Three-Generation Study of Male Rats Gestationally Exposed to High Butterfat and Bisphenol A: Impaired Spermatogenesis, Penetrance with Reduced Severity

Gestational high butterfat (HFB) and/or endocrine disruptor exposure was previously found to disrupt spermatogenesis in adulthood. This study addresses the data gap in our knowledge regarding transgenerational transmission of the disruptive interaction between a high-fat diet and endocrine disruptor bisphenol A (BPA). F0 generation Sprague-Dawley rats were fed diets containing butterfat (10 kcal%) and high in butterfat (39 kcal%, HFB) with or without BPA (25 µg/kg body weight/day) during mating and pregnancy. Gestationally exposed F1-generation offspring from different litters were mated to produce F2 offspring, and similarly, F2-generation animals produced F3-generation offspring. One group of F3 male offspring was administered either testosterone plus estradiol-17β (T + E2) or sham via capsule implants from postnatal days 70 to 210. Another group was naturally aged to 18 months. Combination diets of HFB + BPA in F0 dams, but not single exposure to either, disrupted spermatogenesis in F3-generation adult males in both the T + E2-implanted group and the naturally aged group. CYP19A1 localization to the acrosome and estrogen receptor beta (ERbeta) localization to the nucleus were associated with impaired spermatogenesis. Finally, expression of methyl-CpG-binding domain-3 (MBD3) was consistently decreased in the HFB and HFB + BPA exposed F1 and F3 testes, suggesting an epigenetic component to this inheritance. However, the severe atrophy within testes present in F1 males was absent in F3 males. In conclusion, the HFB + BPA group demonstrated transgenerational inheritance of the impaired spermatogenesis phenotype, but severity was reduced in the F3 generation.

Effects of Gestational Diabetes in Cognitive Behavior, Oxidative Stress and Metabolism on the Second-Generation Off-Spring of Rats

Gestational diabetes (GD) has a negative impact on neurodevelopment, resulting in cognitive and neurological deficiencies. Oxidative stress (OS) has been reported in the brain of the first-generation offspring of GD rats. OS has been strongly associated with neurodegenerative diseases. In this work, we determined the effect of GD on the cognitive behavior, oxidative stress and metabolism of second-generation offspring. GD was induced with streptozotocin (STZ) in pregnant rats to obtain first-generation offspring (F1), next female F1 rats were mated with control males to obtain second-generation offspring (F2). Two and six-month-old F2 males and females were employed. Anxious-type behavior, spatial learning and spatial working memory were evaluated. In cerebral cortex and hippocampus, the oxidative stress and serum biochemical parameters were measured. Male F2 GD offspring presented the highest level of anxiety-type behavior, whilst females had the lowest level of anxiety-type behavior at juvenile age. In short-term memory, adult females presented deficiencies. The offspring F2 GD females presented modifications in oxidative stress biomarkers in the cerebral cortex as lipid-peroxidation, oxidized glutathione and catalase activity. We also observed metabolic disturbances, particularly in the lipid and insulin levels of male and female F2 GD offspring. Our results suggest a transgenerational effect of GD on metabolism, anxiety-like behavior, and spatial working memory.

Risk of malignant neoplasms in the first generation offspring of female workers of Mayak Production Association

The study of the role of parental preconception exposure in development of malignant neo-plasms (MN) in the offspring is a topical point in cancerogenic factors’ research. The objective of the work is assessment of cancer risk among the offspring of female workers of the country’s first atomic production facility – Mayak Production Association (PA) – exposed to long-term occupa-tional radiation exposure prior to conception. We have performed a retrospective epidemiological analysis in a cohort of offspring born in 1949-1990 that contained 2061 children from 1404 fe-male workers. Mothers of 1145 children (55.6%) had accumulated doses of preconception exter-nal gamma-exposure to the ovaries (main group); the remaining 916 children (44.4%) were re-garded as internal control (comparison group) as the offspring of female workers that were not exposed to preconception irradiation of genital organs. We have followed up the vital status and cancer incidence in the offspring up to 31.12.2018. We have performed an analysis of the struc-ture and cancer incidence rates. We had calculated the relative risk (RR) and the excess relative risk (ERR) to a dose unit of external gamma-exposure with a 95% confidence interval using the AMFIT module of the EPICURE software. A total of 92 MN cases were registered in 1949-2018 among the first generation offspring of female workers. A comparative analysis of cancer inci-dence showed no significant difference in the structure and incidence rate of MN in the groups. The only exception were the offspring of the females not exposed to preconception occupational irradiation of genital organs; in this group we had indicated a significant increase of brain MN in male offspring and of the MN of corpus uteri among female offspring. We had registered MN of digestive organs and MN of breast most often in the main group of the offspring. The range of maternal doses of preconception external gamma-exposure to the ovaries varied greatly: maxi-mum dose in male offspring reached 2954.82 mGy and 4075.61 in female offspring. Calculation of RR of MN in the offspring of the main group showed no significant difference from the com-parison group for all the MN, for solid cancers separately, and for other most frequent cancers. Assessment of ERR coefficients in relation to maternal accumulated absorbed dose of precon-ception external gamma radiation to the ovaries had revealed no statistically significant increase of cancer incidence among the offspring of female workers exposed to occupational irradiation of genital organs. We had obtained no reliable evidence in our investigation of the relation be-tween MN in the offspring of Mayak PA female workers and accumulated doses of preconception external gamma-exposure to the gonads. Further research is needed taking into account relative-ly young average age of the observed cohort of the offspring.

Effect of chronic electromagnetic radiation on embryogenesis and early postnatal development of the offspring of irradiated animals

The effect of electromagnetic radiation of the mobile communication frequency range during chronic exposure to the reproductive function of rats, the antenatal and postnatal development of the offspring of irradiated males and females Wistar rats was studied. Irradiation conditions: the carrier frequency 1800 MHz (unmodulated radiation), the power flux density of 85 μW/cm2, the zone of the formed wave (the distance from the radiation source of 1.3 m) from the radiation source. Males (15 individuals) and females (32 individuals) were exposed to radiation in an ane-choic chamber in lattice containers for 1 hour a day, 5 days a week for 4 weeks. Two weeks after the last irradiation session the animals were paired at the rate of the one male for two females. Then pregnant female rats were irradiated from 5 to 17 days of pregnancy with the same expo-sure parameters. The animals of the control group (15 males and 30 females) were subjected to the same manipulation, but with the radiation source turned off. On the 20th day of pregnancy, some of females (13 experimental and 12 control females) were euthanized to study embryo-genesis. To assess embryogenesis, the following factors were studied: ovulatory activity of the ovaries, preimplantation and postimplantation intrauterine death of embryos, the average num-ber of live fetuses, their cranio-caudal sizes and body weight. There was no difference between the experimental and control groups in embryogenesis. From the remaining 10 experimental and 14 control pregnant females, groups were formed to assess the postnatal development of the first generation offspring. No differences were found in the early postnatal ontogenesis of the offspring of irradiated and control animals. Thus, chronic unmodulated electromagnetic radiation with a frequency of 1800 did not have a significant effect on the course of pregnancy of the fe-males and the early postnatal development of their first generation offspring.

Vertical Transmission: A Vector-Independent Transmission Pathway of Babesia microti in the Natural Reservoir Host Peromyscus leucopus

Background Babesia microti, a malaria-like pathogen, is increasing in mammal and human populations in endemic areas and is unlikely to be the sole result of horizontal pathogen transmission. Methods Peromyscus leucopus mice, natural reservoir hosts, were infected via Ixodes scapularis nymphs. Infected parental females (n = 6) produced F1 offspring (n = 36) that were screened for B. microti using quantitative PCR. Xenodiagnostic larvae were fed on infected offspring to determine horizontal transmission and pathogen viability. Fifty engorged larvae were screened; the rest were allowed to molt and then screened to determine transstadial transmission. Infected F1 generation offspring were placed in breeding groups, producing 34 F2 offspring and screened for B. microti infection. Chronic infection was monitored in parental females since time of initial vector infection. Results Vertical transmission of B. microti was 74% efficient in offspring born in the first 6 months. Horizontal transmission occurred in larvae (61% prevalence) and molted nymphs (58% prevalence); these nymphs were able to infect susceptible hosts. F2 generation offspring infection prevalence was 38%. Chronic infection persisted for 1 year in some adults. Conclusions These results demonstrate that vertical transmission is an important nonvector-mediated pathway of B. microti transmission in the natural reservoir host.

Transgenerational modification of dopaminergic dysfunctions induced by maternal immune activation

Prenatal exposure to infectious and/or inflammatory insults is increasingly recognized to contribute to the etiology of psychiatric disorders with neurodevelopmental components. Recent research using animal models suggests that maternal immune activation (MIA) can induce transgenerational effects on brain and behavior, possibly through epigenetic mechanisms. Using a mouse model of MIA that is based on gestational treatment with the viral mimeticpoly(I:C) (= polyriboinosinic-polyribocytidilic acid), the present study explored whether the transgenerational effects of MIA are extendable to dopaminergic dysfunctions. We show that the direct descendants born to poly(I:C)-treated mothers display signs of hyperdopaminergia, as manifested by a potentiated sensitivity to the locomotor-stimulating effects of amphetamine (Amph) and increased expression of tyrosine hydroxylase (Th) in the adult ventral midbrain. In stark contrast, second- and third-generation offspring of MIA-exposed ancestors displayed blunted locomotor responses to Amph and reduced expression of Th. Furthermore, we found increased DNA methylation at the promoter region of the dopamine-specifying factor, nuclear receptor-related 1 protein (Nurr1), in the sperm of first-generation MIA offspring and in the ventral midbrain of second-generation offspring of MIA-exposed ancestors. The latter effect was further accompanied by reduced mRNA levels of Nurr1 in this brain region. Together, our results suggest that MIA has the potential to modify dopaminergic functions across multiple generations with opposite effects in the direct descendants and their progeny. The presence of altered DNA methylation in the sperm of MIA-exposed offspring highlights the possibility that epigenetic processes in the male germline play a role in the transgenerational effects of MIA.

Maternal but Not Paternal High-Fat Diet (HFD) Exposure at Conception Predisposes for ‘Diabesity’ in Offspring Generations

While environmental epigenetics mainly focuses on xenobiotic endocrine disruptors, dietary composition might be one of the most important environmental exposures for epigenetic modifications, perhaps even for offspring generations. We performed a large-scale rat study on key phenotypic consequences from parental (F0) high-caloric, high-fat diet (HFD) food intake, precisely and specifically at mating/conception, focusing on ‘diabesity’ risk in first- (F1) and second- (F2) generation offspring of both sexes. F0 rats (maternal or paternal, respectively) received HFD overfeeding, starting six weeks prior to mating with normally fed control rats. The maternal side F1 offspring of both sexes developed a ‘diabesity’ predisposition throughout life (obesity, hyperleptinemia, hyperglycemia, insulin resistance), while no respective alterations occurred in the paternal side F1 offspring, neither in males nor in females. Mating the maternal side F1 females with control males under standard feeding conditions led, again, to a ‘diabesity’ predisposition in the F2 generation, which, however, was less pronounced than in the F1 generation. Our observations speak in favor of the critical impact of maternal but not paternal metabolism around the time frame of reproduction for offspring metabolic health over generations. Such fundamental phenotypic observations should be carefully considered in front of detailed molecular epigenetic approaches on eventual mechanisms.