Role of homocysteine metabolism in animal reproduction: A review

Exploring optimal folic acid supplementation levels for lactating-pregnant rabbit does with different litter size

The lactation-pregnancy overlap in the industrialized 49-d breeding model increases nutritional demands for lactating-pregnant rabbit does. This study examined the effects of folic acid (FA) on the production performance and intestinal microflora of does with different litter sizes (LS, or number of kits). A total of 144 third-parity Hyplus does, aged 11 mo and weighing approximately 5.00 ± 0.07 kg, were divided into 4 treatment groups: control group (basal diet) and FA groups (basal diet + 15, 30, and 45 mg/kg FA). Does with LS of 5, 7, and 9 were selected after weaning. Our findings revealed that 1) Increased FA supplementation initially increased and then decreased the pre-lactation body weight of 21-d-old kits and prolactin (PRL) level of lactating does, while showing an inverse trend for estrogen (E) level of does. Increased LS significantly (P < 0.05) correlated with reduced milk yield of does. There was a significant (P < 0.05) interaction between FA and LS affecting PRL, E, growth hormone levels of does, and the pre-lactation body weight of 21-d-old kits; 2) Increased FA supplementation initially increased and then decreased the post-lactation body weight of 21-d-old and 35-d-old kits, elevated plasma FA (PFA) level of lactating-pregnant does, and significantly (P < 0.05) impacted the pregnancy rate of does. Increased LS was associated with reduced post-lactation body weight in 21-d-old and 35-d-old kits (P < 0.05). There was a significant (P < 0.05) interaction between FA and LS affecting plasma insulin-like growth factor-1 (IGF-1), homocysteine (HCY), PFA levels of does, the post-lactation body weight of 21-d-old kits, and weaning body weight of 35-d-old kits; and 3) FA supplementation promoted the growth of Ruminococcaceae and Rikenellaceae_RC9_gut_group in the feces of lactating-pregnant does, as well as the proliferation of Lachnospiraceae_NK4A136_group in the feces of pregnant does, suggesting enhanced anti-inflammatory properties and improved crude fiber breakdown. In summary, FA supplementation improved conception rates, regulated lactation-related hormone synthesis and secretion, increased body weight of 21-d-old kits, and enhanced intestinal anti-inflammatory functions.

Homocysteine-specific fluorescence detection and quantification for evaluating S-adenosylhomocysteine hydrolase activity

The medium Ks value of copper complex contributed to the specific reduction of Cu2+ by homocysteine and the formation of a stable six-membered ring species.

Voluntary Exercise Attenuates Hyperhomocysteinemia, But Does not Protect Against Hyperhomocysteinemia-Induced Testicular and Epididymal Disturbances

The hyperhomocysteinemia (HHcy) is toxic to the cells and associated with several diseases. Clinical studies have shown changes in plasma concentrations of Hcy after physical exercise. This study aimed to assess the effect of HHcy on testis, epididymis and sperm quality and to investigate whether voluntary exercise training protects this system against damage caused by HHcy in Swiss mice. In this study, 48 mice were randomly distributed in the control, HHcy, physical exercise, and HHcy combined with physical exercise groups. HHcy was induced by daily administration of dl-homocysteine thiolactone via gavage throughout the experimental period. Physical exercise was performed through voluntary running on the exercise wheels. The plasma concentrations of homocysteine (Hcy) and testosterone were determined. The testes and epididymis were used to assess the sperm count, histopathology, lipoperoxidation, cytokine levels, testicular cholesterol, myeloperoxidase, and catalase activity. Spermatozoa were analyzed for morphology, acrosome integrity, mitochondrial activity, and motility. In the testes, HHcy increased the number of abnormal seminiferous tubules, reduced the tubular diameter and the height of the germinal epithelium. In the epididymis, there was tissue remodeling in the head region. Ultimately, voluntary physical exercise training reduced plasma Hcy concentration but did not attenuate HHcy-induced testicular and epididymal disturbances.

Melatonin Alleviates the Toxicity of High Nicotinamide Concentrations in Oocytes: Potential Interaction with Nicotinamide Methylation Signaling

Despite the numerous studies on melatonin and nicotinamide (NAM, the active form of vitamin B3), the linkage between these two biomolecules in the context of signaling pathways regulating preimplantation embryo development has not yet been investigated. In this study, we used bovine oocyte model to elucidate the effect of melatonin on the developmental competence of oocytes under the stress of high NAM concentrations. Results showed that NAM (20 mM) administration during in vitro maturation (IVM) significantly reduced oocyte maturation and actin distribution, while induced reactive oxygen species (ROS) accumulation and mitochondrial dysfunction, the multiple deleterious effects that were alleviated by melatonin (10⁻⁷ M). The RT-qPCR and/or immunofluorescence showed upregulation of the apoptosis (Caspase-3, Caspase-9, and BAX), autophagy (Beclin-1, LC3A, LC3B, ATG7, LAMP1, and LAMP2), cell cycle (P21, P27, and P53), and DNA damage (COX2 and 8-OxoG) specific markers in oocytes matured under NAM treatment, compared to NAM-melatonin dual-treated and the untreated ones. In addition, the total cleavage and blastocyst development rate, as well as the total number of cells and the inner cell mass (ICM) per blastocyst, were reduced, while DNA fragmentation was induced, in the group of NAM sole treatment than NAM-melatonin cotreatment and control. Inspecting the underlying mechanisms behind NAM-associated toxicity revealed an increase in transcription pattern of NAM methylation (NNMT and AHCY) genes in NAM-treated oocytes while the opposite profile was observed upon melatonin supplementation. In conclusion, to our knowledge, this is the first study reporting that melatonin can protect oocytes and embryos from NAM-induced injury through its ROS-scavenging activity together with potential interaction with NAM methylation signaling.

Involvements of Hyperhomocysteinemia in Neurological Disorders

Homocysteine (HCY), a physiological amino acid formed when proteins break down, leads to a pathological condition called hyperhomocysteinemia (HHCY), when it is over a definite limit. It is well known that an increase in HCY levels in blood, can contribute to arterial damage and several cardiovascular disease, but the knowledge about the relationship between HCY and brain disorders is very poor. Recent studies demonstrated that an alteration in HCY metabolism or a deficiency in folate or vitamin B12 can cause altered methylation and/or redox potentials, that leads to a modification on calcium influx in cells, or into an accumulation in amyloid and/or tau protein involving a cascade of events that culminate in apoptosis, and, in the worst conditions, neuronal death. The present review will thus summarize how much is known about the possible role of HHCY in neurodegenerative disease.

Cysteine and homocysteine as biomarker of various diseases

Cysteine and homocysteine (Hcy), both sulfur-containing amino acids (AAs), produced from methionine another sulfur-containing amino acid, which is converted to Hcy and further converted to cysteine. This article aims to highlight the link between cysteine and Hcy, and their mechanisms, important functions, play in the body and their role as a biomarker for various types of diseases. So that using cysteine and Hcy as a biomarker, we can prevent and diagnose many diseases. This review concluded that hyperhomocysteinemia (elevated levels of homocysteine) is considered as toxic for cells and is associated with different health problems. Hyperhomocysteinemia and low levels of cysteine associated with various diseases like cardiovascular diseases (CVD), ischemic stroke, neurological disorders, diabetes, cancer like lung and colorectal cancer, renal dysfunction-linked conditions, and vitiligo.

Melatonin and vitamin E alleviate homocysteine-induced oxidative injury and apoptosis in endothelial cells

A relationship exists between hyperhomocysteinemia and cardiovascular diseases, although the underlying mechanisms are still incompletely defined. One possibility involves a homocysteine (Hcy)-induced increased oxidative stress. Melatonin (Mel) and vitamin E (vitE) are important anti-oxidants. The main purpose of this study was (1) to compare the effect of treatments with Mel, vitE or both, on Hcy-induced apoptosis in human umbilical vein endothelial cells (HUVECs), and (2) to investigate the underlying mechanisms. Cell proliferation assay was carried out by Water Soluble Tetrazolium-1 (WST-1) assay kit. Apoptotic index was calculated by TUNEL Assay. Anti-oxidant parameters were studied by measurement of reactive oxygen species (ROS) and lipid peroxidation (LPO) levels. mRNA and protein expression levels of apoptotic and anti-apoptotic genes and proteins were studied by quantitative real time polymerase chain reaction (qRT-PCR) and Western blotting experiments respectively. The results showed that treatments with Mel, vitE or Mel + vitE suppressed Hcy-induced cell death, with a higher efficiency for the Mel and Mel + vitE treatments. Our results suggests that the mechanisms by which these anti-oxidants protected endothelial cells include the decrease in ROS and LPO levels, an increase in cell migration, the downregulation of pro-apoptotic proteins Cas 3, Cas 9, Cyt C and Bax and the upregulation of anti-apoptotic protein Bcl 2. Collectively, these results revealed the protective role of vitE and Mel against Hcy-induced cell apoptosis, which may add insight into therapeutic approaches to Hcy-induced damages.