In vitro effect of S-adenosyl methionine on ethanol embryopathy in the rat

S-Adenosine Methionine (SAMe) and Valproic Acid (VPA) as Epigenetic Modulators: Special Emphasis on their Interactions Affecting Nervous Tissue during Pregnancy

S-adenosylmethionine (SAMe) is involved in many transmethylation reactions in most living organisms and is also required in the synthesis of several substances such as monoamine neurotransmitters and the N-methyl-D-aspartate (NMDA) receptor. Due to its important role as an epigenetic modulator, we discuss in some length the process of DNA methylation and demethylation and the critical periods of epigenetic modifications in the embryo, fetus, and thereafter. We also discuss the effects of SAMe deficiency and the attempts to use SAMe for therapeutic purposes such as the treatment of major depressive disorder, Alzheimer disease, and other neuropsychiatric disorders. SAMe is an approved food additive and as such is also used during pregnancy. Yet, there seems to scanty data on the possible effects of SAMe on the developing embryo and fetus. Valproic acid (VPA) is a well-tolerated and effective antiepileptic drug that is also used as a mood stabilizer. Due to its high teratogenicity, it is contraindicated in pregnancy. A major mechanism of its action is histone deacetylase inhibition, and therefore, it acts as an epigenetic modulator, mainly on the brain. This prompted clinical trials using VPA for additional indications i.e., treating degenerative brain disease such as Alzheimer disease, dementia, HIV, and even cancer. Therefore, we discuss the possible effects of VPA and SAMe on the conceptus and early postnatally, during periods of susceptibility to epigenetic modifications. VPA is also used as an inducer of autistic-like behavior in rodents and was found by us to modify gene expression when administered during the first postnatal week but not when administered to the pregnant dams on day 12 of gestation. In contrast, SAMe modified gene expression when administered on day 12 of pregnancy but not postnatally. If administered together, VPA prevented the changes in gene expression induced by prenatal SAMe administration, and SAMe prevented the gene expression changes and autistic-like behavior induced by early postnatal VPA. It is concluded that both VPA and SAMe are powerful epigenetic modifiers with antagonistic actions on the brain that will probably be used in the future more extensively for the treatment of a variety of epigenetic diseases of the nervous system.

Metabolic biomarkers of prenatal alcohol exposure in human embryonic stem cell-derived neural lineages

BACKGROUND

Fetal alcohol spectrum disorders (FASD) are a leading cause of neurodevelopmental disability. The mechanisms underlying FASD are incompletely understood, and biomarkers to identify those at risk are lacking. Here, we perform metabolomic analysis of embryoid bodies and neural lineages derived from human embryonic stem (hES) cells to identify the neural secretome produced in response to ethanol (EtOH) exposure.

METHODS

WA01 and WA09 hES cells were differentiated into embryoid bodies, neural progenitors, or neurons. Cells along this progression were cultured for 4 days with 0, 0.1, or 0.3% EtOH. Supernatants were subjected to C18 chromatography followed by ESI-QTOF-MS. Features were annotated using public databases, and the identities of 4 putative biomarkers were confirmed with purified standards and comparative MS/MS.

RESULTS

EtOH treatment induced statistically significant changes to metabolite abundance in human embryoid bodies (180 features), neural progenitors (76 features), and neurons (42 features). There were no shared significant features between different cell types. Fifteen features showed a dose-response to EtOH. Four chemical identities were confirmed: L-thyroxine, 5'-methylthioadenosine, and the tryptophan metabolites, L-kynurenine and indoleacetaldehyde. One feature with a putative annotation of succinyladenosine was significantly increased in both EtOH treatments. Additional features were selective to EtOH treatment but were not annotated in public databases.

CONCLUSIONS

EtOH exposure induces statistically significant changes to the metabolome profile of human embryoid bodies, neural progenitors, and neurons. Several of these metabolites are normally present in human serum, suggesting their usefulness as potential serum FASD biomarkers. These findings suggest the biochemical pathways that are affected by EtOH in the developing nervous system and delineate mechanisms of alcohol injury during human development.

In Vivo Dysfunction of the Term Alveolar Macrophage After in Utero Ethanol Exposure

BACKGROUND

The effects of in utero alcohol exposure on the immune function of the newborn remain under investigation. Fetal ethanol (ETOH) exposure increases oxidative stress in the developing lung, in part due to decreased availability of the antioxidant glutathione (GSH). We have previously shown that in utero ETOH impairs alveolar macrophage phagocytosis and viability in the premature pup, while maintaining GSH availability with maternal supplementation of S-adenosyl-methionine (SAM) during ETOH ingestion improves macrophage function and viability. We hypothesized that dysfunction of the neonatal alveolar macrophage exposed to ETOH in utero would persist at term gestation.

METHODS

Using a guinea-pig model of fetal ETOH exposure, timed-pregnant guinea-pigs were pair-fed ETOH+/-the GSH precursor SAM and the diet continued until spontaneous delivery. Term alveolar macrophages were evaluated using fluorescent microscopy for phagocytosis and apoptosis after in vitro incubation with Staphalococcus aureus. Using an in vivo model of intranasal Staph. aureus inoculation, the in vivo function of the term alveolar macrophage was also investigated using confocal fluorescent analysis.

RESULTS

In utero ETOH exposure increased oxidant stress in the alveolar macrophage and decreased phagocytosis and viability in vitro and in vivo. Confocal analysis of phagocytosis in vivo demonstrated a marked impairment of internalization of the bacteria by the ETOH-exposed alveolar macrophage. The addition of SAM during maternal ETOH ingestion prevented loss of alveolar macrophage function and viability in vitro and in vivo.

CONCLUSIONS

In utero ETOH exposure impairs alveolar macrophage function and viability in vitro and in vivo even at term gestation. The ETOH-induced changes in macrophage function and viability can be ablated with maternal SAM supplementation. Further investigations are required to identify the mechanisms of ETOH-induced derangement of phagocytosis in the neonatal alveolar macrophage and the clinical ramifications of altered immune function after in utero alcohol exposure for the newborn.

Hepatic S-adenosylmethionine after maternal alcohol exposure on offspring rats

S-adenosylmethionine (SAM) is an universal methyl donor for biological systems in transmethylation reactions. Another metabolic pathway involving S-adenosylmethionine is initiated with the release of -CH3 from the molecule and the formation of S-adenosylhomocysteine and then homocysteine and cysteine, a precursor of the main cellular antioxidant glutathione. Chronic ethanol consumption could affect the bioavailability of amino acids such as methionine. Our purpose was to determine the effect of chronic alcohol feeding during gestation or lactation on hepatic S-adenosyl-methionine, S-adenosylhomocysteine, DNA methylation and homocysteine serum concentration at the end of the lactation period (21-day-old offspring). Wistar dam rats were fed with alcohol during periconceptional, gestation and lactation periods (alcohol-fed rats). This study was conducted with three groups of offspring with different periods of alcohol exposure: control offspring (C), no treatment; and gestation (G) and lactation (L) offspring, exposed to alcohol only during gestation or lactation, respectively. To obtain these last two groups of offspring, on parturition day control newborn rats were cross-fostered to alcohol-fed dams (L) and alcohol new-born rats were cross-fostered to control dams (G). In conclusion, these results indicate that exposure of rats to ethanol during the lactation period affects SAM values more severely than ethanol exposure only during gestation.

Fetal alcohol exposure impairs alveolar macrophage function via decreased glutathione availability

Immature function of the alveolar macrophage increases the risk of pulmonary infections in premature newborns. In utero alcohol increases fetal systemic oxidative stress. Because the premature lung is deficient in glutathione (GSH), we hypothesized that chronic in utero alcohol (ethanol) exposure exacerbates the oxidative stress within the developing lung, thereby impairing alveolar macrophage function. Additionally, we evaluated the effects of in vivo and in vitro GSH availability on ethanol-exposed macrophage function. Using a guinea pig model of chronic in utero ethanol exposure, fetal epithelial lining fluid (ELF) and alveolar macrophage GSH were decreased with increased markers of oxidative stress. Ethanol-exposed macrophage exhibited impaired phagocytosis and increased apoptosis compared with gestational control. When the GSH precursor S-adenosyl-methionine (SAM) was added to the maternal drinking water containing ethanol, fetal ELF and macrophage GSH were maintained and ELF oxidative stress diminished. In vivo maternal SAM therapy maintained macrophage phagocytosis and decreased apoptosis. In vitro GSH supplements also improved phagocytosis and viability in both premature and ethanol-exposed macrophage. This suggested that in utero ethanol impaired premature macrophage function and viability via decreased GSH availability. Furthermore, GSH supplementation during and after ethanol exposure improved fetal macrophage function and viability. These results add a new dimension to the detrimental effects of fetal alcohol exposure on the developing alveolar macrophage, raising the possibility of GSH therapy to augment premature alveolar macrophage function.

Ethanol effects on postimplantation rat embryos: influence of zinc and methionine

Organic zinc salts and thiols, administered simultaneously, protect mice synergistically against ethanol toxicity. Moreover, chronic ethanol consumption could affect the bioavailability of zinc and amino acids such as methionine. This could result in impaired embryonic growth and development. The influence of zinc and methionine on ethanol-induced embryopathy was investigated by simultaneous administration of ethanol, zinc and methionine to pregnant rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet; zinc administered i.p., and methionine was given by gavage. The ethanol group received the liquid ethanol diet; the ethanol + zinc and methionine group received the ethanol diet, zinc and methionine; and the pair-fed control group was given an isocaloric control diet. On day 12 of gestation, embryos of ethanol alone treated rats revealed a significantly reduced embryonic protein content, number of somites, crown-rump length, and lower morphological score (embryological differentiation) compared to the pair-fed control embryos. However, embryonic growth and developmental parameters in the ethanol, zinc and methionine treated group were not significantly different from those exposed to ethanol alone.

Maternal and fetal levels of methionine and homocysteine in early human pregnancy

OBJECTIVE

To investigate methionine metabolism during normal human embryonic development by measuring levels of methionine and total homocysteine in samples of maternal serum, extra-embryonic coelomic fluid, and amniotic fluid.

DESIGN

Cross-sectional observational study.

SETTING

Collaboration between St Bartholomew's Hospital, London, and the University Hospital of Nijmegen in The Netherlands.

PARTICIPANTS

Twenty-three women with uncomplicated pregnancies between 8 and 12 weeks of gestation before surgical termination of an ultrasonographically normal fetus.

METHODS

Maternal serum samples were collected prior to surgery. Samples of extra-embryonic fluid and amniotic fluids were obtained by transvaginal ultrasound-guided coelocentesis and amniocentesis. Methionine was measured using an amino acid analyser and total homocysteine by high performance liquid chromatography.

RESULTS

Levels of methionine were four times higher in extra-embryonic coelomic fluid and twice as high in amniotic fluid compared with maternal serum. In contrast, the total homocysteine concentrations were much lower in both extra-embryonic coelomic fluid and amniotic fluid than in maternal serum. All differences were significant (P < or = 0.01).

CONCLUSIONS

The comparatively high concentrations of methionine in extra-embryonic coelomic fluid and amniotic fluid, and the concomitant low levels of total homocysteine in these fluids, suggest a role for methionine metabolism during early human pregnancy.

Expression of the rat BFGF antisense RNA transcript is tissue-specific and developmentally regulated

The basic fibroblast growth factor (bFGF) gene locus is transcribed into a number of mRNA transcripts including an antisense mRNA derived from the opposite DNA strand of the bFGF gene. Expression of this natural antisense RNA has been implicated in regulation of the bFGF sense mRNA expression and turnover. In the present study we examined the developmental pattern of expression of the bFGF antisense transcript in fetal and postnatal rat tissues. Northern hybridization with a strand-specific cRNA probe detected a 1.5-kb polyadenylated antisense RNA in all tissues examined except brain, in which two transcripts were detected as a doublet of approximately 1.3-1.5 kb in size. The level of antisense transcript expression was markedly tissue- and age-dependent. In the developing brain, both sense and antisense transcripts were detected by Northern hybridization, but the pattern of their expression was inversely related. The 6.0-kb bFGF sense transcript increased in an age-dependent manner from days 3-30 of postnatal development while the antisense transcript decreased to nearly undetectable levels over the same period. In embryonic (days 15-19) liver, kidney, heart and intestine bFGF antisense RNA expression was low but increased dramatically at parturition, rising 5-10-fold over fetal levels by 10 days of age, then declined slowly to a new steady-state level in adult tissues. The level of antisense RNA in these tissues was much higher than that of bFGF sense mRNA, which was undetectable by Northern analysis. Sense and antisense trancripts were also detected in midgestational (11.5 days) embryos by RT-PCR. Antisense expression did not increase when embryos were explanted and cultured for 48 h (9.5-11.5 days). The apparent reciprocal relationship between the abundance of sense and antisense bFGF transcripts in developing brain supports the possibility of a regulatory role for the antisense transcript in this tissue. There was no evidence for a reciprocal relationship between sense and antisense expression in the other tissues examined, indicating that the relationship between sense and antisense RNA expression may be tissue-specific.