Propofol inhibited autophagy through Ca²⁺/CaMKKβ/AMPK/mTOR pathway in OGD/R-induced neuron injury

The neuroprotective role of propofol (PPF) in cerebral ischemia-reperfusion (I/R) has recently been highlighted. This study aimed to explore whether the neuroprotective mechanisms of PPF were linked to its regulation of Ca²⁺/CaMKKβ (calmodulin-dependent protein kinase kinase β)/AMPK (AMP-activated protein kinase)/mTOR (mammalian target of rapamycin)/autophagy pathway.

Cultured primary rat cerebral cortical neurons were treated with oxygen-glucose deprivation and re-oxygenation (OGD/R) to mimic cerebral I/R injury in vitro.

Compared with the control neurons, OGD/R exposure successfully induced neuronal I/R injury. Furthermore, OGD/R exposure notably caused autophagy induction, reflected by augmented LC3-II/LC3-I ratio and Beclin 1 expression, decreased p62 expression, and increased LC3 puncta formation. Moreover, OGD/R exposure induced elevation of intracellular Ca²⁺ concentration ([Ca²⁺]i). However, PPF treatment significantly antagonized OGD/R-triggered cell injury, autophagy induction, and [Ca²⁺]i elevation. Further investigation revealed that both autophagy induction by rapamycin and [Ca²⁺]i elevation by the Ca²⁺ ionophore ionomycin significantly reversed the PPF-mediated amelioration of OGD/R-triggered cell injury. Importantly, ionomycin also significantly abrogated the PPF-mediated suppression of autophagy and CaMKKβ/AMPK/mTOR signaling in OGD/R-exposed neurons. Additionally, activation of CaMKKβ/AMPK/mTOR signaling abrogated the PPF-mediated autophagy suppression.

Our findings demonstrate that PPF antagonized OGD/R-triggered neuronal injury, which might be mediated, at least in part, via inhibition of autophagy through Ca²⁺/CaMKKβ/AMPK/mTOR pathway.