抄録
The ambient temperature (Ta) of the delivery room has been under discussion because high Ta is suspected to relate to neonatal encephalopathy. We investigated the effect of Ta on the voluntary motion ability of adult rat models after neonatal hypoxic-ischemic (HI) insult. Under inspired anesthesia, the left carotid artery of a 7-day-old rat was ligated followed by hypoxic insults made by delivering 8% oxygen at 40 °C for 15 min. The rats were returned to their mother for 1 hr, and then placed in a box at one of two Ta of 40 °C (n=5; HY group) and 34 °C (n=5; HI group). A sham group (n=5; S group) was also established. Three months later, the voluntary motion ability of rats was assessed using an activity wheel. The device was composed of a rotary cage for free running with an attached cage with free access to food and water with a 12:12 LD cycle. We measured the voluntary motion of rats for 72 consecutive hrs. Self-motion was assessed every 24 hrs from the number of rotations. After habituation to the device, we put a rat from one of the three groups in the cage. The S group rotated the wheel up to 1,200 from 500. The HY group increased the number of rotations during the first 48 hours and decreased afterwards. Although no significant difference was observed between rotation times within the HY group and the S group, rotation times in the HI group were significantly fewer than those in the HY group and S group. These results suggest that the HI group may not be accustomed to the sudden change of environment produced by the device. [J Physiol Sci. 2008;58 Suppl:S103]
