Used to measure mouse HPA (hypothalamic-pituitary-adrenal) axis activity by detecting hormone levels such as corticosterone or ACTH in biological samples like serum, plasma, or tissue homogenates. Commonly applied in neuroscience and endocrinology research to study stress responses, behavioral disorders, and the effects of drugs on hormonal regulation. Enables high-throughput, quantitative analysis with high sensitivity and specificity, supporting studies in animal models of depression, anxiety, and metabolic diseases.