Effect of Dietary Histidine on Olfaction, and Rat Brain and Muscle Concentration of Histidine‐containing Dipeptides¹

Young adult male rats were fed three diets; one was devoid of histidine (HF), the second supplied the maintenance requirement (M, 3.7% protein, 0.07% histidine), and the third provided an optimal amount of histidine for growth (G, 10.0% protein, 0.21% histidine). The M diet was pair‐fed with the HF diet. After an 11 weeks experimental period, some HF animals were given the M diet for an 11 day repletion period. On the HF diet carnosine in the olfactory bulb and pectoral muscle, homocarnosine in whole brain and hemoglobin were sharply and significantly reduced in concentration below the levels found in the M and G groups. During the 11 day repletion period all concentrations except for hemoglobin returned to normal. Comparison of olfactory ability between M and HF rats showed no significant difference indicating that if carnosine is involved in olfaction, the amount required must be very small. Restricted food intake had no apparent effect on the concentration of histidine‐containing dipeptides but did influence hemoglobin concentration. The HF rats appeared to exhibit an altered state of emotionality compared to either of the other two treatment groups.