During prolonged starvation, the rate of gluconeogenesis depends on
High-Yield Explanation
Increased alanine levels in liver
In the fasting state, there is a considerable output of alanine from skeletal muscle, far in excess of its concentration in the muscle proteins that are being catabolized.
It is formed by transamination of pyruvate produced by glycolysis of muscle glycogen and is exported to the liver, where, after transamination back to pyruvate, it is a substrate for gluconeogenesis.
This is the glucose-alanine cycle. Which has two major functions:-
Transport of α -amino groups of amino acids (ammonium ion/ammonia) from muscle to liver
Transport of alanine as a substrate for gluconeogenesis