Powers Michael E, Yarrow Joshua F, McCoy Sean C, Borst Stephen E
Division of Athletic Training, Shenendoah University, Winchester, VA 22601, USA.
Med Sci Sports Exerc. 2008 Jan;40(1):104-10. doi: 10.1249/mss.0b013e318158b518.
Oral administration of the amino acid/inhibitory neurotransmitter gamma aminobutyric acid (GABA) reportedly elevates resting serum growth hormone (GH) concentrations.
To test the hypothesis that GABA ingestion stimulates immunoreactive GH (irGH) and immunofunctional GH (ifGH) release at rest and that GABA augments the resistance exercise-induced irGH/ifGH responses.
Eleven resistance-trained men (18-30 yr) participated in this randomized, double-blind, placebo-controlled, crossover study. During each experimental bout, participants ingested either 3 g of GABA or sucrose placebo (P), followed either by resting or resistance exercise sessions. Fasting venous blood samples were acquired immediately before and at 15, 30, 45, 60, 75, and 90 min after GABA or P ingestion and were assayed for irGH and ifGH.
At rest, GABA ingestion elevated both irGH and ifGH compared with placebo. Specifically, peak concentrations of both hormones were elevated by about 400%, and the area under the curve (AUC) was elevated by about 375% (P < 0.05). Resistance exercise (EX-P) elevated time-point (15-60 min) irGH and ifGH concentrations compared with rest (P < 0.05). The combination of GABA and resistance exercise (EX-GABA) also elevated the peak, AUC, and the 15- to 60-min time-point irGH and ifGH responses compared with resting conditions (P < 0.05). Additionally, 200% greater irGH (P < 0.01) and 175% greater ifGH (P < 0.05) concentrations were observed in the EX-GABA than in the EX-P condition, 30 min after ingestion. GABA ingestion did not alter the irGH to ifGH ratio, and, under all conditions, ifGH represented approximately 50% of irGH.
Our data indicate that ingested GABA elevates resting and postexercise irGH and ifGH concentrations. The extent to which irGH/ifGH secretion contributes to skeletal muscle hypertrophy is unknown, although augmenting the postexercise irGH/ifGH response may improve resistance training-induced muscular adaptations.
据报道，口服氨基酸/抑制性神经递质γ-氨基丁酸（GABA）可提高静息血清生长激素（GH）浓度。
检验以下假设，即摄入GABA会刺激静息状态下免疫反应性生长激素（irGH）和免疫功能性生长激素（ifGH）的释放，且GABA会增强抗阻运动诱导的irGH/ifGH反应。
11名抗阻训练男性（18 - 30岁）参与了这项随机、双盲、安慰剂对照的交叉研究。在每次实验回合中，参与者摄入3克GABA或蔗糖安慰剂（P），随后进行静息或抗阻运动。在摄入GABA或P之前以及之后15、30、45、60、75和90分钟立即采集空腹静脉血样，检测irGH和ifGH。
静息状态下，与安慰剂相比，摄入GABA可提高irGH和ifGH水平。具体而言，两种激素的峰值浓度均升高了约400%，曲线下面积（AUC）升高了约375%（P < 0.05）。与静息状态相比，抗阻运动（EX - P）可提高时间点（15 - 60分钟）的irGH和ifGH浓度（P < 0.05）。与静息状态相比，GABA与抗阻运动相结合（EX - GABA）也提高了峰值、AUC以及15至60分钟时间点的irGH和ifGH反应（P < 0.05）。此外，摄入后30分钟，EX - GABA组的irGH浓度比EX - P组高200%（P < 0.01），ifGH浓度高175%（P < 0.05）。摄入GABA并未改变irGH与ifGH的比例，且在所有条件下，ifGH约占irGH的50%。
我们的数据表明，摄入GABA可提高静息和运动后irGH和ifGH浓度。尽管增强运动后irGH/ifGH反应可能会改善抗阻训练诱导的肌肉适应性，但irGH/ifGH分泌对骨骼肌肥大的贡献程度尚不清楚。
