| dc.description.abstract | Postpartum health is important for maintaining normal calving intervals, disruptions in energy balance during this period are frequently linked to reproductive problems. Numerous studies have been conducted on associations between the somatotropic and reproductive axis, leading to a better understanding of the function of substances such as GH, IGF-1, leptin, ghrelin, insulin and glucose in relation to fertility. In addition much research has been performed regarding the effect of non-esterified fatty acids (NEFA’s) on folliculogenesis and oocyte development. The effect of NEFA’s on luteal tissue is still debatable.
In this thesis the effects of NEFA’s on corpus luteum (CL) function and viability were studied using two different experimental methods. In experiment 1 luteal cell cultures were exposed to 100, 250 or 500µM of either palmitic, oleic, stearic or linoleic acid for 24 hours. Similar tests were performed on mixtures of these fatty acids, known to be physiologically present in the bovine circulation at day 7 postpartum. After 24 hours progesterone (P4) production was measured using radioimmunoassay, and the total number of viable cells was manually determined using light microscopy. These two measurements were then related to determine P4 production/1000 cells in order to get more insight in the mechanisms behind the decline in P4 levels in the medium. In experiment 2 a working ovarian perfusion system was developed in order to study the effects of NEFA’s on ovarian function in a more natural configuration. Measurements of lactate, LDH, pO2,pCO2 and progesterone were used to determine organ viability and functionality.
Experiment 1 showed a decline in P4 production and viable cell count after the addition of the saturated fatty acids, palmitic acid (PA) and stearic acid (SA). The P4 production per 1000 cells significantly increased in the stearic acid 250 and 500µM conditions and in one of the two PA 500µM conditions. No significantly different total viable cell count or P4 production per 1000 cells resulted from the physiological mixtures. Experiment 2 gave decent first results indicating that it might be possible to use a perfusion experiment to further study of the effect of NEFA’s on CL function. There was a decrease in lactate concentration over time and immeasurably low levels of LDH indicating that waste products could be flushed out and that there was only minor to no cell damage. pO2 as well as pCO2 levels were out of normal range and still need further adjustments. P4 concentrations in the medium of the final experimental set-up were high enough and remained relatively constant which is suggestive of P4 production by the ovary.
To conclude the studies presented here show that there is a change in total P4, total viable luteal cells and P4 production/1000 cells after the addition of saturated fatty acids to luteal cell cultures. The cause of the change in P4/1000 cells must be further investigated. Possibly perfusion experiments, which were shown to be applicable in our lab, can give additional information on the effects of NEFA’s on the CL in a more in vivo like situation. | |
