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We examined the gastric mucosa structure and inflammatory status in control well-nourished Wistar dams and in Wistar dams deprived of choline, folate, and vitamin B12 during gestation and suckling periods, and in their offspring just before birth and at weaning. In this model of methyl donor deficiency (MDD), structural protein (E-cadherin and actin) N-homocysteinylation was measured through immunoprecipitation and proximity ligation assays. Cellular stress, inflammation, and apoptosis were estimated by the analysis of the NF-κB pathway, and the expression of superoxide dismutase, cyclooxygenase-2, tumor necrosis factor α, caspases 3 and 9, and TUNEL assay. Aberrant gastric mucosa formation and signs of surface layer erosion were detected in MDD fetuses and weanlings. E-cadherin and actin were N-homocysteinylated (+215 and +249% vs. controls, respectively; P<0.001). Expression of β-catenin staining drastically decreased (-98%; P<0.01). NF-κB pathway was activated (+124%; P<0.01). Expressions of all inflammatory factors (+70%; P<0.01), superoxide dismutase (+55%; P<0.01), and caspases (+104%; P<0.01) were markedly increased. These changes were also observed in dams, to a lesser extent. Early MDD induced gastric mucosa injury similar to atrophic gastritis through structural protein N-homocysteinylation, marked inflammation, and apoptosis, despite activation of repair machinery.

Despite the key role in neuronal development of a deficit in the methyl donor folate, little is known on the underlying mechanisms. We therefore studied the consequences of folate deficiency on proliferation, differentiation, and plasticity of the rat H19-7 hippocampal cell line. Folate deficit reduced proliferation (17%) and sensitized cells to differentiation-associated apoptosis (+16%). Decreased production (-58%) of S-adenosylmethionine (the universal substrate for transmethylation reactions) and increased expression of histone deacetylases (HDAC4,6,7) would lead to epigenomic changes that may impair the differentiation process. Cell polarity, vesicular transport, and synaptic plasticity were dramatically affected, with poor neurite outgrowth (-57%). Cell treatment by an HDAC inhibitor (SAHA) led to a noticeable improvement of cell polarity and morphology, with longer processes. Increased homocysteine levels (+55%) consecutive to folate shortage produced homocysteinylation, evidenced by coimmunoprecipitations and mass spectrometry, and aggregation of motor proteins dynein and kinesin, along with functional alterations, as reflected by reduced interactions with partner proteins. Prominent homocysteinylation of key neuronal proteins and subsequent aggregation certainly constitute major adverse effects of folate deficiency, affecting normal development with possible long-lasting consequences.

Objective: Diets rich in protein are often used for weight loss in obese patients, but their long-term effects are not fully understood. Homocysteine (Hcy) is considered to be a risk factor for cardiovascular diseases, and its levels are influenced by diet, particularly the protein and fat content. We studied the effect of diets with varying fat/protein content on body weight and composition, food intake, Hcy, B vitamins, leptin, and several pro-inflammatory cytokines., Methods: For 2 mo, Long-Evans rats were fed either a low protein/high fat (LP), a standard control (C), or a high protein/low fat (HP) diet containing 5, 15, or 40% protein, respectively, and normal carbohydrate content (55% of total energy)., Results: The HP rats ingested 12 to 15% fewer calories (P < 0.001), gained less weight (P < 0.04), and were less fatty (P < 0.01) than the other groups. Plasma Hcy was increased in HP rats compared to C (+23%) and LP (+29%) rats (P < 0.03). It was positively correlated with protein intake (r = 0.386; P < 0.01). No obvious signs of inflammation were observed in any of the groups. Hcy increase was related directly to decrease in plasma folate (r = -0.372; P < 0.02)., Conclusion: These data confirm the beneficial effects of HP diets on body weight but bring attention to the control of folate allowance to limit the adverse effects of elevated Hcy. Ingestion of folate-rich foods or even folate supplementation should be considered when using these HP diets over the long term for weight loss., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The pathomechanisms that associate a deficit in folate and/or vitamin B12 and the subsequent hyperhomocysteinemia with pathological brain ageing are unclear. We investigated the homocysteinylation of microtubule‐associated proteins (MAPs) in brains of patients with Alzheimer's disease or vascular dementia, and in rats depleted in folate and vitamin B12, Cd320 KO mice with selective B12 brain deficiency and H19‐7 neuroprogenitors lacking folate. Compared with controls, N‐homocysteinylated tau and MAP1 were increased and accumulated in protein aggregates and tangles in the cortex, hippocampus and cerebellum of patients and animals. N‐homocysteinylation dissociated tau and MAPs from β‐tubulin, and MS analysis showed that it targets lysine residues critical for their binding to β‐tubulin. N‐homocysteinylation increased in rats exposed to vitamin B12 and folate deficit during gestation and lactation and remained significantly higher when they became 450 days‐old, despite returning to normal diet at weaning, compared with controls. It was correlated with plasma homocysteine (Hcy) and brain expression of methionine tRNAsynthetase (MARS), the enzyme required for the synthesis of Hcy–thiolactone, the substrate of N‐homocysteinylation. Experimental inactivation of MARS prevented the N‐homocysteinylation of tau and MAP1, and the dissociation of tau and MAP1 from β‐tubulin and PSD95 in cultured neuroprogenitors. In conclusion, increased N‐homocysteinylation of tau and MAP1 is a mechanism of brain ageing that depends on Hcy concentration and expression of MARS enzyme. Its irreversibility and cumulative occurrence throughout life may explain why B12 and folate supplementation of the elderly has limited effects, if any, to prevent pathological brain ageing and cognitive decline. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Gestational deficiency in methyl donors such as folate and vitamin B12 impairs homocysteine metabolism and can alter brain development in the progeny. Since short hypoxia has been shown to be neuroprotective in preconditioning studies, we aimed to investigate the effects of brief, non-lesioning neonatal hypoxia (100% N2 for 5 min) on the developing brain of rats born to dams fed either a standard diet or a diet lacking vitamins B12, B2, folate and choline until offspring''s weaning. While having no influence on brain accumulation of homocysteine and concomitant apoptosis in 21-day-old deficient pups, exposure to hypoxia reduced morphological injury of the hippocampal CA1 layer. It also markedly stimulated the incorporation of bromodeoxyuridine (BrdU) in permissive areas such as the subventricular zone and the hippocampus followed by the migration of new neurons. Scores in a locomotor coordination test (days 19–21) and learning and memory behavior in the eight-arm maze (days 80–84) were found to be significantly improved in rats exposed to hypoxia in addition to the deficient diet. Therefore, by stimulating neurogenesis in rat pups, brief neonatal hypoxia appeared to attenuate the long-term effects of early exposure to a deficiency in nutritional determinants of hyperhomocysteinemia. [Copyright &y& Elsevier]