Nguyen, T, Li, GE, Chen, H, Cranfield, CG, McGrath, KC & Gorrie, CA 2019, 'Neurological effects in the offspring after switching from tobacco cigarettes to e-cigarettes during pregnancy in a mouse model.', Toxicological Sciences, vol. 172, no. 1, pp. 191-200.View/Download from: Publisher's site
BACKGROUND:Maternal smoking is currently a public health concern and has been associated with a number of complications in the offspring. E-cigarettes are gaining popularity as a 'safer' alternative to tobacco cigarettes during pregnancy, however, there are a limited number of studies to suggest that it is actually 'safe'. STUDY DESIGN:Balb/C female mice were exposed to ambient air (n = 8; Sham), or tobacco cigarette smoke (n = 8; SE) before gestation, during gestation and lactation. A third group was exposed to cigarette smoke before gestation followed by e-cigarette aerosols during gestation and lactation (n = 8; Switch). Male offspring (12-week old, n = 10-14/group) underwent behavioural assessments to investigate short-term memory, anxiety and activity using the novel object recognition (NOR) and elevated plus maze (EPM) tests. Brains were collected at postnatal day (P)1, P20 and Week13 for global DNA methylation, epigenetic gene expression, and neuronal cell counts. RESULTS:The offspring from mothers switching to e-cigarettes exhibited no change in exploration/activity, but showed a decrease in global DNA methylation, Aurora Kinase (Aurk) A and AurkB gene expression and a reduction in neuronal cell numbers in the cornu ammonis 1 region of the dorsal hippocampus compared to the SE group. CONCLUSIONS:Continuous tobacco cigarette smoke exposure during pregnancy resulted in marked neurological deficits in the offspring. Switching to e-cigarettes during pregnancy reduced these neurological deficits compared to cigarette smoke exposure. However, neurological changes were still observed, so we therefore conclude that e-cigarette use during pregnancy is not advised.
Li, G, Chan, YL, Nguyen, LT, Mak, C, Zaky, A, Anwer, AG, Shi, Y, Nguyen, T, Pollock, CA, Oliver, BG, Saad, S & Chen, H 2019, 'Impact of maternal e-cigarette vapor exposure on renal health in the offspring.', Annals of the New York Academy of Sciences, vol. 1452, no. 1, pp. 65-77.View/Download from: Publisher's site
Maternal smoking during pregnancy is a significant risk factor of renal pathology in the offspring. E-cigarettes are perceived to be a safe option and are increasingly used by pregnant women either continuously during pregnancy or as a replacement for tobacco cigarettes. This study aimed to determine the effects of replacing tobacco cigarettes with e-cigarettes during pregnancy, and continuous e-cigarette use during pregnancy on the offspring's kidneys. Female Balb/c mice were exposed to either air (sham) or tobacco cigarette smoke (SE) for 6 weeks prior to mating, during gestation and lactation. A subset of the "SE group" received e-cigarette vapor (containing nicotine) after mating until pups weaned. Additional female mice were continuously exposed to e-vapor (either with or without nicotine) for 6 weeks prior to mating until pups weaned. Kidneys and urine from the male offspring were assessed at postnatal day 1, day 20 (weaning), and 13 weeks of age (adulthood). E-cigarette replacement was less detrimental to renal development and albuminuria than continuous SE during pregnancy. However, continuous e-vapor exposure during pregnancy increased markers of oxidative stress, inflammation, and fibrosis in the adult offspring, independent of nicotine. E-cigarette use during pregnancy confers future risk to the offspring's kidneys.
Chen, H, Li, G, Chan, YL, Chapman, DG, Sukjamnong, S, Nguyen, T, Annissa, T, McGrath, KC, Sharma, P & Oliver, BG 2018, 'Maternal E-Cigarette Exposure in Mice Alters DNA Methylation and Lung Cytokine Expression in Offspring.', American Journal of Respiratory Cell and Molecular Biology, vol. 58, no. 3, pp. 366-377.View/Download from: Publisher's site
E-cigarette usage is increasing, especially among the young, with both the general population and physicians perceiving them as a safe alternative to tobacco smoking. Worryingly, e-cigarettes are commonly used by pregnant women. As nicotine is known to adversely affect children in utero, we hypothesized that nicotine delivered via e-cigarettes would negatively affect lung development. To test this, we developed a mouse model of maternal e-vapor (nicotine and nicotine-free) exposure and investigated the impact on the growth and lung inflammation in both offspring and mothers. Female Balb/c mice were exposed to e-fluid vapor containing nicotine (18 mg/ml nicotine E-cigarette [E-cig18], equivalent to two cigarettes per treatment, twice daily,) or nicotine free (E-cig0 mg/ml) from 6 weeks before mating until pups weaned. Male offspring were studied at Postnatal Day (P) 1, P20, and at 13 weeks. The mothers were studied when the pups weaned. In the mothers' lungs, e-cigarette exposure with and without nicotine increased the proinflammatory cytokines IL-1β, IL-6, and TNF-α. In adult offspring, TNF-α protein levels were increased in both E-cig18 and E-cig0 groups, whereas IL-1β was suppressed. This was accompanied by global changes in DNA methylation. In this study, we found that e-cigarette exposure during pregnancy adversely affected maternal and offspring lung health. As this occurred with both nicotine-free and nicotine-containing e-vapor, the effects are likely due to by-products of vaporization rather than nicotine.
Nguyen, T, Li, GE, Chen, H, Cranfield, CG, McGrath, KC & Gorrie, CA 2018, 'Maternal E-Cigarette Exposure Results in Cognitive and Epigenetic Alterations in Offspring in a Mouse Model.', Chemical research in toxicology, vol. 31, no. 7, pp. 601-611.View/Download from: Publisher's site
Electronic cigarette (e-cigarette) use is on the rise worldwide and is particularly attractive to young people and as a smoking substitute by pregnant woman. There is a perception in pregnant women and women of child-bearing age that the use of e-cigarettes (vaping) is safer than smoking tobacco cigarettes during pregnancy. However, there is little evidence to support this perception. Here, we examined the offspring from mouse dams that had been exposed during and after pregnancy to ambient air (sham) ( n = 8), e-cigarette aerosols with nicotine ( n = 8), or e-cigarette aerosols without nicotine ( n = 8). Offspring underwent cognitive testing at 12 weeks of age and epigenetic testing of brain tissues at 1 day, 20 days, and 13 weeks after birth. The findings showed deficits in short-term memory, reduced anxiety, and hyperactivity in offspring following maternal e-cigarette exposure using the novel object recognition and elevated plus maze tests. In addition, global DNA methylation was increased in the brains of offspring soon after birth. Using a quantitative-PCR array specific to chromatin modification enzymes on genomic DNA and histones,13 key genes were identified to be significantly altered in the offspring brains from the e-cigarette groups compared to the nonexposed groups. The changes to genes Aurka, Aurkb, Aurkc, Kdm5c, Kdm6b, Dnmt3a, Dnmt3b, and Atf2, all associated with modulating neurological activity, were validated using RT-qPCR. In conclusion, in a mouse model, maternal exposure to e-cigarette aerosols resulted in both cognitive and epigenetic changes in offspring. This suggests that the use of e-cigarettes during pregnancy may have hitherto undetected neurological consequences on newborns.
Chen, H, Li, G, Chan, YL, Nguyen, T, van Reyk, D, Saad, S & Oliver, BG 2018, 'Modulation of neural regulators of energy homeostasis, and of inflammation, in the pups of mice exposed to e-cigarettes.', Neuroscience letters, vol. 684, pp. 61-66.View/Download from: Publisher's site
BACKGROUND:Maternal smoking can lead to perturbations in central metabolic regulators such as neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) signalling components in offspring. With the growing interest in e-cigarettes as a tobacco replacement, this short report assessed central metabolic regulation in offspring of mouse dams exposed to e-cigarettes. We examined the impact of continuous use of e-cigarettes, and e-cigarette replacement of tobacco cigarettes during pregnancy. Supplementation of an antioxidant l-carnitine was also co-used with tobacco cigarette in the mother to determine whether the impact of maternal tobacco smoking was oxidative stress driven. METHODS:Balb/c mice were exposed to either nicotine-containing (E-cig18) or nicotine-free (E-cig0) e-cigarette aerosols or tobacco smoke (SE) prior to mating and until their pups were weaned. After mating, two SE sub-groups were changed to E-cig18 exposure (Replacement), or supplementation l-carnitine while SE was continued. Male offspring were studied at weaning age. RESULTS:The offspring of E-cig0 dams were the heaviest with the most body fat. Replacing SE with E-cig18 during pregnancy resulted in offspring with significantly less body fat. E-cig0 offspring had significantly increased mRNA expression of brain NPY and iNOS. Maternal SE upregulated mRNA expression of NPY, NPY Y1 receptor, POMC downstream components, and iNOS expression, which were normalised in Replacement offspring, but only partially normalised with maternal L-carnitine supplementation during gestation and lactation. CONCLUSIONS:Maternal exposure to either tobacco and nicotine-free e-cigarettes lead to disturbances in the level of central homeostatic control markers in offspring, suggesting that maternal exposure to e-cigarettes is not without risks.
Mao, Y, Nguyen, T, Tonkin, RS, Lees, JG, Warren, C, O'Carroll, SJ, Nicholson, LFB, Green, CR, Moalem-Taylor, G & Gorrie, CA 2017, 'Characterisation of Peptide5 systemic administration for treating traumatic spinal cord injured rats.', Experimental Brain Research, vol. 235, no. 10, pp. 3033-3048.View/Download from: Publisher's site
Systemic administration of a Connexin43 mimetic peptide, Peptide5, has been shown to reduce secondary tissue damage and improve functional recovery after spinal cord injury (SCI). This study investigated safety measures and potential off-target effects of Peptide5 systemic administration. Rats were subjected to a mild contusion SCI using the New York University impactor. One cohort was injected intraperitoneally with a single dose of fluorescently labelled Peptide5 and euthanised at 2 or 4 h post-injury for peptide distribution analysis. A second cohort received intraperitoneal injections of Peptide5 or a scrambled peptide and was culled at 8 or 24 h post-injury for the analysis of connexin proteins and systemic cytokine profile. We found that Peptide5 did not cross the blood-spinal cord barrier in control animals, but reached the lesion area in the spinal cord-injured animals without entering non-injured tissue. There was no evidence that the systemic administration of Peptide5 modulates Connexin43 protein expression or hemichannel closure in the heart and lung tissue of SCI animals. The expression levels of other major connexin proteins including Connexin30 in astrocytes, Connexin36 in neurons and Connexin47 in oligodendrocytes were also unaltered by systemic delivery of Peptide5 in either the injured or non-injured spinal cords. In addition, systemic delivery of Peptide5 had no significant effect on the plasma levels of cytokines, chemokines or growth factors. These data indicate that the systemic delivery of Peptide5 is unlikely to cause any off-target or adverse effects and may thus be a safe treatment option for traumatic SCI.
Mao, Y, Tonkin, RS, Nguyen, T, O'Carroll, SJ, Nicholson, LF, Green, CR, Moalem-Taylor, G & Gorrie, CA 2017, 'Systemic administration of Connexin43 mimetic peptide improves functional recovery following traumatic spinal cord injury in adult rats.', Journal of Neurotrauma, vol. 34, no. 3, pp. 707-719.View/Download from: Publisher's site
Blocking of Connexin43 hemichannels, the main gap junction protein located on astrocytes in the central nervous system, has been shown to reduce neural injury in a number of models. We previously demonstrated that local administration of a Connexin43 mimetic peptide, Peptide5, reduces secondary tissue damage after spinal cord injury (SCI). Here, we investigated whether acute systemic delivery of Peptide5 is also protective in a model of SCI. Rats were subjected to a mild spinal cord contusion using the MASCIS impactor and were injected intraperitoneally with Peptide5 or a scrambled peptide immediately and at 2 and 4 hours post-injury. Rats were tested for locomotor recovery and pain hypersensitivity and euthanised at 8 hours, 24 hours, 2 weeks or 6 weeks post-injury. Compared to control rats, Peptide5 treated rats showed significant improvement in hindlimb locomotor function between 3 and 6 weeks post-injury and reductions in at-level mechanical allodynia from week 1 post-injury. Immunohistochemistry showed that Peptide5 treatment led to a reduction in total Connexin43 and increased phosphorylated Connexin43 at 8 hours compared to scrambled peptide. At 2 and 6 weeks, lesion size, the astrocytic and the activated macrophage and/or microglial response were all decreased in the Peptide5 animals. Additionally, neuronal cell numbers were higher in the Peptide5 animals compared to the scrambled peptide treated rats at 2 and 6 weeks. These results show for the first time that systemic administration of Peptide5 to block the pathological opening of Connexin43 hemichannels is a feasible treatment strategy in this setting, ameliorating the secondary SCI.
Nguyen, T, Mao, Y, Sutherland, T & Gorrie, CA 2017, 'Neural progenitor cells but not astrocytes respond distally to thoracic spinal cord injury in rat models.', Neural regeneration research, vol. 12, no. 11, pp. 1885-1894.View/Download from: Publisher's site
Traumatic spinal cord injury (SCI) is a detrimental condition that causes loss of sensory and motor function in an individual. Many complex secondary injury cascades occur after SCI and they offer great potential for therapeutic targeting. In this study, we investigated the response of endogenous neural progenitor cells, astrocytes, and microglia to a localized thoracic SCI throughout the neuroaxis. Twenty-five adult female Sprague-Dawley rats underwent mild-contusion thoracic SCI (n = 9), sham surgery (n = 8), or no surgery (n = 8). Spinal cord and brain tissues were fixed and cut at six regions of the neuroaxis. Immunohistochemistry showed increased reactivity of neural progenitor cell marker nestin in the central canal at all levels of the spinal cord. Increased reactivity of astrocyte-specific marker glial fibrillary acidic protein was found only at the lesion epicenter. The number of activated microglia was significantly increased at the lesion site, and activated microglia extended to the lumbar enlargement. Phagocytic microglia and macrophages were significantly increased only at the lesion site. There were no changes in nestin, glial fibrillary acidic protein, microglia and macrophage response in the third ventricle of rats subjected to mild-contusion thoracic SCI compared to the sham surgery or no surgery. These findings indicate that neural progenitor cells, astrocytes and microglia respond differently to a localized SCI, presumably due to differences in inflammatory signaling. These different cellular responses may have implications in the way that neural progenitor cells can be manipulated for neuroregeneration after SCI. This needs to be further investigated.
Sutherland, TC, Mathews, KJ, Mao, Y, Nguyen, T & Gorrie, CA 2017, 'Differences in the Cellular Response to Acute Spinal Cord Injury between Developing and Mature Rats Highlights the Potential Significance of the Inflammatory Response.', Frontiers in Cellular Neuroscience, vol. 10, pp. 1-18.View/Download from: Publisher's site
There exists a trend for a better functional recovery from spinal cord injury (SCI) in younger patients compared to adults, which is also reported for animal studies; however, the reasons for this are yet to be elucidated. The post injury tissue microenvironment is a complex milieu of cells and signals that interact on multiple levels. Inflammation has been shown to play a significant role in this post injury microenvironment. Endogenous neural progenitor cells (NPC), in the ependymal layer of the central canal, have also been shown to respond and migrate to the lesion site. This study used a mild contusion injury model to compare adult (9 week), juvenile (5 week) and infant (P7) Sprague-Dawley rats at 24 h, 1, 2, and 6 weeks post-injury (n = 108). The innate cells of the inflammatory response were examined using counts of ED1/IBA1 labeled cells. This found a decreased inflammatory response in the infants, compared to the adult and juvenile animals, demonstrated by a decreased neutrophil infiltration and macrophage and microglial activation at all 4 time points. Two other prominent cellular contributors to the post-injury microenvironment, the reactive astrocytes, which eventually form the glial scar, and the NPC were quantitated using GFAP and Nestin immunohistochemistry. After SCI in all 3 ages there was an obvious increase in Nestin staining in the ependymal layer, with long basal processes extending into the parenchyma. This was consistent between age groups early post injury then deviated at 2 weeks. The GFAP results also showed stark differences between the mature and infant animals. These results point to significant differences in the inflammatory response between infants and adults that may contribute to the better recovery indicated by other researchers, as well as differences in the overall injury progression and cellular responses. This may have important consequences if we are able to mirror and manipulate this response in patients of all ages; howev...