Microstructural analysis of chlordiazepoxide's effects on food preference behavior in Roman high-, control- and low-avoidance rats

Abstract

The effects of chlordiazepoxide (CDP) on feeding performance and on rearing activity were investigated using a food preference test in three Roman strains: Roman Low Avoidance (RLA), Roman Control Avoidance (RCA), and Roman High Avoidance (RHA). The aims of the study were to assess the responses of the three strains to a free choice of familiar and novel foods following a period of food deprivation, and to answer the important psychopharmacogenetic question of whether or not the strains would display differential responsivity to CDP challenges. No strain differences were discovered in relation to the latency to begin feeding, the response to familiar food, or the frequency of rearing in the 10 min food preference test. However, clear differences did emerge in relation to the animals' responses to novel foods. In contrast to the RCA and RHA lines, RLA rats sampled a greater variety of the available foodstuffs, and devoted a greater duration to the consumption of novel foods. Despite previous reports that under conditions of mild stress, RLA animals display greater emotionality, there was no evidence from the present study to show that RLA animals were more neophobic (a possible index of emotionality) than the other two Roman lines. Indeed, the evidence clearly suggests that RLA animals may under certain circumstances pay greater attention to novel cues. CDP treatments produced reductions in rearing, reductions in eating latency, and strongly potentiated the time devoted to feeding. Effects of CDP treatments on familiar and novel foods were dissociable. CDP at 10 mg/kg reliably increased the novel food feeding duration, an effect occurring mainly within the first 5 min of the test. CDP at 5 and 10 mg/kg reliably increased familiar food feeding duration, but this effect was in evidence for both halves of the test. Despite the multiple significant effects of CDP treatments in the food preference test, as well as the capacity of the test to demonstrate selective behavioral differences between the Roman lines, no evidence emerged for a significant interaction between strains and CDP treatments. So far as the behaviors measured in the food preference test were concerned, there was no differential sensitivity separating the Roman strains in response to CDP treatments.