GSDMD-mediated pyroptosis in the dorsal hippocampus is implicated in morphine-induced reward memory in mice.

Abstract

Opioid addiction involves maladaptive neuroplasticity within hippocampal circuits, yet the underlying molecular mechanisms remain incompletely understood. Here, we systematically investigated whether pyroptosis, a pro-inflammatory form of programmed cell death, contributes to morphine-induced neuroadaptations and reward memory formation. Using a combination of behavioral, molecular, pharmacological, and cellular approaches in a mouse model of conditioned place preference (CPP), we demonstrate that morphine exposure selectively activates GSDMD-mediated pyroptotic signaling in the dorsal hippocampus (dHip). Morphine-treated mice exhibited significantly elevated expression of pyroptosis-related proteins (GSDMD, GSDMD-N, Caspase-1, and IL-1β) specifically in the dHip, as well as enhanced immunofluorescence intensity within CA3 neuronal populations. Pharmacological inhibition of GSDMD pore formation with dimethyl fumarate (DMF) not only attenuated morphine-induced CPP but also reversed the upregulation of pyroptotic markers in dHip neurons. Complementary in vitro experiments in HT-22 hippocampal neuronal cells confirmed that morphine directly induces dose-dependent upregulation of pyroptosis-related genes and proteins, effects that were abrogated by DMF co-treatment. These findings identify neuronal pyroptosis as a previously unrecognized mechanism associated with morphine-associated reward memory and position GSDMD as a potential therapeutic target that warrants further investigation for mitigating opioid-induced maladaptive plasticity.