BEHAVIORAL-CHARACTERISTICS OF MICRENCEPHALIC RATS IN HIGH AND LOW SHUTTLEBOX AVOIDANCE LINES

Rats of two lines, selectively bred for high and low shuttlebox avoida nce response, and unselected line of the Sprague-Dawley (SD) rats were given an IP injection of methylnitrosourea (MNU) at 5 mg/kg on day 13 of gestation. Their offspring, all with micrencephaly, were subjected to the Biel maze, shuttlebox avoidance, and wheel cage activity tests during 6 to 9 weeks of age. Results from micrencephalic rats were com pared with those obtained from untreated control offspring of the resp ective lines. The MNU-treated offspring in each line made more errors than controls in the Biel maze, and showed similar avoidance responses to controls in the shuttlebox test. Line differences in effects of MN U treatment were observed in elapsed time in the straight channel, ext inction of shuttlebox avoidance responses, and activity in the wheel c age. These line differences in effects of MNU treatment may be related to control baseline levels of behavior in which the three lines diffe red widely, and suggest that the behavioral effects of prenatal MNU tr eatment vary in rats depending on the lines used. (C) 1997 Elsevier Sc ience Inc.