Precise Definition of Porcine Hippocampal Cornu Ammonis 2: High Histoarchitectural Similarity to Humans but Unequal Sensitivity to Hypoxia

Experimental animal studies of hypoxic-ischemic injury of the hippocampus of pigs are limited due to the unprecise definition of hippocampal subfields, cornu ammonis 1 to 4, compared to humans. Given that the pig model closely mirrors human physiology and serves as an important model for critical care research, a more precise description is necessary to draw valid conclusions applicable to human diseases. In our study, we were able to precisely define the CA2 and its adjacent regions in a domestic pig model by arginine vasopressin receptor 1B (AVPR1B) and calbindin-D28K like (CaBP-Li) expression patterns. Our findings demonstrate that the histoarchitecture of the porcine cornu ammonis subfields closely resembles that of the human hippocampus. Notably, we identified unusually strong neuronal damage in regions of the pig hippocampus following global ischemia, which are typically not susceptible to hypoxic-ischemic damage in humans.