Chronic intrastriatal administration of quinolinic acid produces transient nocturnal hypermotility in the rat

Adult male Sprague-Dawley rats were exposed to 15 mM quinolinic acid solution or vehicle via bilateral intrastriatal dialytic administration for a period of 3 weeks. Animals were tested twice weekly for spontaneous behaviors and nocturnal activity during the 3-week dialysis period and for the 3 weeks following cessation of the dialysis period treatment. Nocturnal activity increased significantly (p < 0.005) during the first week of quinolinic acid exposure compared to vehicle exposed animals. The increase in nocturnal activity subsequently diminished to near control levels by the end of the 3-week dialysis period. During the 3-week period following cessation of dialysis, no significant differences were seen between quinolinic acid and vehicle-exposed animals. In addition, no differences were noted between quinolinic acid and vehicle-exposed animals in spontaneous behaviors either in the 3-week dialysis period or the 3-week period following cessation of dialysis. The results of this study are in agreement with other recent findings of transient nocturnal hyperactivity following striatal damage in rats. One possible explanation for the transient nature of this behavioral change is a transient effect of excitotoxicity in the striatum. During initial exposure to excitotoxins, nocturnal hypermotility could result from premorbid changes in neural function. With continued exposure, this behavioral effect may then diminish as a result of subsequent widespread striatal cell death.