Hrh2, encoding the histamine H2 receptor, is closely associated with multiple physiological and pathophysiological processes. Histamine, via binding to HRH2, is involved in various pathways, and HRH2 has implications for cardiovascular, cerebrovascular, and mental disorders, among others. Genetic models, such as knockout mice, are valuable for studying its functions [1,2].

Endothelial-specific Hrh2 knockout mice were generated to understand the role of endothelial HRH2. These mice were normal, healthy, and fertile, laying the foundation for exploring HRH2's role in related diseases [1]. In the context of schizophrenia, selective knockout of Hrh2 in glutamatergic neurons induced schizophrenia-like phenotypes, suggesting Hrh2 deficit in these neurons may contribute to schizophrenia pathogenesis [2].

In summary, Hrh2 plays crucial roles in multiple biological processes and diseases. The generation of Hrh2 knockout mouse models, especially endothelial-specific and neuron-specific ones, has provided significant insights into its functions in cardiovascular-related conditions and schizophrenia, respectively. These models are valuable for further research on related disease mechanisms and potential therapies.