The expression of insulin-like growth factors and their receptors at pre-implantation stage in reproductive tissue of diabetic mouse
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Date
2007
Authors
Rahimah, Zakaria
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Abstract
We hypothesized that the alteration in the expression of IGFs and their
receptors may create an abnormal intrauterine environment thus affect embryos
development. Therefore, the aims of the present study were to determine the
effects of diabetes on in vitro development of mouse preimplantation embryos
and to determine the mRNA and protein expression of IGF-1, IGF-2, IGF-1R
and IGF-2R in the fallopian tube and uterine tissue of control and diabetic mice.
Sexually mature female ICR mice of 6-8 weeks old were made diabetic by
streptozotocin (200 mg/kg, intraperitoneal). The normal two-cell embryos were
obtained from superovulated control and diabetic mice at 48 post-hCG
treatment. Embryos were separately cultured and examined under an inverted
microscope for 3 consecutive days. Fallopian tubes and uterine tissues were
obtained from the superovulated control and diabetic mice at 48, 72 and 96
hours post-hCG treatment. The mRNA expression was measured using Realtime
PCR using specifically developed homologous internal standards for each
gene. Protein expression was measured by immunohistochemical staining and
a semiquantitative scoring was performed using a standardized 5-scale system.
The number of normal two-cell embryos obtained from diabetic mice was much
reduced when compared to control mice. However, there was no significant difference in the percentage of two-cell embryo development in control and
diabetic mice. The mRNA expression of IGF-1 in the fallopian tube and uterus
of diabetic mice was significantly low at 72 hours and 96 hours post-hCG
treatment, respectively. The mRNA expression of IGF-1R remained high in the
fallopian tube but was significantly low in the uterus of diabetic mice at 96 hours
post-hCG treatment. The mRNA expression IGF-2 in the fallopian tube was
significantly high at 48 and 96 hours post-hCG treatment but was significantly
low in the uterus of diabetic mice at 96 hours post-hCG treatment. The mRNA
expression of IGF-2R in the fallopian tube and uterus of diabetic mice was
significantly high at 48 and 96 hours, and at 48 hours post-hCG treatments,
respectively. For protein expression, the immunohistochemical scoring for both
IGF-1 and IGF-1R was significantly decreased in the fallopian tube of diabetic
mice at 96 hours post-hCG treatment. In contrast, the score for IGF-2 and IGF-
2R was significantly increased in the fallopian tube of diabetic mice at 48 and 72
hours; and at 72 hours post-hCG treatment, respectively. However, there was
no significant difference in the score of IGFs and their receptors in the uterus of
control and diabetic mice. In conclusion, the percentage of the two-cell stage
embryos which developed to blastocysts was similar in control and diabetic
groups but whether the quality of these embryos were the same could not be
confirmed. Both the mRNA and protein expression of IGFs and their receptors
were significantly altered by maternal diabetes, which suggest their role in the
pathogenesis of diabetic embryopathy.
Description
Ph.D
Keywords
Medical science , Insulin-like growth factors