NTPDase and 5′-Nucleotidase Activities in Synaptosomes of Hippocampus and Serum of Rats Subjected to Homocysteine Administration

Böhmer, Ana Elisa; Streck, Emílio L.; Stefanello, Franciele; Wyse, Ângela T. S.; Sarkis, João José Freitas

doi:10.1023/b:nere.0000026400.15098.62

Cited by 6 publications

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“…Studies carried out in our laboratory have showed that NTPDase activity is reduced in synaptosomes from rat cerebral cortex by 2.0 mM of phenylalanine [12] and that homocysteine administration alters the activities of the enzymes involved in nucleotide hydrolysis, both in the CNS and in the serum of adult rats [13]. In addition, we have recently reported that acute administration of Arg decreases the NTPDase and 5¢-nucleotidase activities of rat blood serum [14].…”

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confidence: 99%

NTPDase and 5′-nucleotidase Activities of Synaptosomes from Hippocampus of Rats Subjected to Hyperargininemia

et al. 2007

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ATP is an important excitatory neurotransmitter and adenosine acts as a neuromodulatory structure inhibiting neurotransmitters release in the central nervous system. Since the ecto-nucleotidase cascade that hydrolyzes ATP to adenosine is involved in the control of brain functions and previous studies realized in our laboratory have recently reported that acute administration of Arg decreases the NTPDase and 5'-nucleotidase activities of rat blood serum, in the present study we investigated the effect of arginine administration on NTPDase and 5'-nucleotidase activities by synaptosomes from hippocampus of rats. First, sixty-days-old rats were treated with a single or a triple intraperitoneal injection of arginine (0.8 g/Kg) or an equivalent volume of 0.9% saline solution (control) and were killed 1 h later. Second, rats received an intracerebroventricular injection of 1.5 mM arginine solution or saline (5 microL) and were killed 1 h later. We also tested the in vitro effect of arginine (0.1-1.5 mM) on nucleotide hydrolysis in synaptosomes from rat hippocampus. Results showed that intraperitoneal arginine administration did not alter nucleotide hydrolysis. On the other hand, arginine administered intracerebroventricularly reduced ATP (32%), ADP (30%) and AMP (21%) hydrolysis, respectively. In addition, arginine added to the incubation medium, provoked a decrease on ATP (19%), ADP (17%) and AMP (23%) hydrolysis, respectively. Furthermore, kinetic studies showed that the inhibitory effect of arginine was uncompetitive in relation to ATP, ADP and AMP. In conclusion, according to our results it seems reasonable to postulate that arginine alters the cascade involved in the extracellular degradation of ATP to adenosine.

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Section: Introductionmentioning

confidence: 99%

NTPDase and 5′-nucleotidase Activities of Synaptosomes from Hippocampus of Rats Subjected to Hyperargininemia

et al. 2007

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NTPDase and 5'‐nucleotidase activities in physiological and disease conditions: New perspectives for human health

et al. 2007

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Abstract. Extracellular nucleotides and nucleosides act as signaling molecules involved in a wide spectrum of biological effects. Their levels are controlled by a complex cell surface-located group of enzymes called ectonucleotidases. There are four major families of ectonucleotidases, nucleoside triphosphate diphosphohydrolases (NTPDases/CD39), ectonucleotide pyrophosphatase/phosphodiesterases (E-NPPs), alkaline phosphatases and ecto-5'-nucleotidase. In the last few years, substantial progress has been made toward the molecular identification of members of the ectonucleotidase families and their enzyme structures and functions. In this review, there is an emphasis on the involvement of NTPDase and 5'-nucleotidase activities in disease processes in several tissues and cell types. Brief background information is given about the general characteristics of these enzymes, followed by a discussion of their roles in thromboregulatory events in diabetes, hypertension, hypercholesterolemia and cancer, as well as in pathological conditions where platelets are less responsive, such as in chronic renal failure. In addition, immunomodulation and cell-cell interactions involving these enzymes are considered, as well as ATP and ADP hydrolysis under different clinical conditions related with alterations in the immune system, such as acute lymphoblastic leukemia (ALL), Bchronic lymphocytic leukemia (B-CLL) and infections associated with human immunodeficiency virus (HIV). Finally, changes in ATP, ADP and AMP hydrolysis induced by inborn errors of metabolism, seizures and epilepsy are discussed in order to highlight the importance of these enzymes in the control of neuronal activity in pathological conditions. Despite advances made toward understanding the molecular structure of ectonucleotidases, much more investigation will be necessary to entirely grasp their role in physiological and pathological conditions.

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Proline induces alterations in nucleotide hydrolysis in rat blood serum

2006

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The main objective of the present study was to evaluate the in vivo (acute and chronic) and in vitro effects of proline on serum nucleotide hydrolysis. For acute administration, 29-day-old rats received one subcutaneous injection of proline (18.2 (micromol/g body weight) or an equivalent volume of 0.9% saline solution (control) and were sacrificed 1 h, 3 h or 12 h later. Results showed that acute proline administration provoked a decrease in ATP (42%) and ADP (49%) hydrolysis when rats were sacrificed 1 h after the injection. Furthermore, in rats killed 3 h and 12 h after acute injection, no change in nucleotide hydrolysis were observed. For chronic treatment, buffered proline was injected subcutaneously twice a day at 10 h intervals from the 6(th) to the 28(th) day of age. Rats were sacrificed 3 h or 12 h after the last injection. Chronic administration of proline did not alter the nucleotide hydrolysis when the rats were killed 12 h after the last injection, but decreased ATP (15%) and ADP (32%) hydrolysis when rats were sacrificed 3 h after the last injection. The in vitro effect of proline (3.0 microM - 1.0 mM) on serum nucleotide hydrolysis was also investigated; results showed that 1.0 mM of proline significantly increased ATP (45%), ADP (55%) and AMP (49%) hydrolysis. The data indicate that proline in vivo and in vitro alters nucleotide hydrolysis, which may be involved in the pathogeny of hyperprolinemic patients.

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NTPDase and 5′-Nucleotidase Activities in Synaptosomes of Hippocampus and Serum of Rats Subjected to Homocysteine Administration

Cited by 6 publications

References 33 publications

NTPDase and 5′-nucleotidase Activities of Synaptosomes from Hippocampus of Rats Subjected to Hyperargininemia

NTPDase and 5′-nucleotidase Activities of Synaptosomes from Hippocampus of Rats Subjected to Hyperargininemia

NTPDase and 5'‐nucleotidase activities in physiological and disease conditions: New perspectives for human health

Proline induces alterations in nucleotide hydrolysis in rat blood serum

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