Neonatal morphine and HIV synergy induce persistent neuroimmune and anxiety-related transcriptional states

Abstract Background Early-life opioid exposure can disrupt neurodevelopment and heighten vulnerability to anxiety and affective disorders, particularly in individuals with HIV. Methods Using single-cell RNA sequencing (scRNA-seq), we profiled adolescent brains from wild-type and HIV-1 transgenic (Tg26) mice exposed to morphine during postnatal days 2–7. Results Morphine exposure in Tg26 mice resulted in a highly dysregulated microglial phenotype, characterized by the ectopic upregulation of genes encoding neuronpeptides ( Avp, Hcrt , and Pmch ), while simultaneously showing a reduction in both inflammatory and homeostatic markers ( Map3k6, Lgals3, Ccl3 ). Microglia also showed enhanced expression of dynorphin ( Pdyn ) and κ-opioid receptor ( Oprk1 ) signaling modules implicated in dysphoria and stress-induced negative effects. Furthermore, transcriptomic mapping revealed cell-type-specific neuronal adaptations: cholinergic neurons upregulated genes linked to anxiety and arousal ( Avp, Oxt ), GABAergic neurons upregulated genes linked to condition and aversive behavior, whereas glutamatergic neurons enriched for transcripts associated with thigmotaxis and fear behaviors. Conclusions Together, these findings demonstrate that brief neonatal morphine exposure in an HIV-inflamed milieu induces persistent, cell-type-specific neuroimmune and neurotransmitter reprogramming that engages the dynorphin–KOR pathway and predisposes to anxiety- and aversion-related behaviors.