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Freund's adjuvant induced polyarthritis in rats has been used extensively to study pain processes of long duration. There are limitations of this model for chronic studies of pain/arthritis since the severe systemic changes provoke ethical concerns and also affect behaviour, physiology and biochemistry. Attempts to limit adjuvant-induced arthritis by(More)
Age-related changes in the content of dopamine (DA), homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in anterior cerebral cortex, hippocampus and striatum of the rat have been investigated using HPLC with electrochemical detection. A significant decrease in HVA(More)
Tricyclic antidepressants (TCAs) are used extensively to treat chronic pain in man without an adequate explanation for their activity. The purpose of the present study was to investigate this problem by testing the effect of chronic TCAs in an animal pain model: the arthritic rat. Sprague-Dawley rats with adjuvant-induced arthritis were injected daily for 4(More)
Several studies have demonstrated that a descending dopaminergic pathway innervates the dorsal and the intermediate gray matter of the spinal cord and have suggested that this pathway is involved in pain modulation and in the control of autonomic functions. Other studies have also demonstrated the presence of dopamine (DA) and DA metabolites as well as of(More)
The purpose of this study was to investigate modifications of 5-HT synthesis in a chronic pain model, the arthritic rat, at different times after the inoculation with Freund's adjuvant. This study confirms our previous findings that experimental induced polyarthritis is associated with a marked increase in free tryptophan levels in serum. During the acute(More)
The effects of morphine (10 mg/kg/s.c.) on tryptophan (TRP), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels were studied in normal and arthritic rats. (1) In normal rats morphine induced a discrete but significant increase of 5-HIAA levels in the forebrain and the spinal cord. (2) By contrast, in rats suffering from experimentally(More)
The effects of a nociceptive peripheral stimulus and/or morphine upon endogenous tryptophan levels (TRP), specific activity of tryptophan (S.A. of TRP) and serotonin (5-HT) synthesis in the dorsal and ventral spinal cord, the brainstem and the forebrain were investigated in anaesthetized rats. Whereas endogenous TRP and S.A. of TRP were not found to be(More)
Age-related changes in the levels of dopamine (DA) and its metabolites were measured in seven cerebral cortical areas and in the striatum of 3, 10 and 27 month-old Sprague-Dawley rats. An age-related increase in DA levels was observed in the somatomotor (SM) cortex. In contrast, a decrease was observed in the temporal (T) cortex. Decreases in homovanillic(More)
In a chronic pain model, the arthritic rat, tricyclic antidepressants (TCAs) have been shown to clearly reduce behavioural signs of nociception. In the present work, using a test of acute nociception (vocalization threshold to graded foot pressure) in the same model, we evaluated the possible potentiation of morphine analgesia by 2 TCAs: amitriptyline(More)
The purpose of the present study was to investigate whether the level of norepinephrine and its rate of disappearance after decarboxylase inhibition were modified in the spinal cord of a chronic pain model: the arthritic rat. Chromatographic studies allowing the simultaneous determination of norepinephrine and uric acid by means of HPLC with electrochemical(More)