Circadian rhythm of HMG-CoA reductase and insulin in African green monkeys.
HMG-CoA reductase in hepatic microsomes and serum insulin display circadian rhythm in two strains of Cercopethicus aethiops. Grivets develop higher levels of serum cholesterol than vervets fed cholesterol. Males (n = 20/gp) were adapted to a light cycle (7:30 a.m.-8:30 p.m.) for 60 days and fed a non-cholesterol diet at 8:30 a.m. and 2:00 p.m. Vervet acrophase, reductase activity was synchronized to serum insulin units with a specific activity of 1480 pmol/min/mg protein changing by 7.5-fold from nadir to acrophase. The activity profile in grivets was asynchronous to vervet fluctuations with peaks at 12 noon (160 pmol/min/mg) and 6 p.m. (275 pmol/min/mg). Insulin levels also peaked near these times. The 24-h reductase activity was over 4 times greater in vervet than grivet livers. The similar rhythmic patterns of reductase and insulin support the notion that insulin plays an important role in the rhythm of HMG-CoA reductase in primates.
D000818:Animals; D002250:Carbon Radioisotopes; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000097:blood; D002940:Circadian Rhythm; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D007328:Insulin / Q000097:blood*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*
D002250:Carbon Radioisotopes; D007328:Insulin; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases