Circadian variations of plasma atrial natriuretic peptide and corticosterone in rats with continuous or restricted access to food.
In the present study plasma Atrial Natriuretic Peptide (ANP) and Corticosterone (B) levels were determined in 2 groups of Wistar rats, a Control group (C) with free access to food, and a Food Shift group (FS) with access to food only from 0900 to 1100 h for 2 weeks. Blood samples were collected by decapitation at 4 hour intervals. ANOVA indicated that B varied over time in both groups (F (6.46) = 10.14, p < 0.0001 for C and F (6.5) = 5.10, p = 0.0005 for FS). There was also time variation in plasma ANP levels in both groups (F (6.54) = 3.78, p = 0.003 for C and F (6.48) = 2.73, p = 0.02 for FS group). Plasma B presented circadian variations from 78 +/- 17 nmol/l (mean +/- SEM) at 0800 h to 339 +/- 79 nmol/l at 2000 h. The day peak plasma ANP level (pmol/l) was also attained at 2000 h (68 +/- 19). This value was higher than all others measured throughout the day. The restricted feeding regimen resulted in a 12 hour shift of peak B values (395 +/- 39 vs 125 +/- 24). The FS rats presented the highest ANP level at 0800 h. The present study indicates similar circadian variations of plasma ANP and B in rats on an ad lib or restricted feeding regimen. ANP and B secretion may occur in anticipation of the feeding period or day activity.
Oliveira
M H
MH
Antunes-Rodrigues
J
J
Leal
A M
AM
Elias
L L
LL
Moreira
A C
AC
D000704:Analysis of Variance; D000821:Animal Feed; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood*; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D009320:Atrial Natriuretic Factor; D003345:Corticosterone