Inhibition of gut microbiota-associated trimethylamine N-oxide (TMAO) metabolism attenuates salt-sensitivity in Dahl SS rats

Through untargeted metabolomics, our group has recently identified gut microbiota-associated metabolites related to trimethylamine N-oxide (TMAO) metabolism as potential contributing factors to the sexual dimorphism observed in the progression of salt-sensitive (SS) hypertension in the Dahl SS rat. This pathway has been associated with a broad range of cardiovascular diseases; corresponding with greater severity of disease in male SS rats, we have observed elevated levels of circulating carnitine, choline, and TMAO in males compared to females. The current study sought to test the hypothesis that pharmacological inhibition of TMAO production via 3,3-dimethyl-1-butanol (DMB), a structural analog of choline and inhibitor of the enzyme choline trimethylamine lyase, would attenuate SS hypertension and mitigate renal injury in both sexes. Dahl SS rats were implanted with radiotelemeters for continuous acquisition of mean arterial pressure (MAP). Following a week of recovery, rats were placed on a 21 day high salt (HS; 4.0% NaCl) diet, with weekly overnight urine collections performed to monitor renal functional changes. Concurrent with the start of HS, animals were randomized to receive either standard drinking water (vehicle) or 1.0% DMB, with chow and water available ad libitum. At the end, rats were euthanized, and kidneys were collected, flushed, and processed for immune cell isolation and detailed histopathological evaluation. In male SS rats, MAP did not differ between groups (125±5 vs 124±2 mmHg, DMB vs vehicle, n=9-11) during baseline (low salt, 0.4% NaCl). After HS, DMB treatment significantly attenuated hypertension (133±3 vs 154±5 mmHg, DMB vs vehicle, p< 0.01). Renal structural integrity was also impeccably maintained, evidenced by markedly decreased medullary protein casting (4.96±0.20 vs 16.19±0.94%, DMB vs vehicle, p< 0.01). Intriguingly, these protective effects occurred without substantial changes in albuminuria, proteinuria, or renal immune cell infiltration, which remained similar between the two groups throughout the study. Serum metabolite profiling via HPLC/MS revealed that DMB significantly decreased TMA (14.5±2.1 vs 21.2±1.1 µM, p< 0.02) and carnitine (16.3±2.5 vs 45.2±3.1 µM, p< 0.0001) when compared to vehicle, yet produced no measurable changes in TMAO or choline levels. Importantly, female Dahl SS rats subjected to DMB treatment exhibited similar striking protection from salt-induced hypertension and renal medullary protein casting, underscoring the sex-independent nature of the effects of DMB. Collectively, these data demonstrate that DMB attenuates salt-sensitive hypertension and significantly reduces renal medullary protein casting in both male and female Dahl SS rats. However, the disconnect between DMB-mediated attenuation of hypertension and renal histological damage despite a lack of protection from albuminuria and inflammation supports continued investigation into the contribution of the metabolites related to TMAO metabolism as potential therapeutic targets for salt-sensitive hypertension. Funding: U2CDK133422, TL1DK139566, R56HL161231, AHA 25SFRNPCKMS1467444, U54HL169191, R01HL161231, R01HL166458 This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.