CER suppression, passive-avoidance learning, and stress-induced suppression of drinking in the Syracuse high- and low-avoidance strains of rats (Rattus norvegicus).

Abstract

The Syracuse strains of Long-Evans rats were selectively bred for good (SHA) or poor (SLA) avoidance learning in a two-way shuttle box, which resulted in a phenotypic difference that is correlated with behavior patterns indicative of emotional reactivity, SLA animals showing evidence of greater emotional reactivity than SHA animals. The first three experiments examined conditioned suppression of bar pressing and compared paired and unpaired conditioned- and unconditioned-stimulus presentations to evaluate the influence of conditioning versus primary aversive stimulation on baseline responding. SLA animals acquired conditioned suppression faster than SHA animals and also showed greater suppression of baseline responding than SHA animals. In Experiment 4, SLA animals learned a passive-avoidance task faster than SHA animals. In Experiment 5, SLA animals showed greater stress-induced suppression of drinking a weak quinine solution than SHA animals. These data are consistent with the hypothesis that SLA animals are more emotionally reactive than SHA animals.

Corticotropin-Releasing Factor Receptors Couple to Multiple G-Proteins to Activate Diverse Intracellular Signaling Pathways in Mouse Hippocampus: Role in Neuronal Excitability and Associative Learning

“…Our results add to the existing data showing that the genetic background can affect the behavioral phenotypes of genetically modified mice generated for elucidating the molecular basis of learning and memory (McNamara et al, 1998;Dobkin et al, 2000;Dockstader and van der Kooy, 2001). In view of the contribution of the hippocampus to numerous forms of learning (for review, see Kesner et al, 2000;Kim and Baxter, 2001;Maren, 2001) and the fact that h/rCRF represents an early signal in the neuroendocrine response to stress (Koob and Bloom, 1985), our present findings may represent an important step toward understanding the cellular and molecular processes underlying interstrain variability concerning the impact of stress on learning and memory (Brush et al, 1988;Francis et al, 1995;Palmer and Prinz, 1999).…”

Taste and emotionality in rats selectively bred for high versus low saccharin intake

“…Rats selectively bred on an emotionality phenotype (Gray, 1987) also dif-fer in saccharin consumption and stress-induced suppression ofquinine intake (Brush et al, 1988). The more emotionally reactive lines drink less saccharin and less quinine.…”

The Syracuse Strains, Selectively Bred for Differences in Active Avoidance Learning, may be Models of Genetic Differences in Trait and State Anxiety

“…This idea of a difference in trait anxiety was confirmed quantitatively using a Pavlovian aversive conditioning paradigm (conditioned emotional response, CER, suppression) in which the intensity of conditioned fear (the CER) is measured by the degree of suppression of ongoing appetitive behavior in the presence of a signal which precedes inescapable, unavoidable shock (Brush et al, 1988). Specifically, rats are trained to press a lever for food reward on a variable-interval schedule, which produces a relatively steady rate of lever-press responses.…”

“…To assess the generality of this effect we shifted to an instrumental learning procedure which also requires suppression of ongoing behavior, i.e. the passive avoidance paradigm (Brush et al, 1988). Specifically, rats of the two strains were trained to press a lever for food reward on a fixed-ratio 1 schedule, i.e.…”

“…Using a consummatory response as in the Flaherty and Rowan experiment, we assessed the effects of a mild stressor (being handled and weighed) on consumption of a very mildly aversive quinine solution (Brush et al, 1988). We used Dess's paradigm of several days of habituation to drinking water in a brief (8-min) session in the morning followed by a longer drinking session in the afternoon which precludes dehydration if drinking in the morning happens to be suppressed .…”