Prenatal Caffeine Exposure Impairs Pregnancy in Rats

Retinoic Acid Signaling Plays a Crucial Role in Excessive Caffeine Intake-Disturbed Apoptosis and Differentiation of Myogenic Progenitors

Whether or not the process of somitogenesis and myogenesis is affected by excessive caffeine intake still remains ambiguous. In this study, we first showed that caffeine treatment results in chest wall deformities and simultaneously reduced mRNA expressions of genes involved in myogenesis in the developing chicken embryos. We then used embryo cultures to assess in further detail how caffeine exposure affects the earliest steps of myogenesis, and we demonstrated that the caffeine treatment suppressed somitogenesis of chicken embryos by interfering with the expressions of crucial genes modulating apoptosis, proliferation, and differentiation of myogenic progenitors in differentiating somites. These phenotypes were abrogated by a retinoic acid (RA) antagonist in embryo cultures, even at low caffeine doses in C2C12 cells, implying that excess RA levels are responsible for these phenotypes in cells and possibly in vivo. These findings highlight that excessive caffeine exposure is negatively involved in regulating the development of myogenic progenitors through interfering with RA signaling. The RA somitogenesis/myogenesis pathway might be directly impacted by caffeine signaling rather than reflecting an indirect effect of the toxicity of excess caffeine dosage.

The effects of caffeine on ovarian tissue in rats

Caffeine consumption increases during early adulthood, which has adverse effects on the reproductive system. This study aimed to assess the impact of embryonic caffeine exposure on rat ovary in adulthood. Female Wistar rats (240-270 g) were divided into 5 groups (n = 7): experimental groups were exposed to 26, 45, 100, and 150 mg/kg of caffeine via drinking water during pregnancy and the control group only received drinking water. The ovaries of the offspring were taken out on days 7, 14, 28, 60, 90, and 120 of postnatal development, and then, they were fixed in 10% formaldehyde solution. Ovarian follicles were studied using stereological methods, and data were analyzed using one-way ANOVA followed by the Tukey test in SPSS software. A value of p < 0.05 was considered significant. The body weight, the weight of the ovaries, the ovarian volume, and the number of primordial follicles decreased significantly (p < 0.05) in 45 and 100 mg/kg, and (p < 0.001) in 150 mg/kg caffeine-treated groups at all stages of postnatal development. Significant decreases were observed in the number of primary and secondary follicles in 45 and 100 mg/kg (p < 0.05) and (p < 0.001) in 150 mg/kg caffeine-treated groups on days 7, 14, 28, and 60 compared to the control group. The number of Graafian follicles also decreased significantly (p < 0.001) in 45, 100, and 150 mg/kg caffeine-treated groups on days 14 and 28. Moreover, the mean volume of the oocyte in Graafian follicles reduced considerably in 45, 100, and 150 mg/kg caffeine-treated groups compared to other groups (p < 0.05). The thickness of the zona pellucida (ZP) in the secondary follicles (p < 0.02) and Graafian follicles (p < 0.05) showed a significant reduction in 100 and 150 mg/kg caffeine-treated groups on the 14th, 28th, and 60th days. In conclusion, high-dose caffeine consumption during gestation affects all stages of ovarian follicle development in rat offspring.

Mendelian randomisation approaches to the study of prenatal exposures: A systematic review

BACKGROUND

Mendelian randomisation (MR) designs apply instrumental variable techniques using genetic variants to study causal effects. MR is increasingly used to evaluate the role of maternal exposures during pregnancy on offspring health.

OBJECTIVES

We review the application of MR to prenatal exposures and describe reporting of methodologic challenges in this area.

DATA SOURCES

We searched PubMed, EMBASE, Medline Ovid, Cochrane Central, Web of Science, and Google Scholar.

STUDY SELECTION AND DATA EXTRACTION

Eligible studies met the following criteria: (a) a maternal pregnancy exposure; (b) an outcome assessed in offspring of the pregnancy; and (c) a genetic variant or score proposed as an instrument or proxy for an exposure.

SYNTHESIS

We quantified the frequency of reporting of MR conditions stated, techniques used to examine assumption plausibility, and reported limitations.

RESULTS

Forty-three eligible studies were identified. When discussing challenges or limitations, the most common issues described were known potential biases in the broader MR literature, including population stratification (n = 29), weak instrument bias (n = 18), and certain types of pleiotropy (n = 30). Of 22 studies presenting point estimates for the effect of exposure, four defined their causal estimand. Twenty-four studies discussed issues unique to prenatal MR, including selection on pregnancy (n = 1) and pleiotropy via postnatal exposure (n = 10) or offspring genotype (n = 20).

CONCLUSIONS

Prenatal MR studies frequently discuss issues that affect all MR studies, but rarely discuss problems specific to the prenatal context, including selection on pregnancy and effects of postnatal exposure. Future prenatal MR studies should report and attempt to falsify their assumptions, with particular attention to issues specific to prenatal MR. Further research is needed to evaluate the impacts of biases unique to prenatal MR in practice.

Coffee Extends Yeast Chronological Lifespan through Antioxidant Properties

Aging is a multifactorial process accompanied by loss of cell function. Science has been looking for factors responsible for aging for many years. However, despite identifying a number of possible causes, the definite reason for aging has been elusive so far. One of the factors contributing to aging is oxygen free radicals. In this context, beneficial effects of coffee on various organisms, including humans, were investigated, although the results are far from unequivocal. In our research, we used the budding yeast-something of a workhorse in many studies, including the studies of aging. So far, the impact of coffee on the aging of cells in the budding yeast experimental setup has little known about it. Here, we provide strong evidence that coffee compounds, particularly flavonoids, are responsible for scavenging free radicals and longevity in yeast lacking Sod1, Sod2 and Rad52 proteins. In this paper, we compared Arabica and Robusta coffee types. We present an analysis of the concentration of caffeine and flavonoids measured by the High-Performance Liquid Chromatography method. We show that Robusta has a much greater antioxidant capacity than Arabica. We also conclude that coffee infusions significantly extend the chronological lifespan of the Saccharomyces cerevisiae yeast cells by protecting cells against reactive oxygen species, double DNA-strand break and decrease in metabolic activity.

Intrauterine growth restriction: screening and diagnosis using animal models

Intrauterine growth restriction (IUGR) is a serious condition of multifactorial origin, mainly caused by maternal malnutrition, multiple gestation associated with nutrient competition, abuse of nocive substances and infections. The diagnosis of such syndrome is complex, as its own manifestations can mask its occurrence, requiring a thorough assessment of body weight and size. Moreover, it is not responsive to any kind of treatment. There is evidence that IUGR may predispose the individual to several pathologies, such as diabetes, hypertension and metabolic syndrome in adulthood, and it has also been linked to thrifty phenotype hypothesis. Thus, a healthy lifestyle is needed to better prevent those pathologies. Given the world high prevalence and importance of IUGR, mainly in developing countries, this review is focused on discussing how different animal models contribute to the biological screening and diagnosis of this condition.

Gestational caffeine exposure acts as a fetal thyroid-cytokine disruptor by activating caspase-3/BAX/Bcl-2/Cox2/NF-κB at ED 20

The objective of this examination was to explore the impact of gestational caffeine (1,3,7-trimethylxanthine) exposure on the maternofetal thyroid axis and fetal thyroid-cytokine communications during gestation. Pregnant rats (Rattus norvegicus) were intraperitoneally administered caffeine (120 or 150 mg kg-1) from gestation day (GD) 1 to 20. Both doses of caffeine resulted in maternal hyperthyroidism, whereas the elevation in the concentration of serum free triiodothyronine (FT3) and free thyroxine (FT4) was related to a depletion in the level of TSH at GD 20. Maternal body weight gain and food consumption were markedly increased, while fetal body weight was significantly reduced. These alterations caused fetal hypothyroidism and several pathological lesions in the fetal thyroid gland including a vacuolar colloid, destructive degeneration, atrophy and hyperplasia at embryonic day (ED) 20. The abnormalities in the fetal thyroid gland seemed to depend on the activation of caspase-3, Bcl-2, BAX, Cox2, and NF-κB mRNA expression. Both maternal caffeine doses caused a marked attenuation in the values of fetal serum GH, IGF-II, VEGF, TGF-β, TNF-α, IL-1β, IL-6, leptin and MCP-1, and a noticeable elevation in the value of fetal serum adiponectin at ED 20. Thus, gestational caffeine exposure might disrupt the fetal thyroid-cytokine axis.