Intestinal neurohormones in protein-deficient rats.

The levels of noradrenaline, adrenaline, and serotonin in the jejunum and ileum of weanling rats fed protein-free (deficient) and high-protein (control) diets were analyzed. The concentration of noradrenaline of the deficient rats was markedly increased, both in the jejunum (0.430 +/- 0.039 microgram/g vs. 0.188 +/- 0.019 microgram/g in the control animals, +228%, P < 0.001) and in the ileum (0.492 +/- 0.041 microgram/g vs. 0.212 +/- 0.014 microgram/g in the control rats, +232%, P < 0.001). However, the levels of adrenaline and serotonin were unaltered in deficient rats as compared to controls, both in the jejunum (0.049 +/- 0.009 microgram/g of adrenaline and 1.233 +/- 0.178 microgram/g of serotonin vs. 0.047 +/- 0.006 microgram/g of adrenaline and 1.364 +/- 0.131 microgram/g of serotonin in the controls) and in the ileum (0.027 +/- 0.005 microgram/g of adrenaline and 0.902 +/- 0.150 microgram/g of serotonin vs. 0.038 +/- 0.006 microgram/g of adrenaline and 1.118 +/- 0.192 microgram/g of serotonin in the controls). In view of these results, it can be speculated that the abdominal distension and the reduced intestinal motility usually seen in the states of protein malnutrition could be caused, at least in part, by the accumulation of noradrenaline in the intestine.