The effect of beta-alanine on motor behaviour, body temperature and cerebral monoamine metabolism in rat.

Intracerebroventricular (ICV) injection of beta-alanine produced a decrease in rectal temperature, inhibition of exploratory behaviour and motility, and changes in the metabolism of cerebral monoamines. Dopa and 5-HTP accumulation after inhibition of L-aromatic amino acid decarboxylase, NSD 1015 (3-hydroxybencylhydrazine HCl, 100 mg/kg i.p.) was found to be significantly increased in all the dissected cerebral regions of animals treated with beta-alanine, as compared to the controls. Levels of tyrosine and tryptophan did not show any significant change. Endogenous levels of dopamine (DA), noradrenaline (NA), serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA), did not change. After inhibition of the catecholamines synthesis with alpha-methyltryrosine (alpha-MT), dopamine depletion was retarded and noradrenaline accelerated, but without reaching statistical significance. After intraperitoneal (i.p.) injection of beta-alanine, significant changes in motor behaviour were found. Body temperature and metabolism of brain catecholamine were unchanged. This lack of effect could be explained by poor penetration through the blood-brain barrier.