S-adenosyl-l-methionine (SAM)

Epigenetic changes are an important pathogenic mechanism in many diseases, including a variety of psychiatric disorders such as Autism Spectrum Disorder (ASD) and depression. Methyl donors such as S-Adenosyl-Methionine (SAMe) may cause epigenetic modifications, especially during embryonic development when the epigenetic memory is established. We treated pregnant submissive (Sub) mice exhibiting depressive-like phenotype with SAMe during days 12-14 of gestation aiming to alleviate the depressive - like symptoms in their offspring and normalize the expression in their prefrontal cortex of several genes possibly involved in depression. We also aimed to define possible gender differences of the effects of SAMe on the measured parameters. Treatment of the Dams with SAMe did not affect the early neurodevelopmental milestones in males or females. The results of the behavioral tests showed improvement in some behavioral parameters compared to saline treated Sub mice. Several of these improvements were gender related. Prenatal SAMe treatment mainly improved sociability, as observed in the three chambers social interaction test, in both genders. It also improved the increased locomotion (as observed by the open field test) in the female mice, but not in males. Prenatal SAMe increased the expression of Vegfa and Flt1 in males, but not in females. The expression of IgfII and SynIIb increased in males and decreased in females and the expression of serotonin receptor Htr2A did not change in both genders. In our mouse model of depression, prenatal treatment with SAMe significantly improved some parameters of depressive like behavior and normalized the expression of several genes related to depression. The gender differences observed in our studies may explain the sex related differences in the clinical presentation of depression and the different gender related response to treatment.

To investigate S-adenosyl-methyonine (SAM) effects on PC12 cells viability and neuritogenesis treated with MPP+ (1-methyl-4-phenylpyridinium).

PC12 cell viability test (MTT assay) in DMEM medium with SAM and/or MPP+; PC12 cell neuritogenesis test in F-12K medium with nerve growth factor (NGF); DNMT activity in PC12 cells (DNMT Activity Assay Kit) with SAM and/or MPP+.

(1) MPP+ decreased cell viability; (2) SAM did not affect cell viability per se, but it increased MPP+ neurotoxicity when co-incubated with the neurotoxin, an effect abolished by DNA methyltransferases (DNMT) inhibitors; (3) pretreatment with SAM for 30 min or 24 h before MPP+ addition had no effect on cell viability. Neuritogenesis: Treatment with SAM for 30 min or 24 h (1) increased cell differentiation per se, (2) increased NGF differentiating effects (additive effect) and (3) blocked the neuritogenesis impairment induced by MPP+. SAM with MPP+ increased the DNMT activity, whereas SAM alone or MPP+ alone did not.

(1) SAM might induce neurotoxic or neuroprotective effects on PC12 cells, depending on the exposure conditions; (2) DNMT inhibitors might attenuate the MPP+ exacerbation toxicity induced by SAM; (3) DNA methylation might be involved in the observed effects of SAM (needs further investigation).