metallothionein and Infertility--Female

Correlated responses in female reproductive performance were evaluated following short-term selection within full-sib families for increased 8-week body weight in two replicates of four lines of mice: two ovine metallothionein-ovine growth hormone (oMt1a-oGH) transgene-carrier lines, one from a high-growth background (TM) and one from a control background (TC), and two non-transgenic lines, one from each of these genetic backgrounds (NM and NC, respectively). A fifth line (CC), not containing the transgene, served as a randomly selected control. The initial frequency of the oMt1a-oGH transgene construct in the TM and TC lines was 0.5. The frequency of transgenic females sampled at generations 7 and 8 of selection was 84.0% and 6.1% in the TC and TM lines, respectively. No significant female infertility differences were detected between transgene-carrier and non-transgenic lines or between transgenic and non-transgenic mice within carrier lines, whereas high-growth background lines had a higher infertility than control background lines (P < 0.05). Correlated responses in the TC transgene-carrier line were suggestive of reduced reproductive performance as indicated by increased post-implantation mortality (P < 0.05), number of dead fetuses plus implants (P < 0.05), and loss of fetuses from day 16 to parturition (P < 0.001). For the first two traits, the negative correlated responses were accounted for by the reduced performance of transgenic compared with non-transgenic females. Embryos carrying the transgene may also have a lower viability. In contrast, the NC non-transgenic line did not exhibit reduced reproductive performance for these traits. The low frequency of the transgene in the high-growth background TM line was associated with reduced fitness and a lower additive effect for 8-week body weight compared with the control background TC line.

Topics: Animals; Body Weight; Female; Growth Hormone; Infertility, Female; Metallothionein; Mice; Mice, Transgenic; Ovulation; Reproduction; Sheep

The role of FSH in gonadal tumorigenesis and, in particular, in human ovarian cancer has been debated. It is also unclear what role the elevated FSH levels in the inhibin-deficient mouse play in the gonadal tumorigenesis. To directly assess the role of FSH in gonadal growth, differentiation, and gonadal tumorigenesis, we have generated both gain-of-function and loss-of-function transgenic mutant mice. In the gain-of-function model, we have generated transgenic mice that ectopically overexpress human FSH from multiple tissues using a mouse metallothionein-1 promoter, achieving levels far exceeding those seen in postmenopausal women. Male transgenic mice are infertile despite normal testicular development and demonstrate enlarged seminal vesicles secondary to elevated serum testosterone levels. Female transgenic mice develop highly hemorrhagic and cystic ovaries, have elevated serum estradiol and progesterone levels, and are infertile, mimicking the features of human ovarian hyperstimulation and polycystic ovarian syndromes. Furthermore, the female transgenic mice develop enlarged and cystic kidneys and die between 6-13 weeks as a result of urinary bladder obstruction. In a complementary loss-of-function approach, we have generated double-homozygous mutant mice that lack both inhibin and FSH by a genetic intercross. In contrast to male mice lacking inhibin alone, 95% of which die of a cancer cachexia-like syndrome by 12 weeks of age, only 30% of the double-mutant male mice lacking both FSH and inhibin die by 1 yr of age. The remaining double-mutant male mice develop slow-growing and less hemorrhagic testicular tumors, which are noted after 12 weeks of age, and have minimal cachexia. Similarly, the double-mutant female mice develop slow-growing, less hemorrhagic ovarian tumors, and 70% of these mice live beyond 17 weeks. The double-mutant mice demonstrate minimal cachexia in contrast to female mice lacking only inhibin, which develop highly hemorrhagic ovarian tumors, leading to cachexia and death by 17 weeks of age in 95% of the cases. The milder cachexia-like symptoms of the inhibin and FSH double-mutant mice are correlated with low levels of serum estradiol and activin A and reduced levels of aromatase mRNA in the gonadal tumors. Based on these and our previous genetic analyses, we conclude that elevated FSH levels do not directly cause gonadal tumors. However, these results suggest FSH is an important trophic modifier factor for gonadal tumorigenesis in

Topics: Activins; Animals; Crosses, Genetic; Female; Follicle Stimulating Hormone; Gene Expression Regulation; Hemorrhage; Homozygote; Humans; Infertility, Female; Infertility, Male; Inhibins; Male; Metallothionein; Mice; Mice, Mutant Strains; Mice, Transgenic; Oligopeptides; Ovarian Neoplasms; Ovary; Peptides; Polycystic Ovary Syndrome; Seminal Vesicles; Steroids; Testicular Neoplasms; Urinary Tract; Wasting Syndrome

Transgenic female mice expressing a temporally regulatable ovine metallothionein 1a-ovine growth hormone (oMT1a-oGH) fusion gene can cycle, mate, and support early embryonic development; but they fail to maintain pregnancy or, in most cases, to exhibit signs of pseudopregnancy. The present study was designed to determine whether or not the infertility of oMT1a-oGH transgenic female mice is due to luteal insufficiency. A series of five experiments was conducted in which various hormonal therapies were utilized in an attempt to overcome this infertility. Provision of 1 mg progesterone to oMT1a-oGH females from Days 1 to 17 of gestation rescued pregnancy in 19 of 20 females with an increased mean litter size (p < 0.01) compared to that of wild-type control females. Supplementation with progesterone also appeared on the basis of gross anatomical appearance to maintain CI. Provision of 2 mg progesterone in combination with 25 ng estradiol-17 beta from Days 4 to 17 rescued pregnancy in 14 of 24 oMT1a-oGH females, while provision of 100 or 25 micrograms ovine prolactin from Days 3 to 17 failed to overcome oMT1a-oGH infertility. Transgenic females with rescued pregnancies lactated and raised heavier pups than wild-type females by Day 15 postnatal (p < 0.05). Results indicate that infertility of oMT1a-oGH transgenic mice is caused by luteal insufficiency. Supplementation of transgenic females with progesterone appeared to maintain morphologically normal CL and pregnancy with subsequently increased litter size and normal lactation.

Topics: Animals; Cloning, Molecular; Corpus Luteum Maintenance; Female; Growth Hormone; Infertility, Female; Lactation; Metallothionein; Mice; Mice, Inbred ICR; Mice, Transgenic; Pregnancy; Pregnancy Maintenance; Progesterone; Prolactin; Sheep