Effects of restraint stress on the daily rhythm of hydrolysis of adenine nucleotides in rat serum

Souza Andressa, Medeiros, Caumo Wolnei, Detanico, Rozisky, Hidalgo Maria, Battastini, Torres

Description

Adenosine 5-triphosphate (ATP) and its breakdown products ADP and adenosine can act as extracellular messengers in a range of biological processes. Extracellular adenine nucleotides are metabolized by a number of enzymes including NTPDases and 5'-nucleotidase, which are considered to be the major regulators of purinergic signaling in the blood. Previous work by our group demonstrated that ATPase and ADPase activities in rat serum exhibit a 24-h temporal pattern, with higher enzyme activity during the dark (activity) phase. It was found that stress can cause disruptions in biological circadian rhythms and in the cardiovascular system. Therefore, the aim of the present study was to examine the influence of acute stress exposure upon temporal patterns of NTPDase and 5-nucleotidase enzyme activities in rat blood serum. Methods Adult male Wistar rats were divided into 4 groups: ZT0, ZT6, ZT12 and ZT18. Each group was subdivided in 4 groups: control, immediately, 6 h and 24 h after one hour of restraint stress. ATP, ADP and AMP hydrolysis were assayed in the serum. Results All stressed groups showed significant decreases in all enzyme activities at ZT 12 and ZT 18 when compared with control. Conclusion Acute stress provokes a decrease in nucleotidase activities dependent on the time that this stress occurs and this effect appears to persist for at least 24 hours. Stress can change levels of nucleotides, related to increased frequency of cardiovascular events during the activity phase. Altered levels of nucleotides in serum may be involved in cardiovascular events more frequent during the activity phase in mammals, and with their etiology linked to stress.

Sujets

• Circadian rhythm
• RATS

Informations

• Publié par: biomed
• Publié le: 01 janvier 2011
• Nombre de lectures: 13
• Langue: English

Extrait

Souzaet al.Journal of Circadian Rhythms2011,9:7 http://www.jcircadianrhythms.com/content/9/1/7

R E S E A R C HOpen Access Effects of restraint stress on the daily rhythm of hydrolysis of adenine nucleotides in rat serum 1,3,4†1,3,4†1 1,31,3,4 Andressa Souza, Bernardo C Detanico, Liciane F Medeiros , Joanna R Rozisky, Wolnei Caumo, 3,4 2,31,3,4* Maria Paz L Hidalgo, Ana Maria O Battastiniand Iraci LS Torres

Abstract Background:Adenosine 5triphosphate (ATP) and its breakdown products ADP and adenosine can act as extracellular messengers in a range of biological processes. Extracellular adenine nucleotides are metabolized by a number of enzymes including NTPDases and 5’nucleotidase, which are considered to be the major regulators of purinergic signaling in the blood. Previous work by our group demonstrated that ATPase and ADPase activities in rat serum exhibit a 24h temporal pattern, with higher enzyme activity during the dark (activity) phase. It was found that stress can cause disruptions in biological circadian rhythms and in the cardiovascular system. Therefore, the aim of the present study was to examine the influence of acute stress exposure upon temporal patterns of NTPDase and 5nucleotidase enzyme activities in rat blood serum. Methods:Adult male Wistar rats were divided into 4 groups: ZT0, ZT6, ZT12 and ZT18. Each group was subdivided in 4 groups: control, immediately, 6 h and 24 h after one hour of restraint stress. ATP, ADP and AMP hydrolysis were assayed in the serum. Results:All stressed groups showed significant decreases in all enzyme activities at ZT 12 and ZT 18 when compared with control. Conclusion:Acute stress provokes a decrease in nucleotidase activities dependent on the time that this stress occurs and this effect appears to persist for at least 24 hours. Stress can change levels of nucleotides, related to increased frequency of cardiovascular events during the activity phase. Altered levels of nucleotides in serum may be involved in cardiovascular events more frequent during the activity phase in mammals, and with their etiology linked to stress. Keywords:Adenine nucleotides hydrolysis, Circadian rhythm, Rats, Restraint stress, Temporal pattern

Background Extracellular adenosine 5’triphosphate (ATP) and its breakdown products, adenosine 5’diphosphate (ADP), adenosine 5’monophosphate (AMP) and adenosine, can act as extracellular messengers in a range of biological processes through binding to purinergic receptors. In addition, they have been shown to have pronounced effects on a variety of biological processes such as neuro transmission, regulation of cardiac function and platelet aggregation [1], as well as pathological events including

* Correspondence: [e-mail] †Contributed equally 1 Laboratório de Cronobiologia Experimental, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 90050170, Brazil Full list of author information is available at the end of the article

neurodegenerative and cardiovascular diseases [2]. ATP can be released via stimulation of sympathetic nerves [3] promoting vasoconstriction or vasodilatation, and contri butes to platelet aggregation [4]. Additionally, its break down produces the nucleotide diphosphate (ADP), which is the most important platelet aggregator and also pro motes vasoconstriction [5]. The nucleoside adenosine, also generated by ATP breakdown, is able to act as a vasodilator, inhibitor of platelet aggregation, and it may act as an endogenous cardioprotective substance [4]. Extracellular nucleotides can be hydrolyzed by a variety of enzymes that are located on the surface of cells, or by soluble forms in the interstitial medium or within body fluids [6]. Nucleoside 5’tri and diphosphates (NTP and NDP) may be hydrolyzed by the nucleoside triphosphate

© 2011 Souza et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.