T3 is linked to stress-associated reduction of prolactin in lactating women

Pathogenesis of the crosstalk between reproductive function and stress in animals - part 2: Prolactin, thyroid, inflammation and oxidative stress

Stress has a significant impact on reproductive health and fertility in both humans as well as various animal species. In particular, chronic stress can disrupt the delicate balance of the hormonal system that regulates reproductive function, leading to a variety of reproductive disorders and fertility issues. Beside the action of the hypothalamic-pituitary-adrenal (HPA) system and the sympatho-adrenomedullary system (SAM), other subsequent mechanisms have been incriminated. Thus, stress has also been associated with increased prolactin level, resulting in an inhibition of the hypothalamo-pituitary-gonadal (HPG) system leading to several reproductive disorders. Thyroid function is inhibited during chronic stress, and therefore considered an important regulator of reproductive function. Thus, and in particular by interfering with the HPA system, stress-induced immune dysregulation can have adverse effects on reproduction. In addition, oxidative stress and inflammation have been proposed as potential mechanisms by which chronic stress affects reproductive function. This is caused by an increase in reactive oxygen species (ROS) production that has a harmful effect on cells. Furthermore, inflammation can lead to tissue damage and scarring, which can affect fertility. The present review completes the complex mechanism linking stress and reproduction through the current knowledge in various animal species in a comparative point of view.

Age-related modifications in CYP-dependent drug metabolism: role of stress

Accumulating clinical evidence indicates extensive inter-individual variations in the effectiveness and adverse effects of standard treatment protocols, which are largely attributed to the multifactorial regulation of the hepatic CYP-dependent drug metabolism that is connected with either transcriptional or post-translational modifications. Age and stress belong to the most important factors in CYP gene regulation. Alterations in neuroendocrine responses to stress, which are associated with modified hypothalamo-pituitary-adrenal axis function, usually accompany ageing. In this light, ageing followed by a decline of the functional integrity of organs, including liver, a failure in preserving homeostasis under stress, increased morbidity and susceptibility to stress, among others, holds a determinant role in the CYP-catalyzed drug metabolism and thus, in the outcome and toxicity of pharmacotherapy. Modifications in the drug metabolizing capacity of the liver with age have been reported and in particular, a decline in the activity of the main CYP isoforms in male senescent rats, indicating decreased metabolism and higher levels of the drug-substrates in their blood. These factors along with the restricted experience in the use of the most medicines in childhood and elderly, could explain at an extent the inter-individual variability in drug efficacy and toxicity outcomes, and underscore the necessity of designing the treatment protocols, accordingly.

Cortisol, Maternal Stress, and Breastfeeding Rate at Hospital Discharge: A Systematic Review

Introduction: Breastfeeding is considered the best way to provide essential and necessary nutrients to the newborn, intervening in its growth and development. However, early abandonment of this method is quite common, due to various factors such as stress. Objectives: To determine whether the level of postpartum cortisol can serve as an indicator of maternal stress and whether there is a relationship between the level of cortisol and the rate of exclusive breastfeeding (EBF) at hospital discharge. Methodology: Systematic review of the literature under the PRISMA guidelines. PubMed, Web of Science, CINAHL, and Scopus databases were used. Original articles published from 2017 to 2022 in English, French, Portuguese, and Spanish were included. All study designs were eligible. Of the 3,712 records initially identified, 15 studies were included in this review. Results: Elevated cortisol levels, due to immediate postpartum stressors, have direct effects on the performance of the essential hormones in breast milk production. The EBF rates are negatively influenced by perceived maternal stress. Conclusion: Cortisol levels may be a good indicator of the level of stress to which the mother is subjected during the immediate postpartum period.

Thyroid Hormone Changes in the Northern Area of Tianjin during the COVID-19 Pandemic

PURPOSE

This study aimed to determine whether and how stress-induced thyroid hormone changes occur during the COVID-19 pandemic in the northern area of Tianjin.

METHODS

This study comprised two groups of study subjects in Tianjin: before (2019) and during (2020) the COVID-19 outbreak. Subjects were included if they had FT3, FT4, and TSH concentrations and thyroid TPOAb or TgAb information available. People who were pregnant, were lactating, or had mental illness were excluded. We used propensity score matching to form a cohort in which patients had similar baseline characteristics, and their anxiety level was measured by the Hamilton Anxiety Rating Scale (HAMA).

RESULTS

Among the 1395 eligible people, 224 in Group A and 224 in Group B had similar propensity scores and were included in the analyses. The detection rate of abnormal thyroid function was decreased in pandemic Group B (69.2% vs. 93.3%, χ 2 = 42.725, p < 0.01), especially for hypothyroidism (14.29% vs. 35.71%, χ 2 = 27.429, p < 0.01) and isolated thyroid-related antibodies (25.89% vs. 38.39%, χ 2 = 8.023, p < 0.01). The level of FT4 (z = -2.821, p < 0.01) and HAMA score (7.63 ± 2.07 vs. 5.40 ± 1.65, t = 16.873, p < 0.01) went up in Group B; however, TSH (z = -5.238, p < 0.01), FT3 (z = -3.089, p=0.002), TgAb (z = -11.814, p < 0.01), and TPOAb (z = -9.299, p < 0.01) were lower, and HAMA was positive with FT3 (r = 0.208, p < 0.01) and FT4 (r = 0.247, p < 0.01).

CONCLUSION

People in the northern area of Tianjin during the COVID-19 outbreak were at an increased risk of higher FT4, lower FT3, and lower TSH. The HAMA scores increased in emergency situations and were positively correlated with the levels of FT3 and FT4.