ISSLS PRIZE in basic science 2023: Lactate in lumbar discs-metabolic waste or energy biofuel? Insights from in vivo MRS and T2r analysis following exercise and nimodipine in healthy volunteers

PurposeTo quantitatively assess the dynamic changes of Lactate in lumbar discs under different physiological conditions using MRS and T2r.MethodsIn step1, MRS and T2r sequences were standardized in 10 volunteers. Step2, analysed effects of high cellular demand. 66 discs of 20 volunteers with no back pain were evaluated pre-exercise (EX-0), immediately after targeted short-time low back exercises (EX-1) and 60 min after (EX-2). In Step 3, to study effects of high glucose and oxygen concentration, 50 lumbar discs in 10 volunteers were analysed before (D0) and after 10 days intake of the calcium channel blocker, nimodipine (D1).ResultsLactate showed a distinctly different response to exercise in that Grade 1 discs with a significant decrease in EX-1 and a trend for normalization in Ex-2. In contrast, Pfirrmann grade 2 and 3 and discs above 40 years showed a higher lactate relative to proteoglycan in EX-0, an increase in lactate EX-1 and mild dip in Ex-2. Similarly, following nimodipine, grade 1 discs showed an increase in lactate which was absent in grade 2 and 3 discs. In contrast, exercise and Nimodipine had no significant change in T2r values and MRS spectrum of proteoglycan, N-acetyl aspartate, carbohydrate, choline, creatine, and glutathione across age groups and Pfirrmann grades.ConclusionMRS documented changes in lactate response to cellular demand which suggested a 'Lactate Symbiotic metabolic Pathway'. The differences in lactate response preceded changes in Proteoglycan/hydration and thus could be a dynamic radiological biomarker of early degeneration.

Automated summary

This study used MRS and T2r to quantitatively assess the dynamic changes of Lactate in lumbar discs under different physiological conditions. The results showed that there was a distinct difference in the lactate response to exercise, with Grade 1 discs exhibiting a significant decrease immediately after exercise and a trend towards normalization after 60 minutes. In contrast, Grade 2 and 3 discs and discs above 40 years old showed a higher lactate content relative to proteoglycan at rest, an increase in lactate after exercise, and a mild decrease after 60 minutes. Following nimodipine intake, Grade 1 discs showed an increase in lactate, while Grade 2 and 3 discs did not show any change. Furthermore, exercise and nimodipine had no significant effect on the T2r values and MRS spectrum of other metabolites. These findings suggest that lactate response could be a dynamic radiological biomarker of early degeneration.