This dissertation, "A Rat Model to Study Ovarian Dysfunction in Galactosemia" by Ka-wai, Lai, 黎嘉慧, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled A rat model to study ovarian dysfunction in galactosemia submitted by LAI KA WAI for the degree of Master of Philosophy at The University of Hong Kong in August 2001 Galactosemia is a genetic disease that involves a deficiency of galactose-1-phosphate uridyltransferase, resulting in the accumulation of galactose and galactose-1-phosphate in the blood and tissues. Clinical consequences include mental retardation, visual cataract and ovarian failure. In this study, it was postulated that a change in the molecular mechanism controlling the ovarian granulosa cell apoptosis may be related to decreased ovulation rate and fertility in galactosemic females. A rat model was developed to study the molecular mechanism involved in ovarian failure associated with galactosemia. Female Sprague-Dawley rats (3-4 weeks of age, 8 per group) were fed with normal rat chow (control group) or 50% galactose diet (galactosemic group) for 4 weeks. In order to investigate the effect of high galactose on ovulation, both groups were induced to ovulate on Day 3 of the oestrous cycle with pregnant mare's serum gonadotrophin (PMSG) (50 IU/100 g body weight) followed by human chorionic hormone (hCG) (50 IU/100 g body weight) at 48 hours later. Rats were killed 18 hours post-hCG by sodium pentobarbitone overdose. Plasma galactose-1- phosphate level was high in galactosemic group while it was undetectable in the control. In the galactosemic group, body weight gain, uterine, ovarian and liver weight were significantly lower while the kidneys' weight was significantly higher when compared with the control. The number of ovulated oocytes flushed from the oviducts was significantly lower in galactosemic group. Morphometric analysis of the ovaries showed the number of corpora lutea in the galactosemic group was significantly lower when compared with the control, while the mean volume of corpus luteum was significantly higher. Accumulation of galactose from the dietary treatment might exert galactose toxicity in the galactosemic group. As a result, some clinical symptoms, such as cataract and polyuria were also observed. In order to investigate granulosa cell apoptosis at different follicular stages, rats were killed at different time points: 0 h, 8 h and 13 h post hCG injection. The profiles of Fas and FasL (cell death inducers), Riap and Xiap (survival factors) were examined. Western blot analysis showed the levels of Fas protein in the granulosa cells from the galactosemic group were higher than that of the control at 8 h post-hCG. On the other hand, the levels of Riap and Xiap proteins were lower in the galactosemic group at the same time point. These were confirmed by the results of the immunostaining of ovarian sections. TUNEL showed a higher proportion of atretic follicles in the galactosemic group. Higher incidence of granulosa cells apoptosis in the galactosemic group might be due to the imbalance of cell death inducers (Fas and FasL) and survival factors (Riap and Xiap). The galactose toxicity might down-regulate the protein contents of Riap and Xiap, and up-regulate the protein contents of Fas and FasL in the growing follicles. It is likely that the increased apoptosis in granulosa cells of maturing follicle under galactosemic condition is due to an increased expression of cell death inducers (Fas and FasL), which leads to a decreased expression of survival factors (Riap an