Search results for "dopamine agonists"
showing 10 items of 40 documents
Serotonin-dopamine interaction: electrophysiological evidence.
2008
In this review, the most relevant data regarding serotonin (5-hydroxytryptamine, 5-HT)/dopamine (DA) interaction in the brain, as studied by both in vivo and in vitro electrophysiological methods, are reported and discussed. The bulk of neuroanatomical data available clearly indicate that DA-containing neurons in the brain receive a prominent innervation from 5-HT originating in the raphe nuclei of the brainstem. Furthermore, this modulation seems to be reciprocal; DA neurons innervate the raphe nuclei and exert a tonic excitatory effect on them. Compelling electrophysiological data show that 5-HT can exert complex effects on the electrical activity of midbrain DA neurons mediated by the va…
Physiology and Pathology of Ovarian Hyperstimulation Syndrome
2010
Ovarian hyperstimulation syndrome (OHSS) occurs when ovaries primed with follicle-stimulating hormone/leuteinizing hormone (LH) are subsequently exposed to human chorionic gonadotropin (hCG). The ultimate pathophysiological step underlying this clinical picture is increased vascular permeability (VP). With the administration of hCG, the expression vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR-2) mRNA increases significantly rising to a maximum coinciding with peaked VP. Immunohistochemistry shows the presence of VEGF and VEGFR-2 proteins in the granulosa-lutein and endothelial cells of the entire corpus luteum. These findings suggest that the syndrome can be prevented…
Dopamine agonist administration causes a reduction in endometrial implants through modulation of angiogenesis in experimentally induced endometriosis
2009
Survival of newly implanted retrograde-shed endometrial tissue during menstruation in an ectopic location requires an adequate blood supply. This suggests that angiogenesis is a prerequisite for the development of endometriosis and that its inhibition may be a target for preventing development. Previous studies have shown that vascular endothelial growth factor (VEGF), a heparin-binding glycoprotein, has an essential role in angiogenesis. The main regulatory factor for angiogenesis appears to be binding of VEGF to its type-2 receptor (VEGFR-2). Cabergoline (Cb2) and other dopamine agonists promote endocytosis of the VEGF receptor-2 (VEGFR-2) in endothelial cells, thereby preventing VEGF-VEG…
Targeting the vascular endothelial growth factor system to prevent ovarian hyperstimulation syndrome
2008
BACKGROUND: Ovarian hyperstimulation syndrome (OHSS) typically occurs when ovaries are primed with FSH/ LH and subsequently exposed to hCG. The ultimate pathophysiological step underlying this clinical picture is increased vascular permeability (VP). METHODS: A search of the literature was carried out using PubMed and the authors’ files. RESULTS: In rodents and humans, the expression of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR-2) mRNA increases during ovarian stimulation. With the administration of hCG, the expression of each rises to a maximum. Expression of VEGF/VEGFR-2 mRNAs correlates with enhanced VP, with both peaking 48 h following an injection of hCG. Imm…
Practical importance of neuroprotection in Parkinson's disease.
2003
Consensus could be reached that there is overwhelming evidence of preclinical neuroprotection. However, the evidence of neuroprotection/neurorescue under clinical conditions is limited. Lessons from clinical trials designed to show neuroprotection (selegiline, amantadine, dopamine agonists) demonstrate that with the drugs available neuroprotection/neurorescue has to start as early as possible. A PET-controlled clinical trial with ropinirole shows that there seems to be a good chance for neuroprotection in the early phase of Parkinson's disease in patients treated from the very beginning of the disease while there is no such benefit in patients with a late start of a neuroprotective therapeu…
Effects of dopamine in isolated rat colon strips.
2005
The aim of the present work is to investigate the effects of dopamine on isolated rat colon strips, and whether dopamine receptors are involved in these effects. Experiments on spontaneous motility and under potassium contraction were performed with dopamine and isoprenaline, both in the absence and presence of antagonists (distal colon strips, isotonic recording, Tyrode solution, 31 °C, 1 g of resting tension). At higher concentration (10–4mol/L), dopamine abolished spontaneous motility of the rat colon and this effect was not modified by antagonists. In isolated rat colon strips that were depolarized with potassium, dopamine produced concentration-dependent relaxation, without significant…
Impact of serotonin 2C receptor null mutation on physiology and behavior associated with nigrostriatal dopamine pathway function.
2009
The impact of serotonergic neurotransmission on brain dopaminergic pathways has substantial relevance to many neuropsychiatric disorders. A particularly prominent role has been ascribed to the inhibitory effects of serotonin 2C receptor (5-HT2CR) activation on physiology and behavior mediated by the mesolimbic dopaminergic pathway, particularly in the terminal region of the nucleus accumbens. The influence of this receptor subtype on functions mediated by the nigrostriatal dopaminergic pathway is less clear. Here we report that a null mutation eliminating expression of 5-HT2CRs produces marked alterations in the activity and functional output of this pathway. 5-HT2CR mutant mice displayed i…
Dopamine agonists in schizophrenia: a review.
1995
Although it is unlikely that the different types of course and severity of schizophrenia are caused by one neurochemical abnormality alone, indirect pharmacological evidence still suggests a relative excess of dopaminergic activity being implicated in the pathogenesis of most of the schizophrenic symptoms, e.g. positive symptomatology. Synthesis and release of dopamine as well as firing rates of dopaminergic neurons are controlled by stimulation of autoreceptors via a negative feedback regulation. Investigations on therapeutic effects of autoreceptor-nonselective dopamine agonists in schizophrenia have yielded inconsistent results. Dopamine autoreceptor agonists like pramipexole, roxindole,…
Prevention of OHSS: Current strategies and new insights
2010
Abstract Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic and potentially life threatening condition that affects young healthy patients. Many strategies have been proposed to prevent this syndrome. However, to avoid OHSS without compromising on IVF outcome is still a challenge. The most important action is to identify patients at risk even before ovarian stimulation is initiated and to give them special attention. Coasting is the most popular method to avoid/minimize OHSS. Cycle cancellation, cryopreservation, GnRH antagonists, GnRH agonists, i.v. albumin are other strategies that can provide some kind of benefit but do not completely avoid both early and late forms of OHSS and/or…
The Effects of Epinine on Arterial Blood Pressure and Regional Vascular Resistances in Anesthetized Rats
1998
1. We carried out experiments in anesthetized rats to study the hemodynamic effects of intravenous injections of epinine. 2. Epinine (1-320 micrograms/kg) produced a biphasic effect on mean arterial blood pressure (n = 30). At doses lower than 40 micrograms/kg, arterial blood pressure decreased (by as much as 21.5 +/- 3.4%), though at higher doses it increased dose dependently (by as much as 73.2 +/- 14.5%). Epinine also produced bradicardia in a dose-dependent manner (by as much as 26.4 +/- 4.9%). Sulpiride (100 micrograms/kg) suppressed the hypotensive effect of epinine but did not change the hypertensive effect. In the presence of prazosin (1,000 micrograms/kg), arterial blood pressure r…