Intranasal Delivery of Proenkephalin-Expressing Differentiated Mesenchymal Stem Cells Attenuates Morphine Dependence Behaviors and Modulates Neurotrophic Factors in Rats

Substance use disorder is a chronic relapsing condition characterized by persistent drug seeking, cognitive impairment, and neurobiological alterations in brain reward and memory circuits. Emerging evidence suggests that dysfunction of the endogenous opioid system and reduced neurotrophic signaling contribute to the pathophysiology of opioid dependence. Cell based therapeutic strategies may provide a novel approach to modulate these neural pathways. In the present experimental study, morphine dependence was induced in adult male rats using an escalating dose regimen. Animals were randomly allocated into control, morphine-dependent vehicle, and cell-treated groups. Proenkephalin-expressing differentiated mesenchymal stem cells (PENK-MSCs) were delivered via the intranasal route. Behavioral assessments were performed using conditioned place preference, novel object recognition, and the elevated plus maze to evaluate addiction related behaviors, cognitive performance, and anxiety like responses. Hippocampal brain derived neurotrophic factor (BDNF) expression was examined using immunohistochemistry. Morphine dependent rats exhibited significant behavioral alterations, including enhanced drug related preference, impaired recognition memory, and increased anxiety like behavior compared with control animals. In addition, hippocampal BDNF expression was significantly reduced following morphine exposure. Intranasal cell delivery significantly attenuated morphine-induced preference, reversed recognition memory deficits, mitigated anxiety-like behaviors, and upregulated hippocampal BDNF expression compared with the vehicle-treated morphine group. These findings demonstrate that intranasal delivery of PENK-MSCs attenuates behavioral deficits and promotes neurotrophic recovery in morphine-dependent rats. This approach may represent a promising experimental strategy for targeting neural mechanisms involved in substance use disorder, although further studies are required to confirm its long-term efficacy and translational potential.