Search results for "DOPAMINERGIC"
showing 10 items of 200 documents
Dopamine acting through D2 receptors modulates the expression of PSA-NCAM, a molecule related to neuronal structural plasticity, in the medial prefro…
2008
A "neuroplastic" hypothesis proposes that changes in neuronal structural plasticity may underlie the aetiology of depression and the action of antidepressants. The medial prefrontal cortex (mPFC) is affected by this disorder and shows an intense expression of the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), a plasticity-associated molecule, which is expressed mainly in interneurons. The monoamines serotonin, dopamine and noradrenaline are the principal targets of antidepressant action. Pharmacological manipulation of serotonin levels regulates synaptophysin and PSA-NCAM expression in the adult mPFC. However, the involvement of structural plasticity on the antidepress…
Opposite effects of γ1- and γ2-melanocyte stimulating hormone on regulation of the dopaminergic mesolimbic system in rats
2004
By use of the brain microdialysis technique we show that administration of gamma(1)-melanocyte stimulating hormone (gamma(1)-MSH) into the ventral tegmental area of anaesthetized rats causes an increase in the release of extracellular dopamine and its metabolite 3,4-dihydroxyphenylacetic acid in the nucleus accumbens, while gamma(2)-MSH causes the opposite effect. Moreover, gamma(2)-MSH pre-treatment considerably reduced the gamma(1)-MSH-induced effects. Our findings suggest an opposing action of two gamma-MSH-activated pathways on the mesolimbic dopaminergic system, which could be important in the maintenance of a balanced psychoactivation state.
Mesolimbic dopaminergic system activity as a function of food reward: A microdialysis study
1996
The mesolimbic dopaminergic system (MDS) has been shown to be implicated in feeding behaviors. The present experiment was conducted to examine the effects of the sensory properties of food ingested on MDS activity. Microdialysis coupled to high-performance liquid chromatography with electrochemical detection was employed to measure the extracellular levels of dopamine (DA) and its main metabolites (DOPAC and HVA) in the nucleus accumbens of freely moving rats. During microdialysis sessions rats had access or not to powdered foods varying in palatability: short cakes as highly palatable (HP) food and regular chow as low palatable (LP) food. In the absence of food, there were no alterations i…
Motor intracortical inhibition in PD: L-DOPA modulation of high-frequency rTMS effects
2007
Dopaminergic drugs and deep brain stimulation restore cortical inhibition in Parkinson disease (PD) patients. High-frequency rTMS was also found to increase cortical inhibition in PD but its therapeutic effect is still controversial. Here we hypothesize that, if dopaminergic drugs reverse to normal cortical excitability in M1, the effect of high-frequency (hf)-rTMS in PD patients could depend on whether they are in a medicated or unmedicated state. The present study aims to explore the lasting effects of sub-threshold hf rTMS trains over M1 on cortical inhibition in patients with "on" and without "off" L-DOPA treatment. Fourteen PD patients were examined twice while "on" and "off" medicatio…
Uptake of [3H]dopamine into dopaminergic and noradrenergic neurones of the isolated neurointermediate lobe of the rat hypophysis. Effects of desipram…
1983
The isolated neurointermediate lobe (NIL) of the rat hypophysis accumulates [3H]dopamine from the incubation medium. Column chromatographic analysis showed that 92% of the tissue radioactivity was contained in the catecholamine fraction. [3H]Dopamine represented 70% and [3H]noradrenaline 30% of the [3H]catecholamines. Desipramine (1 microM) prevented the formation of [3H]noradrenaline without affecting the storage of [3H]dopamine. Nomifensine (10 microM) blocked the storage of [3H]dopamine and [3H]noradrenaline. Thus, in the NIL, [3H]dopamine is taken up into dopaminergic and noradrenergic neurones. In the latter, [3H]dopamine is converted to [3H]noradrenaline, indicating a significant dopa…
Functional and neurochemical changes of the gastrointestinal tract in a rodent model of Parkinson's disease.
2009
Patients with Parkinson’s disease develop motor disturbances often accompanied by peripheral autonomic dysfunctions, including gastrointestinal disorders, such as dysphagia, gastric stasis and constipation. While the mechanisms subserving enteric autonomic dysfunctions are not clearly understood, they may involve the enteric dopaminergic and/or nitrergic systems. In the present study, we demonstrate that rats with unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons develop a marked inhibition of propulsive activity compared to sham-operated controls, as indicated by a 60% reduction of daily fecal output at the 4th week of observation. Immunohistochemical data revealed …
Elevation of striatal urate in experimental models of Parkinson's disease: a compensatory mechanism triggered by dopaminergic nigrostriatal degenerat…
2014
Epidemiological studies have indicated an inverse association between high uricemia and incidence of Parkinson's disease (PD). To investigate the link between endogenous urate and neurotoxic changes involving the dopaminergic nigrostriatal system, this study evaluated the modifications in the striatal urate levels in two models of PD. To this end, a partial dopaminergic degeneration was induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice, while a severe dopaminergic degeneration was elicited by unilateral medial forebrain bundle infusion of 6-hydroxydopamine (6-OHDA) in rats. Urate levels were measured by in vivo microdialysis at 7 or 14 days from toxin exposure. The resu…
Implications for Estrogens in Parkinson's Disease: An Epidemiological Approach
2007
Abstract: Evidence from experimental and epidemiological studies suggests a role of sex hormones in the pathogenic process leading to neurodegenerative diseases, (i.e., Alzheimer's and Parkinson's disease). The effects of sexual steroid hormones are complex and vary with the events of women's fertile life. Estrogens are supposed to influence dopamine synthesis, metabolism, and transport; however, there is no consensus regarding the direction, locus, and mechanism of the effect of estrogens on the dopaminergic system. A neuroprotective effect of estrogens has been demonstrated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-animal models of Parkinson's disease (PD). Epidemiological st…
Salivary and serum levels of substance p, neurokinin A and calcitonin gene related peptide in burning mouth syndrome
2009
Background: Burning mouth syndrome (BMS) is an enigmatic condition with the etiopathogenesis remaining largely obscure. However, a neuropathic basis for BMS continues to be an area of active clinical and research interest. Aim: It is becoming increasingly evident that certain oral disorders may be modulated by imbalances in certain neuropeptides such as substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) therefore we measured SP, NKA and CGRP in the saliva and sera of BMS patients as well as controls. Subjects and Methods: Salivary and serum SP, NKA and CGRP were determined in the 26 female patients with burning mouth syndrome (age range 51-78, mean 65.69 yrs), a…
Insulin and raclopride combine to decrease short-term intake of sucrose solutions.
2000
We have previously reported that the hormone insulin can modulate synaptic function of dopamine neurons. To evaluate whether insulin can alter performance of a task which is dependent on intact dopaminergic signaling, we tested rats in a five minute lick rate task, with a range of concentrations of sucrose or oil solutions. Rats received either ip (t -15 min) saline or the D2 receptor antagonist raclopride (50 microg/kg), and intraventricular (t -4 h) saline or insulin (5 mU). Although ineffective on its own, insulin combined with raclopride treatment resulted in significant suppression of sucrose lick rates compared to the saline/saline group. The overall results are consistent with our hy…