Changes of Local Cerebral Glucose Utilization after Repeat Exposure to Isofourane in the Rat

Park, Chong Min

Abstract

The effect of repeat exposure to 1soflurane on cerebral glucose utilization was studied by quantita-tive autoradiography using 19 male Sprague-Dawley rats. Local cerebral glucose utilization was compared between a conscious control and an Isoflurane anesthetized rat (single exposure, repeat exposure for 1 week and repeat exposure for 2 weeks) The results were as follows: 1) There was a small decrease of blood pressure in the anesthetized group, but it was within the range of autoregulation. The PaO2and PaCO2 were influenced by artificial ventilation in the anesthetized group but remained in normal range. 2) 1-CMRg decreased in most regions of the anesthetized group. A larger decreased glucous utilized region was observed with repeat exposure for 1 week than 2 weeks when compared to comscious control. but more regions involved decreased glucose utilization in the 2 week exposure group when compare to the single exposure. In particular the sensory motor cortex, and cerebral assocition areas were most severely affected. 3) There was no statistical significant difference between the 1 week and the 2 week exposure group. However significant decreased glucous utilization was seen on anterior thalamus in the 2 week exposure group. 4) Some regions with increased glucose utilization were the cerebellum nucleus, vestibular nucleus, hippocampus molecular layer and havenula in the single exposure group, Ansignifecant increase was seen in superior colliculus superficialis, anterior thalamus and hippocampus molecular layer in the repeat exposure group. 5) The order of decreased glucose utilization by funtional unit was: myelinated fiber>auditory system>visual system: other regions were ordered differently between groups. 6) The order of decreased glucose utilization according to anatomical regions were: telence- phalone > diencephalon > mesencephalone > metencephalone > myelencephalone in all three groups; i. e, rostral to caudal gradient of glucous utilization was well-maintained in-single or repeat-exposured groups. 7) There were significantly prominent regions appearing in anesthetized rat brains. They were havenular, havenulo-interpeduncular nucleus, and fornix. They were all preserved in repeat-exposure rats.