Protective effects of N-acetylcysteine on peroxidative changes of the fetal rat lungs whose mothers were exposed to cigarette smoke

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

Prenatal adversaries like stress are known to harm the progeny and oxidative stress, which is known to be one of the causative factors. N-acetyl cysteine (NAC), which is a potent antioxidant, has been shown to play a neuroprotective role in humans and experimental animals. This study examines the benefits of NAC on the prenatal stress-induced learning and memory deficits and alteration in brain neurotransmitter in rat pups. Pregnant dams were restrained (45 min; 3 times/day) during the early or late gestational period. Other groups received early or late gestational restrain stress combined with NAC treatment throughout the gestational period. At postnatal day (PND) 28, offspring were tested in a shuttle box for assessing learning and memory, which was followed by a brain neurotransmitter (dopamine, norepinephrine, and serotonin) estimation on PND 36. Late gestational stress resulted in learning deficits, the inability to retain the memory, and reduced brain dopamine content while not affecting norepinephrine and serotonin. NAC treatment in prenatally stressed rats reversed learning and memory deficits as well as brain dopamine content in offspring. These findings suggest that NAC protect the progeny from an undesirable cognitive sequel associated with prenatal stress.

Effect of long-term maternal smoking on the offspring's lung health

Maternal smoking during pregnancy contributes to long-term health problems in offspring, especially respiratory disorders that can manifest in either childhood or adulthood. Receptors for advanced glycation end products (RAGE) are multiligand receptors abundantly localized in the lung, capable of responding to by-products of reactive oxygen species and proinflammatory responses. RAGE signaling is a key regulator of inflammation in cigarette smoking-related pulmonary diseases. However, the impact of maternal cigarette smoke exposure on lung RAGE signaling in the offspring is unclear. This study aims to investigate the effect of maternal cigarette smoke exposure (SE), as well as mitochondria-targeted antioxidant [mitoquinone mesylate (MitoQ)] treatment, during pregnancy on the RAGE-mediated signaling pathway in the lung of male offspring. Female Balb/c mice (8 wk) were divided into a sham group (exposed to air), an SE group (exposed to cigarette smoke), and an SE + MQ group (exposed to cigarette smoke with MitoQ supplement from mating). The lungs from male offspring were collected at 13 wk. RAGE and its downstream signaling, including nuclear factor-κB and mitogen-activated protein kinase family consisting of extracellular signal-regulated kinase 1, ERK2, c-JUN NH2-terminal kinase (JNK), and phosphorylated JNK, in the lung were significantly increased in the SE offspring. Mitochondrial antioxidant manganese superoxide dismutase was reduced, whereas IL-1β and oxidative stress response nuclear factor (erythroid-derived 2)-like 2 were significantly increased in the SE offspring. Maternal MitoQ treatment normalized RAGE, IL-1β, and Nrf-2 levels in the SE + MQ offspring. Maternal SE increased RAGE and its signaling elements associated with increased oxidative stress and inflammatory cytokines in offspring lungs, whereas maternal MitoQ treatment can partially normalize these changes.

AHR2 morpholino knockdown reduces the toxicity of total particulate matter to zebrafish embryos

The zebrafish embryo has been proposed as a 'bridge model' to study the effects of cigarette smoke on early development. Previous studies showed that exposure to total particulate matter (TPM) led to adverse effects in developing zebrafish, and suggested that the antioxidant and aryl hydrocarbon receptor (AHR) pathways play important roles. This study investigated the roles of these two pathways in mediating TPM toxicity. The study consisted of four experiments. In experiment I, zebrafish embryos were exposed from 6h post fertilization (hpf) until 96hpf to TPM0.5 and TPM1.0 (corresponding to 0.5 and 1.0μg/mL equi-nicotine units) in the presence or absence of an antioxidant (N-acetyl cysteine/NAC) or a pro-oxidant (buthionine sulfoximine/BSO). In experiment II, TPM exposures were performed in embryos that were microinjected with nuclear factor erythroid 2-related factor 2 (Nrf2), AHR2, cytochrome P450 1A (CYP1A), or CYP1B1 morpholinos, and deformities were assessed. In experiment III, embryos were exposed to TPM, and embryos/larvae were collected at 24, 48, 72, and 96hpf to assess several genes associated with the antioxidant and AHR pathways. Lastly, experiment IV assessed the activity and protein levels of CYP1A and CYP1B1 after exposure to TPM. We demonstrate that the incidence of TPM-induced deformities was generally not affected by NAC/BSO treatments or Nrf2 knockdown. In contrast, AHR2 knockdown reduced, while CYP1A or CYP1B1 knockdowns elevated the incidence of some deformities. Moreover, as shown by gene expression the AHR pathway, but not the antioxidant pathway, was induced in response to TPM exposure, providing further evidence for its importance in mediating TPM toxicity.

The relationship between plasma lipid peroxidation products and primary graft dysfunction after lung transplantation is modified by donor smoking and reperfusion hyperoxia

BACKGROUND

Donor smoking history and higher fraction of inspired oxygen (FIO2) at reperfusion are associated with primary graft dysfunction (PGD) after lung transplantation. We hypothesized that oxidative injury biomarkers would be elevated in PGD, with higher levels associated with donor exposure to cigarette smoke and recipient hyperoxia at reperfusion.

METHODS

We performed a nested case-control study of 72 lung transplant recipients from the Lung Transplant Outcomes Group cohort. Using mass spectroscopy, F2-isoprostanes and isofurans were measured in plasma collected after transplantation. Cases were defined in 2 ways: grade 3 PGD present at day 2 or day 3 after reperfusion (severe PGD) or any grade 3 PGD (any PGD).

RESULTS

There were 31 severe PGD cases with 41 controls and 35 any PGD cases with 37 controls. Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (28.6 pg/ml vs 19.8 pg/ml, p = 0.03). Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (29.6 pg/ml vs 19.0 pg/ml, p = 0.03) among patients reperfused with FIO2 >40%. Among recipients of lungs from donors with smoke exposure, plasma F2-isoprostane (38.2 pg/ml vs 22.5 pg/ml, p = 0.046) and isofuran (66.9 pg/ml vs 34.6 pg/ml, p = 0.046) levels were higher in severe PGD compared with control subjects.

CONCLUSIONS

Plasma levels of lipid peroxidation products are higher in patients with severe PGD, in recipients of lungs from donors with smoke exposure, and in recipients exposed to higher Fio2 at reperfusion. Oxidative injury is an important mechanism of PGD and may be magnified by donor exposure to cigarette smoke and hyperoxia at reperfusion.

Protective effect of N-acetylcysteine on liver damage during chronic intrauterine hypoxia in fetal guinea pig

Chronic exposure to hypoxia during pregnancy generates a stressed intrauterine environment that may lead to fetal organ damage. The objectives of the study are (1) to quantify the effect of chronic hypoxia in the generation of oxidative stress in fetal guinea pig liver and (2) to test the protective effect of antioxidant treatment in hypoxic fetal liver injury. Pregnant guinea pigs were exposed to either normoxia (NMX) or 10.5% O(2) (HPX, 14 days) prior to term (65 days) and orally administered N-acetylcysteine ([NAC] 10 days). Near-term anesthetized fetuses were excised and livers examined by histology and assayed for malondialdehyde (MDA) and DNA fragmentation. Chronic HPX increased erythroid precursors, MDA (NMX vs HPX; 1.26 ± 0.07 vs 1.78 ± 0.07 nmol/mg protein; P < .001, mean ± standard error of the mean [SEM]) and DNA fragmentation levels in fetal livers (0.069 ± 0.01 vs 0.11 ± 0.005 OD/mg protein; P < .01). N-acetylcysteine inhibited erythroid aggregation and reduced (P < .05) both MDA and DNA fragmentation of fetal HPX livers. Thus, chronic intrauterine hypoxia generates cell and nuclear damage in the fetal guinea pig liver. Maternal NAC inhibited the adverse effects of fetal liver damage suggestive of oxidative stress. The suppressive effect of maternal NAC may implicate the protective role of antioxidants in the prevention of liver injury in the hypoxic fetus.

A further review of inhalation studies with cigarette smoke and lung cancer in experimental animals, including transgenic mice

CONTEXT

The lack of an effective animal model for pulmonary carcinogenesis in smokers is a continuing problem for researchers trying to design Potentially Reduced Risk Products for those smokers who are either unwilling or unable to quit smoking. The major failing of inhalation assays with cigarette smoke in laboratory animals is that these assays produce only small percentages of animals with pulmonary tumors (e.g. adenomas, with the occasional adenocarcinoma), as opposed to the highly invasive carcinomas (e.g. small cell and squamous cell) seen in smokers.

OBJECTIVE

To update previous reviews on animal models, and to add different types of transgenic (Tg) mice to the review.

METHODS

Reviews were made of articles retrieved from PubMed and elsewhere.

RESULTS

The addition of Tg mice to the arsenal of tests used for the evaluation of the carcinogenic potential of cigarettes did not result in any better understanding of the inability of such testing to reflect the epidemiological evidence for lung cancer in smokers.

CONCLUSION

As in previous reviews on the subject, the best assay providing support for the epidemiology data is still the 5-month whole-body exposure of male A/J mice to a combination of mainstream/sidestream smoke, followed by a 4-month recovery.

Prenatal N-acetylcysteine prevents cigarette smoke-induced lung cancer in neonatal mice

Certain adult diseases may have their origin early in life, and perinatal exposures may contribute to cancers both during childhood and later in life. We recently demonstrated that mainstream cigarette smoke (MCS) induces a potent carcinogenic response in mice when exposure starts soon after birth. We also showed that the antioxidant N-acetylcysteine (NAC) prevents the extensive nucleotide and gene expression alterations that occur 'physiologically' at birth in mouse lung. The present study was designed to evaluate whether administration of NAC during pregnancy may affect the yield of tumors in mice exposed to MCS, starting after birth and continuing for 120 days. The results obtained showed that 210 days after birth, one adenoma only was detectable in sham-exposed mice. In contrast, as much as the 61.1% (33/54) of MCS-exposed mice born from untreated dams had lung tumors, including both benign tumors and bronchoalveolar carcinomas. Treatment with NAC during pregnancy strikingly inhibited the formation of benign lung tumors and totally prevented occurrence of carcinomas. In addition, prenatal NAC inhibited the MCS-induced hyperplasia of the urinary bladder epithelium. These findings demonstrate for the first time that treatment during pregnancy with an antioxidant chemopreventive agent can affect the induction of tumors consequent to exposure to a carcinogen after birth.