Effect of acute hyperketonemia on the cerebral uptake of ketone bodies in nondiabetic subjects and IDDM patients

Hypercarnivory and the brain: protein requirements of cats reconsidered

“…Simply put, the elevation of ketone bodies above basal levels signals the carbohydrate-deficient state; conversely, low circulating concentrations of ketone bodies indicate that the rate of glucose appearance (dietary plus endogenous) is sufficient to meet metabolic glucose demands. Ketone bodies are utilised by brain proportional to their arterial concentrations (Hawkins et al 1971;Robinson and Williamson 1980;Blomqvist et al 2002) and in humans, can provide as much as 60% of brain substrate requirements during prolonged starvation (Cahill 1983). This partial substitution of glucose by ketones not only helps to maintain fuel supply to the brain, but also reduces the need for protein catabolism to provide gluconeogenic precursors (Cahill 1983;VanItallie and Nufert 2003) and thus greatly prolongs survival time, as mammals tend to have a greater capacity for catabolism of body fat than body protein.…”

Using positron emission tomography to study human ketone body metabolism: A review

“…There are two main subtypes of MCT in the brain, MCT1 in endothelial cells and MCT2 in neurons and glial cells. Brain ketone uptake consistently shows a roughly linear relationship to blood ketone levels in both rats and humans [35,36,38], with low uptake at relatively low levels of ketonemia in postprandial states and severalfold increased uptake in hyperketonemic states. In rats, ketone metabolism accounts for up to a quarter of brain O 2 consumption after 48 hours fasting [42].…”

“…This may be due to the fact that an appropriate ketone tracer for use in humans has long been unavailable. There are to date two published human studies using a ketone tracer, 11C-betahydroxybutyrate [35,36], but no dual-tracer studies. In animals, rodent studies have been performed using a ketone tracer (11C-acetoacetate) alone [33,37] or as dual-tracer studies with 18F-FDG [38,39], as well as some FDG-only studies to assess glucose metabolism under ketosis [40,41].…”

“…Cerebral metabolic rate of ketones has been measured in a handful of studies on both humans and rats using dynamic PET with the ketone tracers 11C-betahydroxybutyrate and 11C-acetoacetate, respectively [35][36][37][38][39] (see Fig. 3).…”

Automated synthesis of 11C‐β‐hydroxybutyrate by enzymatic conversion of 11C‐acetoacetate using β‐hydroxybutyrate dehydrogenase

“…[15][16][17] This method requires synthesis conditions that involved conversion of carbon dioxide to ammonium cyanide in the preparation of 1-[…”