GABA tea attenuates cardiac apoptosis in spontaneously hypertensive rats (SHR) by enhancing PI3K/Akt-mediated survival pathway and suppressing Bax/Bak dependent apoptotic pathway.

Cardiomyocyte apoptosis is the major risk factor for the development of heart failure (HF). The purpose of this study was to evaluate the effects of Gamma-aminobutyric acid (GABA) tea on hypertension-induced cardiac apoptotic pathways in spontaneously hypertensive rats (SHR). In order to reveal the mechanisms, 36 male SHR at eight weeks of age, 200 g were divided into six groups. One group was fed water as a control group. Other rats were administered one of the following treatments: GABA tea at dose 150 and 300 mg/kg/day as low GABA tea (LGT) and high GABA tea (HGT) groups, respectively, pure GABA at dose 150 and 300 mg/kg/day as LG and HG groups, respectively, green tea (GT) as control of LGT and HGT groups. After 12 weeks, cardiac tissues were analyzed by histological analysis, western blotting, and TUNEL assays. GABA tea, GT, and pure GABA decreased hypertension-induced cardiac abnormalities, including abnormal myocardial architecture. In addition, GABA tea, GT, and pure GABA dramatically increased anti-apoptotic protein, Bcl2. Furthermore, GABA tea, GT, and pure GABA also decreased activated-caspase 9 and activated-caspase 3. Additionally, the survival associated protein IGF-I and PI3K/Akt were enhanced in cardiac tissues upon treatment. Our results showed an optimistic anti-apoptotic and pro-survival effects of GABA tea treatment against hypertensive rat hearts.

GABA tea prevents cardiac fibrosis by attenuating TNF-alpha and Fas/FasL-mediated apoptosis in streptozotocin-induced diabetic rats.

GABA tea is a tea product that contains a high level of gamma-aminobutyric acid (GABA). This study investigated the effects of GABA tea on the heart in a diabetic rat model. Male Wistar rats were injected with 55mg/kg streptozotocin (STZ) to induce diabetes for 2weeks and then orally given dosages of 4.55 and 45.5mg/kg/day GABA tea extract for 6weeks. The results revealed that fasting blood glucose levels returned to normal levels in GABA tea-treated diabetic rats, but not in the untreated diabetic rats. Additionally, GABA tea effectively inhibited cardiac fibrosis induced by STZ. Further experiments showed that the STZ-induced protein levels of tumor necrosis factor-alpha (TNF-alpha), Fas, activated caspase-8 and caspase-3 were significantly inhibited by the GABA tea treatment. Therefore, our data suggest that the inhibiting effect of GABA tea on STZ-induced cardiac fibrosis in diabetic rats may be mediated by reducing blood glucose and further attenuating TNF-alpha expression and/or Fas/Fas ligand (FasL)-mediated apoptosis. These findings will provide implications for the potential anti-diabetic properties of GABA tea.