Early exposure to paracetamol reduces level of testicular testosterone and changes gonadal expression of genes relevant for steroidogenesis in rats offspring

A quantitative weight-of-evidence review of preclinical studies examining the potential developmental and reproductive toxicity of acetaminophen

We previously developed a quantitative weight-of-evidence (QWoE) framework using prespecified scoring criteria for preclinical acetaminophen data to characterize potential developmental neurotoxicity outcomes with considerations for biological relevance of the response to adverse outcomes and the strength of methods and study design. The current analysis uses this framework to characterize potential developmental and reproductive toxicity (DART) outcomes following exposure to acetaminophen. Two-hundred forty-two QWoE entries were documented from in vivo rodent studies identified in 110 publications across five categories: DART endpoints in the context of (1) periadolescent/adulthood (nonpregnancy) exposures; (2) pregnant female exposures; and, for in utero or other developmental exposures, (3) anatomical abnormalities, (4) reproductive development, and (5) other physical development. A mean outcome score and methods score were calculated for 242 QWoE entries. Data analyzed in our framework were of moderate quality showing no consistent evidence of DART in male and female rodents following exposure to acetaminophen at therapeutic and/or non-systemically toxic doses. Similar results were found for the individual context- and outcome-related endpoint analyses and as segregated by sex. Overall, this QWoE analysis on the in vivo rodent data demonstrated no consistent evidence of adverse effects following exposure to therapeutic and/or non-systemically toxic acetaminophen on development or on the structure and function of the reproductive system.

Maternal Administration of Acetaminophen Affects Meiosis Through its Metabolite NAPQI Targeting SIRT7 in Fetal Oocytes

Aim: Acetaminophen (APAP) is clinically recommended as analgesic and antipyretic among pregnant women. However, accumulating laboratory evidence shows that the use of APAP during pregnancy may alter fetal development. Since fetal stage is a susceptible window for early oogenesis, we aim to assess the potential effects of maternal administration of APAP on fetal oocytes. Results: Pregnant mice at 14.5 dpc (days post-coitus) were orally administered with APAP (50 and 150mg/kg.bw/day) for 3 days; meanwhile, 14.5 dpc ovaries were collected and cultured with APAP or its metabolite N-acetyl-p-benzoquinone imine (NAPQI; 5 and 15 μM) for 3 days. It showed that APAP caused meiotic aberrations in fetal oocytes through its metabolite NAPQI, including meiotic prophase I (MPI) progression delay and homologous recombination defects. Co-treatment with nicotinamide (NAM) or nicotinamide riboside chloride (NRC), nicotinamide adenine dinucleotide (NAD+) supplements, efficiently restored the MPI arrest, whereas the addition of the inhibitor of sirtuin 7 (SIRT7) invalidated the effect of the NAD+ supplement. In addition, RNA sequencing revealed distorted transcriptomes of fetal ovaries treated with NAPQI. Furthermore, the fecundity of female offspring was affected, exhibiting delayed primordial folliculogenesis and puberty onset, reduced levels of ovarian hormones, and impaired developmental competence of MII oocytes. Innovation: These findings provide the first known demonstration that NAPQI, converted from maternal administration of APAP, disturbs meiotic process of fetal oocytes and further impairs female fecundity in adulthood. The concomitant oral dosing with NAM further supports the benefits of NAD+ supplements on oogenesis. Conclusion: Short-term administration of APAP to pregnant mouse caused meiotic aberrations in fetal oocytes by its metabolite NAPQI, whereas co-treatment with NAD+ supplement efficiently relieves the adverse effects by interacting with SIRT7.

Contaminants of Emerging Concern (CECs) and Male Reproductive Health: Challenging the Future with a Double-Edged Sword

Approximately 9% of couples are infertile, with half of these cases relating to male factors. While many cases of male infertility are associated with genetic and lifestyle factors, approximately 30% of cases are still idiopathic. Contaminants of emerging concern (CECs) denote substances identified in the environment for the first time or detected at low concentrations during water quality analysis. Since CEC production and use have increased in recent decades, CECs are now ubiquitous in surface and groundwater. CECs are increasingly observed in human tissues, and parallel reports indicate that semen quality is continuously declining, supporting the notion that CECs may play a role in infertility. This narrative review focuses on several CECs (including pesticides and pharmaceuticals) detected in the nearshore marine environment of False Bay, Cape Town, South Africa, and deliberates their potential effects on male fertility and the offspring of exposed parents, as well as the use of spermatozoa in toxicological studies. Collective findings report that chronic in vivo exposure to pesticides, including atrazine, simazine, and chlorpyrifos, is likely to be detrimental to the reproduction of many organisms, as well as to sperm performance in vitro. Similarly, exposure to pharmaceuticals such as diclofenac and naproxen impairs sperm motility both in vivo and in vitro. These contaminants are also likely to play a key role in health and disease in offspring sired by parents exposed to CECs. On the other side of the double-edged sword, we propose that due to its sensitivity to environmental conditions, spermatozoa could be used as a bioindicator in eco- and repro-toxicology studies.