Expression of VEGF and Flk-1 and Flt-1 Receptors during Blood-Brain Barrier (BBB) Impairment Following Phoneutria nigriventer Spider Venom Exposure

Apart from its angiogenic and vascular permeation activity, the vascular endothelial growth factor (VEGF) has been also reported as a potent neuronal protector. Newborn rats with low VEGF levels develop neuron degeneration, while high levels induce protective mechanisms in several neuropathological conditions. Phoneutria nigriventer spider venom (PNV) disrupts the blood-brain barrier (BBB) and causes neuroinflammation in central neurons along with excitotoxic signals in rats and humans. All these changes are transient. Herein, we examined the expression of VEGF and its receptors, Flt-1 and Flk-1 in the hippocampal neurons following envenomation by PNV. Adult and neonatal rats were evaluated at time limits of 2, 5 and 24 h. Additionally, BBB integrity was assessed by measuring the expression of occludin, β-catenin and laminin and neuron viability was evaluated by NeuN expression. VEGF, Flt-1 and Flk-1 levels increased in PNV-administered rats, concurrently with respective mRNAs. Flt-1 and Flk-1 immunolabeling was nuclear in neurons of hippocampal regions, instead of the VEGF membrane-bound typical location. These changes occurred simultaneously with the transient decreases in BBB-associated proteins and NeuN positivity. Adult rats showed more prominent expressional increases of the VEGF/Flt-1/Flk-1 system and earlier recovery of BBB-related proteins than neonates. We conclude that the reactive expressional changes seen here suggest that VEGF and receptors could have a role in the excitotoxic mechanism of PNV and that such role would be less efficient in neonate rats.     

Somal size of immunolabeled pyramidal cells in the prefrontal cortex of subjects with schizophrenia.

BACKGROUND: Although the somal volume of Nissl-stained deep layer 3 pyramidal cells is reduced in prefrontal cortex area 9 of subjects with schizophrenia, the subset of large pyramidal cells immunoreactive (IR) for nonphosphorylated neurofilament protein (NNFP) is not. Consequently, we hypothesized that the somal volume of another subset of pyramidal cells immunoreactive for neuronal calcium binding protein-1 (Necab-1) is significantly reduced in schizophrenia. METHODS: We labeled Necab-1-IR pyramidal neurons using immunoperoxidase techniques and estimated the mean somal volume in deep layer 3 of area 9 in 13 matched pairs of control and schizophrenic subjects. Identical studies were conducted for pyramidal neurons immunoreactive for neuronal nuclear protein (Neu-N), which is present in all neurons. RESULTS: In subjects with schizophrenia, neither the mean somal volume of Necab-1-IR pyramidal neurons nor of Neu-N-IR pyramidal neurons was significantly different from control subjects. In addition, the mean somal volume of Neu-N-IR cells was larger than that of Nissl-stained cells in both subject groups, and the magnitude of this difference was greater for the subjects with schizophrenia. CONCLUSIONS: These findings suggest that immunoperoxidase techniques are associated with an overestimation of the volume of labeled neurons. This confound appears to interact with disease state, and thus obscures differences between diagnostic groups.