Reproducibility via coordinated standardization: a multi-center study in a Shank2 genetic rat model for Autism Spectrum Disorders

Inconsistent findings between laboratories are hampering scientific progress and are of increasing public concern. Differences in laboratory environment is a known factor contributing to poor reproducibility of findings between research sites, and well-controlled multisite efforts are an important next step to identify the relevant factors needed to reduce variation in study outcome between laboratories. Through harmonization of apparatus, test protocol, and aligned and non-aligned environmental variables, the present study shows that behavioral pharmacological responses in Shank2 knockout (KO) rats, a model of synaptic dysfunction relevant to autism spectrum disorders, were highly replicable across three research centers. All three sites reliably observed a hyperactive and repetitive behavioral phenotype in KO rats compared to their wild-type littermates as well as a dose-dependent phenotype attenuation following acute injections of a selective mGluR1 antagonist. These results show that reproducibility in preclinical studies can be obtained and emphasizes the need for high quality and rigorous methodologies in scientific research. Considering the observed external validity, the present study also suggests mGluR1 as potential target for the treatment of autism spectrum disorders.

Pharmacological and genetic evidence indicates that combined inhibition of NR2A and NR2B subunit containing NMDA receptors is required to disrupt prepulse inhibition

RATIONALE

Glutamate signalling through the N-methyl-D-aspartate (NMDA) receptor is of critical importance for normal central nervous system (CNS) function, as indicated by the marked behavioural disturbances produced by non-subtype selective NMDA antagonists such as dizocilpine (MK-801).

OBJECTIVE

The present studies were designed to investigate the involvement of the two major NMDA receptor subunits in the central nervous system, i.e. NR2A and NR2B, on sensorimotor gating in mice.

METHODS

These experiments utilised the non-subtype-selective NMDA antagonist dizocilpine, a line of NR2A-KO mice and the selective NR2B antagonist Ro 63-1908, in the study of pre-pulse inhibition of the startle response (PPI).

RESULTS

The non-selective NMDA receptor antagonist dizocilpine (0.1-1 mg/kg, IP) robustly disrupted PPI in wild-type mice. Conversely, selective genetic or pharmacological inhibition of either the NMDA NR2A or NR2B receptor subunit containing receptors, respectively, had no effect on PPI. Thus, NR2A KO mice showed normal PPI compared with wild-type littermate controls, and administration of Ro 63-1908 (1-10 mg/kg IP) to wild-type mice did not affect PPI. However, selective inhibition of NR2A and NR2B by administration of Ro 63-1908 to NR2A KO mice significantly disrupted PPI.

CONCLUSIONS

These data imply that concomitant inhibition of both NR2A and NR2B subunit-containing NMDA receptors is necessary to disrupt PPI, suggesting that inhibition of NR2A and NR2B-containing NMDA receptors is required to elicit behaviours suggestive of psychomimetic effects in man.