Effects of Repeated Sublethal VX Exposure on Operant Time Estimation in Rats
Abstract
Thirty-two rats were trained to stability under a differential-reinforcement-of-low rates 20-s schedule with a sucrose pellet as the reinforcer and a lever press as the operant response. The exposure groups were saline, 0.3, 0.4, and 0.5LD50 VX delivered subcutaneously. Injections were given for three consecutive days and neurobehavioral evaluations were conducted throughout the week of exposure and for two weeks following. Toxic signs scores were significantly higher in the 0.4 and 0.5LD50 groups. Additionally, body weight, number of responses, and reinforcers earned were significantly lower in the 0.4 and 0.5LD50 groups. Interresponse times changed in the VX-exposed groups. Operant performance recovered to pre-exposure levels by the first day of the following week and remained stable. No persistent or delayed onset neurobehavioral effects were observed following discontinuation of VX injections. Repeated sublethal exposure to VX produced robust but transient response suppression in the 0.4LD50 and 0.5LD50 groups that recovered within two days of terminating the VX exposures. Toxic signs and body weight corroborated the intoxication observed, but these measures were less sensitive than the operant performance measures. Reinforcer-retrieval latency was a sensitive measure of impairment, revealing a deficit in the 0.3LD50 group as early as the second day of exposure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2007
- Accession Number
- ADA501468
Entities
People
- David W. Kahler
- John C. Lamont
- Lucille A. Lumley
- Todd M. Myers
Organizations
- United States Army Medical Research Institute of Chemical Defense