Possible Interaction: Glucagon and Leucine

“Splanchnic removal and uptake of leucine were decreased with increased glucagon infusion.”

“The negative correlation between plasma glucagon and leucine levels was also significant (r=-.684).”

“ Glucagon has a crucial role suppressing skeletal muscle protein synthesis by increasing l-leucine oxidation and the irreversible loss of this amino acid.”

“In summary, leucine at a dose equivalent to that present in a high-protein meal, had little effect on serum glucose or insulin concentrations but did increase the glucagon concentration.”

“Ingested leucine stimulated an increase in glucagon.”

“ Leucine also attenuated the decrease in glucagon expected when glucose alone is ingested.”

“ Glucagon decreased the leucine concentration (-11% +/- 3% in study 2 v study 0, P < .02) and caused a small increment in proteolysis (+6% in study 2 v study 0, P < .01) that was related to the decrement in glutamine concentrations.”

“ Glucagon superinfusion caused a 63% increase in the dynamics of the process in controls (57.7 ± 11.0 L ˙ hr−1; p vs. spontaneous glucagon, p < 0.01), whereas in cirrhosis it increased on average by only 15% (26.7 ± 10.7; p = NS).”

“At a physiological concentration (0.2 mmol/liter), however, leucine was a positive stimulus for glucagon release, especially in the absence of another amino acid.”

“Likewise, leucine (15.0 mmol/liter) reversibly inhibited glucagon secretion evoked by glutamine in the absence of glucose.”

“Moreover, at a low glucose concentration (3.3 mmol/liter) and in the presence of arginine, the highest concentration of leucine (15.0 mmol/liter) provoked a sustained and reversible inhibition of glucagon release.”

“Thus, leucine exerted a dual effect on the secretion of glucagon , the inhibitory effect of leucine prevailing at a high concentration of the branched chain amino acid and when glucagon secretion was already stimulated by arginine or glutamine.”

“ Glucagon , caffeine and cyclic-AMP enhanced the insulinotropic effect of glucose and leucine significantly, but insulin release in response to xylitol was not affected.”

“Concomitantly, a rise in arginase activity up to 2-fold could be measured in response to glucagon , which was largely suppressed by simultaneous presence of leucine in concentrations between 5 and 10 mM.”

“Ten-minute perfusions of 2, 5, and 10 mM L-leucine induced the release of glucagon and insulin in a dose-related manner.”

“ Glucagon also inhibited pancreatic secretion elicited by intraduodenal instillation of a solution of L-tryptophan and L -leucine.”