title: Differential abundance of IGF1, bile acids, and the genes involved in their signaling in the dominant follicle microenvironment of lactating cows and nulliparous heifers.
abstract: It is well documented that incidence of fertility problems is high in lactating cows but not in heifers of the same genetic merit. Understanding the metabolic and molecular differences between fertile heifers and relatively infertile lactating cows will help us understand the pathogenesis of infertility in dairy cows. Follicular waves in lactating cows (30-50 days in milk; n = 12) and heifers (n = 10) were synchronized by ultrasound-guided follicle ablation. Follicular fluid and granulosa cells of the dominant follicle were collected by ultrasound-guided aspiration along with blood sampling on Day 6 after synchronization. Dominant and subordinate follicles were larger in lactating cows than in heifers. Metabolic stress in lactating cows was evidenced by lower glucose and higher ß-hydroxy butyric acid compared with heifers. Insulin-like growth factor 1 signaling was reduced in the dominant follicle in lactating cows through reduced insulin-like growth factor 1 concentrations in plasma and follicular fluid of the dominant follicle, and reduced expression of pregnancy-associated plasma protein A (PAPPA) in their granulosa cells. We also found increased levels of total bile acids in the follicular fluid of the dominant follicle of lactating cows compared with heifers. Granulosa cells of the dominant follicle had higher expression of SLC10A2 and GPBAR1 (bile acid transporter and receptor, respectively) in lactating cows. These novel data are indicative of increased bile acid signaling within the dominant follicles of lactating cows compared with heifers. Overall, we demonstrate in the present study the metabolic, endocrine, and molecular differences within the microenvironment of the dominant follicles in lactating cows and heifers. These differences in follicular microenvironment may contribute toward abnormal ovarian function in lactating dairy cows.
authors: Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors: Ricardo
authors: R
authors: Sanchez
authors: Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors: Yasmin
authors: Y
authors: Schuermann
authors: Centre de recherche en reproduction animale, Université de Montréal, St-Hyacinthe, Quebec, Canada.
authors: Laurianne
authors: L
authors: Gagnon-Duval
authors: Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors: Hernan
authors: H
authors: Baldassarre
authors: Centre de recherche en reproduction animale, Université de Montréal, St-Hyacinthe, Quebec, Canada.
authors: Bruce D
authors: BD
authors: Murphy
authors: Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors: Nicolas
authors: N
authors: Gevry
authors: School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors: Luis B
authors: LB
authors: Agellon
authors: Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
authors: Vilceu
authors: V
authors: Bordignon
authors: Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada. Electronic address: raj.duggavathi@mcgill.ca.
authors: Raj
authors: R
authors: Duggavathi
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D001786:Blood Glucose; D020148:Butyric Acid / Q000097:blood; D002417:Cattle / Q000235:genetics / Q000502:physiology*; D060833:Cellular Microenvironment; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism*; D006080:Ovarian Follicle / Q000378:metabolism*; D015398:Signal Transduction; D014280:Triglycerides / Q000097:blood
chemical_list: D001647:Bile Acids and Salts; D001786:Blood Glucose; D014280:Triglycerides; D020148:Butyric Acid; D007334:Insulin-Like Growth Factor I
keywords: Bile acids; Dairy cattle; Dominant follicle; Fertility; Granulosa cells; IGF1