Lipid profile changes in the rat brain following chronic morphine exposure and buprenorphine treatment

Long-term exposure to opioids is linked to significant neurobiological changes that go beyond neurotransmitter transmission and may include impairment of brain lipid homeostasis. Although lipids are crucial for inflammatory signaling, membrane integrity, and synaptic function, their significance in opioid-induced brain changes and opioid substitution therapy is still unclear. The purpose of this study was to assess the benefits of buprenorphine and look into changes in the lipid composition of the brain after long-term morphine treatment. MALDI-Q-TOF-MS was used to analyze rat brain lipid species both qualitatively and quantitatively in both positive and negative ion modes. The animals were divided into five groups: saline control, morphine (10 mg/kg), or buprenorphine (3, 6, or 10 mg/kg) given half an hour prior to morphine. For ten days, treatments were administered subcutaneously twice a day. Accurate mass and MS/MS fragmentation patterns were used to annotate lipid characteristics. Treatment-associated lipid signatures were found using PCA, hierarchical clustering, Random Forest classification, and volcano plot analysis. Sphingomyelin increased relative abundance, and glycerophospholipid decreased relative signal intensity were caused by long-term morphine administration, whereas buprenorphine reduced these changes in a dose-dependent way. Significant neurobiological alterations that extend beyond neurotransmitter transmission and may involve disruption of brain lipid profile are associated with long-term opioid use. Lipids are essential for inflammatory signaling, membrane integrity, and synaptic function, but it is yet unknown how important they are for opioid-induced brain alterations and opioid replacement therapy. This study examined alterations in the brain’s lipid composition during long-term morphine administration and evaluated the possible advantages of buprenorphine. Chronic morphine administration disrupts brain lipid homeostasis, promoting a shift toward sphingolipid-enriched profiles consistent with lipid dysregulation. Buprenorphine treatment is associated with dose-dependent changes in lipid composition that trend toward the control profile, an observation consistent with, but not confirmatory of, a stabilizing effect on the membrane lipid profile. These findings highlight changes in brain lipid composition as a potentially important biochemical component of opioid-induced neuroadaptation.