BDNF Val66Met polymorphism and protein levels in amniotic fluid.

BACKGROUND: Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which plays survival- and growth-promoting activity in neuronal cells and it is involved in cellular plasticity mechanisms as it controls activity dependent synaptic transmission. A functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF has been associated with memory and cognitive deficits as well as to an increased susceptibility for several psychiatric disorders especially those with a neurodevelopmental origin. To date, no study has evaluated the influence of the Val66Met polymorphism on BDNF levels in a peripheral system that may reflect fetal neurodevelopment. Therefore we investigated in amniotic fluids (AF) obtained from 139 healthy women during 15-17 week of pregnancy, BDNF protein levels in correlation with the Val66Met polymorphism. RESULTS: Interestingly we found a significant BDNF protein levels reduction in 55 Met carriers (Val/Met and Met/Met) (p = 0.002) as compared to 84 non carriers (Val/Val), and no effect of fetus gender, maternal age or gestation week on BDNF levels has been observed. CONCLUSION: These results, although explorative, indicate that during fetal life the Val66Met genotype might influences BDNF protein levels in AF supporting the involvement of this polymorphism in behavioral and functional brain individual differences in the adulthood.

Reduced activation of intracellular signaling pathways in rat prefrontal cortex after chronic phencyclidine administration.

Evidence exists that schizophrenia is characterized by deficits in cell-cell communication and information processing. In the present study, we used the phencyclidine (PCP) animal model of schizophrenia to investigate possible defects in intracellular signaling proteins involved in neuroplasticity. Western Blot analysis has been performed to determine total and phospho-protein levels of extracellular signal-regulated kinases 1/2 (ERK1/2), type II calcium/calmodulin-dependent protein kinase (alphaCaMKII) and cAMP-response element binding protein (CREB) in prefrontal cortex (PFC) and hippocampus (HIP) of rat chronically treated with PCP, whereas their mRNA levels were determined by real time RT-PCR. We found reduced levels of P-ERK1/2, P-alphaCaMKII and P-CREB in prefrontal cortex of PCP-treated animals when compared to controls, whereas no effects were observed on total protein or mRNA levels. Conversely, no significant changes were detected on protein levels or mRNA expression in hippocampus. Given the role of ERK1/2, alphaCaMKII and CREB in neuroplastic mechanisms and cell communication, our data suggest that their decreased activation following chronic PCP administration can contribute to cortical defects occurring in schizophrenia, and may therefore represent potential targets for pharmacological intervention.

Regulation of editing and expression of glutamate alpha-amino-propionic-acid (AMPA)/kainate receptors by antidepressant drugs.

BACKGROUND: Several reports have shown that the glutamatergic system is involved in both the pathogenesis of affective and stress-related disorders and in the action of antidepressant drugs. In particular, antidepressant treatment was shown to modulate expression and function of ionotropic glutamate receptors, to inhibit glutamate release and to restore synaptic plasticity impaired by stress. METHODS: We analyzed the mRNA expression and RNA editing of alpha-amino-propionic-acid (AMPA) and kainate (KA) receptor subunits, in the pre-frontal/frontal cortex (P/FC) and hippocampus (HI) of rats chronically treated with three different drugs: the selective serotonin (5-HT) reuptake inhibitor fluoxetine, the selective noradrenaline (NA) reuptake inhibitor reboxetine and the tricyclic antidepressant desipramine. RESULTS: Our data showed that fluoxetine and desipramine exerted moderate but selective effects on glutamate receptor expression and editing, while reboxetine appeared to be the drug that affects glutamate receptors (GluR) most. The most consistent effect, observed with pronoradrenergic drugs (desipramine and reboxetine), was a decrease of GluR3 expression both in P/FC and HI. Interestingly, in HI, the same drugs also decreased the editing levels of either the flip (desipramine) or flop (reboxetine) form of GluR3. CONCLUSIONS: Overall, these results point to specific and regionally discrete changes in the expression and editing level of glutamate receptors and, in particular, to a selective reduction of conductance for GluR3-containing receptors following treatment with antidepressant drugs. These data support the hypothesis that changes in glutamate neurotransmission are involved in the therapeutic effects induced by these drugs.

Selective phosphorylation of nuclear CREB by fluoxetine is linked to activation of CaM kinase IV and MAP kinase cascades.

Regulation of gene expression is purported as a major component in the long-term action of antidepressants. The transcription factor cAMP-response element-binding protein (CREB) is activated by chronic antidepressant treatments, although a number of studies reported different effects on CREB, depending on drug types used and brain areas investigated. Furthermore, little is known as to what signaling cascades are responsible for CREB activation, although cAMP-protein kinase A (PKA) cascade was suggested to be a central player. We investigated how different drugs (fluoxetine (FLX), desipramine (DMI), reboxetine (RBX)) affect CREB expression and phosphorylation of Ser(133) in the hippocampus and prefrontal/frontal cortex (PFCX). Acute treatments did not induce changes in these mechanisms. Chronic FLX increased nuclear phospho-CREB (pCREB) far more markedly than pronoradrenergic drugs, particularly in PFCX. We investigated the function of the main signaling cascades that were shown to phosphorylate and regulate CREB. PKA did not seem to account for the selective increase of pCREB induced by FLX. All drug treatments markedly increased the enzymatic activity of nuclear Ca2+/calmodulin (CaM) kinase IV (CaMKIV), a major neuronal CREB kinase, in PFCX. Activation of this kinase was due to increased phosphorylation of the activatory residue Thr196, with no major changes in the expression levels of alpha- and beta-CaM kinase kinase, enzymes that phosphorylate CaMKIV. Again in PFCX, FLX selectively increased the expression level of MAP kinases Erk1/2, without affecting their phosphorylation. Our results show that FLX exerts a more marked effect on CREB phosphorylation and suggest that CaMKIV and MAP kinase cascades are involved in this effect.

Association between the G1001C polymorphism in the GRIN1 gene promoter region and schizophrenia.

BACKGROUND: The GRIN1 gene plays a fundamental role in many brain functions, and its involvement in the pathogenesis of the schizophrenia has been widely investigated. Non-synonymous polymorphisms have not been identified in the coding regions. To investigate the potential role of GRIN1 in the susceptibility to schizophrenia, we analyzed the G1001C polymorphism located in the promoter region in a case-control association study. METHODS: The G1001C polymorphism allele distribution was analyzed in a sample of 139 Italian schizophrenic patients and 145 healthy control subjects by a polymerase chain reaction amplification followed by digestion with a restriction endonuclease. RESULTS: We found that the C allele may alter a consensus sequence for the transcription factor NF-kappa B and that its frequency was higher in patients than in control subjects (p =.0085). The genotype distribution also was different, with p =.034 (if C allele dominant, p =.0137, odds ratio 2.037, 95% confidence interval 1.1502-3.6076). CONCLUSIONS: The association reported in this study suggests that the GRIN1 gene is a good candidate for the susceptibility to schizophrenia.