Phytosterol additives increase blood pressure and promote stroke onset in salt-loaded stroke-prone spontaneously hypertensive rats.
1. To assess the effect of dietary phytosterol on stroke and the lifespan of salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP), we investigated the effects of the addition of phytosterol to soybean oil (phytosterol content: 0.3%) on stroke onset, lifespan following onset of stroke and overall lifespan compared with canola oil (phytosterol content: 0.9%). 2. Six-week-old male SHRSP were fed a test diet prepared by the addition of canola oil (CA diet), soybean oil (SO diet), soybean oil plus 0.6% phytosterol (SO + 0.06P diet) or soybean oil plus 4.5% phytosterol (SO + 0.45P diet) as a 10% fat source. 3. Systolic blood pressure (SBP) increased in the SO + 0.06P and SO + 0.45P groups compared with the SO group and the increase was dependent on the amount of phytosterol added, indicating that the addition of phytosterol to soybean oil may promote an increase in SBP in salt-loaded SHRSP. 4. The onset of stroke was shortest in the SO + 0.45P group and survival after the onset of stroke was shortest in the CA group. Consequently, the SO + 0.45P and CA groups showed marked lifespan shortening, indicating that a fivefold greater amount of phytosterol was required to produce an effect equivalent to that of canola oil. 5. Investigation of the mRNA expression of ATP-binding cassette (ABC) transporters involved in intestinal phytosterol absorption indicated significant decreases in the intestinal mRNA expression of Abcg5 and Abcg8 in SHRSP and Wistar-Kyoto rats compared with Wistar rats. 6. In conclusion, the addition of phytosterol to soybean oil elevated SBP and promoted the onset of stroke, which may cause a reduction in survival time. However, a fivefold greater amount of phytosterol was required to produce an effect that was equivalent to the survival time-shortening effect of canola oil. The significant decrease in the intestinal mRNA expression of Abcg5 and Abcg8 in SHRSP may be responsible, at least in part, for the unfavourable effects observed following the addition of phytosterol.
Ogawa
Hiroshi
H
Department of Hygiene and Division of Basic Medical Science, Kinki University School of Medicine, Osaka-Sayama City, Osaka, Japan. ogawa-h@med.kindai.ac.jp
Yamamoto
Kazuo
K
Kamisako
Toshinori
T
Meguro
Tadamichi
T
D018528:ATP-Binding Cassette Transporters / Q000187:drug effects / Q000235:genetics; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000502:physiology; D019358:Fat Substitutes / Q000008:administration & dosage / Q000009:adverse effects / Q000032:analysis; D005229:Fatty Acids, Monounsaturated / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D006973:Hypertension / Q000139:chemically induced* / Q000150:complications; D007422:Intestines / Q000033:anatomy & histology / Q000737:chemistry / Q000187:drug effects; D008297:Male; D010840:Phytosterols / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D012333:RNA, Messenger / Q000737:chemistry / Q000187:drug effects / Q000235:genetics; D000074262:Rapeseed Oil; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D017673:Sodium Chloride, Dietary / Q000494:pharmacology; D013024:Soybean Oil / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D020521:Stroke / Q000139:chemically induced* / Q000150:complications / Q000401:mortality
D018528:ATP-Binding Cassette Transporters; D019358:Fat Substitutes; D005229:Fatty Acids, Monounsaturated; D010840:Phytosterols; D012333:RNA, Messenger; D000074262:Rapeseed Oil; D017673:Sodium Chloride, Dietary; D013024:Soybean Oil