Methionine Exposure Alters Glutamate Uptake and Adenine Nucleotide Hydrolysis in the Zebrafish Brain.

Hypermethioninemic patients may exhibit different neurological dysfunctions, and the mechanisms underlying these pathologies remain obscure. Glutamate and ATP are important excitatory neurotransmitters co-released at synaptic clefts, and whose activities are intrinsically related. Adenosine-the final product of ATP breakdown-is also an important neuromodulator.

Long-term proline exposure alters nucleotide catabolism and ectonucleotidase gene expression in zebrafish brain.

Hyperprolinemia is an inherited disorder of proline metabolism and hyperprolinemic patients can present neurological manifestations, such as seizures cognitive dysfunctions, and psychotic disorders. However, the underlying mechanisms of these symptoms are still unclear. Since adenine nucleotides play crucial roles in neurotransmission and neuromodulation, we evaluated the in vivo and in vitro effects of proline on ectonucleotidase activities and gene expression in zebrafish brain.

Long-term methionine exposure induces memory impairment on inhibitory avoidance task and alters acetylcholinesterase activity and expression in zebrafish (Danio rerio).

Hypermethioninemic patients exhibit a variable degree of neurological dysfunction. However, the mechanisms involved in these alterations have not been completely clarified. Cholinergic system has been implicated in many physiological processes, including cognitive performances, as learning, and memory.

Behavioral changes induced by long-term proline exposure are reversed by antipsychotics in zebrafish.

Hyperprolinemia is an inherited disorder of proline metabolism and patients affected by this disease may present neurological manifestations, including seizures and cognitive dysfunctions. Moreover, an association between adulthood schizoaffective disorders and moderate hyperprolinemia has been reported. However, the mechanisms underlying these behavioral phenotypes still remain unclear.

Adenosine A(2A) receptor agonist (CGS-21680) prevents endotoxin-induced effects on nucleotidase activities in mouse lymphocytes.

Adenosine 5'-triphosphate (ATP) released during inflammation presents proinflammatory properties. Adenosine, produced by catabolism of ATP, is an anti-inflammatory compound. Considering the role of ATP and adenosine in inflammation and the importance of ectonucleotidases in the maintenance of their extracellular levels, we investigated the effect of a selective agonist of the adenosine A(2A) receptor (CGS-21680) on ectonucleotidase activities and gene expression patterns in lymphocytes from mice submitted to an endotoxemia model.

The hydrolysis of striatal adenine- and guanine-based purines in a 6-hydroxydopamine rat model of Parkinson's disease.

Parkinson's disease (PD) is characterized by a progressive neurodegeneration in the substantia nigra and a striatal dopamine decrease. Striatal extracellular adenosine and ATP modulate the dopaminergic neurotransmission whereas guanosine has a protective role in the brain. Therefore, the regulation of their levels by enzymatic activity may be relevant to the clinical feature of PD.

L-NAME-treatment alters ectonucleotidase activities in kidney membranes of rats.

Aims: To investigate the effect of N(omega)-Nitro-L-arginine methyl ester (l-NAME) treatment, known to induce a sustained elevation of blood pressure, on ectonucleotidase activities in kidney membranes of rats.

Main Methods: L-NAME (30 mg/kg/day) was administered to Wistar rats for 14 days in the drinking water. Enzyme activities were determined colorimetrically and their gene expression patterns were analyzed by semi-quantitative RT-PCR.

Exercise effects on activities of Na(+),K(+)-ATPase, acetylcholinesterase and adenine nucleotides hydrolysis in ovariectomized rats.

Hormone deficiency following ovariectomy causes activation of Na(+),K(+)-ATPase and acetylcholinesterase (AChE) that has been related to cognitive deficits in experimental animals. Considering that physical exercise presents neuroprotector effects, we decide to investigate whether exercise training would affect enzyme activation in hippocampus and cerebral cortex, as well as adenosine nucleotide hydrolysis in synaptosomes from cerebral cortex of ovariectomized rats. Female adult Wistar rats were assigned to one of the following groups: sham (submitted to surgery without removal of the ovaries), exercise, ovariectomized (Ovx) and Ovx plus exercise.

Influence of antidepressant drugs on Ecto-nucleotide pyrophosphatase/phosphodiesterases (E-NPPs) from salivary glands of rats.

Xerostomia is commonly caused by antidepressant drugs and ATP can influence the saliva production. Adenosine is the product of extracellular hydrolysis of adenine nucleotides in submandibular gland cells, which occurs by the action of ectonucleotidases. In this study, we have evaluated the effect of three different antidepressants in ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP1-3) activities in cultured cells from salivary glands.

Endotoxemia alters nucleotide hydrolysis in platelets of rats.

Platelets play a critical role in homeostasis and blood clotting at sites of vascular injury, and also in various ways in innate immunity and inflammation. Platelets are one of the first cells to accumulate at an injured site, and local release of their secretome at some point initiate an inflammatory cascade that attracts leukocytes, activates target cells, stimulates vessel growth and repair. The level of exogenous ATP in the body may be increased in various inflammatory and shock conditions, primarily as a consequence of nucleotide release from platelets, endothelium and blood vessel cells.

Lipopolysaccharide alters nucleotidase activities from lymphocytes and serum of rats.

ATP exerts a proinflammatory role and induces cytokine release by acting at P2X(7) receptors. The product of ATP hydrolysis is the nucleoside adenosine, an important immunomodulator. The main source of extracellular adenosine is the hydrolysis of extracellular ATP by a group of ecto-enzymes: ENTPDase family, NPP family and ecto-5'-nucleotidase.

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.

Effects of starvation on haemolymphatic glucose levels, glycogen contents and nucleotidase activities in different tissues of Helix aspersa (Müller, 1774) (Mollusca, Gastropoda).

In the present study, the glucose concentration in the haemolymph and glycogen levels were determined in the various body parts of the Helix aspersa snail after feeding lettuce ad libitum and after various periods of starvation. To characterize the effect of starvation on nucleotidase activity, enzyme assays were performed on membranes of the nervous ganglia and digestive gland. Results demonstrated the maintenance of the haemolymph glucose concentration for up to 30 days of starvation, probably due to the consumption of glycogen from the mantle.

Nucleotidase activities in membrane preparations of nervous ganglia and digestive gland of the snail Helix aspersa.

Nucleotide-metabolizing enzymes play an important role in the regulation of nucleotide levels. In the present report, we demonstrated an enzyme activity with different kinetic properties in membrane preparations of the nervous ganglia and digestive gland from Helix aspersa. ATPase and ADPase activities were dependent on Ca2+ and Mg2+ with pH optima approximately 7.

Different sensitivity of Ca(2+)-ATPase and cholinesterase to pure and commercial pesticides in nervous ganglia of Phyllocaulis soleiformis (Mollusca).

We measured the effects in vitro of pure and commercial pesticides on Ca(2+)-activated ATPase and cholinesterase (ChE) activities in the nervous system of the slug Phyllocaulis soleiformis. The pesticides used in this study included carbamate and organophosphates, which acts as reversible and irreversible anticholinesterases, respectively. Both enzymes were insensitive to pure carbofuran (1 mM), glyphosate (1 mM) and malathion (120 microM).