Amphetamine-induced taste aversion learning in young and old F-344 rats following exposure to 56Fe particles

Abstract

Exposure to 56 Fe particles produces changes in dopaminergic function and in dopaminedependent behaviors, including amphetamine-induced conditioned taste aversion (CTA) learning. Because many of these changes are characteristic of the changes that accompany the aging process, the present study was designed to determine whether or not there would be an interaction between age and exposure to 56 Fe particles in the disruption of an amphetamine-induced CTA. One hundred and forty F-344 male rats 2-, 7-, 12-, and 16-months old, were radiated with 56 Fe particles (0.25-2.00 Gy, 1 GeV/n) at Brookhaven National Laboratory. Three days following irradiation, the rats were tested for the effects of radiation on the acquisition of a CTA produced by injection of amphetamine (3 mg/kg, i.p.). The main effect of age was to produce a significant decrease in conditioning day sucrose intake; there was no affect of age on the acquisition of the amphetamine-induced CTA. Exposing rats to 56 Fe particles disrupted the acquisition of the CTA produced by injection of amphetamine only in the 2-month-old rats. These results do not support the hypothesis of an interaction between age and exposure to 56 Fe particles in producing a disruption of amphetamine-induced CTA learning. As such, these results suggest that the aging produced by exposure to 56 Fe particles may be endpoint specific.

Interaction between age of irradiation and age of testing in the disruption of operant performance using a ground-based model for exposure to cosmic rays

“…Compared to young animals, middle-aged rats also show an increase in baseline anxiety at lower doses following exposure to 56 Fe particles . And, as observed with the current task, exposing old rats (=16 months of age) to HZE particles does not produce a deficit in performance greater than that which occurs as a function of the aging process Carrihill-Knoll et al 2005).…”

“…Specifically, research using S-D rats has shown a progressive deterioration in the performance of an operant responding task using an ascending FR reinforcement schedule following exposure to 56 Fe particles (Rabin et al 2005b, c). Similarly, previous research using Fischer-344 rats has shown that middle-aged rats (7 or 12 months of age) show a performance decrement in the acquisition of an amphetamine-induced conditioned taste aversion following exposure to a lower dose of 56 Fe particles than young rats (2 months of age) (Carrihill-Knoll et al 2005). Compared to young animals, middle-aged rats also show an increase in baseline anxiety at lower doses following exposure to 56 Fe particles .…”

“…Older animals show changes in elevated plus-maze performance and in amphetamine-induced taste aversion learning (Carrihill-Knoll et al 2005) at lower doses of 56 Fe particles than younger animals. However, a limitation of these endpoints is that performance can be measured at only a single point in time.…”

“…At both facilities, the rats were maintained on a 12:12 h light: dark cycle with food and water continuously available except as required by the experimental protocol. While at BNL, the rats were tested for the effects of irradiation on the acquisition of an amphetamine-induced conditioned taste aversion (Carrihill-Knoll et al 2005). Operant responding was tested at UMBC.…”

“…Because the current experiments were designed to determine whether or not there would be a decrease in the threshold dose needed to disrupt operant performance as a function of the age of irradiation/testing and whether there would be a progressive decrease in the dose needed to produce a performance decrement, the doses were selected that were equal to or lower than the threshold dose obtained in the prior experiments (Rabin et al 2005a, b, c). Because previous research had established doses that were likely to produce a deficit in performance as a function of increasing age Carrihill-Knoll et al 2005), not all subjects were tested at all doses.…”