Used in biomedical research to quantify β-endorphin levels in rat biological samples such as plasma, serum, or tissue homogenates. This ELISA kit enables researchers to study the endogenous opioid system, particularly in experiments related to stress, pain modulation, addiction, and neuroendocrine function. It provides a sensitive and specific method for monitoring changes in β-endorphin concentration under experimental conditions, supporting studies in neuroscience, pharmacology, and physiology. The assay is widely applied in preclinical research to evaluate the impact of drugs, hormones, or behavioral interventions on opioid peptide release.