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Chronic cerebral hypoperfusion contributes to a cognitive decline related to brain disorders. Its experimental model in rats is a permanent bilateral common carotid artery occlusion (2VO). Overstimulation of the glutamatergic system excitotoxicity due to brain energetic disturbance in 2VO animals seems to play a pivotal role as a mechanism of cerebral damage. The nucleoside guanosine (GUO) exerts extracellular effects including antagonism of glutamatergic activity. Accordingly, our group demonstrated several neuroprotective effects of GUO against glutamatergic excitotoxicity. Therefore, in this study, we evaluated a chronic GUO treatment effects in rats submitted to 2VO. We evaluated the animals performance in the Morris water maze and hippocampal damage by neurons and astrocytes immunohistochemistry. In addition, we investigated the cerebrospinal fluid (CSF) brain derived neurotrophic factor (BDNF) and serum S100B levels. Additionally, the purine CSF and plasma levels were determined. GUO treatment did not prevent the cognitive impairment promoted by 2VO. However, none of the 2VO animals treated with GUO showed differences in the hippocampal regions compared to control, while 20% of 2VO rats not treated with GUO presented loss of pyramidal neurons and increased glial labeling cells in CA1 hippocampal region. In addition, we did not observe differences in CSF BDNF nor serum S100B levels among the groups. Of note, both the 2VO surgery and GUO treatment changed the purine CSF and plasma profile. In conclusion, GUO treatment did not prevent the cognitive impairment observed in 2VO animals, but our data suggest that GUO could be neuroprotective against hippocampal damage induced by 2VO.

Enzootic stability (herd immunity) in bovine babesiosis occurs when the rate of transmission (inoculation rate) of Babesia spp by the tick vector is sufficient to immunize a majority of susceptible calves before the loss of calfhood resistance. The effect of three tick (Boophilus microplus) control strategies (none, threshold, and strategic) on enzootic stability and the likelihood of babesiosis (Babesia bovis) outbreaks was studied using a spreadsheet age‐class computer simulation model. The model was driven by weekly bovine tick counts from Brazil and Uruguay. The Eldorado do Sul, RS, Brazil bovine population (30°05′ South latitude) was found to be in a naturally occurring state of enzootic stability, corresponding to an inoculation rate exceeding 0.005 throughout the year. Threshold dipping strategies should not increase the risk of babesiosis in cattle so managed. Strategic dipping resulted in an extended period of enzootic instability lasting 30 weeks, which requires protection of the herd through immunization. Because of the more prolonged low winter temperature conditions, the Tacuarembó, Uruguay bovine population (31°40′ South latitude) was found to be in a naturally occurring state of enzootic instability, characterized by a 28 week period in which the inoculation rate was below 0.005. Strategic dipping should lead to eradication of the babesial parasite from tick and bovine populations, but would not result in eradication of the tick vector. This could lead to subsequent outbreaks if Babesia carrier animals were to be introduced into the herd. In both populations, strategic tick control could be accompanied by concurrent babesiosis vaccination.

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