Emergence of overt diabetes in offspring of rats with induced latent diabetes

Uterosomes: The lost ring of telegony?

Telegony refers to the appearance of some characteristics of the female's previously mated male in her subsequent offspring by another male. According to evidence, telegony may occur either through the infiltration of sperm into the somatic tissues of the female genital tract or the presence of fetal genes in the mother's blood. It is highlighted that sperm penetrates into the mucosa of the uterine and possibly alters the genetic structure, affecting the embryo and enduring from one pregnancy to the next, which may be one of the potential mechanisms of telegony. Uterine fluid, uterine gland-derived histotroph, supplies key nutrients for successful embryo implantation and it is important during the first trimester, especially, because of its susceptibility to maternal states. The presence of EVs in uterine fluid (uterosomes) was reported in mice, sheep, and humans, including a wide range of biomolecules, such as proteins, and non-coding RNAs. In this review article, we presented a new idea to explain telegony. Based on our idea, after the previous male sperm entry into the female reproductive system, those sperm which do not participate in fertilization penetrate into the somatic cells of the uterus and store their genetic/epigenetic information there. The sperm of the next partner reaches a location in the female reproductive canal where it exchanges information with the uterosomes and obtains the proteins and non-coding RNAs required for fertilization, development, and implantation.

Epididymosomes: the black box of Darwin’s pangenesis?

Darwin, in the pangenesis theory, imagined particles, named as ‘gemmules’, which are released from all (‘pan’) cells of the body. By cell–cell communication and also circulation through the body, they finally reach the germ cells to participate in the generation (‘genesis’) of the new individual. It has been shown that circulatory exosomes are affected by environmental stressors and they can reach the parental germ cells. Therefore, in the mirror of his theory, circulatory exosomes could interact with epididymosomes: epididymis-derived exosomes which have a wide spectrum of variation in content and size, are very sensitive to environmental stressors, and may be involved in translating external information to the germ cells. The protein and RNA cargo would be transferred by epididymosomes to sperm during sperm maturation, which would be then delivered to the embryo at fertilization and inherited by offspring. Therefore, in this study, we will briefly discuss Darwin’s pangenesis theory and its possible relation with epididymosomes. We believed that epididymosomes could be considered as an attractive candidate for the storage of RNA contents, changing the epigenome of the next generations, and allowing the reappearance acquired characteristics of ancestors. Therefore, epididymosomes, as a black box of Darwin’s pangenesis, may unravel parental life history and also disclose the historical events that affect the life of offspring.

Darwin's Pangenesis and the Lamarckian Inheritance of Acquired Characters

Since the earliest days of evolutionary thought, the problem of the inheritance of acquired characters has been a central debate. Darwin accepted the inheritance of acquired characters as an established fact and gave many instances. His Pangenesis was more than anything else an attempt to provide a theory for its explanation. Over the past several decades, there has been increasing evidence for the inheritance of acquired habit and immunity, and for heritable changes induced by food and fertilizer, stress, chemicals, temperature, light and other environmental factors. Many studies also suggest that parental age has certain influences on the characters of offspring. The current explanations include environmentally induced DNA changes (mainly DNA rearrangements and DNA methylation), RNA-mediated inheritance, and horizontal gene transfer. These mechanistic explanations are consistent with Darwin's Pangenesis.

Does exposure to hyperglycaemia in utero increase the risk of obesity and diabetes in the offspring? A critical reappraisal

BACKGROUND

The idea that exposure to hyperglycaemia in utero is an important factor in the development of obesity and diabetes in the offspring has become entrenched as popular belief.

AIM

To appraise the literature supporting this hypothesis in the light of recent studies that have clarified the main drivers of obesity in children and adolescents.

METHODS

A review of published evidence from animal studies, human observational studies, systematic reviews and experimental trials that address the impact of diabetes (Types 1 and 2, genetic or gestational) on the future risk of obesity and/or glucose intolerance in the offspring.

RESULTS

Some animal studies support a relationship between exposure to hyperglycaemia in utero and future development of obesity and diabetes, but the results are inconsistent. Most of the human studies claiming to show a relationship have not taken into account important known confounders, such as maternal and paternal BMI. Evidence supporting a dose-response relationship between maternal hyperglycaemia exposure and obesity and diabetes in the offspring is weak, and there is no convincing evidence that treating gestational diabetes reduces the later risk of offspring obesity or glucose intolerance.

CONCLUSIONS

Exposure to hyperglycaemia in utero has minimal direct effect on the later risk of obesity and Type 2 diabetes. The increased risk of obesity in the offspring of women with Type 2 or gestational diabetes can be explained by confounding factors, such as parental obesity.

Preconceptional fasting of fathers alters serum glucose in offspring of mice

OBJECTIVE

Maternal nutrition has long-term effects on offspring characteristics. Similar effects mediated through fathers have not been tested.

METHODS

Outbred Swiss male mice were fasted one or six times 1 to 4 wk before mating. Offspring were killed at age intervals of 4 to 10 wk and their sera were analyzed for glucose, corticosterone, and insulin-like growth factor-1. Statistical linear mixed effects models were used to determine treatment (paternal diet restriction versus control) differences and possible effects of covariates, including sex, litter membership, and litter size.

RESULTS

Paternal food deprivation resulted in a consistent decrease in average serum glucose in male and female offspring. Significant changes in corticosterone and insulin-like growth factor-1 were found for some groups. The results indicated a male-mediated transgenerational effect on metabolism- and growth-related parameters, in particular glucose.

CONCLUSIONS

Effects of paternal nutritional experiences on offspring metabolism, if confirmed, would be novel and could have far-reaching implications in the context of transgenerational effects on chronic diseases.

An animal model of gestational diabetes

Glucose tolerance tests (GTTs), hemoglobin A, levels, and pup weights were studied in both normal (C57BL/KsJ-+m/ + m) and heterozygous (C57BL/KsJ-db+/ + m) mice. There was no difference in GTT or hemoglobin A, levels between heterozygotes and normal animals in the nonpregnant state. However, the pregnant heterozygous mouse had significantly elevated GTTs (p less than 0.001) and hemoglobin A, levels (p less than 0.002) when compared to the normal pregnant mouse. The mean weight of pups from heterozygous parents was significantly greater than that of pups from normal parents (p less than 0.0005). Because the heterozygous mouse (C57BL/KsJ-db+/ + m) exhibits these characteristics of gestational diabetes, it may be possible to use it as an animal model of gestational diabetes.

Vertical transmission of acquired ulcer susceptibility in the rat

Premature separation of rat pups from their dams greatly increases their susceptibility to restraint-induced gastric erosions. When prematurely separated female rats grow to adulthood and mate with stock males, their normally reared F 1 progeny also have increased susceptibility to restraint-induced erosions. Cross-fostering studies show that prenatal rather than postnatal factors transmit this susceptibility to the F 1 progeny.

The effects of alloxan diabetes on Yucatan miniature swine and their progeny

Alloxanization as a method to induce diabetes has been successfully undertaken in several laboratory animal models. The genetic transmissibility of the alloxan-diabetic condition has been investigated and confirmed by several studies in rodents. The Yucatan miniature pig is a potential laboratory animal model for diabetes. Studies were conducted to investigate the possibility that alloxan diabetes could be transmitted to subsequent generations in these animals. Diabetic pigs were produced directly with alloxanization, but the genetic transmissibility of this trait was not substantiated through the F2 generation. On the basis of these data, alloxan diabetes is not transmissible in Yucatan pigs in the same way that it is in rats.