Giana de Paula Cognato

Ontogenetic profile of ectonucleotidase activities from brain synaptosomes of pilocarpine-treated rats

Adenosine, a well‐known neuromodulator, can act as an endogenous anticonvulsant via the activation of adenosine A1 receptors. This adenine nucleoside can be produced in the synaptic cleft by the ectonucleotidase cascade, which includes the nucleoside triphosphate diphosphohydrolase (NTPDase) family and ecto‐5′‐nucleotidase. It has been previously reported that ectonucleotidase activities are increased in female adult rats submitted to the pilocarpine model of epilepsy. Several studies have suggested that the immature brain is less vulnerable to morphologic and physiologic alterations after status epilepticus (SE). Here, we evaluate the ectonucleotidase activities of synaptosomes from the hippocampus and cerebral cortex of male and female rats at different ages (7–9, 14–16 and 27–30‐day old) submitted to the pilocarpine model of epilepsy. Our results show that ATP and ADP hydrolysis in the hippocampus and cerebral cortex were not altered by the pilocarpine treatment in female and male rats at 7–9, 14–16 and 27–30 days. There were no changes in AMP hydrolysis in female and male rats submitted to the model at different ages, but a significant increase in AMP hydrolysis (71%) was observed in synaptosomes from the cerebral cortex of male rats at 27–30 days. Pilocarpine‐treated male rats (60–70‐day old) presented an enhancement in ectonucleotidase activities in the synaptosomes of the cerebral cortex (33, 40 and 64% for ATP, ADP and AMP hydrolysis, respectively) and hippocampus (55, 98 and 101% for ATP, ADP and AMP hydrolysis, respectively). These findings highlight differences between the purinergic system of young and adult rats submitted to the pilocarpine model of epilepsy.

Expression mapping of ectonucleotide pyrophosphatase/phosphodiesterase 1-3 (E-NPP1–3) in different brain structures during rat development

Ecto‐nucleotide pyrophosphatases/phosphodiesterases (E‐NPPs) are membrane‐bound ecto‐enzymes involved in the modulation of purinergic signaling. Important physiological roles related to brain development have been associated to purinergic neurotransmission. NPP1, two splice isoforms of NPP2, and NPP3 have already been identified in adult rat brain. However, there are no studies evaluating the mRNA expression of these NPP members during the brain development. The effort of the present study was to map NPP gene expression pattern in olfactory bulb, hippocampus, cerebral cortex, striatum, and cerebellum at crucial ages for rat development (7, 14, 21, 60, and 150 days old) by a semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) strategy. Our results demonstrated an increase in the relative expression of NPP1 throughout the aging in all structures analyzed, except in hippocampus, where the higher expression has been detected in 14 days old rats. Both NPP2 isoforms have shown a similar pattern of expression among all structures. The relative expression of NPP3 decreased during the aging mainly on cerebellum, hippocampus, and olfactory bulb. Altogether, the different patterns of NPP gene expression during rat brain development reinforce the idea that each enzyme may play a distinct role on modulating the purinergic signaling throughout aging.