Diet and rat strain as factors in nervous system function and influence of confounders.

The necessity for understanding normal human cognitive processes and behavior, and the mechanisms which result in dysfunction in these processes are dependent on utilization of a suitable animal model. In order to develop pharmaceutical agents to alleviate mental disturbances and enable the individual to cope within the norms of society, it is incumbent upon investigators to choose a species in which pharmacokinetic principles are established and resemble those of humans. The choice of rats in cognition research studies has specific advantages in that these animals possess similar pharmacodynamic parameters to humans. Further advantages include availability, low cost, ease of breeding, maintenance and an extensive literature database which enable comparisons to present findings. However, there are substantial differences in the performance of various rat strains in tasks of learning, memory, attention, and responses to stress or drugs. In addition to rat strain, quantity of food also exerts profound consequences on animal behavior. The aim of this review is to demonstrate that there are differences in the central nervous system responsiveness of rat strains to chemical and these could be related to factors such as source of supplier, type and quantity of feed, or season of the year. It is also evident that the genotype differs amongst strains and this may be responsible for the observed differences in CNS sensitivity to chemicals. Strain differences must be identified and taken into consideration in interpretation of assessment of neurobehavioral functions. It is also incumbent upon the investigators to utilize healthy (diet-controlled) animal models.