Sex differences in the acoustic startle response and prepulse inhibition in Wistar rats

The prepulse inhibition paradigm (PPI) is based on the phenomenon that the acoustic startle response (ASR) to an acoustic stimulus is reduced when the stimulus is preceded by a weak prepulse. It has been shown that PPI is dramatically disrupted in patients with schizotypic disorders. Since PPI can be easily tested in animals as well as in humans it is a widely used model to investigate the neurobiological mechanisms underlying those disorders. In humans it has been demonstrated that men show increased PPI at weak prepulses relative to women. Only very few studies have investigated PPI sex differences in rats and these report negative findings. Studies are reported on here where consistent differences have been found in ASR and PPI between adult male and female Wistar rats. Compilation of data from a series of experiments demonstrates that ASR and PPI are both greater in males than in females in this rat strain, a finding which is largely in line with the human evidence. This study therefore adds weight to the argument that PPI of the ASR provides an animal model with high validity for the study of important human disorders which are characterized by sensorimotor gating deficits.