Annie Larouche

Role of perinatal inflammation in cerebral palsy.

Inflammatory molecules are promptly upregulated in the fetal environment and postnatally in brain-damaged subjects. Intrauterine infections and inflammation are often associated with asphyxia. This double-hit effect by combined infection or inflammation and hypoxia is therefore a frequent concomitant in neonatal brain damage. Animal models combining hypoxia and infection were recently designed to explore the mechanisms underlying brain damage in such circumstances and to look for possible neuroprotective strategies. Proinflammatory cytokines are thought to be major mediators in brain injury in neonates with perinatal asphyxia, bacterial infection, or both. Cytokines, however, could also have neuroprotective properties. The critical point in the balance between neurodamaging and neuroprotective effects of cytokines has yet to be unraveled. This understanding might help to develop new therapeutic approaches to counteract the inflammatory disequilibrium observed in the pathophysiologic mechanisms associated with brain injury.

Neuronal injuries induced by perinatal hypoxic-ischemic insults are potentiated by prenatal exposure to lipopolysaccharide: animal model for perinatally acquired encephalopathy.

We developed an original rat model for neonatal brain lesions whereby we explored the sequential effects of infectious and hypoxic-ischemic aggressions. We investigated the influence of combined exposure to prenatal infection with neonatal hypoxic-ischemic insult. Infectious effect was produced by administrating lipopolysaccharide (LPS) intraperitoneally to pregnant rats starting on embryonic day 17. Hypoxia-ischemia (H/I) was induced in the pups at postnatal day 1 (P1) by ligature of the right common carotid artery followed by exposure to hypoxia (8% O2) for 3.5 h. Animals were randomized into four groups: (1) control group: pups born to mothers subjected to intraperitoneal saline injection; (2) LPS group: pups exposed in utero to LPS; (3) H/I group: pups exposed to postnatal hypoxia after ligation of the right carotid artery, and (4) H/I plus LPS group: in utero exposure to LPS followed by postnatal hypoxia after ligation of the right carotid artery. Neuropathological findings in pups examined at P3 and P8 showed that groups 2, 3, and 4 presented a pattern of neuronal injury similar to those characterized as ‘selective neuronal necrosis’ within the context of human perinatal encephalopathy. Neuronal cellular injuries were particularly seen in the neocortex, mainly in parasagittal areas. The extent of neuronal cell injury in the brain of rats exposed to postnatal H/I was significantly increased by antenatal exposure to LPS. This animal model provides an experimental means to explore the respective roles of anoxic and infectious components in the pathogenesis of perinatal brain lesions and consequent cerebral palsy.

DRD3 Ser9Gly Polymorphism Is Related to Thermal Pain Perception and Modulation in Chronic Widespread Pain Patients and Healthy Controls

UNLABELLED Experimental studies showed that dopamine influences pain perception in healthy volunteers. Dopamine dysfunctions have been linked to the physiopathology of fibromyalgia (FM), which is associated with hyperalgesia and deficient pain inhibition. We sought to investigate the relationships between catecholamine-related polymorphisms [dopamine-D(3) receptor (DRD3) Ser9Gly and catechol-O-methyltransferase (COMT) Val158Met] and thermal pain measures in healthy subjects and FM patients. Seventy-three subjects (37 FM patients and 36 controls) participated in this study. Thermal pain thresholds (TPTs) were measured using a Peltier thermode. Inhibitory systems were elicited using a thermal tonic pain stimulation administered before and after activation of the diffuse noxious inhibitory controls (DNIC) by means of a cold-pressor test. Genetic analyses were performed using polymerase chain reaction. Regression analyses were performed across and within groups. FM was associated with lower TPTs and deficient pain inhibition. DRD3 Ser9Gly polymorphism predicted (1) DNIC efficacy across groups and (2) thermal TPTs in FM patients. COMT Val158Met and thermal pain measures were not related. These preliminary results suggest that the DRD3 Ser9Gly polymorphism influences DNIC efficacy and TPTs and that this latter relationship is present only in FM patients. Two core psychophysical features of FM appear to be significantly influenced by limbic dopamine functioning. PERSPECTIVE This experimental study is the first to relate DNIC and TPTs to a functional polymorphism of limbic dopamine-D3 receptors. As lowered pain thresholds and deficient pain inhibition are 2 core features of fibromyalgia, these preliminary results may help identify a subgroup of FM patients who require closer medical attention.

Pro-inflammatory disequilibrium of the IL-1β/IL-1ra ratio in an experimental model of perinatal brain damages induced by lipopolysaccharide and hypoxia-ischemia

Bacterial infections and hypoxia/ischemia (H/I) are implicated in human neonatal brain damage leading to cerebral palsy (CP). We developed an animal model presenting similar perinatal brain damage by combining bacterial endotoxin and H/I insults. Interleukin (IL)-1beta is a mediator of brain damage and its action(s) is counteracted by its cognate anti-inflammatory IL-1 receptor antagonist (IL-1ra). We tested the hypothesis that the balance between agonist and antagonist in the IL-1 system is shifted towards inflammation in perinatal brains exposed to endotoxin and/or H/I. Lipopolysaccharide (LPS) and/or H/I enhanced both intracerebral IL-1beta mRNA and protein levels, with a maximum increase observed with combined LPS and H/I insults. Conversely, IL-1ra expression was significantly downregulated by LPS, H/I, or both combined, with a maximum magnitude of imbalance between IL-1beta and sIL-1ra noticed with the double hit. The nuclear factor (NF)kappaB component of the signaling pathway activated by IL-1beta-binding to its receptor was activated following exposure to LPS and/or H/I. We show for the first time that, perinatally, bacterial products, H/I, or both combined, induce downregulation in sIL-1ra expression concomitant with upregulation in IL-1beta. The resulting pro-inflammatory orientation in the IL-1/IL-1ra balance might play a role in the initiation of perinatal brain damages.

No relationship between the ins del polymorphism of the serotonin transporter promoter and pain perception in fibromyalgia patients and healthy controls

Background: In animals, decades of research have shown that serotonin (5‐HT) is involved in endogenous pain inhibition systems, which are deficient in chronic pain disorders such as fibromyalgia (FM). In humans, there is preliminary evidence showing that 5‐HT is involved in the FM pathophysiology. In the current endophenotyping study, we sought to investigate, for the first time in humans, the relationships between the serotonin transporter promoter region (5‐HTTLPR) polymorphism and experimentally‐induced pain perception/inhibition in healthy controls (HC) and FM patients.

Combination of prenatal immune challenge and restraint stress affects prepulse inhibition and dopaminergic/GABAergic markers

Gestational immune challenge with the viral-like antigen poly I:C is a well-established neurodevelopmental model of schizophrenia. However, exposure to inflammation during early life may sensitize the developing brain to secondary insults and enhance the central nervous system vulnerability. To gain a better understanding of the pathophysiology of schizophrenia, we thus developed a two-hit animal model based on prenatal poly I:C immune challenge followed by restraint stress in juvenile mice. C57BL/6 gestational mice were intraperitoneally injected with poly I:C or saline at gestational day 12. Pups were then submitted or not, to restraint stress for 2h, for three consecutive days, from postnatal days 33 to 35. Prepulse inhibition (PPI) of acoustic startle response is commonly used to assess sensorimotor gating, a neural process severely disrupted in patients with schizophrenia. Our results revealed that the combination of prenatal immune challenge with poly I:C followed by a restraint stress period was able to induce a PPI disruption in 36-day-old pups, as opposed to each insult applied separately. PPI deficits were accompanied by dopaminergic and GABAergic abnormalities in the prefrontal cortex and striatum. Indeed, measurements of cortical and striatal dopamine D2 receptor (D2R) mRNA and protein levels revealed that the combination of gestational exposure to poly I:C and postnatal restraint stress induced an increase in D2R protein and mRNA levels. Likewise, the combination of both insults reduced the mRNA and protein expression levels of the 67 kDa form of glutamic acid decarboxylase (GAD67), in those two brain regions. To our knowledge, this two-hit animal model is the first in vivo model reporting PPI deficits at pubertal age. This two-hit animal model may also help in studying innovative therapies dedicated to the treatment of schizophrenia, especially in its early phase.

Hypotensive effects of hemopressin and bradykinin in rabbits, rats and mice. A comparative study.

Hemopressin is a novel vasoactive nonapeptide derived from hemoglobins alpha-chain as recently reported by Rioli et al. [Rioli V, Gozzo FC, Heimann AS, Linardi A, Krieger JE, Shida CS, et al. Novel natural peptide substrates for endopeptidase 24.15, neurolysin, and angiotensin-converting enzyme. J Biol Chem 2003;278(10):8547-55]. In anesthetized male Wistar rats, this peptide exhibited hypotensive actions similar to those of bradykinin (BK) when administered intravenously (i.v.), and was found to be metabolized both in vitro and in vivo by several peptidases, including the angiotensin-converting enzyme (ACE). In this study, these findings were expanded upon by examining: (i) the degradation kinetics following incubation with ACE purified from rabbit lung and (ii) the blood pressure lowering effects of HP and BK injected i.v. or intra-arterially (i.a.) in male rabbits, rats, and mice. Our findings demonstrate that, in vitro, HP and BK are both degraded by ACE, but at different velocity rates. Furthermore, both HP and BK induced transient hypotension in all animals tested, although the responses to HP relative to the administration sites were significantly lower (by 10-100-fold) on an equimolar basis compared to those of BK. In rabbits, the decrease of blood pressure induced by HP (10-100 nmol/kg) did not differ whether it was administered i.v. or i.a., suggesting an absence of pulmonary/cardiac inactivation in contrast to BK (0.1-1 nmol/kg). The in vivo effect of HP was significantly potentiated in rabbits immunostimulated with bacterial lipopolysaccharide (LPS), but was unaffected by both the B2 receptor antagonist HOE 140 (0.1 micromol/kg) and captopril (100 microg/kg), contrary to BK. Therefore, HP acts as a weak hypotensive mediator, which does not activate kinin B2 receptors, but uses a functional site and/or signaling paths appearing to be up-regulated by LPS.

Lipopolysaccharide and hypoxia/ischemia induced IL-2 expression by microglia in neonatal brain.

Using a model of perinatal brain lesions induced by lipopolysaccharide and hypoxia/ischemia, we hypothesized that interleukin-2 (IL-2), a neurotoxic cytokine, was enhanced within injured brains. We showed that lipopolysaccharide and hypoxia/ischemia enhanced both intracerebral IL-2 mRNA and protein levels, with a maximum increase upon lipopolysaccharide and hypoxia/ischemia. The lack of detectable T lymphocytes suggested the synthesis of IL-2 by neural cells. Lipopolysaccharide and hypoxia triggered IL-2 synthesis by cultured microglia with a peak after exposure to lipopolysaccharide and hypoxia. Double-labeling showed, in vivo and in vitro, that IL-2 immunoreactivity was colocalized with a microglia/macrophage marker. These results disclosed the ability of microglia to produce IL-2 and also suggest the implication of IL-2 in neural cell death triggered by perinatal lipopolysaccharide and hypoxia/ischemia exposures.

Comparative effectiveness and safety of antipsychotic drugs in schizophrenia treatment: a real-world observational study

The objective was to compare, in a real‐world setting, the risk of mental and physical health events associated with different antipsychotic drugs (clozapine, olanzapine, risperidone, quetiapine and first‐generation antipsychotics) in patients with SZ.

Antipsychotic-induced DRD2 upregulation and its prevention by α-lipoic acid in SH-SY5Y Neuroblastoma cells

Most antipsychotic (AP) drugs are dopamine (DA) D2 receptor (DRD2) antagonists and remain the main pharmacological treatment of schizophrenia. Long‐term AP use can give rise to tardive dyskinesia. It has been reported that chronic treatment with APs induces DRD2 upregulation and oxidative stress, which have been associated with tardive dyskinesia. We showed previously that H2O2‐induced oxidative stress increased DRD2 expression in human SH‐SY5Y neuroblastoma cells. We report here the effects of AP drugs on DRD2 expression levels in the same cell line and the effects of the inhibition of oxidative phenomena by (±)‐α‐lipoic acid treatment. Haloperidol, a first‐generation AP, induced an increase in DRD2 protein and mRNA levels, whereas amisulpride, a second‐generation AP, had no significant effect. (±)‐α‐Lipoic acid pretreatment reversed the haloperidol‐induced DRD2 upregulation in mRNA and protein levels. Furthermore, haloperidol induced a larger increase of oxidative stress biomarkers (protein carbonylation, lipid peroxidation, and superoxide anion production) than amisulpride. (±)‐α‐Lipoic acid also attenuated AP‐induced oxidative stress. Inhibition of catecholamine synthesis by α‐methyl‐DL‐tyrosine (AMPT) increased DRD2 expression and prevented further increase by APs. Our results suggest that haloperidol‐induced DRD2 upregulation is linked to oxidative stress and provide potential mechanisms by which (±)‐α‐lipoic acid can be considered as a therapeutic agent to prevent and treat side effects related to the use of first‐generation APs. Synapse, 2011.