Neuroprotective Role of N-acetylcysteine against Learning Deficits and Altered Brain Neurotransmitters in Rat Pups Subjected to Prenatal Stress

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.

Neuroprotective Effect of N-acetylcysteine Against Monocrotophos-Induced Oxidative Stress in Different Brain Regions of Rats

Monocrotophos (MCP) is systemic organophosphate insecticide used against crop pests. It is reported to cause mammalian toxicity through both acute and chronic exposure. In the present study, we have shown the protective role of N-acetylcysteine (NAC) against MCP-induced oxidative stress in frontal cortex, corpus striatum and hippocampus brain regions of rats. Male Albino Wistar rats were divided into control, NAC-treated, MCP and NAC + MCP-treated groups. An oral dose of MCP (0.9 mg/kg b.wt) and NAC (200 mg/kg b.wt) was administered for 28 days. Results showed an increase in lipid peroxidation (LPO) and protein oxidation followed by decreased antioxidant enzymes after 28 days of MCP exposure. Histopathological analysis showed that monocrotophos exposure caused neurodegenerative changes as evident by neurons with dystrophic changes in the form of shrunken hyperchromatic nuclei in all the regions of the rat brain. N-acetylcysteine supplementation to MCP-treated rats showed a reduction in oxidative stress and ameliorated cellular alterations in all of the three regions. The results of the study indicate that N-acetylcysteine offers neuroprotection by improving antioxidant response and decreasing oxidative stress in different regions of the rat brain.

The Impact of Maternal Antioxidants on Prenatal Stress Effects on Offspring Neurobiology and Behavior

Prenatal stress is a neuropsychiatric risk factor, and effects may be mediated by prenatal oxidative stress. Cell types in the brain sensitive to oxidative stress-cortical microglia and cortical and hippocampal interneurons-may be altered by oxidative stress generated during prenatal stress and may be neurobiological substrates for altered behavior. Our objective was to determine the critical nature of oxidative stress in prenatal stress effects by manipulating prenatal antioxidants. CD1 mouse dams underwent restraint embryonic day 12 to 18 three times daily or no stress and received intraperitoneal injections before each stress period of vehicle, N-acetylcysteine (200 mg/kg daily), or astaxanthin (30 mg/kg before first daily stress, 10 mg/kg before second/third stresses). Adult male and female offspring behavior, microglia, and interneurons were assessed. Results supported the hypothesis that prenatal stress-induced oxidative stress affects microglia; microglia ramification increased after prenatal stress, and both antioxidants prevented these effects. In addition, N-acetylcysteine or astaxanthin was effective in preventing distinct male and female interneuron changes; decreased female medial frontal cortical parvalbumin interneurons was prevented by either antioxidant; increased male medial frontal cortical parvalbumin interneurons was prevented by N-acetylcysteine and decreased male hippocampal GAD67GFP+ cells prevented by astaxanthin. Prenatal stress-induced increased anxiety-like behavior and decreased sociability were not prevented by prenatal antioxidants. Sensorimotor gating deficits in males was partially prevented by prenatal astaxanthin. This study demonstrates the importance of oxidative stress for persistent impacts on offspring cortical microglia and interneurons, but did not link these changes with anxiety-like, social, and sensorimotor gating behaviors.

Cellular stress mechanisms of prenatal maternal stress: Heat shock factors and oxidative stress

Development of the brain prenatally is affected by maternal experience and exposure. Prenatal maternal psychological stress changes brain development and results in increased risk for neuropsychiatric disorders. In this review, multiple levels of prenatal stress mechanisms (offspring brain, placenta, and maternal physiology) are discussed and their intersection with cellular stress mechanisms explicated. Heat shock factors and oxidative stress are closely related to each other and converge with the inflammation, hormones, and cellular development that have been more deeply explored as the basis of prenatal stress risk. Increasing evidence implicates cellular stress mechanisms in neuropsychiatric disorders associated with prenatal stress including affective disorders, schizophrenia, and child-onset psychiatric disorders. Heat shock factors and oxidative stress also have links with the mechanisms involved in other kinds of prenatal stress including external exposures such as environmental toxicants and internal disruptions such as preeclampsia. Integrative understanding of developmental neurobiology with these cellular and physiological mechanisms is necessary to reduce risks and promote healthy brain development.