Maternal hyperhomocysteinemia increases seizures susceptibility of neonatal rats

Adolescent-onset hyperhomocysteinaemia: cases report and literature review

We summarize and review the clinical and genetic characteristics of four adolescents with Hyperhomocysteinemia. Four cases of adolescent-onset Hyperhomocysteinemia diagnosed at Qingdao University Affiliated Hospital were selected as research subjects. Clinical data, whole exome sequencing and Sanger sequencing information of the patients were collected, and gene variation analysis and literature review were conducted. The pathogenic variants carried by the four patients were MAT1A c.895C>T(p.Arg299Cys), CBS c.374G>A(p.Arg125Glu), CBS c.785C>T(p.Thr262Met), and MMACHC c.482G>A(p.Arg161Glu) and c.658_660del(p.Lys220del) along with other site mutations. There were three cases with epileptic seizures as initial manifestation, three cases with varying degrees of intellectual disability, two cases with lens dislocation, one case with cervical artery occlusion leading to cerebral infarction, and one case with extensive white matter lesions. Four patients showed relief of symptoms after treatment with vitamin B and necessary antiepileptic drugs. We combined the cases and relevant literature to retrospectively analyze the characteristics and treatment related to the disease. The onset of Hyperhomocysteinemia in adolescents is early, and the clinical manifestations are broad and atypical. At the same time, it has a significant impact on the growth and development of adolescents and can affect future life for a long time. Early detection and diagnosis have an important impact on prognosis.

Homocysteine enhances the excitability of cultured hippocampal neurons without altering the gene expression of voltage-gated ion channels

Elevated plasma homocysteine (Hcy) levels lead to hyperhomocysteinemia, a condition associated with various neurological disorders affecting multiple brain regions, including the hippocampus. In this study, we investigated the effects of exposing cultured rat hippocampal neurons to Hcy concentrations corresponding to mild, moderate, and severe hyperhomocysteinemia. A short 24-hour exposure had minimal effects, whereas prolonged exposure up to 14 days moderately enhanced hippocampal excitability without altering the gene expression of voltage-dependent calcium, sodium, or potassium channels or intracellular calcium levels. These findings suggest that Hcy-induced changes in neuronal excitability may contribute to neuropathologies associated with hyperhomocysteinemia.

Prenatal Hyperhomocysteinemia Leads to Synaptic Dysfunction and Structural Alterations in the CA1 Hippocampus of Rats

Prenatal hyperhomocysteinemia (HCY) is associated with neurodevelopmental deficits, yet its long-term impact on hippocampal synaptic function remains poorly understood. This study examines the effects of moderate maternal HCY on excitatory synaptic transmission in the CA1 region of the dorsal hippocampus in rat offspring at juvenile (P21) and adult (P90) stages. Using field postsynaptic potential (fPSP) recordings, electron microscopy, and Western blot analysis, we observed a significant age-dependent decline in the efficiency of excitatory synaptic transmission in HCY-exposed rats. Electron microscopy revealed structural alterations, including synaptic vesicle agglutination in the stratum radiatum, suggesting impaired neurotransmitter release. Additionally, a significant reduction in pyramidal neuron density was observed in the CA1 region, although seizure susceptibility remained unchanged. Western blot analysis showed altered expression of Synapsin I, indicating presynaptic dysfunction. These findings suggest that moderate prenatal HCY leads to persistent deficits in synaptic transmission and structural integrity, potentially contributing to cognitive impairments in adulthood. Our results highlight the importance of maternal homocysteine levels in shaping hippocampal function and could offer insights into neurodevelopmental disorders associated with metabolic disturbances.

Proinflammatory factors inhibition and fish oil treatment: A promising therapy for neonatal seizures

Brain injury is one of the most important causes of infant mortality and chronic neurological disabilities. Hypoxia is an acute brain injury which led to various cognitive, behavioral, and memory disorders throughout life. Previous studies reported neuroprotective possibilities for fish oil (FO) in brain-injured situations. In this study, we evaluated the effect of the FO diet during the lactation period on seizure activity, behavioral performance, histomorphometry, and inflammatory changes in the brains of hypoxia rats. Male Wistar rats were randomly divided in to 4 groups: Sham (intact rats), hypoxia, FO and FO+hypoxia groups. Hypoxia was induced by keeping neonate rats at PND12 in a hypoxic chamber (7 % oxygen and 93 % nitrogen intensity) for 15 minutes. In the FO groups, rats received oral FO (1 ml/day) for 12 days during the lactation period. Seizure activity was assessed by measuring the number of tonic-clonic seizures and seizure thresholds. Novel object recognition tests (NORT), rotarod, and open field tests were used to measure behavioral performances. A Histological study was performed to evaluate histomorphometric changes in the hippocampus and cerebellum. The gene expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) was measured using RT-PCR. Findings showed that the number of tonic-clonic seizures, atrophy, and cell death in the hippocampus and cerebellum, the gene expression of TNF-α and IL-1β in the hippocampus, and behavioral disorders were significantly increased in the hypoxia rats compared to the sham group. Administration of FO in the hypoxia groups significantly decreased the gene expression of TNF-α and IL-1β, the number of tonic-clonic seizures, and neuronal cell death in the hippocampus and cerebellum compared to the hypoxia groups. Furthermore, it can improve behavioral tasks and cognitions.

H2S prevents the disruption of the blood-brain barrier in rats with prenatal hyperhomocysteinemia

Elevation of the homocysteine concentration in the plasma called hyperhomocysteinemia (hHCY) during pregnancy causes a number of pre- and postnatal developmental disorders. The aim of our study was to analyze the effects of H2S donors -NaHS and N-acetylcysteine (NAC) on blood-brain barrier (BBB) permeability in rats with prenatal hHCY. In rats with mild hHCY BBB permeability assessed by Evans Blue extravasation in brain increased markedly throughout life. Administration of NaHS or NAC during pregnancy attenuated hHCY-associated damage and increased endogenous concentrations of sulfides in brain tissues. Acute application of dl-homocysteine thiolactone induced BBB leakage, which was prevented by the NMDA receptor antagonist MK-801 or H2S donors. Rats with hHCY demonstrated high levels of NO metabolite - nitrites and proinflammatory cytokines (IL-1β, TNF-α, IL-6) in brain. Lactate dehydrogenase (LDH) activity in the serum was higher in rats with hHCY. Mitochondrial complex-I activity was lower in brain of hHCY rats. NaHS treatment during pregnancy restored levels of proinflammatory cytokines, nitrites and activity of the respiratory chain complex in brain as well as the LDH activity in serum. Our data suggest that H2S has neuroprotective effects against prenatal hHCY-associated BBB disturbance providing a potential strategy for the prevention of developmental impairments in newborns.

Implications of high homocysteine levels in migraine pain: An experimental study of the excitability of peripheral meningeal afferents in rats with hyperhomocysteinemia

OBJECTIVES

Investigation of chronic homocysteine action on the excitability and N-methyl-D-aspartate (NMDA) sensitivity of the peripheral trigeminovascular system of rats.

BACKGROUND

Migraine is a neurological disease that affects 15%-20% of the general population. Epidemiological observations show that an increase of the sulfur-containing amino acid homocysteine in plasma-called hyperhomocysteinemia-is associated with a high risk of migraine, especially migraine with aura. In animal studies, rats with hyperhomocysteinemia demonstrated mechanical allodynia, photophobia, and anxiety, and higher sensitivity to cortical spreading depression. In addition, rats with hyperhomocysteinemia were more sensitive in a model of chronic migraine induced by nitroglycerin which indicated the involvement of peripheral nociceptive mechanisms. The present work aimed to analyze the excitability of meningeal afferents and neurons isolated from the trigeminal ganglion of rats with prenatal hyperhomocysteinemia.

METHODS

Experiments were performed on male rats born from females fed with a methionine-rich diet before and during pregnancy. The activity of meningeal afferents was recorded extracellularly in hemiskull preparations ex vivo and action potentials were characterized using cluster analysis. The excitability of trigeminal ganglion neurons was assessed using whole-cell patch clamp recording techniques and calcium imaging studies. Meningeal mast cells were stained using toluidine blue.

RESULTS

The baseline extracellular recorded electrical activity of the trigeminal nerve was higher in the hyperhomocysteinemia group with larger amplitude action potentials. Lower concentrations of KCl caused an increase in the frequency of action potentials of trigeminal afferents recorded in rat hemiskull ex vivo preparations. In trigeminal ganglion neurons of rats with hyperhomocysteinemia, the current required to elicit at least one action potential (rheobase) was lower, and more action potentials were induced in response to stimulus of 2 × rheobase. In controls, short-term application of homocysteine and its derivatives increased the frequency of action potentials of the trigeminal nerve and induced Ca2+ transients in neurons, which are associated with the activation of NMDA receptors. At the same time, in rats with hyperhomocysteinemia, we did not observe an increased response of the trigeminal nerve to NMDA. Similarly, the parameters of Ca2+ transients induced by NMDA, homocysteine, and its derivatives were not changed in rats with hyperhomocysteinemia. Acute incubation of the meninges in homocysteine and homocysteinic acid did not change the state of the mast cells, whereas in the model of hyperhomocysteinemia, an increased degranulation of mast cells in the meninges was observed.

CONCLUSIONS

Our results demonstrated higher excitability of the trigeminal system of rats with hyperhomocysteinemia. Together with our previous finding about the lower threshold of generation of cortical spreading depression in rats with hyperhomocysteinemia, the present data provide evidence of homocysteine as a factor that increases the sensitivity of the peripheral migraine mechanisms, and the control of homocysteine level may be an important strategy for reducing the risk and/or severity of migraine headache attacks.