J Korean Neurol Assoc.  1992 Sep;10(3):268-287.

The Effect of Naloxone on the Size of Infarction and the Regional Cerebral Blood Flow (rCBR) in Focal Cerebral Ischemia of Rats

• Hong SB
• Rha JH
• Yoon BW
• Roh JK
• Lee SB
• Kim SE
• Lee MC

Abstract

A rat model of focal cerebral ischelma has been established by mhe tecbnique of elecvrocamtery for me middle oerebral artery occlusion (MCAO). We investigated mhe effect of naloxone pretreatment on the size of infarction and the regional cerebral blood flow (rCBF) Another purpose of this study was to determine the effecbve dose (high-or lowdose) in focal cerebral ischemia. The rats were given Img/Kg I.v. (low-dose), 4mg/Kg I.v. (high-dose) of naloxone 30 min before MCAO and infused continuously with 0.5mg/Kg/hr (low dose) or 2mg/Kg/hr (high-dose) over next I hour by am infusion pump. The control group was given normal salin of the same amount by the same method. Dunng the peDod of saline amd naloxone infusion, mean arterial blood pressure was monitored. Arterial blood gas analysis and blood glucose measuremert were performed just after MCAO. The rectal temperature of rat was maintained within 37)0.5C by a heating lamp. Twenty-fow hours after MCAO, eight 2mm-thick coronal sections of one rat brain were stained by TTC solution and the size of infarction was described as the percentage of ipsilateral hemisphere. The rCBFs were measured by an autoradiography using 14C-iodoantipyrine and the chamges of rCBFs were analyzed by three methods of (1) rCBF ratio, (2) 1 mm-serial rCBF measurement of cerebral cortex, and (3) areas of rCBF below critical values(<25, 25-50, <50ml/100g/min). The results were as follows; 1. There was no significamt chamge of blood pressure during the infusion of saline. Iow-dose and high-dose naloxones 2. Arterial blood gas amalysis amd blood glucose measurement showed that there were no significant differences of pH, PC02, PO2 and blood glucose between saline and low dose and high-dose naloxone groups 3. High-dose naloxone pretreatment reduced significantly the size of infarction(p<0.05 vs saline-treated group by Mann-Whitney U test). 4. High-dose naloxone pretreatment improved significantly the rCBF ratios of caudate head and CA 3 area (p<0.05 vs. saline-treated group by Mann-Whitney U test) There was no significant improvement of rCBF ratios in the low-dose naloxone treated group. 5. One-mm serial rCBF measurement of cerebral cortex indicated that while low-dose naloxone group showed no improvement of rCBF of cerebral cortex, high-dose nalox one pretreatment produced an improvement of rCBF in penumbra and its neighboring area 6. The area below 25ml/100g/min or rCBF was reduced significantly by high-dose naloxone pretreatment(high-dose naloxone group: 15.0+4.1mm2, saline group:23.3)5.3 mm2, p <0.05). In summary these results indicate that high-dose naloxone pretreatment reduced the size of infarction and improved the rCBFs in the focal cerebral ischemia of rats.

MeSH Terms

Animals
Arterial Pressure
Arteries
Autoradiography
Blood Gas Analysis
Blood Glucose
Blood Pressure
Brain
Brain Ischemia*
Cerebral Cortex
Head
Heating
Hot Temperature
Hydrogen-Ion Concentration
Infarction*
Infusion Pumps
Models, Animal
Naloxone*
Rats*
Blood Glucose
Naloxone