The venom of P. nigriventer contains potent

neurotoxic peptides that interfere in the physiology of Bioactive Compound Library cell line ion channels and hence in the neurotransmitter uptake/release and causes excitatory signals ( Fontana and Vital Brazil, 1985; Love and Cruz-Höfling, 1986; Gomez et al., 2002; Pinheiro et al., 2006); PNV toxicity activates and delays the inactivation of the TTX-sensitive voltage-gated Na+ channel, blocks K+ and Ca2+ channels and blocks glutamate exocytosis but also inhibits glutamate uptake ( Prado et al., 1996; Mafra et al., 1999; Reis et al., 2000; Vieira et al., 2003). Moreover, PNV causes neuroinflammation ( Cruz-Höfling et al., 2009) and activates neurons which express the protein Fos after activation of the oncogene cFos ( Cruz-Höfling et al., 2007). Corroborating this view, we found changes in the neuron electric activity of rats exposed to PNV and inferred that Ca2+-, K+- and Na+-acting neuropeptides BLZ945 clinical trial present in the venom ( Gomez et al., 2002) generated neurotransmission disturbances which were registered in the EEG recordings ( Ferrari et al., 2010). All these effects are consistent with neurochemical and metabolic changes in the cerebellum microenvironment, so affecting basket cells and stellate interneurons of the ML, Purkinje neurons of the PL and

granule neurons and Golgi interneurons of the GL. Likewise, these changes would affect the inputs of afferent fibers to the cerebellar cortex, i.e. the climbing and mossy fibers which enter across the granular layer to synapse to Purkinje cells Glutamate dehydrogenase and granule cells (see Barlow, 2002). Altogether, the findings of the present study provide compelling evidence that PNV affects AQP4 expression.

The regional modulation would depend on the interaction between astrocytes and the neurochemical and structural characteristic of the cerebellum at a given region. A remarkable body of investigation has proven astrocytes as fundamental for neuronal activity (Kimelberg and Nedergaard, 2010). Astrocytes are involved in the control of brain homeostasis which involves reuptake of extracellular K+ and excitatory amino acids after neuronal activity, calcium balance, neural growth factor production, development and maintenance of the BBB, blood vessel permeability, blood flow, glucose supply and scar formation after brain injury, and others. Aggression against the CNS promotes an immediate reaction of astrocytes which may proliferate and migrate to the injury site concomitant with increased expression of the cytoskeletal GFAP protein. These events named reactive astrogliosis can be considered either neuroprotective (Li et al., 2008) or hazardous (Nair et al., 2008) depending on whether the injury is transitory and of low severity or is chronic and severe, respectively.