Neuroimaging reveals distinct brain glucose metabolism patterns associated with morphine consumption in Lewis and Fischer 344 rat strains

Abstract

Vulnerability to addiction may be given by the individual's risk of developing an addiction during their lifetime. A challenge in the neurobiology of drug addiction is understanding why some people become addicted to drugs. Here, we used positron emission tomography (PET) and statistical parametric mapping (SPM) to evaluate changes in brain glucose metabolism in response to chronic morphine self-administration (MSA) in two rat strains with different vulnerability to drug abuse, Lewis (LEW) and Fischer 344 (F344). Four groups of animals were trained to self-administer morphine or saline for 15 days. 2-deoxy-2-[18F]-fluoro-d-glucose (FDG)-PET studies were performed on the last day of MSA (acquisition phase) and after 15 days of withdrawal. PET data were analyzed using SPM12. LEW-animals self-administered more morphine injections per session than F344-animals. We found significant brain metabolic differences between LEW and F344 strains in the cortex, hypothalamus, brainstem, and cerebellum. In addition, the different brain metabolic patterns observed after the MSA study between these rat strains indicate differences in the efficiency of neural substrates to translate the drug effects, which could explain the differences in predisposition to morphine abuse between one individual and another. These findings have important implications for the use of these rat strains in translational morphine and opiate research.

Updated Perspectives on the Neurobiology of Substance Use Disorders Using Neuroimaging

“…Different brain metabolic patterns observed via PET imaging after morphine self-administration suggests differences in potential predisposition to morphine misuse between individuals. 55 …”

“…Different brain metabolic patterns observed via PET imaging after morphine self-administration suggests differences in potential predisposition to morphine misuse between individuals. 55 One group of researchers performed a data-driven study in 2022 to evaluate the predictive efficacy of resting-state functional magnetic resonance imaging (rs-fMRI) during early abstinence from alcohol dependency. 56 They reported that alcohol dependency was related to deficits in regional homogeneity of the left postcentral gyrus, low-frequency fluctuations of the right fusiform gyrus, and frontal cortex between the right fusiform gyrus and the right middle cingulum.…”