Learning and memory deficits in rats following exposure to 3,3'-iminodipropionitrile

Rats were examined using a learning and memory test battery 4 weeks following exposure to 3,3'-iminodipropionitrile (IDPN). Initial testing revealed deficits in olfactory discrimination and passive avoidance (PA) conditioning. In order to dissociate learning and performance effects, additional tests were conducted. First, to rule out the possibility that IDPN reduced the aversiveness of foot shock, rats were tested in a simple shock sensitivity paradigm. The results indicated no change in shock sensitivity produced by IDPN. Second, to determine if the hyperactivity produced by IDPN was responsible for deficits in conditioning, several additional tests were conducted including (a) repeated-trials active avoidance (AA) and PA conditioning, (b) a PA study which included both a 1- and 24-hr training-testing interval, and (c) long-delay flavor-aversion conditioning. Rats treated with IDPN required more conditioning trials to reach criterion on both AA and PA procedures suggesting that they were capable of performing the required response but acquired those responses at a much slower rate. The deficits in PA conditioning were similar at both the 1- and 24-hr training-testing interval. Finally, the effects of IDPN on flavor-aversion conditioning depended on the delay separating flavor intake and lithium administration during conditioning. Rats treated with IDPN demonstrated robust flavor aversions when trained with a 30-min but not with a 6-hr delay. In summary, the neurotoxic profile of effects produced by IDPN must be expanded to include a prominent cognitive component characterized by protracted deficits in learning and memory capacity. The present experiment illustrates how chemically induced disruption of learning and memory produced by IDPN can be experimentally dissociated from associate neurological symptoms using a simple, routine battery of neurobehavioral tests.