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Results for “Indophenol”

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At least 775 records · Page 43Linked to original sources
PubMed2003

Brain region-specific alterations of 5-HT2A and 5-HT2C receptors in serotonin transporter knockout mice.

The aim of the present studies was to determine the effects of reduced or absent serotonin (5-HT) transporters (5-HTTs) on 5-HT2A and 5-HT2C receptors. The density of 5-HT2C receptors was significantly increased in the amygdala and choroid plexus of 5-HTT knockout mice. On the other hand, the density of 5-HT2A receptors was significantly increased in the hypothalamus and septum, but reduced in the striatum, of 5-HTT knockout mice. However, 5-HT2A mRNA was not changed in any brain region measured. 5-HT2C mRNA was significantly reduced in the choroid plexus and lateral habenula nucleus of these mice. The function of 5-HT2A receptors was evaluated by hormonal responses to (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Oxytocin, but not adrenocorticotrophic hormone or corticosterone, responses to DOI were significantly greater in 5-HTT knockout mice. In addition, Gq and G11 proteins were not significantly changed in any brain region measured. The present results suggest that the constitutive alteration in the function of 5-HTTs changes the density of 5-HT2A and 5-HT2C receptors in a brain region-specific manner. These changes may not be mediated by alterations in their gene expression or in the level of Gq/11 proteins. The alterations in these receptors may be related to the altered behaviors of 5-HTT knockout mice.

Animals↗
PubMedDate not supplied

Interactive effects of cholecystokinin-8S and various serotonin receptor agonists on the firing activity of neostriatal neuronesin rats.

In rats anaesthetized with urethane single unit activity was extracellularly recorded in the neostriatum, and several drugs were microiontophoretically ejected. Separate administration of the sulfated octapeptide cholecystokinin (CCK-8S), serotonin (5-HT) or 8-OH-DPAT (a 5-HT(1A/7) receptor agonist) predominantly induced increases in the neuronal discharge rates (Wilcoxon test significant P<0.05), whereas the 5-HT(2A/2C) receptor agonist DOI affected only a few neurones and mainly reduced firing. After coadministration of CCK-8S and serotonin, activating effects also predominated (Wt P<0.05), but the neuronal responsiveness was significantly reduced (Chi2P<0.01). Similarly, concomitant application of CCK-8S and 8-OH-DPAT led to significant activation accompanied with a reduction of inhibitory effects. The block of serotonin- or 8-OH-DPAT-effects through specific 5-HT(1A) receptor antagonists implies the involvement of this receptor subtype within the striatum. In conclusion, concomitant action of CCK-8S and serotonin induces a mean level of neuronal activation that might promote normal function.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2003

Sub-chronic treatment effects of an extract of Hypericum perforatum (St. John's Wort, Li 160) on neuroendocrine responses to the 5-T2A agonist, DOI in the rat.

Clinical studies have demonstrated the antidepressant efficacy of LI 160 extracts, which is comparable to antidepressants such as imipramine. The study was undertaken to assess the sub-chronic effects of LI 160 extract on plasma corticosterone and prolactin (PRL) responses to the post-synaptic 5-HT 2A receptor agonist, 2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI), in the male rat. Results show that sub-chronic treatment with the LI 160 extract reduced corticosterone and PRL responses to DOI. LI 160 may modify brain 5-HT function in the rat, possibly by reducing the sensitivity of central 5-HT 2A receptors. This may be a result of decreased receptor expression, signal transduction or intracellular messengers. These findings could be relevant to the therapeutic efficacy of St. John's Wort.

Animals↗
PubMed2003

In vivo modulation of the activity of pyramidal neurons in the rat medial prefrontal cortex by 5-HT2A receptors: relationship to thalamocortical afferents.

The activation of 5-HT(2A) receptors in medial prefrontal cortex (mPFC) by the hallucinogen DOI increases the firing activity of dorsal raphe (DR) 5-HT neurons and prefrontal 5-HT release. Here we show that the i.v. administration of DOI markedly affected the firing rate of identified pyramidal neurons recorded extracellularly. DOI excited (481%) 21/56 neurons, inhibited (11%) 17/56 neurons and left the rest unaffected (overall 2.4-fold increase in firing rate). Both effects were antagonized by 5-HT(2A) receptor blockade. 5-HT(2A)-mediated orthodromic excitations were recorded in pyramidal neurons projecting to DR after electrical stimulation of this nucleus. We also examined whether the effects of DOI in mPFC involve thalamic excitatory inputs. The disinhibition of the mediodorsal and centromedial nuclei of the thalamus by local bicuculline resembled the effects of DOI as it increased pyramidal cell firing and 5-HT release in mPFC. However, the selective activation of prefrontal micro -opioid and mGlu II receptors counteracted the effects of the thalamic disinhibition but not those of DOI. Moreover, extensive thalamic lesions did not alter the effect of DOI on pyramidal cell firing and 5-HT release. We conclude that DOI increases the activity of the mPFC-DR circuit by an action on postsynaptic 5-HT(2A) receptors unrelated to thalamocortical afferents.

Action Potentials↗
PubMed1986

2,6-Dichlorophenolindophenol-reducing activity of phagocytosis-associated NADPH oxidase.

The 2,6-dichlorophenolindophenol (DCIP)-reducing activity of the phagocytosis-associated NADPH oxidase was investigated using homogenates and a membrane fraction (F2) of elicited guinea pig peritoneal macrophages stimulated by phorbol myristate acetate. Essentially all of the stimulation-specific DCIP reduction under aerobic conditions could be inhibited when high concentrations of superoxide dismutase (SOD), about 10 times those usually used to inhibit the superoxide (O-2)-mediated cytochrome c reduction, were used. SOD inhibited the DCIP reduction by chemically generated O2- in the same manner as the stimulation-specific DCIP reduction by the macrophage F2, and the concentration of SOD necessary for 50% inhibition was about 10 times that for the reduction of cytochrome c. Under anaerobic conditions, however, the NADPH oxidase could reduce DCIP, though the rate was slow because we could not use a sufficiently high DCIP concentration. The observations indicate that the NADPH oxidase preferentially reduces oxygen under aerobic conditions, though the oxidase can reduce DCIP in the anaerobic state.

2,6-Dichloroindophenol↗
PubMed1999

Cardiovascular responses produced by microinjection of serotonin-receptor agonists into the paraventricular nucleus in conscious rats.

Activation of serotonin (5-hydroxytryptamine, 5-HT) receptors in the brain produces cardiovascular responses by altering autonomic outflow. The paraventricular nucleus (PVN) contains a modest density of 5-HT receptors and has connections to autonomic centers. Experiments were designed to determine whether cardiovascular responses were produced by the administration of 5-HT2- and 5-HT1A-receptor agonists into the PVN of conscious rats. The microinjection of the 5-HT2-receptor agonist DOI [(+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl] into the PVN produced dose-dependent (1-10 nmol) increases in heart rate and blood pressure; the peak responses were +39 +/- 10 beats/min and +6 +/- 2 mm Hg, respectively. Both responses were blocked by the concomitant administration of the selective 5-HT2-receptor antagonist LY53857 into the PVN. By contrast, the microinjection of the selective 5-HT1A-receptor agonist R(+)-8-OH-DPAT [R(+)8-hydroxy-2-(di-n-propylamino) tetralin HBr; 1-10 nmol] into the PVN did not affect blood pressure or heart rate. These data suggest that 5-HT neurons projecting from the raphe nuclei to or near the PVN can participate in the central control of the cardiovascular system by way of 5-HT2 receptors. Apparently 5-HT neurons terminating in the PVN can increase blood pressure and heart rate and produce sympathoadrenal activation, metabolic and hormonal responses consistent with those observed in several different stress paradigms.

8-Hydroxy-2-(di-n-propylamino)tetralin↗