Increased behavioural and histological variability arising from changes in cerebrovascular anatomy of the Mongolian gerbil

Abstract

The bilateral common carotid artery occlusion (BCCAO) in the Mongolian gerbil has been used as a simple and highly reproducible model of forebrain ischemia due to an incomplete circle of Willis. However, increased behavioral and histological variability to a typical 5 min period of ischemia in this modelled us to conclude that the vasculature was changing. To test this hypothesis I compared gerbils from two Canadian suppliers. Gerbils from Charles River (CR) exhibited a greater incidence of complete or partial circle of Willis compared to their High Oak (HO) counterparts. This altered vasculature pattern in the CR versus HO gerbils was associated with reductions in behavioral activation that characteristically accompany conditions of milder ischemia resulting in less severe hippocampal CA1 cell loss (e.g. ~70% CA1 cell loss vs. 95% CA1 loss). -- Gerbils from CR, the main supplier in North America, no longer represent a reliable model for use in forebrain ischemia studies. Gerbils from HO while superior to those from HO are also more variable in their response to BCCAO than those used as recently as 5 years ago. Thus the gerbil model of forebrain ischemia, at least using CR animals, no longer produces consistent injury and behavioral alterations. Investigators are urged to consider adopting other models in future neuroprotection studies or ensure that their gerbil population lacks communicating arteries.