Short-term feed restriction decreases the systemic and intrafollicular concentrations of leptin and increases the vascularity of the preovulatory follicle in mares.
Abstract: The objective of this study was to evaluate the effect of short-term feed restriction on characteristics of the preovulatory follicle and on concentrations of systemic hormones (leptin, follicle-stimulating hormone [FSH], luteinizing hormone [LH]) and follicular fluid hormones and growth factors (leptin, estradiol, inhibin-A, activin-A, free insulin-like growth factor-1 [IGF1], insulin-like growth factor binding protein 2 [IGFBP2], vascular endothelial growth factor [VEGF]). Mares were submitted to a short-term (48 h) feed restriction when the expected ovulatory follicle was > or =27 mm (Hour 0) or served as controls (n=8/group). No effect of short-term feed restriction was detected for systemic concentrations of FSH and LH and for intrafollicular concentrations of estradiol, activin-A, free IGF1, and IGFBP2. Restricted mares had decreased systemic concentrations of leptin at Hour 24 (approached significance) and at Hours 36 and 48 (P<0.04). Follicular fluid of restricted mares at Hour 48 had lower (P<0.02) concentration of leptin and a tendency (P<0.1) for greater concentrations of inhibin-A and VEGF. The percentage of wall of the preovulatory follicle with color-Doppler signals of blood flow at Hour 48 was greater (P<0.04) in the restricted group. Intrafollicular concentration of leptin (combined groups) was positively correlated with score for body condition (r=+0.60; P<0.002) and negatively correlated with the percentage of the follicle wall with blood-flow signals (r=-0.60; P<0.02). Our favored interpretation is that the preovulatory follicle seems to compensate for a nutritional deficiency by increasing the blood flow in the follicle wall.
2010 Elsevier Inc. All rights reserved.
Publication Date: 2010-03-11 PubMed ID: 20226513DOI: 10.1016/j.theriogenology.2009.11.032Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates the effect of short-term feed restriction on hormone levels and preovulatory follicle characteristics in mares. The research found that feed restriction lowers systemic and intrafollicular leptin concentrations, and increases the vascularity of the preovulatory follicle, suggesting the follicle may compensate for nutritional deficiency by increasing blood flow.
Objective and Method
- The aim of the study was to understand the influence of short-term feed restriction on the preovulatory follicle’s characteristics and hormone concentrations. Specific hormones of interest included leptin, FSH (follicle-stimulating hormone), LH (luteinizing hormone), estradiol, inhibin-A, activin-A, IGF1 (insulin-like growth factor-1), IGFBP2 (insulin-like growth factor binding protein 2), and VEGF (vascular endothelial growth factor). This study thus focused on mare biology.
- Mares were exposed to a short-term (48-hour) feed restriction when the expected ovulatory follicle was 27mm or larger (marked as Hour 0), while others served as controls.
Results
- The study found no significant changes in concentrations of FSH, LH, estradiol, activin-A, IGF1, and IGFBP2 in response to short-term feed restriction.
- Nevertheless, the feed-restricted mares exhibited lower systemic and intrafollicular concentrations of leptin after 24, 36, and 48 hours.
- In addition, the follicular fluid of the restricted mares at Hour 48 depicted lower leptin concentrations and a higher tendency for greater inhibin-A and VEGF concentrations. VEGF is generally associated with increased vascularity.
- Furthermore, researchers noticed an increase in the percentage of the preovulatory follicle wall with color-Doppler blood flow signals in the restricted group after 48 hours.
- Leptin concentration within the follicle was observed to directly correlate with the body condition score (positively) and inversely with the percentage of blood flow signals in the follicle wall.
Interpretation
- Based on these findings, the researchers proposed that the preovulatory follicle could attempt to counteract nutritional deficiency by increasing blood flow to the follicle wall. They note that leptin, a hormone known for regulating energy balance in the body, might play a crucial role in this compensatory response.
Cite This Article
APA
Gastal MO, Gastal EL, Beg MA, Ginther OJ.
(2010).
Short-term feed restriction decreases the systemic and intrafollicular concentrations of leptin and increases the vascularity of the preovulatory follicle in mares.
Theriogenology, 73(9), 1202-1209.
https://doi.org/10.1016/j.theriogenology.2009.11.032 Publication
Researcher Affiliations
- Eutheria Foundation, Cross Plains, Wisconsin, USA. egastal@siu.edu
MeSH Terms
- Animals
- Blood Flow Velocity
- Female
- Follicular Fluid / chemistry
- Follicular Phase / physiology
- Food Deprivation / physiology
- Horses / physiology
- Inhibins / analysis
- Insulin-Like Growth Factor I / analysis
- Leptin / analysis
- Leptin / blood
- Ovarian Follicle / blood supply
- Ovarian Follicle / chemistry
- Ovarian Follicle / diagnostic imaging
- Ultrasonography
- Vascular Endothelial Growth Factor A / analysis
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