Systemic but not intraovarian concentrations of insulin-like growth factor-I are affected by short-term fasting.
To determine whether systemic and/or intraovarian concentrations of insulin-like growth factor-I (IGF-I) are affected by short-term fasting, 24 heifers were blocked by weight and, within block, were assigned to one of three treatments: fasted for 0 h (controls; n = 8), fasted for 24 h (n = 8), or fasted for 48 h (n = 8). Blood plasma was collected every 8 h from -64 h to 0 h before ovariectomy (OVEX). OVEX was performed per vagina under local anesthesia during the follicular phase of an estrous cycle (36-42 h after synchronization with prostaglandin-F2 alpha). Follicular fluid (FFL) and granulosa cells were collected individually from follicles greater than or equal to 6 mm (large), and FFL was pooled from follicles 1.0-5.9 mm (small) in diameter. Fasting did not affect (p greater than 0.20) the number (mean +/- SE) of small (52 +/- 7) or large (1.5 +/- 0.4) follicles per heifer, specific binding of 125I-hCG to granulosa cells of follicles greater than or equal to 8 mm in diameter, or concentrations of progesterone in FFL of small follicles. At OVEX, body weight was less (p less than 0.01) for 24 h- and 48 h-fasted heifers (412 +/- 7 kg and 399 +/- 7 kg, respectively) than for 0 h-fasted heifers (442 +/- 7 kg). At OVEX, plasma concentrations of IGF-I were lower (p less than 0.05) in the 48 h-fasted group (105 +/- 8 ng/ml) than in the 0 h-fasted group (140 +/- 8 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
Spicer
L J
LJ
Department of Animal Science, Oklahoma State University, Stillwater 74078.
Crowe
M A
MA
Prendiville
D J
DJ
Goulding
D
D
Enright
W J
WJ
D000818:Animals; D001826:Body Fluids / Q000378:metabolism; D002417:Cattle; D004958:Estradiol / Q000378:metabolism; D005215:Fasting / Q000097:blood / Q000378:metabolism*; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D003341:Luteolysis / Q000502:physiology; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000378:metabolism; D010052:Ovariectomy; D010053:Ovary / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism; D011974:Receptors, LH / Q000378:metabolism
D011974:Receptors, LH; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I