Developmental exposure to glyphosate-based herbicide and depressive-like behavior in adult offspring: Implication of glutamate excitotoxicity and oxidative stress.

We have previously demonstrated that maternal exposure to glyphosate-based herbicide (GBH) leads to glutamate excitotoxicity in 15-day-old rat hippocampus. The present study was conducted in order to investigate the effects of subchronic exposure to GBH on some neurochemical and behavioral parameters in immature and adult offspring. Rats were exposed to 1% GBH in drinking water (corresponding to 0.36% of glyphosate) from gestational day 5 until postnatal day (PND)-15 or PND60. Results showed that GBH exposure during both prenatal and postnatal periods causes oxidative stress, affects cholinergic and glutamatergic neurotransmission in offspring hippocampus from immature and adult rats. The subchronic exposure to the pesticide decreased L-[14C]-glutamate uptake and increased 45Ca2+ influx in 60-day-old rat hippocampus, suggesting a persistent glutamate excitotoxicity from developmental period (PND15) to adulthood (PND60). Moreover, GBH exposure alters the serum levels of the astrocytic protein S100B. The effects of GBH exposure were associated with oxidative stress and depressive-like behavior in offspring on PND60, as demonstrated by the prolonged immobility time and decreased time of climbing observed in forced swimming test. The mechanisms underlying the GBH-induced neurotoxicity involve the NMDA receptor activation, impairment of cholinergic transmission, astrocyte dysfunction, ERK1/2 overactivation, decreased p65 NF-κB phosphorylation, which are associated with oxidative stress and glutamate excitotoxicity. These neurochemical events may contribute, at least in part, to the depressive-like behavior observed in adult offspring.

Increased susceptibility to amyloid-ß-induced neurotoxicity in mice lacking the low-density lipoprotein receptor.

Familial hypercholesterolemia is caused by inherited genetic abnormalities that directly or indirectly affect the function of the low-density lipoprotein (LDL) receptor. This condition is characterized by defective catabolism of LDL which results in increased plasma cholesterol concentrations and premature coronary artery disease. Nevertheless, there is increasing preclinical and clinical evidence indicating that familial hypercholesterolemia subjects show a particularly high incidence of mild cognitive impairment. Moreover, the LDL receptor (LDLr) has been implicated as the main central nervous system apolipoprotein E receptor that regulates amyloid deposition in distinct mouse models of ß-amyloidosis. In this regard, herein we hypothesized that the lack of LDLr would enhance the susceptibility to amyloid-ß-(Aß)-induced neurotoxicity in mice. Using the acute intracerebroventricular injection of aggregated Aß(1-40) peptide (400 pmol/mouse), a useful approach for the investigation of molecular mechanisms involved in Aß toxicity, we observed oxidative stress, neuroinflammation, and neuronal membrane damage within the hippocampus of C57BL/6 wild-type mice, which were associated with spatial reference memory and working memory impairments. In addition, our data show that LDLr knockout (LDLr(-/-)) mice, regardless of Aß treatment, displayed memory deficits and increased blood-brain barrier permeability. Nonetheless, LDLr(-/-) mice treated with Aß(1-40) peptide presented increased acetylcholinesterase activity, astrogliosis, oxidative imbalance, and cell permeability within the hippocampus in comparison with Aß(1-40)-treated C57BL/6 wild-type mice. Overall, the present study shows that the lack of LDLr increases the susceptibility to Aß-induced neurotoxicity in mice providing new evidence about the crosslink between familial hypercholesterolemia and cognitive impairment.

Plasma levels of oxidative stress biomarkers and hospital mortality in severe head injury: a multivariate analysis.

INTRODUCTION: The association between biomarkers of oxidative stress and the prognosis of patients with traumatic brain injury (TBI) remains inconclusive. OBJECTIVE: The objective was to investigate the association between plasma levels of lipid peroxidation (thiobarbituric acid reactive species [TBARS]) and protein oxidation (carbonyl) biomarkers and the hospital mortality of patients with severe TBI. METHODS: Plasma levels of TBARS and carbonyl were determined in 79 consecutive patients with severe TBI (Glasgow Coma Scale [GCS] ≤8) at a median of 12 hours (interquartile range [IQ] 25-75, 6.5-19.0), 30 hours (IQ 25-75, 24.7-37.0), and 70 (IQ 25-75, 55.0-78.5) hours after TBI and were compared with age- and sex-matched controls. The association between the TBARS and carbonyl levels and the hospital mortality was analyzed by multiple logistic regression analysis. RESULTS: The mean age of patients was 34.8 years. Eighty-six percent were male. The TBARS and carbonyl levels were significantly higher in patients than in controls. There was a trend (P = .09) for higher plasma levels of TBARS and carbonyl proteins at 12 hours, but not at 30 or 70 hours, after trauma in nonsurvivors than in survivors. These findings were not confirmed after the adjustments by multiple logistic regression analysis. The final model showed a higher adjusted odds ratio for death for patients with admission GCS lower than 5 (odds ratio [OR] = 4.04; 95% confidence interval [CI], 1.33-12.13; P = .01) than those with higher GCS scores. Abnormal pupils were also associated with higher mortality (OR = 3.97; 95% CI, 1.22-12.13; P = .02). There was a nonsignificant trend for association between glucose greater than or equal to 150 mm/dL in the first 12 hours and death than levels between 70 and 149 mg/dL (OR = 2.92; 95% CI, 0.96-9.02; P = .06). CONCLUSIONS: Plasma levels of TBARS and carbonyl increase significantly in the first 70 hours after severe TBI but are not independently associated with the hospital mortality.

Role of the glucose-dependent insulinotropic polypeptide and its receptor in the central nervous system: therapeutic potential in neurological diseases.

Glucose-dependent insulinotropic polypeptide (GIP) is a 42-amino acid hormone, secreted from the enteroendocrine K cells, which has insulin-releasing and extra-pancreatic actions. GIP and its receptor present a widespread distribution in the mammalian brain where they have been implicated with synaptic plasticity, neurogenesis, neuroprotection and behavioral alterations. This review attempts to provide a comprehensive picture of the role of GIP in the central nervous system and to highlight recent findings from our group showing its potential involvement in neurological illnesses including epilepsies, Parkinson's disease and Alzheimer's disease.

Role of the macrophage inflammatory protein-1alpha/CC chemokine receptor 5 signaling pathway in the neuroinflammatory response and cognitive deficits induced by beta-amyloid peptide.

The hallmarks of Alzheimer's disease include the deposition of beta-amyloid (Abeta), neuroinflammation, and cognitive deficits. The accumulation of activated glial cells in cognitive-related areas is critical for these alterations, although little is known about the mechanisms driving this event. Herein we used macrophage inflammatory protein-1alpha (MIP-1alpha(-/-))- or CC-chemokine receptor 5 (CCR5(-/-))-deficient mice to address the role played by chemokines in molecular and behavioral alterations induced by Abeta(1-40). Abeta(1-40) induced a time-dependent increase of MIP-1alpha mRNA followed by accumulation of activated glial cells in the hippocampus of wild-type mice. MIP-1alpha(-/-) and CCR5(-/-) mice displayed reduced astrocytosis and microgliosis in the hippocampus after Abeta(1-40) administration that was associated with decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase, as well as reduced activation of nuclear factor-kappaB, activator protein-1 and cyclic AMP response element-binding protein. Furthermore, MIP-1alpha(-/-) and CCR5(-/-) macrophages showed impaired chemotaxis in vitro, although cytokine production in response to Abeta(1-40) was unaffected. Notably, the cognitive deficits and synaptic dysfunction induced by Abeta(1-40) were also attenuated in MIP-1alpha(-/-) and CCR5(-/-) mice. Collectively, these results indicate that the MIP-1alpha/CCR5 signaling pathway is critical for the accumulation of activated glial cells in the hippocampus and, therefore, for the inflammation and cognitive failure induced by Abeta(1-40). Our data suggest MIP-1alpha and CCR5 as potential therapeutic targets for Alzheimer's disease treatment.

Cellular prion protein modulates defensive attention and innate fear-induced behaviour evoked in transgenic mice submitted to an agonistic encounter with the tropical coral snake Oxyrhopus guibei.

The cellular prion protein (PrP(C)) is a neuronal anchored glycoprotein that has been associated with distinct functions in the CNS, such as cellular adhesion and differentiation, synaptic plasticity and cognition. Here we investigated the putative involvement of the PrP(C) in the innate fear-induced behavioural reactions in wild-type (WT), PrP(C) knockout (Prnp(0/0)) and the PrP(C) overexpressing Tg-20 mice evoked in a prey versus predator paradigm. The behavioural performance of these mouse strains in olfactory discrimination tasks was also investigated. When confronted with coral snakes, mice from both Prnp(0/0) and Tg-20 strains presented a significant decrease in frequency and duration of defensive attention and risk assessment, compared to WT mice. Tg-20 mice presented decreased frequency of escape responses, increased exploratory behaviour, and enhancement of interaction with the snake, suggesting a robust fearlessness caused by PrP(C) overexpression. Interestingly, there was also a discrete decrease in the attentional defensive response (decreased frequency of defensive alertness) in Prnp(0/0) mice in the presence of coral snakes. Moreover, Tg-20 mice presented an increased exploration of novel environment and odors. The present findings indicate that the PrP(C) overexpression causes hyperactivity, fearlessness, and increased preference for visual, tactile and olfactory stimuli-associated novelty, and that the PrP(c) deficiency might lead to attention deficits. These results suggest that PrP(c) exerts an important role in the modulation of innate fear and novelty-induced exploration.

Adenosine receptor antagonists for cognitive dysfunction: a review of animal studies.

Over the last decade, adenosine receptors in the central nervous system have been implicated in the modulation of cognitive functions. Despite the general view that endogenous adenosine modulates cognition through the activation of adenosine A1 receptors, evidence is now emerging on a possible role of A2A receptors in learning and memory. The present review attempts to examine results reported in different studies using diverse animal models, to provide a comprehensive picture of the recent evidence of a relationship between adenosinergic function and memory deficits. The present data suggest that caffeine (a nonselective adenosine receptor antagonist) and selective adenosine A2A receptor antagonists can improve memory performance in rodents evaluated through different tasks. They might also afford protection against memory dysfunction elicited in experimental models of aging, Alzheimer's disease, Parkinson's disease and, in spontaneously hypertensive rats (SHR), a putative genetic model of attention deficit hyperactivity disorder (ADHD).