A next-generation sequencing study on mechanisms by which restraint and social instability stresses of male mice alter offspring anxiety-like behavior.

Pathophysiological mechanisms for depression/anxiety are largely unknown. Evidence for transgenerational transmission of acquired epigenetic marks remains limited. We bred unstressed (US) female mice with adolescently restraint-stressed (RS), social instability-stressed (SI) or US males to produce RS, SI and control F1 offspring, respectively. Compared to controls, while paternal RS decreased anxiety-like behavior (ALB) in both female and male offspring, paternal SI increased ALB only in female offspring. Next-generation sequencing and bioinformatics using RS and SI female offspring identified 5 candidate anxiety-transmitting (CAT) genes; each showed a consistent pattern of DNA methylation from F0 spermatozoa through F1 blastocysts to fetal and adult hippocampi. Further analyses validated 4 CAT genes, demonstrated that paternal SI caused ALB differences between male and female offspring through modifying the CAT genes, and indicated a strong correlation between inflammation and ALB pathogenesis and an important function for intronic DNA methylation in regulating ALB-related genes. In conclusion, this study identified important CAT genes and suggested the possibility that stresses on males might alter offspring's ALB by modifying sperm DNA methylation.

Mechanisms by which in vitro meiotic arrest and sexual maturity improve developmental potential of mouse oocytes.

To study the relationship between chromatin condensation, gene transcription and developmental competence during oocyte maturation and to explore the mechanisms by which meiotic arrest maintenance (MAM) and sexual maturity improve oocyte competence, we examined effects of MAM with roscovitine or db-cAMP on chromatin condensation, gene transcription and developmental potential of NSN or SN oocytes from prepubertal or adult mice. MAM with roscovitine improved the developmental competence and global gene transcription of prepubertal NSN (prep-NSN) and adult-SN oocytes while having no effect on those of prep-SN oocytes. MAM with db-cAMP facilitated neither development nor transcription in any type of oocytes. MAM with either roscovitine or db-cAMP promoted chromatin condensation of prep-NSN oocytes. MAM with roscovitine promoted gene transcription and chromatin condensation simultaneously through inhibiting cyclin-dependent kinase (CDK) 5 and 2, respectively. The results suggested that MAM with roscovitine improved oocyte competence by promoting gene transcription via inhibiting CDK5. Oocyte cytoplasmic maturation is correlated with gene transcription but not with chromatin condensation. The difference in developmental competence between prepubertal NSN and SN oocytes and between prepubertal and adult SN oocytes was because while the former had not, the latter had completed or acquired the ability for transcription of important genes.

Parental life events cause behavioral difference among offspring: Adult pre-gestational restraint stress reduces anxiety across generations.

While effects of gestational, neonatal or adolescent stress on psychological alterations in progeny have been extensively studied, much less is known regarding the effects of adult pre-gestational life events on offspring behavior. Although full siblings often display behavioral differences, whether the different parental life events prior to different pregnancies contribute to these behavioral differences among siblings is worth studying. In this study, male and female adult mice were restrained for 60 days before mating with unstressed or stressed partners. F1 offspring were examined for anxiety or mated to generate F2. Both F1 females and males from restrained mothers and/or fathers showed significantly reduced anxiety and serum cortisol and increased mRNA levels of glucocorticoid receptor and brain-derived neurotrophic factor compared to control offspring from unstressed parents. Similar behavioral and molecular changes were also observed in F2 females and males. Although restraint of adolescent mice reduced anxiety in F1 of both sexes, social instability of them increased anxiety predominantly in F1 females. Thus, adult pre-gestational restraint reduced offspring's anxiety across generations; different stressors on parents may cause different phenotypes in offspring; individual behaviors can depend on adult life experiences of parents.

Stresses on Female Mice Impair Oocyte Developmental Potential: Effects of Stress Severity and Duration on Oocytes at the Growing Follicle Stage.

AIM: Although previous studies found that 1-time acute stress applied during follicle maturation impaired oocyte competence, it is unknown whether repeated chronic stress, which is known to cause animal behavioral adaptation, would damage oocytes when applied during follicle growth. METHODS AND RESULTS: In this study, female mice were exposed to repeated restraint stress (RRS) or unpredictable stress (UPS) for different days before equine chorionic gonadotropin injection to initiate oocyte prematuration development and to observe effects of different stressors on oocytes in the growing follicles. The results showed that although oocyte pre- and postimplantation development was unaffected when mice were exposed to RRS or UPS once a day for 4 days, development was impaired when mice were exposed to RRS for 8 or more days or to UPS twice a day for 4 days (4 × 2). The 4 × 2 UPS caused more oxidative stress in oocytes and severer apoptosis in antral follicles than did the 4-day RRS. The RRS mice were stressed consistently from days 1 to 23 of restraint, and the stress that a mouse had 4 × 2 UPS was severer than that from 4-day RRS. CONCLUSION: The results suggest that (1) the degree that a stress damages oocytes is the product of duration × severity of the stress; (2) RRS impaired oocyte developmental potential through cumulative effects on growing follicles; and (3) preantral follicles were not as sensitive to stress as antral follicles were.