미배아 발효로부터 얻은 GABA 시료를 이용하여 양성대조군으로 사용된 우유와 doxylamine succinate, 음성대조군으로 사용된 caffeine, 일반대조군으로 사용된 증류수와 함께 실험군인 GABA 시료를 농도별로 투여하여 실험을 수행하였다. 멜라토닌 함량을 측정한 결과, 대조군의 $2.607{pm}0.410;pg/mL$에 비해 GABA 60 mg/mL 투여군은 $3.243{pm}0.154;pg/mL$, GABA 120 mg/mL 투여군은 $3.425{pm}0.182;pg/mL$, 우유에 녹인 GABA 120 mg/mL 투여군은 $3.464{pm}0.205;pg/mL$으로 나타났다. 반면에 GABA 시료의 섭취 기간에 따른 멜라토닌 호르몬의 누적효과는 유의성이 없었다. 세로토닌 함량을 측정한 결과 대조군의 $4.73{pm}0.67;ng/mL$에 비해 GABA 60 mg/mL 투여군은 $4.71{pm}1.22;ng/mL$, GABA 120 mg/mL 투여군은 $5.37{pm}0.96;ng/mL$, 우유에 녹인 GABA 120 mg/mL 투여군은 $6.34{pm}0.59;pg/mL$으로 대조군의 평균값과 같거나 비교적 높은경향을 보였으며 농도별로 유의성이 있음을 확인하였다. 특히, GABA 120 mg/mL 투여시 멜라토닌과 세로토닌 모두 시판되는 수면보조제보다 높은 것으로 나타났다.
Relatively large amounts of GABA can be produced by the fermentation of rice bran. Therefore, this study was conducted to investigate the effects of GABA on the secretion of melatonin and serotonin for the development of a sleep inductive compound. The secretion levels of melatonin and serotonin from mice were found to be $3.425{pm}0.182;pg/mL$ and $5.37{pm}0.963;ng/mL$, respectively, in response to feeding 120 mg/mL of GABA while they were $2.607{pm}0.41;pg/mL$ in the control. The secretion of both melatonin and serotonin was increased up to the 13.51% and 34.99%, respectively, when compared to the negative control. However, the feeding of milk alone did not have a great effect on the melatonin and serotonin secretions. Conversely, feeding of milk with GABA enhanced the secretion of serotonin. The amounts of both melatonin and serotonin secreted increased with respect to the increase in GABA concentrations during feeding. Interestingly, the induction level of melatonin was relatively higher than that of serotonin in response to feeding 120 mg/mL of GABA. This is the first study to report that GABA has an ability to induce sleep related hormones in mice; therefore, it has the potential for use as a natural sleep aid.
