Early inflammation and immune response mRNAs in the brain of AD11 anti-NGF mice.

We characterized the gene expression profile of brain regions at an early stage of the Alzheimer's like neurodegeneration in the anti-NGF AD11 model. Total RNA was extracted from hippocampus, cortex and basal forebrain of postnatal day 30 (P30) and postnatal day 90 (P90) mice and expression profiles were studied by microarray analysis, followed by qRT-PCR validation of 243 significant candidates. Wide changes in gene expression profiles occur already at P30. As expected, cholinergic system and neurotrophins related genes expression were altered. Interestingly, the most significantly affected clusters of mRNAs are linked to inflammation and immune response, as well as to Wnt signaling. mRNAs encoding for different complement factors show a large differential expression. This is noteworthy, since these complement cascade proteins are involved in CNS synapse elimination, during normal brain developing and in neurodegenerative diseases. This gene expression pattern highlights that an early event in AD11 neurodegeneration is represented, together with neurotrophic deficits and synaptic remodeling, by an inflammatory response and an unbalance in the immunotrophic state of the brain. These might be key events in the pathogenesis and development of AD.

The interplay of two single nucleotide polymorphisms in the CACNA1A gene may contribute to migraine susceptibility.

Migraine is a common disorder with a significant genetic component. Mutations in the CACNA1A gene are found in hemiplegic migraine (HM). Basilar-type (BM), another subtype of migraine with aura, differs from HM only by the absence of motor deficits. BM and HM may thus share common genetic features. In the present study, two single nucleotide polymorphisms (SNPs) of the CACNA1A gene were characterized in a population of migraine patients and healthy controls. The polymorphisms, E918D, predicting a glutamic acid-to-aspartic acid substitution at codon 918 and E993V, predicting a glutamic acid-to-valine substitution at codon 993, were frequently detected among patients and controls. Seven BM, 10 SHM, 5 FHM, 57 migraine with typical aura, 32 migraine without aura patients and 107 healthy controls were screened. The E918D and E993V SNPs were found in 30/117 (25.6%) and 32/117 (27.3%) migraine patients, respectively. The prevalence of these SNPs taken separately was not significantly different from that of control subjects (n=28/107, 26.2% for E918D; n=29/107 for E993V, 27.1%) neither for the total migraine population nor for the various migraine subtypes. By contrast, coexistence of both SNPs was more frequent in migraineurs (25/117, 21%) than in healthy controls (12/107, 11%; p=0.048), a difference that was significant for every migraine subtype. This result suggests that the interplay of minor genetic variants such as single nucleotide polymorphisms may influence the P/Q-type calcium channel function in several subtypes of migraine.

Insulin secretion is controlled by mGlu5 metabotropic glutamate receptors.

Recent evidence suggests that metabotropic glutamate (mGlu) receptors are involved in the regulation of hormone secretion in the endocrine pancreas. We report here that endogenous activation of mGlu5 receptors is required for an optimal insulin response to glucose both in clonal beta-cells and in mice. In clonal beta-cells, mGlu5 receptors were expressed at the cell surface and were also found in purified insulin-containing granules. These cells did not respond to a battery of mGlu5 receptor agonists that act extracellularly, but instead responded to a cell-permeant analog of glutamate with an increase in [Ca2+]i and insulin secretion. Both effects were largely attenuated by the mGlu5 receptor antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP). MPEP and its structural analog, (E)-2-methyl-6-styryl-pyridine (SIB-1893), reduced the increase in [Ca2+]i and insulin secretion induced by glucose in clonal beta-cells, whereas a mGlu1 receptor antagonist was inactive. mGlu5 knockout mice showed a defective insulin response at all times after a glucose pulse (1.5 g/kg, i.p.), whereas wild-type mice treated with MPEP (10 mg/kg, i.p.) showed a selective impairment in the late phase of insulin secretion in response to glucose challenge. Mice injected with MPEP or lacking mGlu5 receptors also showed a blunted glucagon response to an insulin challenge. We conclude that insulin secretion is under the control of mGlu5 receptors both in clonal beta-cells and in vivo. Drugs that modulate the function of mGlu5 receptors might affect glucose homeostasis by altering the secretion of pancreatic hormones.