This study examined the effects of two chronic stress regimens upon depressive-like behavior, A(1) and A(2A) adenosine receptor binding and immunocontent. Male rats were subjected to unpredictable chronic mild stress (UCMS) or to chronic restraint stress (CRS) for 40 days. Subsequently, depressive-like behaviors (forced swimming and consumption of sucrose) were evaluated, and A(1) adenosine or A(2A) adenosine receptors were examined in the hippocampus or striatum, respectively.
View Article and Find Full Text PDFNeurochem Res
May 2011
This study was undertaken to evaluate the effects of chronic variate stress and lithium treatment on glutamatergic activity and neuronal vulnerability of rat hippocampus. Male Wistar rats were simultaneously treated with lithium and submitted to a chronic variate stress protocol during 40 days, and afterwards the hippocampal glutamatergic uptake and release, measured in slices and synaptosomes, were evaluated. We observed an increased synaptosomal [(3)H]glutamate uptake and an increase in [(3)H]glutamate stimulated release in hippocampus of lithium-treated rats.
View Article and Find Full Text PDFIn this study, we examined the effects of two chronic stress regimens upon anxiety-like behavior, Na(+), K(+)-ATPase activity and immunocontent, and oxidative stress parameters (antioxidant enzymes and reactive oxygen species production) in the amygdala. Male rats were subjected to chronic unpredictable and to chronic restraint stress for 40 days. Subsequently, anxiety-like behavior was examined.
View Article and Find Full Text PDFPrevious studies have shown sex-specific oxidative changes in spinal cord of rats submitted to chronic stress, which may be due to gonadal hormones. Here, we assessed total radical-trapping potential (TRAP), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and lipid peroxidation (evaluated by the TBARS test) in the spinal cord of ovariectomized (OVX) female rats. Female rats were subjected to OVX, and half of the animals received estradiol replacement.
View Article and Find Full Text PDFPharmacol Biochem Behav
November 2009
Caffeine is widely consumed in beverages and food, and its consumption in high doses is associated with anxiety increase. Stress situations are often associated to coffee consumption, and have a strong influence on oxidative DNA damage. As there are sex-specific differences in many metabolic, neurochemical and behavioral aspects, the aim of this study is to verify the interaction between chronic consumption of caffeine and chronic stress on anxiety and DNA breaks in the hippocampus on male and female rats.
View Article and Find Full Text PDFGlutamate is an excitatory neurotransmitter involved in neuronal plasticity and neurotoxicity. Chronic stress produces several physiological changes on the spinal cord, many of them presenting sex-specific differences, which probably involve glutamatergic system alterations. The aim of the present study was to verify possible effects of exposure to chronic restraint stress and 17beta-estradiol replacement on [3H]-glutamate release and uptake in spinal cord synaptosomes of ovariectomized (OVX) rats.
View Article and Find Full Text PDFThis study was undertaken to verify if repeated long-term separation from dams would affect the development of parameters related to post-traumatic stress disorder (PTSD) after animals are subjected to inescapable shock when adults. Wistar rats were subjected to repeated maternal separation during post-natal days 1-10. When adults, rats from both sexes were submitted to a PTSD model consisting of exposure to inescapable footshock, followed by situational reminders.
View Article and Find Full Text PDFThis study evaluated the effects of chronic stress and lithium treatments on oxidative stress parameters in hippocampus, hypothalamus, and frontal cortex. Adult male Wistar rats were divided into two groups: control and submitted to chronic variate stress, and subdivided into treated or not with LiCl. After 40 days, rats were killed, and lipoperoxidation, production free radicals, total antioxidant reactivity (TAR) levels, and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were evaluated.
View Article and Find Full Text PDFNeurobiol Learn Mem
September 2005
This study was undertaken to verify the effects of chronic stress and lithium treatments on the hippocampal Na+,K(+)-ATPase activity of rats, as well as to investigate the effects of stress interruption and post-stress lithium treatment on this enzyme activity and on spatial memory. Two experiments were carried out; in the first experiment, adult male Wistar rats were divided into two groups: control and submitted to a chronic variate stress paradigm, and subdivided into treated or not with LiCl. After 40 days of treatment, rats were killed, and Na+,K(+)-ATPase activity was determined.
View Article and Find Full Text PDFIt has been reported that animals submitted to repeated restraint stress present various adaptation responses which are dependent on the sex. These adaptations include changes in nociception and adenine nucleotide hydrolysis. In this study, we report the effect of chronic administration of a gonadal steroid (17beta-estradiol) on ATP, ADP and AMP hydrolysis in spinal cord synaptosomes of adult ovariectomized (OVX) Wistar rats submitted to repeated restraint stress over 40 days.
View Article and Find Full Text PDFSeveral studies have shown that high corticosteroid hormone levels increase neuronal vulnerability. Here we evaluate the consequences of in vivo acute or repeated restraint stress on cellular viability in rat hippocampal slices suffering an in vitro model of ischemia. Cellular injury was quantified by measuring lactate dehydrogenase (LDH) and neuron-specific enolase released into the medium.
View Article and Find Full Text PDFDifferent effects of exposure to acute or to repeated stress have been observed upon the nociceptive response in rats. In the present study, we repeatedly submitted Wistar rats to restraint for 40 days, a treatment known to induce an increase in the nociceptive response in the tail-flick test. Afterwards, the effect of repeated restraint stress on the density of opioid receptors in rat spinal cord, frontal cortex, and hippocampus was investigated.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
January 2005
Changes in transport, receptors and production of extracellular adenosine have been observed after induction of hyperthyroidism. Adenosine is associated with inhibitory actions such as reduction in release of excitatory neurotransmitters and antinociception at spinal site. In contrast, ATP acts as an excitatory neurotransmitter and produces pronociceptive actions.
View Article and Find Full Text PDFNeurochemical gender-specific effects have been observed following chronic stress. The aim of this study was to verify the effects of chronic variable stress on free radical production (evaluated by DCF test), lipoperoxidation (evaluated by TBARS levels), and total antioxidant reactivity (TAR) in three distinct structures of brain: hippocampus, cerebral cortex and hypothalamus of female rats, and to evaluate whether the replacement with estradiol in female rats exerts neuroprotection against oxidative stress. Results demonstrate that chronic stress had a structure-specific effect upon lipid peroxidation, since TBARS increased in hypothalamus homogenates of stressed animals, without alterations in the other structures analyzed.
View Article and Find Full Text PDFHyperactivity of the stress response has long been recognized as maladaptive. The hippocampus, a brain structure important in mediating this response, is known to be affected by chronic stress, a situation reported to induce changes in adenine nucleotide hydrolysis in the rat. The enzymes catalyzing the hydrolysis of ATP to adenosine in the synaptic cleft are thought to have a role in modulating and controlling synaptic transmission.
View Article and Find Full Text PDFStress responses cover a wide range of physiological changes, including alterations in the perception of and response to pain. Animals submitted to repeated stress present altered nociception and this effect is part of this process of adaptation; in addition pleasant and unpleasant experiences with tastes and odors have been shown to affect distinct behavioral aspects, such as pain perception. The aim of the present study is to verify the responses of repeatedly stressed rats (1 h of daily immobilization during 40 days) to pleasant and unpleasant tastes on nociception, when compared to control animals.
View Article and Find Full Text PDFHyperalgesia and altered activities of enzymes involved in nucleotide hydrolysis are observed after exposure to repeated restraint in rats. Here, we investigated the effect of an adenosine A(1) receptor agonist, N(6)-cyclopentyladenosine (CPA, 3.35 mg/kg, i.
View Article and Find Full Text PDFAlterations of enzyme activities involved in adenine nucleotide hydrolysis have been reported in spinal cord and blood serum after repeated restraint stress. On the other hand, no effect was observed in the spinal cord of rats after acute stress. In the present study, we investigated the effect of acute stress on the hydrolysis of adenine nucleotides in rat blood serum.
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