Porcine dynorphin A (1-13) is a potent, endogenous κ opioid receptor agonist and is antinociceptive at physiological concentrations.
Dynorphin A (1-13) exposure (33 μM) causes a significant loss in neuronal viability at 4 h with a visible destruction in neuronal morphology seen at 16 h. Exposure to dynorphin A (1-13) causes acute increases in [Ca2+]i in individual neurons similar to increases seen with acute NMDA treatment. Continuous exposure to dynorphin A (1-13) (100 μM) causes a significant loss of neurons over time[1].
References:
[1]. Hauser KF, et al. Dynorphin A (1-13) neurotoxicity in vitro: opioid and non-opioid mechanisms in mouse spinal cord neurons. Exp Neurol. 1999 Dec;160(2):361-75.