Effects of phencyclidine on prepulse inhibition of acoustic startle response in the macaque

Rationale: Prepulse inhibition (PPI) of the acoustic startle response (ASR) provides an index of neurophysiological dysfunction in schizophrenia and a method for analyzing underlying neurochemical mechanisms. In rodents, phencyclidine (PCP) and other N-methyl-D-aspartate receptor (NMDAR) antagonists induce schizophrenia-like PPI deficits. Similar effects have recently been observed in a New World monkey species, Cebus apella. Objectives: The present study evaluates the degree to which similar effects are observed in an Old World monkey, M. fascicularis. Methods: An initial study evaluated effects of interstimulus interval on PPI amplitude and latency. A subsequent study evaluated effects of PCP (0.25 mg/kg IM) on PPI of the ASR. Results: Prepulses reduced bout the amplitude and latency of the ASR. PCP treatment prevented both effects without affecting amplitude or latency of the ASR itself. Conclusions: These results demonstrate that both amplitude reduction and latency facilitation are observed during PPI in the monkey and are disrupted by PCP.