BEHAVIORAL AND NEURAL BIOLOGY 51, 145-164 (1989) Rats (Rattus norvegicus) Selectively Bred to Differ in Avoidance Behavior Also Differ in Response to Novelty Stress, in Glycemic Conditioning, and in Reward Contrast CHARLES F. FLAHERTY AND GRACE A. ROWAN 1 Rutgers University The behavior of the Syracuse high avoidance (SHA) and Syracuse low avoidance (SLA) rats, selectively bred by Brush (F. R. Brush, J. C. Froehlich, & P. Sakellaris, 1979, Behavior Genetics, 9, 309-316) to differ in avoidance behavior, was examined in several different tasks. The SLA rats showed a greater elevation in plasma glucose when exposed to a novel environment; after 7 days of exposure to this environment there was evidence of habituation in the SHA rats but not in the SLA rats; the SHA rats showed a hyperglycemic conditioned response in a glycemic conditioning procedure, the SLA rats showed no evidence of conditioning but had higher overall levels of plasma glucose; both strains showed reliable successive negative contrast effects in consummatory behavior when shifted from 32 to 4% sucrose, but the contrast was larger in the SLA rats; the administration of chlordiazepoxide eliminated negative contrast in the SLA rats but had no effect on contrast in the SHA rats; and the SLA rats were reliably heavier than the SHA rats. The behavioral differences were considered in the context of differences in emotional reactivity between the two strains. © 1989 Academic Press, Inc. Brush et al. (e.g., Brush, Froehlich, & Sakellaris, 1979; Brush, 1985) have selectively bred two lines of rats that differ in active avoidance learning. The performance of the Syracuse high avoidance (SHA) rats substantially exceeds that of the Syracuse low avoidance (SLA) rats, and this difference is not due to differences in activity level, sensory capacity, or general learning ability (Brush, 1985; Brush et al., 1985). There are, however, apparent differences in the emotional reactivity of the two strains. The SLA animals defecate more in the open field than the SHA animals, show more prolonged thigmotaxis, and show suppressed responding at lower shock intensities in a conditioned emotional response i This research was supported by grants from the National Institute of Mental Health (MH40489), the National Science Foundation (BNS 83-02838), and the Charles and Johanna Busch Memorial Fund. Address correspondence and reprint requests to Charles Flaherty, Psychology Department, Busch Campus, Rutgers University, New Brunswick, NJ 08903. 145 0163-1047/89 $3.00 Copyright © 1989 by Academic Press, Inc. All rights of reproduction in any form reserved.