Endomorphins-2 (EM-2) could decrease both the frequency and amplitude of the sEPSC of the motoneurons in lamina IX, which was reversed by the MOR antagonist CTOP. EM-2-IR fibers originated from primary afferent fibers form symmetric synaptic connections with motoneurons innervating skeletal muscles of the lower limbs in lamina IX of the spinal ventral horn and EM-2 might exert inhibitory effects on the activities of these motoneurons through both presynaptic and postsynaptic mechanisms.

Endomorphin 2 TFA, displays reasonable affinities for kappa3 binding sites, with Ki value between 20 and 30 nM. a high affinity, highly selective agonist of the μ-opioid receptor,

Acetyl tetrapeptide-15 Acetate (Skinasensyl Acetate), a synthetic peptide used in cosmetic products for sensitive skin, is an endomorphin-2 derivative that extends the range of neuronal excitability thresholds in the μ-opioid receptor via an endorphin-like pathway, and can be used to study inflammatory and neuropathic pain produced by skin hyperreactivity. Inflammatory and neuropathic pain produced by skin hyperresponsiveness.