Luteal activity of pregnant rats with hypo-and hyperthyroidism

Intermittent Fasting and Vitamin E Supplementation Attenuates Hypothyroidism-Associated Ophthalmopathy

Visualization is a complex-integrated procedure of the eyes and brain that allows to see this colorful world. Hypothyroidism-associated ophthalmopathy (HAO), often known as dry eyes, swelling around the eyes, blurred vision, glaucoma, and cataracts, are some eye-related issues caused by hypothyroidism. Yet there is no permanent cure for hypothyroidism; taking medicine throughout life is the only solution to keep its harmful effects under control. This study used intermittent fasting (IF) and vitamin E (Vit.E) supplementation to prevent hypothyroidism-associated ophthalmopathy. This study hypothesized that intermittent fasting-like diet regimens and vitamin supplementation should reduce the propagation of HAO by its antioxidant potential. In the present study, experimental animals are divided into five groups: normal, hypothyroidism control, dual, Vit. E, and IF. Hypothyroidism is generated in the experimental groups by taking propylthiouracil (PTU) for 24 days while also taking IF and Vit. E supplements. The hypothyroid-induced experimental animals demonstrated an increase in IOP and lipid peroxidation while thyroid hormone levels depicted a massive decline which is a clear denotation of the effects of the thyroid on eyes and lifestyle. Ancient Ayurveda inspires these proposed therapies and has successfully reduced all the damage to the thyroid gland and the eye.

Thyroid hormone transport and metabolism are disturbed in the placental villi of miscarriage

BACKGROUND

It has been long known that thyroid hormone regulates placental villi development, which is associated with the occurrence of miscarriage. However, whether abnormal thyroid hormone metabolism and transport in placental villi are involved in miscarriage is still to be verified.

METHODS

Placental villi of elective terminations of pregnancies (ETPs) and miscarriage were collected. Proliferative activity and apoptosis of villi trophoblasts and angiogenesis were detected by TUNEL and immunochemistry. The expressions of thyroid hormone receptors (THRs), transthyretin (TTR), monocarboxylate transporter 8 (MCT8), organic anion transporting polypeptides 1A1 (OATP1A1), deiodinase 2 (Dio2) and Dio3 were examined by RT-PCR, Western blot, immunohistochemistry and immunofluorescence. JEG3 cell was treated with iopanoic acid (IOP), an inhibitor of Dio2 activity, the expressions of Dio2, placenta growth factor (PLGF) and sFlt1 were detected by RT-PCR and Western blot.

RESULTS

Cell proliferation was suppressed and apoptosis was increased in placental villi cytotrophoblasts of miscarriage. CD34+ vessel number and vascular endothelial growth factor (VEGF) protein abundance were decreased in miscarriage. In miscarriage group, the gene expression of Dio2, Dio3, TTR and THRα, but not THRβ, MCT8 and OATP1A1, were downregulated. The protein abundances of TTR and THRα were downregulated in miscarriage group, but not THRβ. The protein abundance of Dio2 in miscarriage villi was decreased compared with that in ETP. In JEG3 cells, the gene expression of PLGF was decreased and the expression of sFlt1 was increased in IOP treatment; The protein abundance of Dio2 was downregulated but the gene expression of Dio2 was unaffected in IOP treatment.

CONCLUSION

Thyroid hormone transport and metabolism in miscarriage were disturbed and may impaired angiogenesis of placental villi, which was associated with the occurrence of miscarriage.

Kisspeptin Treatment Restores Ovarian Function in Rats with Hypothyroidism

Background: Hypothyroidism causes ovarian dysfunction and infertility in women, in addition to being associated with hyperprolactinemia and reduced hypothalamic expression of kisspeptin (Kp). However, it remains unknown whether and how Kp is able to reverse the ovarian dysfunction caused by hypothyroidism. Methods: Hypothyroidism was induced in adult female Wistar rats using 6-propyl-2-thiouracil for 3 months. In the last month, half of the animals received Kp10. Blood samples were collected for dosage of free thyroxine, thyrotropin (TSH), luteinizing hormone (LH), prolactin (PRL), progesterone (P₄), and estradiol (E₂), and uteruses and ovaries were collected for histomorphometry. Body and ovarian weight and the number of corpora lutea were also evaluated. Half of the brains were evaluated by immunohistochemistry to Kp, and the other half had the arcuate nucleus of hypothalamus (ARC) and preoptic area microdissected for gene evaluation of Kiss1, Nkb, Pdyn, and Gnrh1. The pituitary gland and corpora lutea were also dissected for gene evaluation. Results: Hypothyroidism kept the animals predominantly acyclic and promoted a reduction in ovarian weight, number of corpora lutea, endometrial thickness, number of endometrial glands, and plasma LH, in addition to increasing the luteal messenger RNA (mRNA) expression of Star and Cyp11a1 and reducing 20αHsd. An increase in plasma PRL and P₄ levels was also caused by hypothyroidism. Kp immunoreactivity and Kiss1 and Nkb mRNA levels in the ARC and Kiss1 in the anteroventral periventricular nucleus of hypothalamus were reduced in hypothyroid rats. Hypothyroid animals had lower pituitary gene expression of Gnrhr, Lhb, Prl, and Drd2, and an increase in Tshb. The treatment with Kp10 restored estrous cyclicality, plasma LH, ovarian and uterine morphology, and Cyp11a1, 3βHsd, and 20αHsd mRNA levels in the corpora lutea. Kp10 treatment did not alter gene expression for Kiss1 or Nkb in the ARC of hypothyroid rats. Nevertheless, Kp10 increased Lhb mRNA levels and reduced Tshb in the pituitary compared with the hypothyroid group. Conclusions: The present findings characterize the inhibitory effects of hypothyroidism on the hypothalamic-pituitary-gonadal axis in female rats and demonstrate that Kp10 is able to reverse the ovarian dysfunction caused by hypothyroidism, regardless of hyperprolactinemia.

Maternal hypothyroidism causes oxidative stress and endoplasmic reticulum stress in the maternal-fetal interface of rats

Maternal hypothyroidism is associated with pre-eclampsia and intrauterine growth restriction, gestational diseases involving oxidative stress (OS) and endoplasmic reticulum stress (ERS) in the placenta. However, it is not known whether hypothyroidism also causes OS and ERS at the maternal-fetal interface. The aim was to evaluate the fetal-placental development and the expression of mediators of OS and of the unfolded protein response (UPR) in the maternal-fetal interface of hypothyroid rats. Hypothyroidism was induced in Wistar rats with propylthiouracil and the fetal-placental development and placental and decidual expression of antioxidant, hypoxia, and UPR mediators were analyzed at 14 and 18 days of gestation (DG), as well the expression of 8-OHdG and MDA, and reactive oxygen species (ROS) and peroxynitrite levels. Hypothyroidism reduced fetal weight at 14 and 18 DG, in addition to increasing the percentage of fetal death and reducing the weight of the uteroplacental unit at 18 DG. At 14 DG, there was greater decidual and/or placental immunostaining of Hif1α, 8-OHdG, MDA, SOD1, GPx1/2, Grp78 and CHOP in hypothyroid rats, while there was a reduction in placental and/or decidual gene expression of Sod1, Gpx1, Atf6, Perk, Ho1, Xbp1, Grp78 and Chop in the same gestational period. At 18 DG, hypothyroidism increased the placental ROS levels and the decidual and/or placental immunostaining of HIF1α, 8-OHdG, MDA, ATF4, GRP78 and CHOP, while it reduced the immunostaining and enzymatic activity of SOD1, CAT, GST. Hypothyroidism increased the placental mRNA expression of Hifα, Nrf2, Sod2, Gpx1, Cat, Perk, Atf6 and Chop at 18 DG, while decreasing the decidual expression of Sod2, Cat and Atf6. These findings demonstrated that fetal-placental restriction in female rats with hypothyroidism is associated with hypoxia and dysregulation in placental and decidual expression of UPR mediators and antioxidant enzymes, and activation of oxidative stress and endoplasmic reticulum stress at the maternal-fetal interface.

The effects of thyroid dysfunction on DNA damage and apoptosis in liver and heart tissues of rats

OBJECTIVES

Thyroid hormones affect many enzymes, organs, and systems. They also play a role in complex biological events including development and growth. The main objective of this study was to analyze the effects of thyroid dysfunction on DNA damage and apoptosis in liver and heart tissues as well as the treatment of these disorders.

METHODS

Thirty-eight Wistar-albino male rats were randomly divided into five groups: 1. Control group (n=6): The rats were sacrificed without any application and liver and heart samples were collected. 2. Hypothyroidism group (n=8): Prophyltiouracil (PTU)-10 mg/kg/day was applied to induce hypothyroidism by intraperitoneal route for two weeks. 3. Hypothyroidism + Thyroxine group (n=8): After one week of PTU application (10 mg/kg/day), a high dose of l-thyroxine (1.5 mg/kg/day) was applied by intraperitoneal route for one week. 4. Hyperthyroidism group (n=8): l-thyroxine (0.3 mg/kg/day) was applied intraperitoneally to induce hyperthyroidism for two weeks. 5. Hyperthyroidism + PTU group (n=8): After one week of high dose l-thyroxine application, PTU (10 mg/kg/day) was applied for one week.

RESULTS

Liver and heart tissues were collected to evaluate 8-hydroxy-2 deoxyguanosine (8-OHdG), caspase-8 and caspase-9 levels. Hypothyroidism caused DNA damage in the liver, while hyperthyroidism caused DNA damage in the heart tissue. Hyperthyroidism also led to a significant increase in levels of caspase-8 and caspase-9 in liver tissue.

CONCLUSIONS

The results of the study show that DNA damage and caspase levels in the heart and liver are affected differently in experimental hypothyroidism and hyperthyroidism.

The effects of hypothyroidism and hyperthyroidism on placental Hofbauer cells of pregnant rats

We investigated the effects of maternal thyroid disorders on Hofbauer cells of both the placenta and the fetus in pregnant rats. We divided 21 rats into three groups: control group, induced hypothyroidism (hypo) group and induced hyperthyroidism (hyper) group. Hypothyroidism was induced using propylthiouracil and hyperthyroidism was induced using L-thyroxine. We measured maternal weight, maternal free thyroxine, fetal weight, fetal viability and placental morphology. At the end of the experiment, fetuses of the hypo and hyper groups were less developed than those of the control group. In the hypo and hyper groups, the thickness of the labyrinth zone was decreased, but thickness of the basal zone and decidua basalis was increased. The number of Hofbauer cells was increased in both the hypo and hyper groups. Vascular endothelial growth factor expression was increased in both the hypo and hyper groups compared to controls. Our findings indicate that maternal thyroid disorders exert a negative effect on fetal growth and placental development.

Effect of levothyroxine supplementation on pregnancy loss and preterm birth in women with subclinical hypothyroidism and thyroid autoimmunity: a systematic review and meta-analysis

BACKGROUND

Subclinical hypothyroidism (SCH) and thyroid autoimmunity (TAI) are associated with adverse pregnancy outcomes such as pregnancy loss and preterm birth. However, the ability of levothyroxine (LT4) supplementation to attenuate the risks of these outcomes remains controversial.

OBJECTIVE AND RATIONALE

This systematic review and meta-analysis was conducted to determine the effect of LT4 supplementation on pregnancy loss rate (PLR) and preterm birth rate (PBR) among pregnant women with SCH and TAI.

SEARCH METHODS

A systematic literature search of the PubMed, EMBASE, Web of Science and Cochrane Controlled Trials Register databases and Clinicaltrials.gov was performed to identify all relevant English studies published up to April 2018. The following terms were used for the search: [subclinical hypothyroidism OR thyroid autoimmunity OR thyroperoxidase antibody (TPO-Ab) OR thyroglobulin antibodies (Tg-Ab)] AND (levothyroxine OR euthyrox) AND [pregnancy outcome OR miscarriage OR abortion OR pregnancy loss OR preterm birth OR premature delivery OR early labo(u)r]. The reference lists of the relevant publications were also manually searched for related studies. Published manuscripts were included if they reported data on pregnancy loss, preterm birth or both. We separately analysed the pooled effects of LT4 supplementation on PLR and PBR in women with SCH and TAI.

OUTCOMES

Overall, 13 eligible studies including 7970 women were included in the meta-analysis. Eight and five of these studies were randomized controlled trials (RCTs) and retrospective studies, respectively. The pooled results indicated that LT4 supplementation significantly decreased the PLR [relative risk (RR) = 0.56, 95% confidence interval (CI): 0.42-0.75, I2 = 1%, 12 studies] and PBR (RR = 0.68, 95% CI: 0.51-0.91, I2 = 21%, eight studies) in women with SCH and/or TAI. We further found that LT4 supplementation significantly decreased the risk of pregnancy loss (RR = 0.43, 95% CI: 0.26-0.72, P = 0.001, I2 = 0%) but not of preterm birth (RR = 0.67, 95% CI: 0.41-1.12, P = 0.13, I2 = 0%) in women with SCH. Furthermore, LT4 supplementation significantly decreased the risks of both pregnancy loss (RR = 0.63, 95% CI: 0.45-0.89, P = 0.009, I2 = 0%) and preterm birth (RR = 0.68 95% CI: 0.48-0.98, P = 0.04, I2 = 46%) in women with TAI. These results were consistent when only RCTs were included in the analysis. Further, in women with SCH, LT4 supplementation reduced the risk of pregnancy loss in pregnancies achieved by assisted reproduction (RR = 0.27, 95% CI: 0.14-0.52, P < 0.001, I2 = 14%) but not in naturally conceived pregnancies (RR = 0.60, 95% CI: 0.28-1.30, P = 0.13, I2 = 0%). By contrast, in women with TAI, LT4 supplementation reduced the risks of both pregnancy loss (RR = 0.61, 95% CI: 0.39-0.96, P = 0.03, I2 = 0%) and preterm birth (RR = 0.49, 95% CI: 0.30-0.79, P = 0.003, I2 = 0%) in naturally conceived pregnancies but not in pregnancies achieved by assisted reproduction (RR = 0.68, 95% CI: 0.40-1.15, P = 0.15, I2 = 0% for pregnancy loss and RR = 1.20, 95% CI: 0.68-2.13, P = 0.53, I2 not applicable for preterm birth).

WIDER IMPLICATIONS

This meta-analysis confirmed the beneficial effects of LT4 supplementation, namely the reduced risks of pregnancy loss and preterm birth, among pregnant women with SCH and/or TAI. The different effects of LT4 supplementation on naturally conceived pregnancies and pregnancies achieved by assisted reproduction in women with SCH and/or TAI suggest that these women should be managed separately. Due to the limited number of studies included in this meta-analysis, especially in the subgroup analysis, further large RCTs and fundamental studies are warranted to confirm the conclusions and better clarify the molecular mechanism underlying these associations.

Glucosamine Supplementation in Premating Drinking Water Improves Within-Litter Birth Weight Uniformity of Rats Partly through Modulating Hormone Metabolism and Genes Involved in Implantation

Within-litter birth weight variation in multiparous animals has become a big issue due to high incidence of low birth weight neonates, which gives rise to high preweaning mortality and morbidity. Foetus with various birth weights is the outcome of diverse embryos competence which is affected by oocyte quality. Glucosamine (GlcN) has been reported to be involved in oocyte maturation; however, its effect on pregnant outcomes remains unknown. The present study was conducted to investigate the effects of premating GlcN supplementation via drinking water on within-litter birth weight variation and its underlying mechanism. Fifty eight Sprague-Dawley female rats were randomly assigned to one of two groups with normal drinking water or drinking water supplemented with 0.5 mM GlcN from six to eight weeks old. Variation of within-litter birth weight in the GlcN group was 5.55%, significantly lower compared with 8.17% in the control group. Birth weight was significantly increased in the GlcN group (2.27 ± 0.06) compared with the control group (2.08 ± 0.04). Both absolute and relative weights of the ovary at the end of GlcN treatment were higher in the GlcN group than in the control group (P < 0.05). In the GlcN group, there were more successfully implanted blastocysts (13.38 ± 0.63 and 15.75 ± 0.59 in the control and treatment group, respectively) with more uniform distribution along the two uterine horns compared with the control group. Besides, gene expressions of Alk3 and Bmp2 were increased in the implantation sites, while IGF-1 and Mucin-1 were decreased significantly in rats administrated with GlcN. Maternal progesterone, estradiol, and IGF-1 concentrations on D 19.5 were significantly increased, while insulin and total cholesterol levels were significantly decreased in contrast with control dams. In summary, the administration of 0.5 mM GlcN solution before mating reduced within-litter birth weight variation, accompanied with increased fetal weight. Further investigation indicated that the improved outcome of pregnancy results at least partly from the increased ovary weights of the rats, the homogeneous embryo developmental competence, the enhanced receptivity of the uterine environment, and the adjusted maternal hormone levels.

Thyroid hormones and female reproduction

Thyroid hormones are vital for the proper functioning of the female reproductive system, since they modulate the metabolism and development of ovarian, uterine, and placental tissues. Therefore, hypo- and hyperthyroidism may result in subfertility or infertility in both women and animals. Other well-documented sequelae of maternal thyroid dysfunctions include menstrual/estral irregularity, anovulation, abortion, preterm delivery, preeclampsia, intrauterine growth restriction, postpartum thyroiditis, and mental retardation in children. Several studies have been carried out involving prospective and retrospective studies of women with thyroid dysfunction, as well as in vivo and in vitro assays of hypo- and hyperthyroidism using experimental animal models and/or ovarian, uterine, and placental cell culture. These studies have sought to elucidate the mechanisms by which thyroid hormones influence reproduction to better understand the physiology of the reproductive system and to provide better therapeutic tools for reproductive dysfunctions that originate from thyroid dysfunctions. Therefore, this review aims to summarize and update the available information related to the role of thyroid hormones in the morphophysiology of the ovary, uterus, and placenta in women and animals and the effects of hypo- and hyperthyroidism on the female reproductive system.

Distribution of thyroid hormone and thyrotropin receptors in reproductive tissues of adult female rabbits

PURPOSE

Thyroid dysfunctions are related to anovulation, miscarriages, and infertility in women and laboratory animals. Mechanisms associated with these effects are unknown, although indirect or direct actions of thyroid hormones and thyrotropin could be assumed. The present study aimed to identify the distribution of thyroid hormones (TRs) and thyrotropin (TSHR) receptors in reproductive organs of female rabbits.

MATERIAL AND METHODS

Ovary of virgin and pregnant rabbits, as well as the oviduct, uterus, and vagina of virgin rabbits were excised, histologically processed, and cut. Slices from these organs were used for immunohistochemical studies for TRα1-2, TRß1, and TSHR.

RESULTS

The presence of TRs and TSHR was found in the primordial, primary, secondary, tertiary, and Graafian follicles of virgin rabbits, as well as in the corpora lutea, corpora albicans, and wall of hemorrhagic cysts of pregnant rabbits. Oviductal regions (fimbria-infundibulum, ampulla, isthmus, and utero-tubal junction), uterus (endometrium and myometrium), and vagina (abdominal, pelvic, and perineal portions) of virgin rabbits showed anti-TRs and anti-TSHR immunoreactivity. Additionally, the distal urethra, paravaginal ganglia, levator ani and iliococcygeus muscles, dorsal nerve and body of the clitoris, perigenital skin, and prostate had TRs and TSHR.

CONCLUSIONS

The wide presence of TRs and TSHR in female reproductive organs suggests varied effects of thyroid hormones and thyrotropin in reproduction.

Endothelial Functioning and Hemodynamic Parameters in Rats with Subclinical Hypothyroid and the Effects of Thyroxine Replacement

OBJECTIVE

Subclinical hypothyroidism (SCH) and its associations with atherosclerosis (AS) and cardiovascular disease remain controversial. The purpose of our study was to observe changes in endothelial functioning and hemodynamics in rats with SCH and to determine whether L-thyroxine (L-T4) administration affects these changes.

METHODS

In total, sixty male Wistar rats were randomly divided into the following three groups with 20 rats each: control euthyroid rats, SCH rats and SCH rats that had been treated with thyroxine (SCH+T4). The SCH rats were induced by administration of 10 mg x kg(-1) x d(-1) methimazole (MMI) once daily by gavage for 3 months. The SCH+T4 rats were administered the same dose of MMI for three months in addition to 2 μg x kg(-1) x d(-1) L-T4 once daily by gavage after 45 days of MMI administration. The control rats received physiological saline via gavage.

RESULTS

The SCH group had significantly higher thyroid-stimulating hormone (TSH), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and endothelin (ET) levels and a lower nitric oxide (NO) level than the control and SCH+T4 groups. The tail and carotid artery blood pressures, left ventricular systolic pressure, heart rate and aorta ventralis blood flow were significantly lower in the SCH group than in the control and SCH+T4 groups. ACH treatment caused concentration-dependent relaxation, which was reduced in the SCH arteries compared with the control and SCH+T4 arteries. Histopathological examination revealed the absence of pathological changes in the SCH rat arteries.

CONCLUSIONS

These findings demonstrate that L-T4 treatment ameliorates endothelial dysfunction and hemodynamic changes in SCH rats.