Effect of central administration of carnosine and its constituents on behaviors in chicks

Even though their contents in the brain are high, the function of brain carnosine and its constituents has not been clarified. Both carnosine and anserine inhibited food intake in a dose dependent fashion when injected intracerebroventricularly. The constituents of carnosine, β-alanine (β-Ala) and L-histidine (His), also inhibited food intake, but their effects were weaker than carnosine itself. Co-administration with β-Ala and His inhibited food intake similar to carnosine, but also altered other behaviors. Injection of carnosine induced hyperactivity and increased plasma corticosterone level, whereas β-Ala plus His induced hypoactivity manifested as sleep-like behavior. This later effect seemed to be derived from β-Ala, not His. These results suggest that central carnosine may act in the brain of chicks to regulate brain function and/or behavior in a manner different from its constituents.