Effects of isolation on adulthood on pain and frustration.

Abstract

Animals isolated in adulthood present behavioral indicators of chronic stress, anxiety and hypoalgesia. While there is a wide range of treatments that demonstrate the relationship between frustration, pain and anxiety, there are few studies of the effect of isolation in adulthood on the devaluation of incentives. Isolated (ISO) and grouped (Group) rats from 60 days of age were evaluated on the hot plate test (HP) and the effect of partial reinforcement on consummatory successive negative contrast (ERP-cSNC). In the ERP-cSNC, two groups of animals (ISO- Group) were given a preshift phase under a continuous reinforcement schedule (CR, 32% consumption of sugar solution) and two other groups (ISO- Group), under a partial reinforcement schedule (PR, 50% reinforced and unreinforced 32%); in postshift phase all groups received a 4% solution. Goal tracking time was measured. ISO rats showed hypoalgesia in HP. In the ERP-CSNC, both ISO and Group rats trained in PR showed greater persistence of goal tracking time during the postshift phase. These results are discussed considering previous research and the possible mechanisms involved.