Effect of a gamma-aminobutyric acid-enriched dairy product on the blood pressure of spontaneously hypertensive and normotensive Wistar-Kyoto rats.
We investigated the blood-pressure-lowering effects of gamma-aminobutyric acid (GABA) and a GABA-enriched fermented milk product (FMG) by low-dose oral administration to spontaneously hypertensive (SHR/Izm) and normotensive Wistar-Kyoto (WKY/Izm) rats. FMG was a non-fat fermented milk product produced by lactic acid bacteria, and the GABA contained in FMG was made from the protein of the milk during fermentation. A single oral dose of GABA or FMG (5 ml/kg; 0.5 mg GABA/kg) significantly (P<0.05) decreased the blood pressure of SHR/Izm from 4 to 8 h after administration, but did not increase that of WKY/Izm rats. The hypotensive activity of GABA was dose-dependent from 0.05 to 5.00 mg/kg in SHR/Izm. During the chronic administration of experimental diets to SHR/Izm, a significantly slower increase in blood pressure with respect to the control group was observed at 1 or 2 weeks after the start of feeding with the GABA or FMG diet respectively (P<0.05) and this difference was maintained throughout the period of feeding. The time profile of blood-pressure change due to administration of FMG was similar to that of GABA. FMG did not inhibit angiotensin 1-converting enzyme. Furthermore, an FMG peptide-containing fraction from reverse-phase chromatography lacked a hypotensive effect in SHR/Izm rats. The present results suggest that low-dose oral GABA has a hypotensive effect in SHR/Izm and that the hypotensive effect of FMG is due to GABA.
Yakult Central Institute for Microbiological Research, Tokyo, Japan. kazuhito-hayakawa@yakult.co.jp
Kazuhito
K
Hayakawa
Masayuki
M
Kimura
Keiko
K
Kasaha
Keisuke
K
Matsumoto
Hiroshi
H
Sansawa
Yukio
Y
Yamori
D000284:Administration, Oral; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000378:metabolism; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D043302:Cultured Milk Products; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004435:Eating; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000494:pharmacology*
D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D005680:gamma-Aminobutyric Acid