Animal Models of Depression: Classification and Relevant Validation Criteria

Abstract

In the last years, a change in the ways of understanding and applying experimental models has been observed. Taking into account the conceptual difference between a model, a test, and a paradigm, a classification of the current animal models of depression is proposed. This classification follows an empirical criterion and is catalogued according to the practical nature of the technical procedures implied in the experimental process. It diverges in some sense from the one proposed by Willner. He described 18 models following the conceptual rigor of his classical notions about validation criteria. It is worth considering that the design of a model fundamentally aims at imitating the etiological process of transformation from a healthy organism into a pathological organism through a vulnerability state in time. Most experimental models employ either genetic manipulations or some type of environmental stress or even a combination of both. Validating those experimental models is required in order to certify the applicability of their findings and abbreviate the distance between basic research and medical practice. Each one serves a particular purpose which determines the validation criteria that it must satisfy. Finally, the classification here proposed is open to modifications regarding future discoveries and findings in the field of neurobiological research and human phenomenology that may change our comprehension of the experimental models currently in use.

“For it is then that we have need of pleasure,

When we feel pain owing to the absence of pleasure.”

Epicurus (341–270 B.C.)