Social interaction of rats is related with baseline prepulse inhibition level.

Abstract

The symptoms of schizophrenia are evaluated in three general categories: positive, negative and cognitivesymptoms. Disruption of prepulse inhibition (PPI) of the acoustic startle reflex is commonly used to modelpositive and cognitive symptoms in experimental animals. On the other hand, deficient social interaction(SI) is a common model of negative symptoms. Here we tested whether PPI provides information aboutnegative symptoms by using a SI test. Baseline PPI and its relation with anxiety-like behavior were alsoexamined with elevated plus maze (EPM) test. In the first experiment, baseline PPI levels of 30 Wistarrats were measured and animals with the highest 1/3 and the lowest 1/3 of PPI scores were respectivelyassigned in high-inhibitory (HI) and low-inhibitory (LI) groups. Subsequently, rats in the HI and LI groupswere paired with animals from the same group and tested for SI. In the second experiment, another batchof animals was assigned to HI and LI groups and they were investigated in the EPM test. The results demon-strate a significant difference between the PPI values of HI and LI groups. Both the SI time and the movingdistance of LI rats were significantly lower, and the average distance between rat pairs was significantlylonger than HI rats. In the EPM test LI and HI rats showed similar levels of anxiety-like behaviors, howeverour results imply that performance of the rats in the SI test is related to baseline PPI levels. Thus PPI testcan provide predictive information about the outcome of animal models for negative symptoms in rats.