Essentiality of histidine in adult mice

The difficulty in demonstrating a histidine deficiency in adult animals may be due in part to the histidine reserve in skeletal muscle in the form of carnosine. Mice are unusual among vertebrates in that their muscle is free of carnosine and its methylated analogue, anserine. When mice were fed a histidine-free diet, weight loss was noticeable within 3 d and continued over a period of 18 d. At this point the animals had lost 25-30% of their original weight. These results are compatible with the view that a dietary histidine deficiency can be offset by carnosine. Mice, whose muscle contains no carnosine, show early signs of a deficiency when deprived of histidine.