Effects of maternal lead exposure on RGMa and RGMb expression in the hippocampus and cerebral cortex of mouse pups

Lead Toxicity and Maternal Exposure: Characterisation of Alveolar Bone Changes on Offspring Rats

Lead poisoning is a global public health concern. Maternal exposure during intrauterine and lactational periods can present a higher susceptibility of harm to the offspring. Thus, pregnant female Wistar rats (Rattus norvegicus) were randomly divided in two experimental groups: control group and Lead group. The animals were exposed to 50 mg/kg of Lead Acetate daily for 42 days (21 days of gestational period + 21 days of lactational period). After the exposure period, the mandibles of the offspring were collected for lead quantification, Raman spectroscopy analysis, micro-CT, morphometric e histochemical analysis. Lead exposure altered the physical-chemical composition of alveolar bone and caused histological damage associated with a reduction in osteocyte density and collagen area fraction, increase in collagen maturity, as well as a reduction in bone volume fraction. An increase in trabecular spaces with anatomical compromise of the vertical dimensions of the bone was observed. Thus, the results suggest that developing alveolar bone is susceptible to toxic effects of lead when organisms are exposed during intrauterine and lactation periods.

Lead exposure and its association with neurological damage: systematic review and meta-analysis

Lead (Pb) is one of the most toxic and abundant elements in the earth's crust, which is pointed out that the intoxication caused by it may damage biological systems. This systematic review with meta-analysis aimed to evaluate the association between Pb exposure and neurological damage. This work was executed according to PRISMA guidelines, and seven online databases were consulted. Based on the PECO strategy, studies presenting humans as participants (populations) exposed to Pb (exposure) compared to non-exposed to Pb (control) evaluating the neurological impairment (outcome) were included. The quality and risk of bias were verified by Fowkes and Fulton checklist. Two meta-analyses were conducted considering Digit Symbol and Profile Mood tests. The certainty of the evidence was evaluated with the GRADE tool. This review identified 2019 studies, of which 12 were eligible according to the inclusion criteria. Eight were considered with a low risk of bias. All the studies elected showed that exposure to Pb is associated with neurological damage, but the meta-analysis did not show any difference for the evaluated tests, and the certainty of the evidence was considered very low. Nevertheless, the included studies showed that Pb occupational exposure is associated with neurological damage, and the main parameters evaluated for possible neurological damage were related to mnemonic aspects, reaction time, intelligence, attention disorders, and mood changes. Thus, our results revealed that a definitive demonstration of an association of Pb and neurological changes in humans is still a pending issue. Future studies should take into consideration more confident methods to answer this question.

Ferulic acid exerts Nrf2-dependent protection against prenatal lead exposure-induced cognitive impairment in offspring mice

Prenatal and/or early postnatal exposure to lead (Pb) may be associated with deficits in cognitive function in the toddler offspring, and oxidative stress likely play a central role in mediating these adverse effects. Here, we tested the hypothesis that ameliorative effect of ferulic acid (FA) on lead-induced cognitive deficits attributed to its antioxidant properties in a nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent manner in the context of prenatal Pb exposure. To test this hypothesis, Nrf2 knockout and C57BL/6 wild type mouse dams were exposed/unexposed to PbAc (250 ppm) during gestation day 5 to postnatal day 14 via drinking water, and FA (50 mg/kg)/vehicle was administered orally to dams for 31 d. Spatial learning and memory in pups was assessed by Morris water maze. Biochemical assays, real-time PCR, western blot techniques were employed to evaluate oxidative stress and signaling pathways in the brain of pups. We report that lead acetate (PbAc) leads to deficits in cognitive functions in offspring, which were partially attenuated by FA (P<.05). In parallel, pretreatment with FA also significantly inhibited the PbAc-induced oxidative stress, as indicated by a change in NAD+/NADH ratio, glutathione (GSH) and malondialdehyde contents (all P<.05). Interestingly, FA significantly elevated the glutamate cysteine ligase and heme oxygenase 1 at levels of transcription and translation in both mice exposed and unexposed to Pb, increasing de novo synthesis of GSH (all P<.05). Furthermore, maternal FA administration activates extracellular signal-regulated kinases 1 and 2 and promotes more Nrf2 nuclear accumulation by increasing the Nrf2 total protein in brain of offspring mice (all P<.05). Conversely, FA failed to influence Pb-induced both memory deficits and oxidative stress in offspring of Nrf2 knockout mice (all P≥.05), suggesting that Nrf2 is essential in mediating the cognition-enhancing and antioxidant effects of FA. Overall, our results demonstrate that FA protects against Pb-induced offspring's cognitive deficits, suggesting that it is a promising candidate for the treatment of Pb toxicity.

Long-term exposure to lead reduces antioxidant capacity and triggers motor neurons degeneration and demyelination in spinal cord of adult rats

Lead is a toxic metal found in environment with great neurotoxic potential. The main effect is associated with impairments in hippocampus and cerebellum, driving to cognitive and motor dysfunctions, however, there is a lack of evidences about the effects over the spinal cord. In this way, we aimed to investigate in vivo the effects of long-term exposure to lead acetate in oxidative biochemistry and morphology of rats' spinal cord. For this, 36 male Wistar rats (Rattus norvegicus) were divided into the group exposed to 50 mg/kg of lead acetate and control group, which received only distilled water, both groups through intragastric gavage, for 55 days. After the exposure period, the animals were euthanized and the spinal cords were collected to perform the analyses of lead levels quantification, oxidative biochemistry evaluation by levels of malondialdehyde (MDA), nitrites and the antioxidant capacity against peroxyl radicals (ACAP). Besides, morphological evaluation with quantitative analysis of mature and motor neurons and reactivity to myelin basic protein (MBP). Our results showed high levels of lead in spinal cord after long-term exposure; there was a reduction on ACAP level; however, there was no difference observed in MDA and nitrite levels. Moreover, there was a reduction of mature and motor neurons in all three regions, and a reduction of immunolabeling of MBP in the thoracic and lumbar segments. Therefore, we conclude that long-term exposure to lead is able of increasing the levels of the metal in spinal cord, affecting the antioxidant capacity and inducing morphological impairments in spinal cord parenchyma. Our results also suggest that the tissue impairments triggered by lead may be resultant from others molecular mechanisms besides the oxidative stress.

Progress in Research on Brain Development and Function of Mice During Weaning

Lactation is a critical phase for brain function development. New dietary experiences of mouse caused by weaning can regulate brain development and function, increase their response to food and environment, and eventually give rise to corresponding behavioral changes. Changes in weaning time induce the alteration of brain tissues morphology and molecular characteristics, glial cell activity and behaviors in the offspring. In addition, it is also sensitive to the intervention of environment and drugs during this period. That is to say, the study focused on brain development and function based on mouse weaning is critical to demonstrate the underlying pathogenesis of neuropsychiatric diseases and find new drug targets. This article mainly focuses on the developmental differentiation of the brain during lactation, especially during weaning in mice.