Introduction:
Early embryonic mortality in beef cattle is a major problem in agriculture, something must be done to fix this issue. The loss of pregnancy in cattle costs the beef industry and American ranchers millions of dollars annually. This cost translates directly to the American consumer. In pregnant cattle, the embryo releases a cytokine named interferon-T 14 to 18 days after conception to reduce the production of PGF2α in the uterus. Without the apoptotic PGF2a hormone process, the cow can continue to produce the hormone progesterone, which is essential for implantation and early embryonic development and decreasing the mother’s immune response to the embryo. Since the mother’s body sees the embryo as a foreign object, it will try to attack the embryo as if it were a virus or infection; therefore, the production of progestrone is mandatory for a pregnancy to be upheld and sustained.
Past studies have shown that supplementing cattle with fish meal enriched with omega-3 fatty acids allows for improved fertility. Omega-3 fatty acids may also have an effect on the ovaries of ovulating cows through a controversial process known as lipid microdomains and cell signaling.
Lipid microdomains are small, organized, areas of the cell membrane comprised mostly of cholesterol and sphingolipids (Pike, 2003). These microdomains have many cellular functions to include cellular signaling platforms to activate signal transduction within the cell (Calder, 2007). However, these microdomains were very hard to isolate, and there remains still much controversy to the question of whether or not they can be easily isolated and what are their exact purposes (Calder, 2007). Nonetheless, one way that the lipid microdomains are able to be tracked today is by the proteins we associate with them. The identification of flotillin and caveolin in multiple lipid microdomains by a variety of methods indicated that they were legitimate markers for the domains (Pike, 2009). These lipid microdomains are a major part in cell signaling due to the proteins they contain. The caveolin makes up dent-like structures on both the inner and outer membrane areas of the cell and allows various molecules to “dock” with it. This causes the structure called a caveolae to form a vesicle and transport the molecule into or out of the cell though the cell membrane or act as a second messenger in cellular transduction (Pike, 2003).
The corpus luteum (“yellow body” in Latin) is a small gland that is key in the production of progestrone during the estrous cycle of mammals (Mann, 2001). When a mammal ovulates, the corpus luteum develops and begins secreting a hormone known as progestrone. Progestrone is essential in implantation and early embryonic development in early pregnancy. If the egg is not fertilized, the corpus luteum naturally regresses, and progesterone is no longer produced in what is known as luteolysis. After implantation, the embryo trophoblast cells produce interferon Tau, a cytokine, that in correct concentrations will trigger maternal recognition of pregnancy (Pansky, 2013). Prostaglandin (PG) F 2α is a hormone produced by the uterus of a non-pregnant cow late in the estrous cycle responsible for the regression of the corpus luteum (structural regression). When the corpus luteum regresses, progesterone synthesis is significantly reduced (functional regression). Without the production of progestrone, termination of the cow’s pregnancy will occur, restarting the cow’s estrous cycle for future pregnancy (Mann, 2001). This regulation of maternal PGF2α is essential to improve bovine pregnancy calving rates. One such novel approach to regulating PGF2α is the use of fish oils or fish meal enriched with omega-3 fatty acids as a diet supplement for cattle.
Omega-3 fatty acids, which are commonly found in fish oils, are poly unsaturated long-chain fatty acids. These fatty acids, when incorporated in bovine luteal cells, attenuate the PGF 2α metabolism possibly by disrupting the luteal lipid microdomains (Mann, 2001). It is postulated that the omega-3 fatty acids disperse the ordered regions of cholesterol and sphingolipids in the microdomain. Thus, inhibiting the bound PGF2α hormone and its receptor from docking and initiating an apoptotic cell signaling pathway that will regress the CL. If cell signaling PGF2α is inhibited, the embryo has more time to build up concentrations of interferon Tau and possibly improve pregnancy. When beef cattle were supplemented with fish meal, these omega-3 fatty acids were more prominent in luteal cells. With the incorporation of these fatty acids, cattle have more of a chance at staying pregnant (Burns, 2003). We hypothesize that the incorporation of omega-3 fatty acids found in fish oils to bovine luteal cells will cause a shift in proteins associated to lipid microdomains to bulk lipids. The objective of this research was to examine the effect of fish oils enriched with omega-3 fatty acids on distribution of lipid microdomain proteins flotillin and caveolin in bovine luteal cells.
Past studies have shown that supplementing cattle with fish meal enriched with omega-3 fatty acids allows for improved fertility. Omega-3 fatty acids may also have an effect on the ovaries of ovulating cows through a controversial process known as lipid microdomains and cell signaling.
Lipid microdomains are small, organized, areas of the cell membrane comprised mostly of cholesterol and sphingolipids (Pike, 2003). These microdomains have many cellular functions to include cellular signaling platforms to activate signal transduction within the cell (Calder, 2007). However, these microdomains were very hard to isolate, and there remains still much controversy to the question of whether or not they can be easily isolated and what are their exact purposes (Calder, 2007). Nonetheless, one way that the lipid microdomains are able to be tracked today is by the proteins we associate with them. The identification of flotillin and caveolin in multiple lipid microdomains by a variety of methods indicated that they were legitimate markers for the domains (Pike, 2009). These lipid microdomains are a major part in cell signaling due to the proteins they contain. The caveolin makes up dent-like structures on both the inner and outer membrane areas of the cell and allows various molecules to “dock” with it. This causes the structure called a caveolae to form a vesicle and transport the molecule into or out of the cell though the cell membrane or act as a second messenger in cellular transduction (Pike, 2003).
The corpus luteum (“yellow body” in Latin) is a small gland that is key in the production of progestrone during the estrous cycle of mammals (Mann, 2001). When a mammal ovulates, the corpus luteum develops and begins secreting a hormone known as progestrone. Progestrone is essential in implantation and early embryonic development in early pregnancy. If the egg is not fertilized, the corpus luteum naturally regresses, and progesterone is no longer produced in what is known as luteolysis. After implantation, the embryo trophoblast cells produce interferon Tau, a cytokine, that in correct concentrations will trigger maternal recognition of pregnancy (Pansky, 2013). Prostaglandin (PG) F 2α is a hormone produced by the uterus of a non-pregnant cow late in the estrous cycle responsible for the regression of the corpus luteum (structural regression). When the corpus luteum regresses, progesterone synthesis is significantly reduced (functional regression). Without the production of progestrone, termination of the cow’s pregnancy will occur, restarting the cow’s estrous cycle for future pregnancy (Mann, 2001). This regulation of maternal PGF2α is essential to improve bovine pregnancy calving rates. One such novel approach to regulating PGF2α is the use of fish oils or fish meal enriched with omega-3 fatty acids as a diet supplement for cattle.
Omega-3 fatty acids, which are commonly found in fish oils, are poly unsaturated long-chain fatty acids. These fatty acids, when incorporated in bovine luteal cells, attenuate the PGF 2α metabolism possibly by disrupting the luteal lipid microdomains (Mann, 2001). It is postulated that the omega-3 fatty acids disperse the ordered regions of cholesterol and sphingolipids in the microdomain. Thus, inhibiting the bound PGF2α hormone and its receptor from docking and initiating an apoptotic cell signaling pathway that will regress the CL. If cell signaling PGF2α is inhibited, the embryo has more time to build up concentrations of interferon Tau and possibly improve pregnancy. When beef cattle were supplemented with fish meal, these omega-3 fatty acids were more prominent in luteal cells. With the incorporation of these fatty acids, cattle have more of a chance at staying pregnant (Burns, 2003). We hypothesize that the incorporation of omega-3 fatty acids found in fish oils to bovine luteal cells will cause a shift in proteins associated to lipid microdomains to bulk lipids. The objective of this research was to examine the effect of fish oils enriched with omega-3 fatty acids on distribution of lipid microdomain proteins flotillin and caveolin in bovine luteal cells.