2019 Volume 22 Issue 2 Pages 84-94
Yoghurt, one of the most widely consumed traditional dairy products, uses bacterial fermentation and has physiological benefits as it includes many nutrients such as vitamins, amino acids, peptides, proteins,and lipids. Moreover, because the amount of lactose is lower in yoghurt than in milk due to the fermentation,the risk of diarrhea in mammals is reduced. Whey is a byproduct of yoghurt, cheese, and butter making, and we propose that yoghurt whey could be used as a food ingredient for companion animals as well as for human and domestic animals. To assess the functions of yoghurt whey in the present study, we investigated whether the oral administration of yoghurt whey produced by Lactobacillus delbrueckii subsp. bulgaricus 2038 and Streptococcus thermophilus 1131 affected the concentrations of free amino acids in the brain and behavior in rats. We evaluated motor activity, anxiety-like behavior, and learning ability by the open field test and depression-like behavior by the forced swimming test. We also determined the concentrations of d - and l-amino acids in the plasma and brain regions by ultra-performance liquid chromatography. No significant effects were noted between yoghurt whey and distilled water (control) treatments in all parameters of behavioral tests. However, d- and l-Ser, l-Gln, l-His, l-Ala, l-Arg, l-Phe, l-Val, l-Leu, L-Ile, and Tau in the thalamus and l-Gln in the brainstem were lowered, and GABA in the hypothalamus was increased by yoghurt whey treatment. In conclusion, the oral administration of yoghurt whey altered several amino acid concentrations in specific brain regions of rats, but did not affect the mental conditions judging from behavioral tests.
