The role of tachykinin 1 in a mouse model of trait anxiety

The molecular mechanisms controlling the innate drive towards more or less anxious behaviour or passive versus active coping strategies are poorly understood. To investigate these phenomena in more detail, the hyper- (HAB) and hypo- (LAB) anxious mice, which were selectively inbred for the respective traits from the outbred CD1 mouse population, represent a valid animal model of trait anxiety. They do not only feature the stable and robust anxiety-related phenotype they have been selected for, but also typical comorbid depression-like behaviour. Addressing these versatile phenotypes that are as complex as their genetic background, a microarray analysis was performed to identify genes that are similarly regulated in a variety of brain regions. Among others, differential regulation of tachykinin 1 (Tac1) was observed in this study. To further confirm this finding, the analysis for Tac1 has been repeated by quantitative PCR that clearly revealed a three times higher expression in HAB mice compared to their LAB counterparts. This makes an involvement of the tachykinin peptide family in the respective phenotype more than likely. They either serve as a biomarker or are directly involved in generating high or low trait anxiety. However, the exact mechanisms of interaction still remain to be elucidated. Especially as the tachykinins are a complex peptide family with many different peptides that all act on similar receptors, only differing in their sequence and specific affinity.