Impact of gestational hypothyroidism on uterine implantation and reproductive performance in the rat.

GAMARRA LUQUES C; CAMPO VERDE ARBOCCO F; PIETROBON EO; SCANLAN T; JAHN GA; HAPON MB

Buenos Aires

Congreso; VI SLIMP & V LASRI,; 2015

SLIMP

Maternal hypothyroidism may affect uterine implantation and reproductiveperformance in the rat.Objective: To evaluate the effect of maternal hypothyroidism and T3 or GC-1 (a thyroid hormone receptor b1 selective agonist) replacement onuterine implantation, reproductive performance and hormonal profile inthe rat.Methods: Hypothyroid was induced in female Wistar rats by dailyadministration of 6-propyl-2-thiouracil (PTU 0.1 g/L in drinking water) (n> 5). The replacement treatment consisted of daily i.p. administration ofphysiological doses of T3 (0.6 mg/100g) or equimolar doses of GC-1(0.3 mg/100 g). The reproductive performance (length of gestation, number of pupsper litter and pups weight) was monitored. One group of rats was sacrificedon day 7 of gestation and the number of implantation sites wasrecorded. Progesterone, Estradiol, T3 and TSH serum level were measuredby radioimmunoassay. Progesterone receptor mRNA expression wasdetermined by real time RTqPCR.Results: Hypothyroidism decreased the number of implantation sites perrat, the number of pups per litter and weight of the newborns (p < 0.05).The administration of T3 or GC-1 reversed the effect caused by hypothyroidismon implantation, number of pups per litter and weight gain.Hypothyroidism delayed the onset of parturition (p < 0.001). Only T3overcame the effect of hypothyroidism on parturition. Neither progesteronenor estradiol or progesterone receptor mRNA expression wasaltered by hypothyroidism on the post-implantation period. The administrationof T3 or GC-1 alone had no detrimental effect during gestation inthe rat.Conclusions: The presence of an adequate level of thyroid hormonesduring gestation has an important role in uterine implantation andreproductive performance in the rat. The selective effect of the hormonalreplacement reflects the importance of the thyroid hormone receptorspecificity on reproduction.