Dietary fish protein lowers blood pressure and alters tissue polyunsaturated fatty acid composition in spontaneously hypertensive rats.
OBJECTIVE
To investigate the effect of two types of dietary protein on blood pressure, liver fatty acid desaturation and composition, and urine 6-keto-prostaglandin-F (PGF(1alpha)) level, the metabolite of prostacyclin.


METHODS
5-wk-old spontaneously hypertensive rats were fed 20% casein or purified fish protein. The fat source was 5% ISIO oil, which contains 47.9% (omega-6) and 1.7% (omega-3) total polyunsaturated fatty acids. After 2 mo on the diet, systolic blood pressure was reduced with fish protein compared with casein (189.8 +/- 10.5 versus 220.7 +/- 8.7).


RESULTS
Excretion of 6-keto-PGF(1alpha) in urine was negatively correlated with blood pressure. Liver cholesterol and phospholipid concentrations were 1.71- and 1.27-fold lower with fish protein than with casein, respectively. The fish protein diet lowered the 20:4(omega-6) proportion and the ratio of 20:4(omega-6) to 18:2(omega-6) in liver microsomal lipids and phospholipids, which was due to the reduced microsomal Delta6(omega-6) desaturation activity. Dietary protein source did not affect omega-3 fatty acid composition, and this was associated with a similar activation of Delta6(omega-3) desaturation in liver microsomes.


CONCLUSIONS
The present data indicated a significant blood pressure-lowering effect caused by fish protein, rather than by casein, that modified the fatty acid composition of liver phospholipids and liver microsomal total lipids.
Ait-Yahia
Dalila
D
Laboratoire de Nutrition Clinique et Métabolique, Faculté des Sciences, Université d'Oran, Es Sénia, Algeria.
Madani
Sihem
S
Savelli
Jean-Luc
JL
Prost
Josiane
J
Bouchenak
Malika
M
Belleville
Jacques
J
D015121:6-Ketoprostaglandin F1 alpha / Q000652:urine; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D002364:Caseins / Q000378:metabolism; D004042:Dietary Fats, Unsaturated / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D029941:Fish Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D006973:Hypertension / Q000178:diet therapy; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009929:Organ Size / Q000187:drug effects; D011460:Prostaglandins F / Q000652:urine; D051381:Rats; D011918:Rats, Inbred SHR
D000959:Antihypertensive Agents; D002364:Caseins; D004042:Dietary Fats, Unsaturated; D004044:Dietary Proteins; D005231:Fatty Acids, Unsaturated; D029941:Fish Proteins; D008055:Lipids; D011460:Prostaglandins F; D015121:6-Ketoprostaglandin F1 alpha; D044943:Fatty Acid Desaturases; C100006:prostaglandin F1