Taar5, a member of the trace-amine associated receptor family, is a G-protein-coupled receptor. It is known to recognize tertiary amines, mainly functioning in the olfactory system to detect diverse ethological signals like predators, spoiled food, etc. Outside the olfactory system, Taar5 is expressed in various regions of the central nervous system, and is involved in multiple biological processes such as regulating brain serotonin functions, emotional behaviors, and may be associated with some neuropsychiatric diseases [1,3].

In Taar5 knockout (KO) mice, enhanced adult neurogenesis and dopamine neurotransmission in the striatum were observed. Gene expression profiling showed higher expression of genes related to dopaminergic signaling and down-regulation of gliogenesis-associated genes. Also, the KO striatum had more D2 dopamine receptor-expressing medium spiny neurons but fewer astrocytes. These findings suggest that Taar5 may play a role in striatum-dependent cognitive or motor functions [2]. Taar5 KO mice also demonstrated improved cognitive performance with a reduced number of errors in a temporal-decision-making task, highlighting its role in modulating specific cognitive domains [4].

In conclusion, Taar5 is crucial for olfactory sensing and has significant functions in the central nervous system. Studies using Taar5 KO mouse models have revealed its roles in neurogenesis, dopamine signaling, and cognitive functions, indicating its potential as a target for treating related neuropsychiatric diseases.

References:

1. Gainetdinov, Raul R, Hoener, Marius C, Berry, Mark D. . Trace Amines and Their Receptors. In Pharmacological reviews, 70, 549-620. doi:10.1124/pr.117.015305. https://pubmed.ncbi.nlm.nih.gov/29941461/

2. Vaganova, Anastasia N, Fesenko, Zoia S, Efimova, Evgeniya V, Katolikova, Nataliia V, Gainetdinov, Raul R. 2024. Knocking Out TAAR5: A Pathway to Enhanced Neurogenesis and Dopamine Signaling in the Striatum. In Cells, 13, . doi:10.3390/cells13221910. https://pubmed.ncbi.nlm.nih.gov/39594659/

3. Vaganova, Anastasia N, Murtazina, Ramilya Z, Shemyakova, Taisiia S, Katolikova, Nataliia V, Gainetdinov, Raul R. 2021. Pattern of TAAR5 Expression in the Human Brain Based on Transcriptome Datasets Analysis. In International journal of molecular sciences, 22, . doi:10.3390/ijms22168802. https://pubmed.ncbi.nlm.nih.gov/34445502/

4. Maggi, Silvia, Bon, Carlotta, Gustincich, Stefano, Gainetdinov, Raul R, Espinoza, Stefano. 2022. Improved cognitive performance in trace amine-associated receptor 5 (TAAR5) knock-out mice. In Scientific reports, 12, 14708. doi:10.1038/s41598-022-18924-z. https://pubmed.ncbi.nlm.nih.gov/36038766/