The gut microbiome contributes to somatic morphine withdrawal behavior and implicates a TLR2 mediated mechanism

ABSTRACT

The ongoing opioid epidemic has left millions of people suffering from opioid use disorder due to the over-prescription of highly addictive substances. Chronic opioid exposure leads to dependence, where the absence of the drug results in negative symptoms of withdrawal, often driving patients to continue drug use; however, few therapeutic strategies are currently available to combat the cycle of addiction and the severity of morphine withdrawal. This study investigates the microbiome as a potential therapeutic target for morphine withdrawal, as gut dysbiosis caused by morphine use has been proven to contribute to other aspects of opioid use disorders, such as tolerance. Results show that although the microbiome during morphine withdrawal trends toward recovery from morphine-induced dysbiosis, there continues to be a disruption in the alpha and beta diversity as well as the abundance of gram-positive bacteria that may still contribute to the severity of morphine withdrawal symptoms. Germ-free mice lacking the microbiome did not develop somatic withdrawal symptoms, indicating that the microbiome is necessary for the development of somatic withdrawal behavior. Notably, only TLR2 but not TLR4 whole-body knockout models display less withdrawal severity, implicating that the microbiome, through a gram-positive, TLR2 mediated mechanism, drives opioid-induced somatic withdrawal behavior.

KEYWORDS:

• Morphine
• withdrawal
• microbiome
• TLR2
• behavior

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Sequence data are reposited at the Biostudies database (https://www.ebi.ac.uk/biostudies/) under accession number S-BSST1068 (https://www.ebi.ac.uk/biostudies/studies/S-BSST1068).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19490976.2023.2242610

Additional information

Funding

This work was supported by National Institute of Drug Abuse, National Institute of Health, Bethesda, MD (Grant Numbers: R01 DA050542, R01 DA047089, R01 DA044582, R01 DA043252, R01 DA037843, R01 DA034582, T32 DA045734).