaine / Q000627:therapeutic use*; D008297:Male; D017551:Microdialysis; D018696:Neuroprotective Agents; D018377:Neurotransmitter Agents / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D016548:Prosencephalon / Q000098:blood supply / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D000779:Anesthetics, Local; D004338:Drug Combinations; D006993:Hypnotics and Sedatives; D018696:Neuroprotective Agents; D018377:Neurotransmitter Agents; D018698:Glutamic Acid; D020927:Dexmedetomidine; D008012:Lidocaine; D009638:Norepinephrine